Q - 11th International Conference
Medical Applications of Novel Biomaterials and Nanotechnology
Session Q-1 - Advances in Stimuli Responsive, Active and Multi-functional Biomaterials
Q-1:IL01 Biodegradable Thermoplastic Elastomeric Composites
P.T. MATHER, E. MCMULLIN, J.M. ROBERTSON, P.A. FALCONE, Syracuse Biomaterials Institute and Biomedical and Chemical Engineering Department, Syracuse University, Syracuse, NY, USA
There is a need for biodegradable elastomers for use as implanted biomaterials as medical devices contacting soft tissue. Recently, we have been successful in developing biodegradble thermoplastic elastomers in neat and composite (blend) form with a combination of good elasticity and degradability. Here we present the design and synthesis of the biodegradable elastomer, which is a multiblock polyurethane constricted from uniquely designed soft segments and POSS-based hard segments. Here, POSS refers to the hybrid moiety, polyhedral oligomeric silsesquioxane. We present the structure property relations for this family of polymers, revealing the role of each block and principles governing the desired elasticity and degradation behavior. Seeking to further tune the properties, we have adopted dual electrospinning to blend the new biodegradable thermoplastic elastomers with other degradable polymers at the submicron scale. We will show how an additional phase added in this manner can be used to modulate properties with fine tuning. We will also discuss opportunities that dual spinning enables for the preparation of tubular elastomers with unique structure of us in a number of medical applications.
Q-1:IL02 Bioinspired and Multifunctional Phospholipid Polymer Nanoparticles
KAZUHIRO ISHIHARA, The University of Tokyo, Tokyo, Japan
The surface of the fluorescence nanoparticles decorated with cytocompatible and multifunctional phospholipid polymer was achieved. To obtain stable and highly sensitive bioimaging fluorescence probe, quantum dots (QDs) were embedded in the polymer nanoparticles. Semiconductor nanocrystal, QDs are promising alternative to organic fluorescence dyes for bioimaging. However, their use has been strongly limited by difficulties in obtaining biocompatibility of QDs. The QDs were covered with a well-known cytocompatible, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. The MPC polymer showed resistance to cellular uptake from HeLa cells owing to the nature of the phosphorylcholine groups. On the other hand, when an arginine octapeptide, which was one of the cell penetrating peptide, was immobilized at the surface of the nanoparticles, they could penetrate the membrane of HeLa cells effectively. Additionally, responsive function against the surrounding circumstances in the cell was introduced in the MPC polymer. Thus we obtained stable fluorescent polymer nanoparticles covered with artificial cell membrane, which are useful as an excellent probe evaluation for biomolecular function in the target cells. This research was supported by ‘‘Nanomedicine Molecular Science’’ from MEXT.
Q-1:IL04 Design of Biodegradable Injectable Polymer Systems Exhibiting Temperature-responsive Covalent Hydrogel Formation
YUICHI OHYA, YASUYUKI YOSHIDA, KEISUKE KAWAHARA, AKINORI KUZUYA, Department of Chemistry and Mterials Engineering, Kansai University, Suita, Osaka, Japan
Biodegradable polymers exhibiting temperature-responsive sol-gel transition between room temperature and body temperature are expected to be applied as injectable polymer (IP) systems in biomedical applications. IP solution containing drugs or living cells can be injected by simple syringe injection at the target site in the body to form a hydrogel acting as sustained drug releasing depots or scaffolds for tissue regeneration. Biodegradable IP systems using block copolymers of aliphatic polyesters and PEG were reported. However, such IP systems forming physically cross-linked hydrogel are likely to dissociate to sol state under highly wet condition such as intra-peritoneal space. To overcome the problems, we developed an injectable polymer formulation forming chemically cross-linked hydrogel in response to temperature change. We synthesized PCGA-PEG-PCGA triblock copolymer bearing succinimidyl groups on its termini. The copolymer was mixed with water-soluble polymers bearing amine groups such as polylysine. The mixture solution showed irreversible sol-gel transition and covalent bond formation in response to temperature. The obtained hydrogel soaked in PBS solution showed longer duration time as gel state.
Q-1:IL05 Multifunctional Organic Electronics for Cell Sensing and Manipulation
PEILIN CHEN, Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
An optically transparent poly(3,4-ethylenedioxythiophene) (PEDOT) based organic electronic devices have been developed to investigate the behavior of human mesenchymal stem cell (hMSC) and to sense and to capture circulating tumor cells. We first conducted a control experiment on electrical cell-substrate impedance sensing (ECIS) device by culturing the hMSC on the chip. According to our result, the impedance increased reflected the hMSC proliferation, attachment and motility during the first 16 hours of cell culture. In order to control the differentiation of human mesenchymal stem cell (hMSC) on chip, we also developed all-solution-processed multifunctional organic devices, comprising reduced graphene oxide (rGO) and dexamethasone 21-phosphate disodium salt (DEX) drug loaded poly(3,4-ethylenedioxythiophene) (PEDOT) microelectrode arrays on indium tin oxide glass, that can be used to manipulate differentiation. In our devices, the rGO micropatterns were used as the adhesive coating to attract the adhesion of hMSC cells whereas PLL-g-PEG coated PEDOT electrodes served as the anti-adhesive coating where no hMSC cells can attach. In addition, the PEDOT electrodes also work as drug releasing components where control DEX release from PEDOT matrix can be achieved.
Q-1:L06 Non-adhesive, Slippery, Antimicrobial Surfaces using Dynamic Surface Lubricant Layers
B.D. HATTON1, N. LAVIELLE2, D. ASKER1, 1University of Toronto, Toronto, ON, Canada; 2ESPCI ParisTech and Ecole Polytechnique, France
The interaction between bacteria and surfaces is complex and involves several mechanisms. Understanding these relationships is important due to the persistent problem of biomaterial infection rates (often hospital-acquired), and an increasing problem for antibiotic-resistant strains. The roles of surface micro-topographies and wettability have not been clearly identified, but they have promise as ‘physical’, non-specific methods to broadly prevent bacterial adhesion. Herein we show that non-wetting, superhydrophobic surfaces can be designed to prevent bacterial attachment when the surface features are less than the cell size (ie; 3 µm). Further, we have shown that surface microstructures can stabilize a thin lubricant layer, for non-adhesive ‘slippery liquid-infused porous surfaces’ (SLIPS). We have demonstrated the effectiveness of SLIPS surfaces to prevent bacterial adhesion and blood clotting. Recently we have developed a silicone-based SLIPS surface that can maintain a 100-200 nm PDMS liquid layer that can recover dynamically at the surface, and can be controlled by external stimuli as a smart, responsive non-adhesive surface. These SLIPS materials can maintain bacterial (CFU) counts at rates 10^3 to 10^4 lower than conventional PDMS, over 30 days.
Q-1:IL07 Nitric Oxide -A Key Player for Novel Anti-cancer Immuno-therapeutics-
YUKIO NAGASAKI, Department of Materials Science and Medical Sciences, Satellite Laboratory, International Center for Materials Nanoarchitectonics (WPI-MANA), University of Tsukuba, Japan
Nitric oxide (NO) is a free radical endogenously synthesized in the body and plays multiple physiological roles. We have hypothesized that site-specific accumulation of NO molecules controls tumor progression. Due to the poor bioavailability of NO, however, great efforts have been made to develop a methodology for the controlled delivery of exogenous NO in living systems. This study showed a new approach of NO-triggered cancer immunotherapy. Induced NO synthase (iNOS) in macrophages produces NO using arginine as substrate to induce apoptosis in tumors. We designed polyion complex micelles composed of PEG-block-poly(L-arginine) as one of component. Our idea was to cooperate our PIC nanoparticle and macrophage in tumor site to generate effective amount of NO. After phagocytosis of this nanoparticle by macrophages, it is confirmed that the cells significantly accelerated production of nitric oxide in vitro. This nanoparticle can be delivered into tumor tissue via systemic administration and confirmed to increase the anti-tumor activity. We believe that the PIC nanoparticle composed of poly(L-arginine) opens new strategy for cancer immunotherapy.
Q-1:IL08 Design of Nanogel Particles for Capture and/or Release of Target Molecules/Ions
YU HOSHINO, Kyushu University, Fukuoka, Japan
Synthetic nanogel particles (NPs) that recognize and neutralize specific molecules/ions have attracted attention. In this presentation, recent progress on the development of NPs with tailor-made affinity to target peptide, protein and ions will be presented. NPs that bind with target peptide/ions can be prepared by optimizing combination and proportion of functional monomers. The NPs with stronger affinity to target can further be prepared by molecular imprinting and/or affinity purification process. The NPs which bind strongly to target can be used as affinity ligands for protein purification and antidote for toxic peptides.
Q-1:L09 In Vitro Bioactivity Study of TiCaPCO(N) and Ag-doped TiCaPCO(N) Films in Simulated Body Fluid
E.V. LEVASHOV, D.V. SHTANSKY, I.V. SUKHORUKOVA, A.N. SHEVEYKO, Ph.V. KIRYUKHANTSEV-KORNEEV, E.I. ZAMULAEVA, National University of Science and Technology "MISIS", Moscow, Russia
Bioactivity of multicomponent TiCaPCO(N) and Ag-doped TiCaPCO(N) films was evaluated in vitro using simulated body fluid (SBF) and compared with that of bioactive glass Biogran. The first group of films was fabricated by magnetron sputtering of composite TiС0.5-Ti3POx-CaO target produced via the self-propagating high-temperature synthesis (SHS) method (TiCaPCON films), after which their surface was implanted with Ag+ ions to obtain Ag-doped TiCaPCON films. The second group of films was fabricated by pulsed electrospark deposition (PED) using SHS- composite TiС0.5-Ti3POx-CaO and TiС0.5-Ti3POx-CaO-Ag electrodes. After immersion in SBF, the structure and composition of surface were well characterized using a combination of various microanalytical techniques, such as SEM, XRD, Fourier transform infrared spectroscopy, Raman spectroscopy, and glow discharge optical emission spectroscopy. The results showed that the surfaces of the TiCaPCO(N) and Ag-doped TiCaPCO(N) films were bioactive in vitro and induced the formation of an apatite layer during exposure in SBF. In the case of the magnetron-sputtered films, the apatite layer was formed over 14 days, while 28 days were needed to form CaP phase on the surface of PED-modified samples. Coatings structure and properties were studied.
Session Q-2 - Multifunctional Materials in Tissue Engineering and Regenerative Medicine
Q-2:IL01 Engineering Anisotropy at Nano- to Macroscale: Towards Bioactive Biomaterials
S.SANT, Department of Pharmaceutical Sciences, Department of Bioengineering, McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA
Biological tissues/organs consist of hierarchical organization of various extracellular matrix (ECM) molecules with spatial arrangement of cells and soluble factors. Highly hydrated ECM molecules assemble to form fibrils, microfibrils that organize into regional tissue structures such as muscle fiber bundles or osteons, tightly adapted to the specific tissue functions. Along with such multiscale hierarchy, ECM, cells and tissues also exhibit peculiar directionality or anisotropicity, instrumental to their functionality. Thus, biophysical factors like multiscale hierarchy and anisotropicity are inherent to the efficient function of biological systems. Inspired by such biological principle of “Form follows Function”, and enabled by various micro/nanotechnologies, we strive to engineer bioactive multiscale materials with intricate structural features observed in nature. In this invited talk, I will highlight our recent efforts on engineering anisotropic nanoparticles for various drug/gene delivery and tissue engineering applications. In another example, I will also highlight how such anisotropy coupled with hierarchy can be exploited to engineer bioactive scaffolds without added growth factors, an important paradigm towards functional tissue engineering.
Q-2:L03 Robust Regenerative Engineering of the Shoulder
R. JAMES, C.T. LAURENCIN, Department of Orthopaedic Surgery and The Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, University of Connecticut Health Center, Farmington, CT, USA
Current strategies to address critical size defects, such as volumetric muscle loss and rotator cuff lacerations involve combinations of autograft or allograft, and augmentation to strengthen and support the injury. Regeneration, especially of multi-scale tissues such as the tendon and the muscle is challenging and necessary as these function as a cohesive unit to allow limb movement. Severe injuries cause significant loss of function and reduced quality of life. Our convergence efforts in the areas of science and engineering integrates the advances in tissue engineering, with advanced materials science, physics, developmental biology and stem cell science to create functional multi-tissue components. We have defined this field as ‘Regenerative Engineering’. We have developed biomaterials and biomimetic structures to function as stem cell niches, transmit physical forces and support tissue regeneration. Depending on material composition, the properties of the biomaterial platforms are robust. Nanoscale topography is paramount to realizing the regenerative potential, which includes controlling cell fate and maturation. The promise of this new polymeric matrix system is the modulation and control of cellular response, and the regeneration of complex soft musculoskeletal tissues.
Q-2:L04 Fabrication of Interconnected Porous Calcite from Calcium Sulfate and its Tissue Response
KUNIO ISHIKAWA, KANJI TSURU, Dept. of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
Calcite has attracted attention as bone substitutes as well as precursor for carbonate apatite which is also a promising bone substitutes. However, limited studies have been made so far for the fabrication of calcite block. In the present study, interconnected porous calcite was fabricated by the compositional transformation based on dissolution–precipitation reaction using an interconnected porous calcium sulfate anhydrous as a precursor. The porous calcium sulfate anhydrous was made by heating the mixture of gypsum and nylon cut fiber at 700°C and burned out the nylon fiber. Then, it was immersed in 2 mol/L Na2CO3 solution at room temperature for 1day. Although, no macroscopic change was observed, its composition transformed from calcium sulfate anhydrous to calcite. The interconnected porous calcite granules were implanted at the bone defect of the rabbit skull. No inflammatory response was observed. Micro CT and histological analysis revealed that the granules was bonded with the bone and, bone tissue was penetrated inside the porous calcite granules. We concluded, therefore, that interconnected porous calcite fabricated based on the dissolution-precipitation reaction using a calcium sulfate as a precursor has potential value to be an ideal bone substitute.
Q-2:L05 Progress in Calcium-magnesium Phospho-silicate Hydraulic Bio-cements
T. TROCZYNSKI, M. YAGHTIN, Materials Engineering, University of British Columbia, Vancouver B.C., Canada
The novel Calcium Phosphate Silicate Cement (CPSC) combines the best biological and structural properties of Calcium Phosphate Cement (CPC) and of Calcium Silicate Cement (CSC). The resulting CPSC is relatively stronger than CPC and has extended and controlled degradability time range, as compared with CPC. One area of active CPSC research concerns its setting time, as the currently known CPSC variants set within ~1 hr after water contact. There is a desire to shorten this time to < 10 min for certain dental and orthopaedic applications. One approach explored in this work is through admixture of biocompatible/biodegradable and fast-setting Mg compounds to CPSC, rendering it now Calcium-Magnesium Phosphate Silicate Cement (CMPSC). This work reviews our research progress on such novel, faster-setting bio-cements, including the effects of Ca/Mg on the properties of CMPSC after hydration (setting) at 37ºC for various length of time, and its final properties (variation of pH, compressive and 3-point bending strength, in vitro bioactivity). The phase transformations in CMPSC during setting show that calcium hydroxide, produced during the hydration of calcium silicates, reacts with the phosphate additives to form hydroxyapatite. The in-situ formation of a nanocomposite from the hydroxyapatite and calcium silicate hydrates appears responsible for the significant enhancement in CMPSC strength, bioactivity, and biocompatibility, compared to pure CSC.
Q-2:IL06 Developmentally Inspired Approach to Cartilage Tissue Engineering
E. JABBARI, University of South Carolina, Columbia, SC, USA
The structural organization of articular cartilage is rooted in the arrangement of mesenchymal stem cells (MSCs) into morphologically distinct zones during embryogenesis as a result of spatiotemporal gradients in biochemical, mechanical, and cellular factors that direct the formation of stratified structure of articular cartilage. These gradients are central to the function of cartilage as an articulating surface. Strategies that mimic zonal organization of the articular cartilage are more likely to create an engineered tissue with more effective clinical outcome. The objective of this work was to measure the response of human hMSCs encapsulated in engineered gels that simulate the stiffness of the superficial, middle and calcified zones of articular cartilage supplemented with zone specific growth factors. The size of the encapsulated cells increased from the gel simulating superficial to those simulating middle and calcified zones. GAG content progressively increased from Superficial to Middle and Calcified gels. hMSCs in the gel simulating the superficial zone showed up-regulation of Sox-9 and SZP whereas hMSCs in calcified gel showed up-regulation of ALP. Results demonstrate that a developmental approach can potentially regenerate the zonal structure of articular cartilage.
Q-2:IL07 Supramolecularly Movable Polyrotaxane Surfaces Directing Stem Cell Differentiation
N. YUI, J.-H. SEO, Tokyo Medical and Dental University, Tokyo, Japan; T. YAMAOKA, S. KAKINOKI, M. HIRATA, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
We have clarified that cellular function can be directed on the surfaces of supramolecular polyrotaxane (PRX) with a wide range of hydrated molecular mobility (Mf). In particular, it was demonstrated that mesenchymal stem cell (MSC) differentiation can be directed by changing the Mf of PRX block-copolymer surfaces. On the PRX surfaces with a high Mf, the MSCs showed a narrow and protruded morphology, and RhoA-ROCK signaling pathway was greatly down-regulated, thus providing a favorable condition for adipogenesis. However, the MSCs on the methacrylate copolymer surfaces with a low Mf showed a broad and spread morphology and an up-regulated RhoA-ROCK signaling pathway, leading to osteogenesis. These results strongly suggest the importance of regulating the molecular mobility of hydrated supramolecular surfaces in directing stem cell fate without changing the bulk properties of biomaterials. Based on these knowledge, we succeeded to clarify that the PRX surfaces with a high Mf are feasible for cardiomyogenesis and beating colony formation from iPS cells. Finally, it can be concluded that surface hydrated molecular mobility varied by PRX architecture plays a significant role in controlling cytoskeletal signaling pathways, eventually contributing to directing stem cell commitment.
Q-2:IL08 Enhanced Tissue Infiltration into Porous Scaffolds by Active Growth Factor-immobilizing Technology
T. YAMAOKA, S. KAKINOKI, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan; Y. HASHIMOTO, S. BABA, Osaka Dental University, Chuo-ku, Osaka, Japan
Tissue ingrowth along with neovascularization into porous structures is one of the key issues in scaffold-based regenerative medicine for dermis, bone, nerve, and so on. The implanted porous scaffolds are often encapsulated by the fibrous tissue, which strongly inhibit tissue regeneration. Here, basic fibroblast growth factor (bFGF) was immobilized onto porous materials made of biodegradable polymer, nondegradable polymer, or ceramics through our immobilization process, and the scaffolds were implanted into mice for up to 6 months. The process is composed of mild and biologically safe three-step reactions: (1) modification with a surface-modifier. penta-lysine/mussel-adhesive peptide, (2) electrostatic binding of heparin with the penta-lysine, and (3) biologically specific binding of bFGF to heparin. Half of the control scaffolds were extruded out of the body in 4 months, but bFGF immobilization completely prevented the rejection. It was found that the three step reaction inhibit denaturation of bFGF and lead to rapid ingrowth of both soft and hard tissues into the sdcaffolds.
This study was supported by the Intramural Research Fund of the National Cerebral and Cardiovascular Center (25-2-22) and S-Innovation Project of JST Tokyo Japan.
Q-2:L10 Synthesis and Characterization of an Innovative Radially-compliant Scaffold for Large Osteochondral Defects: The Honey
F. SCALERA, B. PALAZZO, A.N. CANCELLI, S. SCIALLA, A. SANNINO, F. GERVASO, University of Salento, Lecce, Italy; D. IZZO, Dhitech S.c.a.r.l, Lecce, Italy; A. BARCA, IRCCS San Raffaele Scientific Institute (Section of Lecce), Lecce, Italy; G. PERETTI, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
One of the major challenges in the orthopedic field is the repair of critical size osteochondral (OC) defects. The authors have already developed a substitute, made of a porous hydroxyapatite (HA) scaffold perfectly interconnected with a collagen layer, for the treatment of subchondral lesions1. Good results have been obtained in terms of mechanical properties, biocompatibility and tissue regeneration. In this work they propose the enhancement of the bony material reasorbability, changing the ceramic powder composition (Mg doped HA (Mg-HA) or Wollastonite (Ws)/HA mixtures) and increasing the radial compliance of the 3D scaffold, trough the design of a new configuration: HONEY. Collagen and inorganic layers have been characterized by SEM, EDX, XRD, compression tests, degradation experiments and MTT assays by MG63 cell line. The best results have been obtained mixing WS with HA. Infact, these scaffolds showed a higher value of stress at the failure (1,35 MPa) and a resorbability 20 times higher after 6 months. In vitro tests highlighted that both inorganic and organic layers are cytocompatible, without significant differences in terms of vitality. Contemporarily, a new scaffold configuration has been designed improving the scaffold radial compliance.
1.Sosio, TE Part A,vol21(2015)
Q-2:L11 Preparation of Gradient-type Decellularized Tissue-polymer Complex for Soft Tissue-polymer Interlinking Device
A. KISHIDA, Y. ZHANG, K. NAM, T. KIMURA, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
The connecting technology for the synthetic materials to living body has been necessary for preparing percutaneous devices, artificial blood vessels, and artificial ligament, etc. One of the most serious problems is formation of the distinct interface between synthetic materials and tissue. To overcome this problem, we tried to apply the tissue engineering technology. Our strategy is to develop a decellularized tissue-polymer complex with gradient polymer concentration, which has compatibility to the synthetic materials on one side and to the soft tissue on the other so as to interlink them. To prepare the gradient complex, we put the decellularized dermis into the methyl methacrylate (MMA) monomer and initiator solution, and controlled the absorption time by pulling the dermis out of the solution at the certain speed. Then MMA was polymerized at room temperature. Using this process, we succeeded in obtaining a gradient dermis-poly(MMA) complex. The compression test showed that the mechanical strength of the complex changed gradually from dermis side to polymer side, indicating that the polymer exists in dermis with gradient centration. As conclusion, we believe that this complex possesses high potential for the new type of soft tissue-synthetic materials interlinking device.
Q-2:L12 Collagen Fiber Bio-composite Laminates and Constructs
M. SHARABI, R. HAJ-ALI, The Fleischman Faculty of Engineering, D. BENAYAHU, Sackler School of Medicine, Y. BENAYAHU, George S. Wise Faculty of Life Sciences,Tel Aviv University, Tel Aviv, Israel
Soft tissues are characterized by a complex structure responsible for their mechanical behavior and overall nonlinear hyperelastic response. The structural complexity is manifested in the presence of several hierarchical levels; from the natural material structure to its arrangement as composite laminates and up to its macro-arrangement as a tissue construct. A new bio-composite made of unique collagen fibers embedded in a hydrogel matrix, was fabricated as plied laminates to mimic the hyperelastic behavior and composition of soft tissues. The mechanical behavior is tested showing a remarkable hyperelastic response that can be adaptive by controlling the fiber fraction and orientation. It can be tailored to a wide range of behaviors using calibrated finite elements modeling. These laminates were stacked together to create bio-inspired constructs that can withstand physiologic loading modes as planar pressures in both experimentally and computationally methods. In silico models were generated to simulate these composite constructs behavior and alternative fibers arrangements were designed to explore the global structure-function behavior. These proposed constructs closely mimic a range of soft tissues and have a good potential for future substitutes.
Session Q-3 - Smart Drug/Gene Delivery and Release Systems
Q-3:IL01 Manipulation of Lipid Bilayer Membranes by Peptide/Cationic Copolymer Complex
A. MARUYAMA, Tokyo Institute of Technology, Yokohama, Japan
E5 peptide (GLFEAIAEFIEGGWEGLIEG) is a 20-residue peptide mimicking the N-terminal (OK?) fusogenic domain of influenza hemagglutinin. E5 forms an ordered conformation with α-helix structure due to protonation of the Glu residues and acquires membrane-disrupting activity at acidic pH. Low solubility of the peptide however hampers its membrane disrupting activity. We previously found that cationic comb-type copolymer, polyallylamine-graft-dextran copolymer(PAA-g-Dex), composed of a cationic backbone and hydrophilic graft chains spontaneously formed soluble interpolyelectrolyte complex with E5. The copolymer folded E5 to the ordered conformation with α-helix structure and induced membrane-disrupting activity at neutral pH. Furthermore, when E5/PAA-g-Dex complex was added to a liposome suspension, liposomal membranes were perforated and developed into lipid bilayer sheets. We speculated that E5/PAA-g-Dex complexes localized along the sheet rim and stabilized the interface between hydrophobic parts of lipid membranes and aqueous media.
Q-3:L05 BN Nanoparticles with a Petal-like Surface as Anticancer Drug-delivery System
D.V. SHTANSKY1, I.V. SUKHORUKOVA1, I.V. ZHITNYAK2, A.M. KOVALSKII1, A.T. MATVEEV1, O.I. LEBEDEV3, X. LI4, N.A. GLOUSHANKOVA2, D. GOLBERG3, 1National University of Science and Technology "MISIS", Moscow, Russia; 2N.N. Blokhin Russian Cancer Research Center, Moscow, Russia; 3CRISMAT, UMR 6508, CNRS-ENSICAEN, Caen, France; 4National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, Japan
Nanoparticles (NPs) have a great potential as nanosized drug delivery carriers. Such systems must safely deliver the drug to the site of tumor without drug leakage, effectively penetrate inside cancer cells, and provide intracellular drug release. Herein we developed an original and simple method aimed at the fabrication of spherical boron nitride NPs (BNNPs), 100-200 nm in diameter, via chemical vapor deposition. Thorough structural characterization revealed that the surface of hollow BNNPs had been made of numerous nanosheet petals. Such BNNPs with ultimately porous structures can be utilized as nanocontainers for the delivery of various chemotherapeutic agents in chemotherapy-resistant tumor cells. They revealed low cytotoxicity and rapid cellular uptake. BNNPs were saturated with doxorubicin (DOX) and then dispersed. The BNNPs loaded with DOX (BNNPs-DOX) were stable at neutral pH but effectively released DOX at pH 4.5–5.5. MTT assay and cell growth test showed that the BNNPs-DOX nanocarriers had been toxic for IAR-6-1 cells. The cytotoxicity of BNNPs-DOX was comparable with free DOX at identical concentrations in the range of 0.26-1.04 µg/ml. BNNPs loaded with DOX penetrated into the neoplastic IAR-6-1 cells using endocytic pathways, and then DOX released into cytoplasm and the cell nuclei and resulted in cell death.
Q-3:IL06 Advances in Delivery of Stimuli-sensitive Combination Nanopreparations of siRNA and Chemotherapeutic Drugs to Treat Multidrug Resistant Tumors
V. TORCHILIN, Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, MA, USA
Tumor therapy of multidrug resistant cancers could be significantly enhanced by using siRNA down-regulating the production of proteins involved in cancer cell resistance, such as Pgp or survivin. Even better response is achieved if such siRNA could be delivered to tumors together with chemotherapeutic agent. We have developed several types of lipidic systems based on PEG-phospholipid or PEI-phospholipid conjugates, which are biologically inert, demonstrate prolonged circulation in the blood and can firmly bind non-modified or reversibly-modified siRNA. Additionally, these nanopreparations can be loaded into their lipidic core with poorly water soluble chemotherapeutic agents, such as paclitaxel or camptothecin. It was shown that such preparations can significantly down-regulate target proteins in cancer cells, enhance drug activity, and reverse multidrug resistance. To unload such nanopreparations inside tumors, those can be designed sensitive to local tumor-specific stimuli. Using pH-, hypoxia-, or MMP2-sensitive bonds between different components of nanopreparations co-loaded with siRNA and drugs, one is able to specifically deliver biologically active agents in tumors, inside tumor cells, or even to individual cell organelles providing improved therapeutic response.
Q-3:IL07 Engineering of Enzyme Nano-capsules for Biomedical Applications
A. KISHIMURA, Department of Applied Chemistry, Faculty of Engineering, Kyushu University, and Center for Molecular Systems, Kyushu University, Japan
Enzyme is quite a useful and promising tool for chemical synthesis and chemical transformation with high efficiency and specificity. The applications of enzymes have been studied, especially for industrial and biomedical applications. However, technology of encapsulation or immobilization of enzymes without deactivation, and stabilization of enzymes for the long-term use have been still a key issue. Thus, development of more versatile and advanced “engineered” platform is desired for future application of enzymes. In this study, to develop novel enzyme-reactors, we focused on the polymeric vesicles “PICsomes”, and exploited them as a submicrometer-sized compartment. PICsomes are characterized by their semipermeable polymeric membrane, and also facile preparation method, which allows encapsulation of enzymes in the vesicle cavity without loss of enzyme activity. Furthermore, we previously demonstrated their characteristic properties for biomedical applications, such as long blood circulation and excellent tumor accumulation. Herein, we report biomedical applications of enzyme-loaded PICsomes. Particularly, we found their unique physicochemical properties, and confirmed their performance as in vivo nano-reactors for bioimaging and therapeutics.
Q-3:L08 Novel Sol Gel Antibiotic Release Coatings for Cementless Arthroplasty Fixations
R. AKID1, T. NICHOL2, T.J. SMITH2, J.T. CALLAGHAN3, P.V. HATTON3, 1School of Materials, University of Manchester, UK; 2BioMedical Research Centre, Sheffield Hallam University, UK; 3School of Clinical Dentistry, University of Sheffield, UK
Cementless arthroplasty fixation necessitates systemic antibiotic delivery, with a resulting potential risk of impaired local infection control and possible antibiotic resistance by the patient. Furthermore, when considering arthroplasty revision surgery, both cemented and uncemented fixations receive systemic prophylaxis. With current practice there remains no local antibiotic delivery system for uncemented reconstructions. Given that the surgery time for a revision is longer than that of a primary, the potential infection rate associated with a revision is greater than that of the primary intervention. Therefore an urgent clinical need exists to develop a therapeutic coating system that is able to release antibiotic(s), locally to eliminate pathogenic microorganisms, whilst allowing the regeneration of local bone tissue. We report on the development of a sol gel coating system designed to release an antibiotic, above the minimally inhibitory concentration over an optimal timescale, having the capacity to substantially reduce the risk of device infection. The presentation includes data showing comparative antibiotic elution kinetics (sol gel and cement), kill-efficacy against key bacterial pathogens and a small animal in vivo study.
Session Q-4 - Nanomaterials Systems for Bio-imaging and Therapy
Q-4:IL01 Dynamic Culturing Systems for Cell-seeded Functionalized Implantable Scaffolds
V. SIKAVITSAS1,2, C. WILLIAMS2, A. SIMMONS1, Z. MUSSETT2, 1Schools of Chemical, Biological, and Materials Engineering, 2Stephenson School of Biomedical Engineering, The University of Oklahoma, Norman, OK, USA
Flow perfusion bioreactors have been proposed as ideal vehicles for the culture of mesenchyma stem cell seeded scaffold constructs for bone tissue engineering, due to their ability to provide improved nutrient transport and expose the cultured cells to shear stress that has been shown to stimulate osteoblastic differentiation. In order to better understand the mechanosensation and nutrient transport, we are investigating the bone matrix mineralization over time in polymer scaffolds for bone tissue engineering using micro-computed tomography and analyzing the effects of oxygen and nutrient concentration gradients and at different stages of the culture. The influence of cell adhesion peptides on the osteoblastic differentiation of MSC exposed to fluid shear is also explored. During the culture period, we measure the levels of oxygen, glucose, and lactate and compare these measurements with expected values obtained from fluid dynamic simulations. These samples are then imaged using micro-computed tomography to determine cell and mineralized matrix distribution. Mechanosensation in the form of tension is also explored as a mechanism to induce tenocytic differentiation in mesenchyma stem cells using a custom bioreactor and decellularized human umbelical veins as scaffolds.
Q-4:IL02 Interaction of Noble Nanoparticles of Different Morphology with Human Skin and Skin Cells
C. GRAF, D. NORDMEYER, E. RÜHL, Freie Universität Berlin, Berlin Germany; F. RANCAN, S. AHLBERG, A. VOGT, J. LADEMANN, Charité - Universitätsmedizin, Berlin, Germany; C. SENGSTOCK, M. KÖLLER, Bergmannsheil University Hospital, Bochum, Germany; J. DIENDORF, M. EPPLE, University of Duisburg Essen, Essen, Germany; J. RAABE, Paul Scherrer-Institut, Villigen, Switzerland
Noble metal nanoparticles (NP) are widely used in applications where they come into contact with the human body. The shape of metal NP can affect their uptake into human tissue and cells but also their dissolution and hence, their toxicity in body fluids. Here, the shape dependent interaction of Ag NP known for their high cytotoxicity and more inert Au NP are investigated. Solubility studies indicate that Ag NP dissolve only slightly in pure H2O but strongly degrade in isotonic saline or at lower pH. Thereby, Ag prisms dissolve faster than spheres. Scanning Transmission X-Ray Microscopy (STXM) and TEM are used to image the uptake of the NP in human Mesenchymal Stem Cells (hMSC) and human keratinocytes (HaCaT). The NP loose >90% of their original volume after cellular uptake. While hMSC take up much more prisms than spheres, no significant difference are found for HaCaT cells. Reasons for this behavior are discussed. The uptake of Au nanorods (length ~250 nm) and spherical Au NP (~80 nm) in intact skin and barrier disrupted skin is compared. While no NP uptake is found in intact skin, in skin with barrier disrupted by pricking uptake is proven by cryo-SEM and STXM. STXM results indicate that NP penetrate deep into the dermis once they have passed the skin surface at a prick site.
Q-4:IL03 Stealth Liposomes Conferred with Light-triggered Cargo Release for Theranostic Applications
D. LUO, K.A. CARTER, A. RAZI, J. GENG, S. SHAO, D. GIRALDO, U. SUNAR, J. ORTEGA, J.F. LOVELL, University at Buffalo, State University of New York, Buffalo, NY, USA
Stealth liposomes can be used to extend the blood circulation time of encapsulated therapeutics. Inclusion of a small amount of porphyrin-phospholipid (PoP) imparted optimal near infrared (NIR) light-triggered release of doxorubicin (Dox) from conventional sterically stabilized stealth liposomes. The type and amount of PoP affected drug loading, serum stability and drug release induced by NIR light. Cholesterol and PEGylation were required for Dox loading, but slowed light-triggered release. Dox in stealth PoP liposomes had a long circulation half-life in mice of 21.9 h and was stable in storage for months. Following intravenous injection and NIR irradiation, Dox deposition increased ∼7 fold in treated human pancreatic xenografts. Phototreatment induced mild tumor heating and complex tumor hemodynamics. A single chemophototherapy treatment with Dox-loaded stealth PoP liposomes eradicated tumors while corresponding chemo- or photodynamic therapies were ineffective. A low dose 3 mg/kg Dox phototreatment with stealth PoP liposomes was more effective than a maximum tolerated dose of free or conventional long-circulating liposomal Dox. To our knowledge, Dox-loaded stealth PoP liposomes represent the first reported long-circulating nanoparticle capable of light-triggered drug release.
Q-4:L07 Functional Nanoparticles for Tumor Imaging
MINGYUAN GAO, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
Through either passive or active targeting, functional nanoparticles have shown great potentials in visualizing tumors in vivo. In this presentation, we will present our recent results on tiny tumor imaging, tumor micrometastasis imaging and the visualization of tumor microenvironment as well, apart from the synthesis and surface functionalization of versatile inorganic nanoparticles[1-8].
1. C. Liu, Y. Qi, R. Qiao, Y. Hou, K. Chan, Z. Li, J. Huang, L. Jing, J. Du*, and M. Y. Gao*, Nanoscale, in press. 2. Jianfeng Zeng, Ming Chen, Yong Wang, Ling Wen, Zhen Li*, Yongyou Wu*, Mingyuan Gao*, and Zhifang Chai, Adv. Health. Mater., in press. 3. M. Jiao, J. Zeng, L. Jing, C. Liu, and M. Y. Gao*, Chem. Mater., 2015, 27, 1299. 4. Y. Hou, J. Zhou, Z. Gao, X. Sun, C. Liu, D. Shangguan, W. Yang, and M. Y. Gao*, ACS Nano, 2015, 9, 3199. 5. R. Qiao, C. Liu, M. Liu, H. Hu, C. Liu, Y. Hou, K. Wu*, Y. Lin, J. Liang, M. Y.*, ACS Nano, 2015, 9, 2120. 6. L. Jing, S. V. Kershaw, T. Kipp, S. Kalytchuk, K. Ding, J. Zeng, M. Jiao, X. Sun, A. Mews, A. L. Rogach, and M. Y. Gao*, J. Am. Chem. Soc., 2015, 137, 2073. 7. J. Zeng, L. Jing, Y. Hou, M. Jiao, R. Qiao, Q. Jia, C. Liu, F. Fang, H. Lei, and M. Y. Gao*, Adv. Mater., 2014, 26, 2694. 8. J. Zeng, B. Jia, R. Qiao, C. Wang, L. Jing, F. Wang and M. Y. Gao*, Chem. Commun., 2014, 50, 2170
Q-4:L08 Fluorescent Nanoparticles of Silicon and Carbon for Breast Cancer Imaging
J.S. KANATHASAN, V. SWAMY, U.D. PALANISAMY, Monash University Malaysia, Bandar Sunway, Selangor, Malaysia; A.K. RADHAKRISHNAN, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
Silicon and carbon nanostructures are widely investigated for theranostics, biolabelling and drug delivery owing to their suitable optoelectronic properties (efficient photoluminescence, long light emission wavelength, and large Stokes shifts which could overcome photobleaching under fluorescence imaging), longer photostability and minimal cytotoxicity. The present study focuses on bioconjugated fluorescent carbon and silicon nanomaterials for breast cancer imaging. Macrophage plays an important role in host defense by removing dead cells, foreign particles and recruitment of guard cells of innate and adaptive immunity. Tumor-associated macrophage (TAM) infiltrates tumor growth area. It has been shown that TAM cells facilitate cancer progression through invasion of tumor cells into surrounding stroma and intravasation of tumor cells into the bloodstream. In the present study, Si and C nanoparticles were surface functionalized with a peptide biomarker that is compatible with TAM cells and were characterized using spectroscopy. The bioconjugated nanoparticles were treated with TAM cells and 4 different types of mammary cell lines. The presence of specific biomarkers in tumor cells and TAM cells was investigated using fluorescence assisted cell sorting and confocal microscopy.
Q-4:IL10 Design of Functionalized Iron Oxide Nanoparticles for Theranostics
D. FELDER-FLESCH, D. MERTZ, S. BEGIN, IPCMS UMR CNRS Unistra 7504, Strasbourg Cedex, France
Some of the significant and most promising applications for inorganic nanoparticles (NPs) lie in the fields of biology and biomedicine. Due to their magnetic properties tuned by their shape and/or composition, superparamagnetic iron oxide NPs (SPIO) with appropriate surface chemistry can be used in numerous in vivo applications such as MRI contrast enhancement, hyperthermia treatment, cell sorting, drug delivery... In that context, we have developped functionalized iron oxide nanoparticles able to combine diagnosis by MRI and/or optical imaging and targeted therapy by hyperhermia and/or drug delivery. The shape and composition of iron oxide NPs have been optimized for hyperthermia and then these NPs have been coated with either dendron molecules to provide suitable in vivo properties and targeting abilities or by silica or proteins to deliver drug.
Q-4:IL11 3D Chiral Nanostructure for High-sensitivity Molecular Imaging with Optical Coherence Tomography
NANGUANG CHEN, KALPESH MEHTA, PENGFEI ZHANG, Department of Biomedical Engineering, National University of Singapore, Singapore
Fluorescence microscopy has been an indispensible tool in modern biomedical sciences due to its molecular specificity. However, there are some limitations when applying fluorescence microscopy to in vivo imaging of biological tissues. The most significant problems include limited imaging depth and photobleaching. Optical coherence tomography (OCT) is a widely used structural imaging method, which allows in-vivo imaging at video rate and enjoys a penetration depth of 2-3 mm in biological tissues. However, it has limited use in molecular imaging due to the lack of an effective contrast mechanism. We have discovered and demonstrated a novel approach towards remarkable contrast enhancement, which is achieved by the use of a circular-polarization optical coherence microscopy system and 3-dimensional chiral nanostructures as contrast agents. By detecting the circular intensity differential depolarization (CIDD), we successfully acquired high quality images of single chiral nanoparticles underneath a 1-mm-thick tissue-mimic phantom.
Q-4:L13 Ultrasensitive in Vivo Detection of Primary Gastric Tumor and Lymphatic Metastasis Using Upconversion Nanoparticles
R.R. QIAO1, C.H. LIU2, K.C. WU2, M.Y. GAO1, 1Institute of Chemistry, the Chinese Academy of Sciences, Beijing, China; 2State Key Laboratory of Cancer Biology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China
Lymphatic metastasis is an important prognostic factor regarding long-term survival rate of gastric cancer (GC) patients. Pretreatment knowledge of lymph node status is extremely helpful for planning treatment and prognosis. However, to date, no imaging method has been demonstrated to be effective for detecting lymphatic metastasis in GC. Molecular imaging probes based on upconversion nanoparticles with unique optical and magnetic properties have provided great hope for early tumor detection. Herein we report highly sensitive detection of lymphatic spread using core@shell structured NaGdF4:Yb, Er@NaGdF4 upconversion nanoparticles coated with polyethylene glycol (PEG). A GC-specific probe was constructed through “click” reaction between the maleimide moiety of PEG ligand and the thiol group from partly reduced antigastric cancer antibody MGb2. The primary tumor and adjacent lymphatic metastasis site were clearly differentiated by upconversion luminescence imaging after the GC-specific probe was delivered through tail vein injection into tumor-bearing mice. Moreover, lymphatic metastases smaller than 1 mm were successfully detected, owing to the ultralow background under 980 nm excitation. It has been demonstrated that both primary and lymphatic metastatic sites in an orthotopic mouse model of human gastric cancer can be optically detected by using GC-specific upconversion luminescence nanoprobes. The current studies may therefore provide a highly effective approach for GC diagnosis.
1. Hou, Y.; Qiao, R. R.; Fang, F.; Wang, X. X.; Dong, C. Y.; Liu, K.; Liu, C. Y.; Liu, Z. F.; Lei, H.; Wang, F.; Gao, M. Y., NaGdF4 Nanoparticle-Based Molecular Probes for Magnetic Resonance Imaging of Intraperitoneal Tumor Xenografts in Vivo. ACS Nano 2013, 7 (1), 330-338. 2. Liu, C. Y.; Gao, Z. Y.; Zeng, J. F.; Hou, Y.; Fang, F.; Li, Y. L.; Qiao, R. R.; Shen, L.; Lei, H.; Yang, W. S.; Gao, M. Y., Magnetic/Upconversion Fluorescent NaGdF4:Yb,Er Nanoparticle-Based Dual-Modal Molecular Probes for Imaging Tiny Tumors in Vivo. ACS Nano 2013, 7 (8), 7227-7240. 3. Liu, C. Y.; Hou, Y.; Gao, M. Y., Are Rare-Earth Nanoparticles Suitable for In Vivo Applications? Adv. Mater. 2014, 26 (40), 6922-6932. 4. Qiao, R. R.; Liu, C. H.; Liu, M. H.; Hu, H.; Liu, C. Y.; Hou, Y.; Wu, K. C.; Lin, Y. N.; Liang, J. M.; Gao, M. Y., Ultrasensitive in Vivo Detection of Primary Gastric Tumor and Lymphatic Metastasis Using Upconversion Nanoparticles. ACS Nano 2015, 9 (2), 2120-2129.
Q-4:L14 A Protease-activated Ratiometric Fluorescent Probe for pH-mapping of Malignant Tumor
YI HOU1, J. ZHOU1, ZHENYU GAO2, X.Y. SUN1, C.Y. LIU1, D.H. SHANGGUAN1, W.S. YANG2, M.Y. GAO1, 1Institute of Chemistry, the Chinese Academy of Sciences, Zhong Guan Cun, Beijing, China, 2College of Chemistry, Jilin University, Changchun, China
Tumor microenvironment is strongly correlated with prognostic factors relating to growth, invasion, and metastasis of malignant tumors.1-3 Furthermore, there is increasing awareness of the impact of spatiotemporal heterogeneity in tumor properties that impact therapeutic administration. Therefore, developing noninvasive methods for visualizing tumor microenvironment is critical not only for tumor diagnostics, but also for predicting the metastasis potential, determining therapeutic efficacy, therapy development, and prognostics. In a clinical scenario, this information could also direct personalized care specified by the tumor response. Herein, a protease-activated ratiometric fluorescence probe based on fluorescence resonance energy transfer (FRET) between a pH-sensitive fluorescence dye and biocompatible Fe3O4 nanocrystals was constructed. A peptide substrate of MMP-9 served as a linker between the particle quencher and the chromophore that was covalently attached to anti-tumor antibody. The optical response of the probe to activated MMP-9 and gastric cell line SGC7901 tumor cells was investigated, followed by in vivo tumor imaging. Based on the ratiometric pH response to tumor microenvironment, the resulting probe was successfully used to image the pH of subcutaneous tumor xenografts.4
1. Chambers, A. F.; Matrisian, L. M. J. Natl. Cancer. Inst. 1997, 89, 1260-1270. 2. Webb, B. A.; Chimenti, M.; Jacobson, M. P.; Barber, D. L. Nat. Rev. Cancer 2011, 11, 671-677. 3. Stearns, M. E.; Wang, M. Cancer. Res. 1993, 53, 878-883. 4. Hou, Y.; Zhou, J.; Gao, Z. Y.; Sun, X. Y.; Liu, C. Y.; Shangguan, D. H.; Yang, W. S.; Gao, M. Y. ACS Nano 2015, 9, 3199-3205.
Q-4:L15 Relaxor Single-crystal Plates with Nano Size Ferroelectric Domains Applied to Ultrasonic Probe for Medical Uses
TOSKIO OGAWA, TAIKI IKEGAYA, Department of Electrical and Electronic Engineering, Shizuoka Institute of Science and Technology, Fukuroi, Japan
In order to improve sensor responses of an ultrasonic probe for medical use, piezoelectric transducers composed of relaxer single-crystal plates were investigated. Since it is significant to clarify the equality of piezoelectric responses, ferroelectric domain distribution in the single-crystal plate transducer was evaluated from nano, micro to macro sizes. In this pursuit, longitudinal and transverse wave velocities propagated in the direction of thickness and DC poling field in relaxor single-crystal plates of (100) 0.70Pb(Mg1/3Nb2/3)TiO3-0.30PbTiO3 (dimensions: 20Lx14Wx0.39T mm) were measured by an ultrasonic precision thickness gauge (Olympus Model 35DL). Elastic constants such as Young’s modulus, Poisson’s ratio, rigidity, and bulk modulus were calculated from the sound velocities. Furthermore, ferroelectric domains in the plates were observed by a transmission optical microscope together with the measurement of dielectric and piezoelectric properties. As a result, while relatively high electromechanical coupling factor of thickness mode (kt) around 63% was confirmed, several domains were observed in the plates before and after poling. These phenomena correspond to fluctuations of elastic constants and frequency responses of impedance due to plate vibrations.
Q:P02 Preparation of Bone-hemostasis Materials with Sugar-containing Hydroxyapatite and Natural Plant-derived Polymer
YEONJEONG NOH1, T. UMEDA1, T. MUSHA2, K. ITATANI1, 1Department of Materials and Life Sciences, Sophia University, Tokyo, Japan; 22nd Department of Orthopaedic Surgery, Toho University, Tokyo, Japan
The preparation conditions of bone-hemostasis materials were examined using hydroxyapatite (Ca10(PO4)6(OH)2: HAp) and natural plant-derived polymer. The sol was prepared by dissolving 2 mass% locust bean gum (LBG) / guar gum (GG) and 3 mass% phosphoryl oligosaccharide of calcium (POs-Ca) into the de-ionized water. Further, 2 mass% sodium alginate (AG; M/G ratio = 0.9) was added to the mixture in order to encourage the gelation with calcium ions being released from the POs-Ca solution. The resulting gels were vigorously agitated for the inclusion of bubbles, hydrothermally-treated at 100ºC for 5 h and freeze-dried at -50ºC for 24 h to form porous materials. According to the X-ray diffractometry and FT-IR spectroscopy, the composite contained hydrolyzed materials of POs-Ca, i.e., the sugar-containing HAp (s-HAp), as well as LBG and GG. The microstructural observation by electron microscopy showed that the pore sizes were controlled in the range of 5 to 50 nm through the changes in LBG/GG ratio. The composite showed the noted absorption of simulated body fluid (197%) at 37.0ºC, which was effective properties for the hemostasis of bleeding. Overall, the composites of s-HAp and natural plant-derived polymer are found to be promising materials for the bone hemostasis.
Q:P07 Functionalizing Surface Electrical Potential of Hydroxyapatite Coatings
L. PLUDUMA, K.A. GROSS, E. FREIMANIS, I. DAENKE, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Latvia; P. VUORISTO, H KOIVULUOTO, Department of Materials Science, Tampere Univeristy of Technology, Finland
While considerable work has chemically functionalized hydroxyapatite, little has been done on tailoring its electrical surface potential. This has been due to limitations in the available methods to impart a surface charge. Work to date has charged conventionally manufactured hydroxyapatite exhibiting a random crystal orientation. At the outset, the microstructure has not been tailored for the highest surface potential. The objective of this work was to take the next step and orient the crystals for further increasing the surface electrical potential. Two methods were adopted. Firstly, a coating was sprayed under the influence of an electric field so as to include oriented crystals and polarize the coating in-situ. Secondly, a textured coating was heated in hydrothermal conditions and then in an electric field. Aligned crystals were achieved, as determined by X-ray diffraction. There was little influence of the electric field on the surface electrical potential; a greater effect was due to the particle size. A smaller particle size produced a greater electrical surface potential. Raman spectroscopy showed a surface hydroxylated layer that appeared to aligned from the underlying oxyapatite layer. The second approach achieved a higher surface potential.
Q:P09 Sol-gel Synthesis of Biocompatible Glasses: A Study of Particle Growth Kinetics using Dynamic Light Scattering
R. BORGES, J. MARCHI, Federal University of ABC, Santo André, Brazil
In this work, a Dynamic Light Scattering approach was used to measure the particle size of biocompatible glasses during the sol-gel processing under different conditions. The synthesis settings were planned as follows: pH between 10 and 11; surfactant concentration (PEG) between 0 to 20g/L; and the composition studies was based on the 47SiO2-(38 – x)Na2O-(9 + x)CaO-6P2O5 system ( x = 0, 10 and 20). For each experimental condition, the kinetics of particle growth (Kc.t-1) was calculated, and the values obtained were analyzed by factorial design of experiments. The results evidence a synergetic effect when higher pH, higher surfactant concentration and lower Na/Ca ionic ratio are combined together, then leading to lower values for kinetics of particle growth, which are, in turn, associated with lower particle size.
Q:HP24 Enhancing Neurogenesis and Angiogenesis with Target Delivery of Stromal Cell derived Factor-1a using a Dual Ionic pH-sensitive Copolymer
YOUNG KYU SEO1, DONG HEE KIM2, OH YOUNG BANG2, DOO SUNG LEE1, 1School of Chemical Engineering, Theranostic Macromolecules Research Center, Sungkyunkwan University, Suwon, Republic of Korea; 2Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Rep.of Korea
We evaluated the effects of targeted delivery of SDF-1a using a pH-sensitive polymer poly (urethane amino sulfamethazine) (PUASM), a synthetic macromolecule with potential for targeted drug delivery in acidic conditions, to enhance therapeutic neurogenesis and angiogenesis in a rat model of permanent middle cerebral artery occlusion. A dual ionic pH-sensitive copolymer PUASM-based random copolymer was designed and synthesized for the controlled release of SDF-1a in stroke. Owing to the unique characteristics of PUASM, it exhibited a dual ionic pH-sensitive property in an aqueous solution. At pH 8.5, the copolymer exhibited a negative charge and was water soluble. Interestingly, when the pH decreased to 7.4, PUASM could form a micelle and encapsulate protein effectively via the ionic interaction between a negatively charged polymer and a positively charged protein. At pH 5.5, the ionization of tertiary amines led to the disassembly of the micellar structure and released the protein rapidly. Then, we investigated the effect of systemic administration of SDF-1a-loaded pH-sensitive polymeric micelles in a stroke induced rat model.
Q:HP25 Hypoxia-sensitive Block Copolymer Micelles for Triggered Delivery of Doxorubicin
THAVASYAPPAN THAMBI, DOO SUNG LEE, School of Chemical Engineering, Theranostic Macromolecules Research Center, Sungkyunkwan University, Suwon, Rep.of Korea
Hypoxia occurs in a variety of pathological conditions including stroke, rheumatoid arthritis, atherosclerosis, cardiopathy and vascular diseases. Herein, an amphiphilic block copolymer, composed of poly(ethylene glycol) as the hydrophilic block and poly(ɛ-(4-nitro)benzyloxycarbonyl-L-lysine) as the hypoxia-sensitive hydrophobic block, was prepared for hypoxia-sensitive drug delivery. Owing to its amphiphilic nature, the block copolymer formed hypoxia-sensitive polymeric micelles (HS-PMs) and encapsulated hydrophobic doxorubicin (DOX) in an aqueous condition. HS-PMs released DOX in a sustained manner under the normoxic condition (physiological condition), whereas the drug release rate was markedly enhanced under the hypoxic condition. From the in vitro cytotoxicity tests, it was found the DOX-loaded HS-PMs showed higher toxicity to hypoxic cells than to normoxic cells. Microscopic observation showed that the HS-PMs could effectively deliver DOX into nuclei of SCC7 cancer cells under hypoxic conditions. Overall, it is evident that the HS-PMs prepared in this study have the potential to effectively deliver hydrophobic drugs into the hypoxic cells involved in numerous intractable diseases.
Q:HP26 Poly(ethylene glycol)-poly(amino-carbonate-urethane) based pH-/temperature-sensitive, Biodegradable and Injectable Hydrogel for Protein Delivery
V.H. GIANG PHAN, DOO SUNG LEE, Theranostic Macromolecules Research Center, Department of Chemical Engineering, Sungkyunkwan University, Suwon, Rep.of Korea
A new pH-/temperature-sensitive, biocompatible and biodegradable, injectable hydrogel has been developed for protein delivery which was based on poly(ethylene glycol)-poly(amino-carbonate-urethane) [PEG-PACU]x copolymer. This hydrogel exists in sol state at low pH (e.g. pH 6.0 and room temperature) but change to gel state at physiological condition (pH 7.4 and 37 °C). The hydrogel has been thoroughly characterized using 1H NMR, FT-IR, scanning electron microscopic (SEM), rheological analysis, cytotoxicity evaluation. In this study, human growth hormone (hGH) was used as a model protein to investigate the potential of the hydrogel for protein encapsulation and delivery. The results have indicated that the hydrogel has homogeneously porous structure, cytocompatibility and biodegradability. In comparison with hGH solution administration, the hGH release profile from hGH-loaded injectable hydrogel showed a much lower initial burst and significantly prolonged release period. The developed hydrogel has great potential for protein encapsulation and delivery.
Q:HP27 Sulfamethazine-based pH-sensitive Hydrogels with Potential Application for Transcatheter Arterial Chemoembolization Therapy
JAE SEUNG LYM, QUANG VINH NGUYENA, DA WOON AHN, CONG TRUC HUYNH, HWAN JUN JAE,YOUNG IL KIM, DOO SUNG LEE, Theranostic Macromolecules Research Center, Department of Chemical Engineering, Sungkyunkwan University, Suwon, Rep.of Korea
Transcatheter arterial chemoembolization (TACE) is the most common palliative therapy for unresectable hepatocellular carcinoma (HCC). The conventional TACE technique, which employs the Lipiodol® emulsion seems to be inconsistent and unstable in maintaining a high concentration of drugs. Here, we developed a novel sulfamethazine-based anionic pH-sensitive block copolymer with potential application as a radiopaque embolic material. The copolymer, named PCL-PEG-SM, and comprised of poly(ε-caprolactone), sulfamethazine, and poly(ethylene glycol), was fabricated by free radical polymerization. An aqueous solution of the developed copolymer underwent a sol-to-gel phase transition upon lowering the environmental pH to create a gel region that covered the physiological condition and the low pH conditions at tumor sites. The release of doxorubicin from DOX-loaded hydrogels could be sustained for more than 4 weeks in vitro. The radiopaque embolic formulations that were prepared by mixing with Lipiodol®, a long-lasting X-ray contrast agent, could exhibit the gelation inside the tumor using a VX2 carcinoma hepatic tumor rabbit model. These results suggest that a novel anionic pH-sensitive copolymer has been developed with a potential application as a radiopaque embolic solution for TACE.
Q:HP28 pH-responsive Polymer/Gold Nanoparticle Composite for Theranostic Application
QUANG NAM BUI, YI LI, DOO SUNG LEE, Theranostic Macromolecules Research Center, Department of Chemical Engineering, Sungkyunkwan University, Suwon, Rep.of Korea
In this study, pH-responsive biocompatible polymer/gold nanoparticle composite is reported as a potential candidate for theranostic applications. Among various types of gold particles (sphere, rod, cage, shell,…), the gold nanorod (AuNR) was chosen and prepared via CTAB surfactant. The low molecular weight hyaluronic acid (LMWHA) was grafted with sulfadiazine as pH-sensitive moiety, and with lipoic acid as anchor. Subsequently, the resultant polymer easily self-assembles onto AuNR surface. In physiological conditions, the nano composite system possesses a negative charged surface due to the ionization of sulfadiazine groups, which keeps the system being stable, and escaping from non-specific cellular uptakes. At low pH sites either of tumoral environment or intracellular environment, this nano-scale system can be aggregated due to the deionization of sulfadiazine that induces the high tumoral-accumulation of AuNR. Additionally, LWHA also plays an important role in targeting the AuNR to CD44-high expression cancer cells. In our studies, pH-sensitive AuNR was employed in a series of experiments to evaluate the reversible dispersion-aggregation transition, targeting ability, as well as hyperthermic effect which affirmed feasibility and applicability of our proposed concept.
Q:HP29 Antibacterial Nanocoatings on Ocular Devices
F. BAINO, S. PERERO, M. MIOLA, M. FERRARIS, Applied Science and Technology Department, Politecnico di Torino, Torino, Italy
Bacterial issues in ophthalmic applications, with particular reference to postoperative infection of ocular implants, cause significant problems that can require additional, stressful and expensive treatments for the patients. In this work we applied antibacterial coatings on two kinds of polymeric ocular devices, i.e. poly(methyl methacrylate) artificial eyes for enucleated patients and silicone scleral buckles for retinal detachment surgery. The coatings, constituted by silver nanoclusters embedded in a silica matrix, were produced by RF sputtering and investigated by SEM and EDS. The antibacterial effect of the coating was confirmed by the in vitro formation of an inhibition halo against Staphylococcus aureus, which is one of the most common pathogens involved in ocular infections. The approach proposed in this study for treating implant-related ocular infections can have a significant impact in the field of ophthalmic biomaterials, suggesting a valuable alternative to the administration of antibiotics that may become ineffective towards resistant bacterial strains.
Q:HP30 Silver Nanoparticles Synthesized with Polyphenols from Cornus Sanguinea Extract. Study of their Biologic Effects
M. PERDE-SCHREPLER, M. POTARA, F. IMRE-LUCACI, L. DAVID, I. BRIE, L. OLENIC, Institute of Oncology "Prof. Dr. I. Chiricuta", Cluj-Napoca, Romania
Nanoparticle synthesis using plant extracts (green synthesis) is an environmentally friendly and cost-effective process, having a rapid synthesis rate. Silver nanoparticles are frequently used in products directed to the skin due to their antimicrobial properties, thus evaluating the consequences of dermal exposure is crucial. The aim of our study was to evaluate the biologic effects of silver nanoparticles synthesized with Cornus sanguinea extract on HaCaT cell line. We assessed: cellular uptake (atomic absorption spectroscopy), cytotoxicity (cell titer blue viability test), generation of reactive oxygen species (ROS), genotoxicity (comet assay) and immunotoxicity: secretion of IL1 α, IL6 and TNF α. (ELISA). The NPs were stable in solution and had a dominant plasmonic band at 409 nm. The amount of silver uptaken by the cells was concentration and time dependent. Silver NPs showed dose- dependent cytotoxicity. Their presence had no significant effect on the release of ROS. No significant increase of the DNA lesion score was recorded at 24h after treatment. The presence of the NPs in the culture media resulted in the modulation of inflammatory cytokines' release. Conclusions: The synthesized NPs showed no significant cytotoxicity, genotoxicity or immunotoxicity on HaCaT cells.
Q:HP31 Towards New Hybrid Structures for Clinical Applications in Regenerative Medicine
I.-C. BRIE1, O. SORITAU1, M. PERDE-SCHREPLER1, N. DARZU2, V. PASCALAU2, C. POPA2, G. DINDELEGAN3, 1Institute of Oncology "Prof. Dr. I. Chiricuta", Cluj-Napoca, Romania; 2Technical University Cluj-Napoca, Romania; 3University of Medicine and Pharmacy "Iuliu Hatieganu", Cluj-Napoca, Romania
Background. Tissue engineering and regenerative medicine is focused on the development of alternative therapies for tissue/organ repair. Biocompatibility improvement of the implantable products (scaffolds) is a cutting edge research subject. Stem cells have emerged as important players in the generation and maintenance of tissues. Aim. To improve the result of tissue grafting by using tissue engineered hybrid composites synthetic scaffolds - stem cells (SCs) produced locally. Materials and methods: The SCs were cultured on application-tailored scaffolds made of titanium, aiming the differentiation towards the tissue corresponding to the desired medical application. The SCs were assisted during attachment by bioactive layers coated on the scaffolds and during differentiation by the synergistic action of the substrate and growth factors delivery. Results: The biocompatibility of titanium scaffolds was excellent. They allowed and sustained the growth of SCs and their differentiation toward multiple lineages (osteoblastic, neuronal, endothelial). Conclusions. The new biomaterials and hybrid composite structures successfully passed the in-vitro testing. The next step is the optimization of the hybrid structures and synthesis technologies, through in vivo testing and assessment.
Q:HP32 Osteoregeneration by Supramolecular Sulfonated Polyrotaxane/BMP-2 Polyelectrolyte Complexes in Mouse Calvarial Defect Model
M. TERAUCHI, T. INADA, A. TAMURA, S. YAMAGUCHI, N. YUI, Tokyo Medical and Dental University, Tokyo, Japan
Bone reconstruction has been recognized as an important theme in the maxillofacial surgery because of surgical removal for the bone disease. Herein, we focused on the design of biomaterials using supramolecular polyrotaxanes (PRXs) consisting of α-cyclodextrins threaded along a poly(ethylene glycol) chain capped with terminal bulky stopper molecules. In our previous studies, a modality of sulfonated PRXs (S-PRXs) were prepared to form polyelectrolyte complexes with BMP-2, and more osteoregeneration ability than heparin/BMP-2 complexes or BMP-2 was confirmed in vitro. In the present study, we evaluated bone healing ability of the S-PRX/BMP-2 complexes compared with BMP-2 or heparin/BMP-2 complexes in vivo. The S-PRX/BMP-2 complexes were found to be retained in the implanted site for more prolonged time. Bone healing in each mouse calvarial defect model was evaluated by scanning the computed X-ray, and it was found that the S-PRX/BMP-2 complexes showed higher scores than the heparin/BMP-2 and BMP-2 at 4 weeks after the operation. In addition, few effect of the S-PRX/BMP-2 complex on the metabolic function was confirmed by biochemical blood tests. From these results, it is concluded that the S-PRX/BMP-2 complexes can provide a promising surgical tool for bone tissue engineering.
Q:HP33 Ex Vivo Evaluation of a Chitosan-based Composite with Potential Use as Bone Adhesive
F.J. CEDANO1, L.M. PINZON2, C.I. CASTRO1, J.C. BRICENO1, F. SALCEDO2, J.P. CASAS3, 1Department of Biomedical Engineering, Universidad de los Andes, Bogotá, Colombia; 2Department of Chemical Engineering, Universidad de los Andes, Bogotá, Colombia; 3Department of Mechanical Engineering, Universidad de los Andes, Bogotá, Colombia
Fracture fixation using chitosan-based adhesives is a promising alternative for the treatment of complex fractures. Such an adhesive should exhibit: easiness/quickness to prepare in operating room conditions, small time to develop adhesion with the bone fragments, non-toxicity, biocompatibility and an adequate adhesion strength to bone in aqueous environments. The formulated composite studied in this work is based on chitosan mixed with calcium carbonate, hydroxyapatite and glutaraldehyde. For this proposed adhesive the rheological and adhesion strength properties (using a butt joint test with bovine cancellous bone fragments as substrates), as well as the biocompatibility and cytotoxicity (by human osteoblast cell culture) were evaluated. The composite exhibited a gelation time of 821±78 s and tensile bond strengths up to 28.6 ± 9.2 kPa. MTT showed large percentage of active cells at sixth day of culture. High vacuum SEM observation permitted to localize and study the morphology of osteoblast presented in the adhesive. In conclusion, the evaluated composite could be tried as a bone adhesive in in vivo experiments, due its adequate working time, adhesion strength to bone surface in aqueous environment, biocompatibility and capability to allow osteoblast cells adhesion/growth.