Abstract: Scaffolds made of chitosan nanofibers are often too mechanically weak for their application and often their manufacturing processes involve the use of harmful and flammable organic solvents. In the attempt to improve the mechanical properties of nanofibrous scaffolds made of chitosan without the use of harmful chemicals, pectin, an anionic polymer was blended with chitosan, a cationic polymer, to form a polyelectrolyte complex and electrospun into nanofibers for the first time. The electrospun chitosan-pectin scaffolds, when compared to electrospun chitosan scaffolds, had a 58% larger diameter, a 21% higher Young's modulus, a 162% larger strain at break, and a 104% higher ultimate tensile strength. Compared to the chitosan scaffolds, the chitosan-pectin scaffolds' swelling ratios decreased by 55% after 60 min in a saline solution and more quickly released the preloaded tetracycline HCl. The L929 fibroblast cells proliferated slightly slower on the chitosan-pectin scaffolds than on the chitosan scaffolds. Nonetheless, cells on both materials deposited similar levels of extracellular type I collagen on a per DNA basis. In conclusion, a novel chitosan-pectin nanofibrous scaffold with superior mechanical properties than a chitosan nanofibrous scaffold was successfully made without the use of harmful solvents.

Abstract: Novel biocompatible poly(lactide-co-glycolide) (PLGA) nanofiber mats with favorable biocompatibility and good mechanical strength were prepared, which could serve as an innovative type of tissue engineering scaffold or an ideal controllable drug delivery system. Both hydrophobic and hydrophilic drugs, Cefradine and 5-fluorouracil were successfully loaded into PLGA nanofiber mats by emulsion electrospinning. The natural bioactive protein gelatin (GE) was incorporated into the nanofiber mats to improve the surface properties of the materials for cell adhesion. Nanofibrous scaffolds were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, contact angle and tensile measurements. Emulsion electrospun fibers with GE had perfect hydrophilic and good mechanical property. The in vitro release test showed thedrugs released from emulsion electrospun fibers, which achieved lower burst release. The cells cytotoxicity experiment indicated that emulsion electrospun fibers were less toxic and tended to promote fibroblasts cells attachment and proliferation, which implied that the electrospun fibers had promising potential application in tissue engineering or drug delivery.

Abstract: Engineered nanofibers are generally focused on filtration, solar cells, sensors, smart textile fabrication, tissue engineering, etc. Electrospun nanofibers have potential advantages in tissue engineering and regenerative medicine, because of the ease in the incorporation of drugs, growth factors, natural materials, and inorganic nanoparticles in to these nanofiber scaffolds. Electrospun nanofiber scaffolds composed of synthetic and natural polymers are being explored as scaffolds similar to natural extracellular matrix for tissue engineering. The requirement of the inorganic composites in the nanofiber scaffolds for favouring hard and soft tissue engineering applications is dealt in detail in the present review. Regarding drug delivery applications of the composite nanofibers, the review emphasizes on wound healing with silver nanoparticles incorporated nanofibers, bone tissue engineering, and cancer chemotherapy with titanium and platinum complexes loaded nanofibers. The review also describes gold nanopa...

Abstract: Human bone marrow-derived mesenchymal stem cells (hBMSCs) are known for their potential to undergo mesodermal differentiation into many cell types, including osteocytes, adipocytes, and chondrocytes. Therefore, hBMSCs can be used for a variety of regenerative medicine therapies, in fact, hBMC-derived osteocytes have already been used in bone reconstruction. This study discusses the viability and the differentiation properties of hBMSCs that have been cryopreserved in the absence of proteins or dimethyl sulfoxide (DMSO) by using a novel polyampholyte cryoprotective agent (CPA). This CPA is based on carboxylated poly-l-lysine (COOH-PLL) and it was produced by a reaction between e-poly-l-lysine and succinic anhydride. (1)H-NMR and two-dimensional correlation ((1)H-(13)C HSQC) spectroscopy revealed that COOH-PLL did not have a special structure in solution. The hBMSCs can be cryopreserved for 24 months at -80 °C by using a 7.5% (w/w) cryopreserving solution of COOH-PLL, which introduces carboxyl groups that result in > 90% cell viability after thawing. Furthermore, the cryopreserved hBMSCs fully retained both their proliferative capacity as well as their potential for osteogenic, adipogenic, and chondrogenic differentiation. Confocal laser-scanning microscopy showed that the polyampholyte CPA did not penetrate the cell membrane; rather, it attached to the membrane during cryopreservation. These results indicate that the cryoprotective mechanisms of COOH-PLL might differ from those of currently used small molecule CPAs. These results also suggest that using COOH-PLL as a CPA for hBMSC preservation can eliminate the use of proteins and DMSO, which would be safer if these cells were used for cell transplantation or regenerative medicine.

Abstract: Macroporous, biostable scaffolds with controlled porous architecture were prepared from poly(dimethylsiloxane) (PDMS) using sodium chloride particles and a solvent casting and particulate leaching technique. The effect of particulate size range and overall porosity on the resulting structure was evaluated. Results found 90% v/v scaffolds and particulate ranges above 100 μm to have the most optimal open framework and porosity. Resulting hydrophobic PDMS scaffolds were coated with fibronectin and evaluated as a platform for adherent cell culture using human mesenchymal stem cells. Biocompatibility of PDMS scaffolds was also evaluated in a rodent model, where implants were found to be highly biocompatible and biostable, with positive extracellular matrix deposition throughout the scaffold. These results demonstrate the suitability of macroporous PDMS scaffolds for tissue engineering applications where strong integration with the host is desired.

Abstract: A completely synthetic polyampholyte cryoprotectant was developed with cationic and anionic monomers by reversible addition-fragmentation chain transfer polymerization. The neutralized random polyampholyte, which had an equal composition ratio of monomers, showed high cryoprotective properties in mammalian cells. Introduction of a small amount of hydrophobic monomer enhanced cell viability after cryopreservation, indicating the importance of hydrophobicity. Leakage experiments confirmed that these polyampholytes protected the cell membrane during cryopreservation. Due to low cytotoxicity, this polyampholyte has the potential to replace the convention cryoprotective agent dimethyl sulfoxide. The present study is the first to show that we can design a polymeric cryoprotectant that will protect the cell membrane during freezing using appropriate polymerization techniques.

Abstract: The goal of this study was to develop a long-term active antimicrobial coating for surgical sutures. To this end, two water-insoluble polymeric nanocontainers based on hyperbranched polylysine (HPL), hydrophobically modified by either using glycidyl hexadecyl ether, or a mixture of stearoyl/palmitoyl chloride, were synthesized. Highly stabilized silver nanoparticles (AgNPs, 2–5 nm in size) were generated by dissolving silver nitrate in the modified HPL solutions in toluene followed by reduction with L-ascorbic acid. Poly(glycolic acid)-based surgical sutures were dip-coated with the two different polymeric silver nanocomposites. The coated sutures showed high efficacies of more than 99.5% reduction of adhesion of living Staphylococcus aureus cells onto the surface compared to the uncoated specimen. Silver release experiments were performed on the HPL-AgNP modified sutures by washing them in phosphate buffered saline for a period of 30 days. These coatings showed a constant release of silver ions over more...

Abstract: In order to augment bone formation, a new biodegradable scaffold system was fabricated using different ratios of hydroxyapatite (HAp) blended with synthetic polymer polycaprolactone (PCL) and natural polymer gelatin (GE) followed by electrospinning method. Three different concentrations of HAp were used in PCL/GE to obtain a blend of 10, 30, and 50% (w/v) HAp–PCL/GE. These HAp-loaded PCL/GE blends were then compared with PCL/GE blends by different mechanical and biological in vitro and in vivo studies to understand the applicability of the system. Scanning electron microscopy, X-ray diffraction analysis, and tensile strength measurement were done to obtain physical properties. Fifty Percent HAp–PCL/GE blends possessed the highest mechanical strength. In vitro cytotoxicity and proliferation of osteoblast cells on the PCL/GE and HAp–PCL/GE scaffolds were examined and shown that addition of HAp in PCL/GE was beneficial by increasing cell viability (>85%) proliferation and cell-surface attachment. Expression ...

Abstract: In this work, polypyrrole (PPy) was in situ polymerized onto the surface of bacterial nanocellulose (BNC) produced by Gluconacetobacter xylinus, by chemical oxidation in aqueous medium using ammonium persulfate. Composites (BNC/PPy) were produced with varying concentrations of pyrrole (Py). The produced BNC/PPy membranes were used as a template for the seeding of PC12 rat neuronal cells. Cell suspensions were directly seeded onto the surfaces of the BNC/PPy membranes. The Py concentration affected the behavior of neuronal cells that adhered and grew significantly more on BNC/PPy comparatively to BNC. Scanning electron microscopy (SEM) micrographs revealed that PC12 cells adhered on the surface of the BNC and BNC/PPy membranes. Conductive PPy coatings on nanofibers acting as an active interface for tissue engineering may be used to regulate cell activity through electrical stimulations.

Abstract: This study aimed at evaluating the therapeutic remineralising effects of innovative light-curable materials (LCMs) containing two experimental calcium silicate-based micro-fillers (TCS) modified with β-TCP only or β-TCP, zinc oxide (ZnO)/polyacrylic acid (PAA) on mineral-depleted bonded-dentine interfaces in simulated body fluids (SBFS). Three experimental LCMs were formulated: (1) resin A, containing a β-TCP-modified TCS (βTCS) micro-filler; (2) resin B, containing a polycarboxylated β-TCP/ZnO-modified TCS (βZn-TCS) micro-filler; and 3) resin C, containing no filler (control). Acid-etched (35% H3PO4) dentine specimens were bonded using the three LCMs and submitted to atomic force microscope (AFM)/nano-indentation analysis to evaluate the modulus of elasticity (Ei) and hardness (Hi) across the interface after SBFS storage (24 h/1 m/3 m). The ultramorphology and micropermeability of the resin–dentine interface were evaluated using confocal laser microscopy. Resin–dentine sticks were created and submitted t...

Abstract: Chitosan has numerous biomedical applications such as tissue engineering scaffolds, drug/gene delivery systems, hemostasis materials, antibacterial materials, wound dressing, etc. In any case, chitosan administered in vivo would positively or passively contact or enter blood tissue. In this situation, the interaction of chitosan with blood components is critical to determine the efficacy and safety of the polymer. In this study, the effect of chitosan with different molecular weight and its derivative carboxymethyl chitosan (CMC) on the structure and function of clotting-related proteins was studied. Specifically, the structural and conformational change of fibrinogen, an important clotting protein, was studied by using UV, fluorescence, and circular dichroism spectroscopy, respectively. Further, the impact of chitosan and CMC on the clotting function was evaluated with activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen time (FT), and thromboelastography (TEG) assays. These results showed that, chitosan and fibrinogen can form complex mainly by electrostatic attraction. As a result, the structure and conformation of fibrinogen are altered by chitosan and CMC. Additionally, the presence of chitosan and CMC has little impact on the values of APTT, PT and FT, but causes significant abnormality in the clotting process by changing TEG parameters. These results provide important insight into the molecular basis for the biological response to chitosan and other biopolymers.

Abstract: In order to endow dental resin with antibacterial activity, a series of antibacterial quaternary ammonium methacrylate monomers (QAM) with different substituted alkyl chain length (from 10 to 18) were incorporated into commonly used 2,2-bis[4-(2′-hydroxy-3′-methacryloyloxy-propoxy)-phenyl]propane (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) (50 wt/50 wt) dental resin as immobilized antibacterial agents. Double bond conversion (DC), flexural strength (FS) and modulus (FM), and young and mature biofilms inhibition effectiveness of prepared dental resins were studied and Bis-GMA/TEGDMA without QAM was used as reference. Results showed that there was no significant difference on DC, FS, and FM between copolymer with and without 5 wt% QAM. Substituted alkyl chain length of QAM had no influence on DC, FS, and FM of copolymer, but had influence on antibacterial activity of copolymer. Antibacterial activity of copolymer increased with increasing of substituted alkyl chain length of QAM, and the sequence fo...

Abstract: Myocardial infarction is the major cause of death in many industrialized nations as it leads to end-stage heart failure. Tissue engineering (TE) approaches for treatment of the infarcted tissue have gained huge attention over the recent years and research in this direction mainly aims for the optimization of a biomaterial scaffold with suitable cell source for tissue regeneration. In this regard, we fabricated completely natural polymeric scaffolds using fibrinogen and gelatin in two different weight ratios and performed cross-linking [Fib/Gel(1:4)-CL; Fib/Gel(2:3)-CL] while cross-linked fibrinogen scaffolds were used as the control. The fiber diameters of the fabricated scaffolds were obtained in the range of 150–300 nm. Chemical characterization of the scaffolds confirmed the presence of both the proteins and showed the absence of any chemical reactions between them. The tensile strength and the stiffness values of Fib/Gel(1:4)-CL matrices were found to be 0.0125 and 0.46 MPa, respectively, which were m...

Abstract: In this study, a novel hybrid polyurethane/polycaprolactone (PU/PCL) tubular scaffold was fabricated using the electrospinning process for blood vessel prosthesis applications. The detailed microstructure and material properties such as porosity, tensile and bust strength, contact angle, and biocompatibility were investigated and compared with those of monolithic PU and PCL scaffolds. The mechanical properties of the hybrid PU/PCL scaffold (tensile strength: 18 MPa, pressure strength: 590 mmHg) were found to be within the range needed for artificial blood vessel applications. The pore sizes of the PU/PCL scaffold ranged from 5–150 um in diameter, are sufficient enough to allow nutrient diffusion across the membrane. The reduced hydrophobic property of the PU/PCL scaffold was the result of the addition of relatively less hydrophobic PU compared with monolithic PCL scaffold. The biocompatibility of the PU/PCL scaffold was evaluated through cytotoxicity testing, and morphological observation by scanning elec...

Abstract: Three-dimensional (3D) growth of cell is of particular interest in the field of tissue engineering and regenerative medicine. Scaffolds used for this purpose are often tailor-made to mimic the microenvironment and the extracellular matrix of the tissue with defined role such as to provide appropriate structural, chemical, and mechanical support. The aim of the study was to design the macroporous matrix with potential in the field of tissue engineering especially for lung muscle regeneration. Blend of hydroxyethyl methacrylate-alginate-gelatin (HAG) cryogel scaffold was synthesized using cryogelation technique and this polymer material combination is being reported first time. The rheology study showed the elastic property of the material in wet state with no variation in storage modulus (G′), loss modulus (G″), and phase angle upon temperature variation. The microcomputer tomography (micro-CT) analysis confirmed the homogenous polymer structure with average pore diameter of 84 μm. Scaffold synthesized usi...

Abstract: Emulsion electrospinning is an advanced technique to fabricate core-shell structured nanofibrous scaffolds, with great potential for drug encapsulation. Incorporation of dual factors hydroxyapatite (HA) and laminin, respectively, within the shell and core of nanofibers through emulsion electrospinning might be of advantageous in supporting the adhesion, proliferation, and maturation of cells instead of single factor-encapsulated nanofibers. We fabricated poly(L-lactic acid-co-e-caprolactone) (PLCL)/hydroxyapaptite (PLCL/HA), PLCL/laminin (PLCL/Lam), and PLCL/hydroxyapatite/laminin (PLCL/HA/Lam) scaffolds with fiber diameter of 388 ± 35, 388 ± 81, and 379 ± 57 nm, respectively, by emulsion electrospinning. The elastic modulus of the prepared scaffolds ranged from 22.7-37.0 MPa. The osteoblast proliferation on PLCL/HA/Lam scaffolds, determined on day 21, was found 10.4% and 12.0% higher than the cell proliferation on PLCL/Lam or PLCL/HA scaffold, respectively. Cell maturation determined on day 14, by alkaline phosphatase (ALP) activity, was significantly higher on PLCL/HA/Lam scaffolds than the ALP activity on PLCL/HA and PLCL/Lam scaffolds (p ≤ 0.05). Results of the energy dispersive X-ray studies carried out on day 28 also showed higher calcium deposition by cells seeded on PLCL/HA/Lam scaffolds. Osteoblasts were found to adhere, proliferate, and mature actively on PLCL/HA/Lam nanofibers with enhanced cell proliferation, ALP activity, bone protein expression, and mineral deposition. Based on the results, we can conclude that laminin and HA individually played roles in osteoblast proliferation and maturation, and the synergistic function of both factors within the novel emulsion electrospun PLCL/HA/Lam nanofibers enhanced the functionality of osteoblasts, confirming their potential application in bone tissue regeneration.

Abstract: Supercritical Emulsion Extraction in a Continuous operation layout is proposed for the production of poly-lactic-co-glycolic acid (PLGA) microspheres loaded with insulin, selected as a model of bioactive signal. Microspheres with different mean sizes of 2 μm (±0.9 μm) and 3 μm (±2.2 μm) and insulin loadings of 3 and 6 mg/g were obtained by processing different water–oil–water emulsions; an encapsulation efficiency of about 60% w/w was measured in all cases. Insulin release profiles from PLGA microspheres were also characterized in two different media (Phosphate-Buffered Saline and Dulbecco’s Modified Eagle Medium) and kinetic constants were estimated by using a model proposed in literature. The produced microspheres were, then, used for the cultivation of rat embryonic ventricular myoblasts in a serum-free medium to monitor the biological effect of the released insulin. The best cell viability and proliferation, supported by released insulin, was monitored when microspheres with mean size of 3 μm loaded w...

Abstract: Drug-delivery systems, using natural drug carriers, have become increasingly important because of their nontoxicity and biodegradability. In this study, firstly, quaternized carboxymethyl chitosan (QCMC) was intercalated into the interlayer of organic montmorillonite (OMMT) to obtain the QCMC/OMMT nanocomposites, their structure, morphology, and thermal stability were investigated. Next, crosslinked alginate/QCMC/OMMT (AQCOM) microsphere was obtained by crosslinking with CaCl2, and the drug-controlled release behavior was evaluated with bovine serum albumin (BSA) as model drug. The results suggested that, carboxyl groups in alginate and QCMC crosslinked with Ca(2+), quaternary ammonium groups in QCMC or OMMT electrostatically interacted with carboxyl groups in alginate, and there was stable three-dimensional network in AQCOM microsphere. The swelling ratio of AQCOM microspheres decreased with the increase of OMMT content, the lowest one was only about 45% compared to the microsphere without OMMT of 197%. Besides, the in vitro release results for BSA indicated that the AQCOM microsphere displayed more excellent encapsulation and controlled release capacities than the microsphere without OMMT. The in vitro active cutaneous anaphylaxis test was carried out on Guinea pigs, which revealed that AQCOM microsphere did not cause anaphylaxis. Therefore, QCMC/OMMT nanocomposites from natural materials are considerably suitable to apply as drug-controlled release carriers.

Abstract: In recent years, injectable chitosan-based hydrogels have been widely studied towards biomedical applications because of their potential performance in drug/cell delivery and tissue regeneration. In this study, we introduce a simple and organic solvent-free method to prepare tyramine–tetronic–grafted chitosan (TTeC) via activation of four terminal hydroxyl groups of tetronic, partial tyramine conjugate into the activated product and grafting the remaining activated moiety of tetronic-tyramine onto chitosan. The grafted copolymer was well characterized by UV–Visible, 1H NMR, and Thermogravimetric analysis. The aqueous TTeC copolymer solution rapidly formed hydrogel in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) at physiological conditions. The gelation time of the hydrogel was performed within a time period of 4–60 s, when the concentrations of HRP, H2O2, and polymers varied. The hydrogel exhibited highly porous structure which could be controlled by using H2O2. In vitro cytot...

Abstract: Thermosensitive hydrogel containing drug-loaded liposomes delivery system offers the possibility of reduced dosing frequency and sustained drug action. In the study, a soluble chitosan derivative, ...

Abstract: This study compares the efficacy of growth factors that are covalently immobilized to those that are adsorbed in improving the bioactivity of a biomaterial. Bone morphogenetic protein-2 (BMP-2) or fibroblast growth factor-2 (FGF-2) was covalently bonded to chitosan films using carbodiimide chemistry. For BMP-2, a growth factor loading efficiency of ∼64% was obtained with this method compared to ∼25% from adsorption. As for FGF-2, the growth factor loading efficiency of the two methods was similar at ∼50%. The covalently immobilized BMP-2 promoted attachment, proliferation, and differentiation of osteoblasts in a dose-dependent manner, whereas the covalently immobilized FGF-2 stimulated fibroblast attachment, proliferation, and collagen synthesis. After three weeks immersion in phosphate buffered saline, about 80% of the covalently immobilized growth factors were retained on the films, while only ∼16 and ∼21% of the adsorbed BMP-2 and FGF-2 remained on the corresponding films. The higher retention rate of the covalently immobilized growth factors enabled their stimulatory effects to persist for a longer period than when adsorbed growth factors were used.

Abstract: The aim of this study is to prepare a novel wound dressing material which provides burst release of an antibiotic in combination with sustained release of growth factor delivery. This might be beneficial for the prevention of infections and to stimulate wound healing. As a wound dressing material, the semi-interpenetrating network (semi-IPN) hydrogel based on polyacrylamide (PAAm) and chitosan (CS) was synthesized via free radical polymerization. Ethylene glycol dimethacrylate was used for cross-linking of PAAm to form semi-IPN hydrogel. The hydrogel shows high water content (∼1800%, in dry basis) and stable swelling characteristics in the pH range of the wound media (∼4.0–7.4). The antibiotic, piperacillin–tazobactam, which belongs to the penicillin group was loaded into the hydrogel. The therapeutic serum dose of piperacillin–tazobactam for topic introduction was reached at 1st hour of the release. Additionally, in order to increase the mitogenic activity of hydrogel, epidermal growth factor (EGF) was e...

Abstract: Novel nanocomposite hydrogels composed of hyaluronan (HA), poly(vinyl alcohol) (PVA) and silver nanoparticles were prepared by several cycles of freezing and thawing. The nanocomposite was then characterised using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD) and scanning electron microscopy (SEM). The complex hydrogels consisted of semi-interpenetrating network structures, with PVA microcrystallines as junction zones. By increasing the HA content, the crystallinity and melting temperature of the complex hydrogels decreased, whereas the glass transition temperatures of these materials increased because of the steric hindrance of HA and the occurrence of intermolecular interactions through hydrogen bonding between HA and PVA in the complex hydrogels. Swelling studies showed that in comparison with the swelling properties of the cryogels from PVA alone, those of the complex hydrogels can be significantly improved and presented in ...

Abstract: In this article, a sustained release formulation of the antioxidant gallic acid (GA) is presented in the form of glutathione responsive disulfide cross-linked poly(ethylene glycol)-based nanogels synthesized via aqueous inverse miniemulsion using atom transfer radical polymerization. The particle size was found to be in the range from 227 ± 51.78 to 573.3 ± 207.2 nm at three drug loading levels achieved i.e. 6.6, 14.26, and 18.29 wt.% of the nanogels with loading efficiency in the range of 60–70%. The release profile of the GA studied at three drug loading levels suggested a controlled release and the nanogels were capable of scavenging radicals and retained the antioxidant activity. The GA-loaded nanogels were found to be biocompatible on human cervical cancer cell lines (HeLa). DCFH-DA (2,7-dichlorofluorescin diacetate) assay evidenced that the nanogels were capable of scavenging the reactive oxygen species in cellular environment.

Abstract: This study aimed to investigate the efficacy of an artificial dermis composed of hyaluronic acid (HA) and collagen (Col) with or without epidermal growth factor (EGF), both in in vitro and in vivo. The cross-linked high molecular weight HA spongy sheet was prepared by freeze-drying. The spongy sheet was immersed in a mixed solution of high molecular weight HA, low molecular weight HA, and heat-denatured Col, and then lyophilized to obtain a two-layered spongy sheet. Cross-linking among Col molecules was induced by ultraviolet irradiation to prepare the artificial dermis (Type I). In a similar manner, a two-layered artificial dermis containing EGF (Type II) was prepared using a similar mixed solution containing EGF. The in vitro experiments demonstrated that EGF released from the Type II artificial dermis stimulates fibroblasts to produce increased amounts of vascular endothelial growth factor and hepatocyte growth factor. The therapeutic efficacy of artificial dermis was evaluated in animal tests using Sp...

Abstract: Alginate, a polysaccharide extracted from brown seaweed, remains the most widely used biomaterial for immobilizing cells to be transplanted, because of the good viability of the encapsulated cells and the relatively ease of processing for cell encapsulation. However, the main drawback is the immune reaction in vivo. To overcome this problem, we have demonstrated a modified Korbutt method for alginate purification. After alginate microcapsules were manufactured, NIH/3T3 fibroblast cells were seeded in purified and non-purified alginate microcapsules, and the cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide assay. Reverse transcriptase-polymerase chain reaction was performed to assess the mRNA expression of RAW 264.7 macrophage cells for inflammation cytokines such as TNF-α. Purified and non-purified alginate microcapsules were implanted into Wister rats, and subsequently extracted after 1–2 weeks. Tissues surrounding the implants were harvested and underwent h...

Abstract: An ideal material for maxillofacial prostheses has not been found. We created a novel material: silicone elastomer filled with hollow microspheres and characterized its biomechanical properties. Expancel hollow microspheres were mixed with MDX4-4210 silicone elastomer using Q7-9180 silicone fluid as diluent. The volume fractions of microspheres were 0, 5, 15, and 30% v/v (volume ratio to the total volume of MDX4-4210 and microspheres). The microspheres dispersed well in the matrix. The physical properties and biocompatibility of the composites were examined. Shock absorption was the greatest by the 5% v/v composite, and decreased with increasing concentrations of microspheres. The density, thermal conductivity, Shore A hardness, tear and tensile strength decreased with increasing concentrations of microspheres, while elongation at break increased. Importantly, the tear strength of all composites was markedly lower than that of pure silicone elastomer. Cell viability assays indicated that the composite was...

Abstract: A straightforward method to prepare nonionic polymer (polyacrylamide, PAM) cross-linked chitosan hydrogel has been developed. The chitosan-polyacrylamide (CS-PAM) hydrogel could be quickly obtained by simply mixing of chitosan and polyacrylamide solutions under very benign condition (room temperature, <30 s). The cytotoxicity and hemocompatibility of the CS-PAM hydrogel were subsequently investigated. Cells retained normal morphology even when the concentration of CS-PAM hydrogel in culture system was as high as 640 μg mL(-1), indicating the CS-PAM hydrogel has minimal cytotoxicity to A549 and HeLa cells. Meanwhile, no hemolysis was observed after incubating the CS-PAM hydrogel with red blood cells for 6 h, further suggesting excellent biocompatibility of the hydrogel. Scanning electron microscopy images illustrated that the CS-PAM hydrogel can absorb red blood cells through the interaction between the protonated amine groups on chitosan and the negative charged residues on red blood cell membranes. Given its low cost, simple preparation, and excellent biocompatibility, this CS-PAM hydrogel might be a potential biomaterial for future healthcare and biomedical applications.

Abstract: In this study, three dimensional (3D) polycaprolactone/bio-derived hydroxyapatite (PCL/BHA) composite scaffolds were fabricated by using a melt-deposition system (MDS) for the applications in bone repair. PCL/BHA composites with BHA contents of 0, 10, 20, and 40% were successfully processed into 3D scaffolds by using MDS, while it was failed to fabricate PCL/BHA scaffold with BHA content of 60%. The scaffolds produced were demonstrated to possess the same structures as the predefined with highly uniform and completely interconnected pores. The compressive modulus and strength of the PCL/BHA scaffold increased from 27 to 56 MPa and from 1.9 to 4.5 MPa, respectively, as BHA content increased from 0 to 40%. The wettability of PCL/BHA composite scaffold was also improved with the increase of BHA content. Moreover, the PCL/BHA scaffolds fabricated by MDS showed satisfactory biocompatibility and were capable of being integrated with the surrounding host bone. This study shows the feasibility of fabricating 3D P...