Soluble‐eggshell‐membrane‐protein‐modified porous silk fibroin scaffolds with enhanced cell adhesion and proliferation properties

In this study, a porous silk fibroin (SF) scaffold was modified with soluble eggshell membrane protein (SEP) with the aim of improving the cell affinity properties of the scaffold for tissue regeneration. The pore size and porosity of the prepared scaffold were in the ranges 200–300 μm and 85–90%, respectively. The existence of SEP on the scaffold surface and the structural and thermal stability were confirmed by energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The cell culture study indicated a significant improvement in the cell adhesion and proliferation of mesenchymal stem cells (MSCs) on the SF scaffold modified with SEP. The cytocompatibility of the SEP‐conjugated SF scaffold was confirmed by a 3‐(4,5‐dimethyltriazol‐2‐y1)‐2,5‐diphenyl tetrazolium assay. Thus, this study demonstrated that the biomimic properties of the scaffold could be enhanced by surface modification with SEP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40138.     

Assessment of cell proliferation in salt‐leaching using powder (SLUP) scaffolds with penetrated macro‐pores

In this study, a salt‐leaching using powder (SLUP) scaffold with penetrated macropores was proposed to enhance cell proliferation. A SLUP scaffold is a salt‐leaching scaffold with an arbitrary pore configuration. Although SLUP scaffolds have several advantage over traditional salt‐leaching scaffolds, the cell ingrowth might be poor compared with solid freeform fabrication scaffolds, which have well‐interconnected pores. We therefore proposed SLUP scaffolds with penetrated macropores to assist the cell ingrowth. First, polycaprolactone (PCL) powders with a grain size of 63–100 μm and NaCl powders with a grain size of 100–180 μm were prepared. Next, a uniformly perforated mold was fabricated using an rapid prototyping (RP) system. Then, 500‐, 820‐, or 1200‐μm‐diameter needles were inserted into the holes of the RP mold. Subsequently, the mold was filled with a mixed powder of PCL/NaCl (30 : 70 vol %). The mold was then heated in the oven at 100°C for 30 min, and both the needles and the mold were removed from the PCL/NaCl mixture. Then, the PCL/NaCl mixture was soaked in DI water for 24 h to leach out NaCl particles and dried in a vacuum desiccator for 24 h. The porosity of fabricated scaffolds was calculated using a simple equation, and the compressive stiffness was measured using a universal testing machine. Moreover, each scaffold (10 × 10 × 10 mm³) was seeded with 100,000 Saos‐2 cells and cultured for 14 days. The cell proliferation characteristics were assessed using a CCK‐8 assay at 1, 7, and 14 days for comparison with the control scaffolds, that is, the SLUP scaffolds with no penetrated macropores. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40240.     

Silk fibroin‐chondroitin sulfate‐alginate porous scaffolds: Structural properties and in vitro studies

The development of porous biodegradable scaffolds is of great interest in tissue engineering. In this regard, exploration of novel biocompatible materials is needed. Silk fibroin‐chondroitin sulfate‐sodium alginate (SF‐CHS‐SA) porous hybrid scaffolds were successfully prepared via lyophilization method and crosslinked by 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide‐ethanol treatment. According to the scanning electron microscopy studies, mean pore diameters of the scaffolds were in the range of 60–187 μm. The porosity percentage of the scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (w/w/w %) was 92.4 ± 3%. Attenuated total reflectance Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry results confirmed the transition from amorphous random coil to crystalline β‐sheet in treated SF‐CHS‐SA scaffold. Compressive modulus was significantly improved in hybrid scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (3.35 ± 0.15 MPa). Cytotoxicity assay showed that the scaffolds have no toxic effects on chondrocytes. Attachment of chondrocytes was much more improved within the SF‐CHS‐SA hybrid scaffold. Real‐time polymerase chain reaction analyses showed a significant increase in gene expression of collagen type II, aggrecan, and SOX9 and decrease in gene expression of collagen type I for SF‐CHS‐SA compared with SF scaffold. This novel hybrid scaffold can be a good candidate to be utilized as an efficient scaffold for cartilage tissue engineering. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41048.     

Biodegradation of in situ‐forming gel of poly(DLLA‐co‐CL) in vivo

Poly(dl ‐lactide‐co‐caprolactone) was dissolved in N‐methyl‐2‐pyrolidone (NMP) for preparing blank group formulation, and drug group was prepared by dissolving testosterone undecanoate (TU) as model drug in blank group. These formulations rapidly gelled by solvent diffusion effect after subcutaneous injection. The in vivo degradation of copolymer gel in rabbits was investigated after injection. The GPC and ¹H NMR results showed that no matter the gel contained drug or not, it had no effect on degradation rate for the P(DLLA‐co‐CL) carrier. Degradation products of copolymer were absorbed or excreted based on metabolism. Copolymer molar composition changed slightly in 3 months. The structures and characteristic of copolymers were characterized via DSC, TGA, and SEM, respectively. Experimental results showed that the copolymer had excellent heat resistance. Crystallinity increased gradually during degradation process. A dense cross‐sectional structure formed after 90 days. In addition, it can be obviously found that the degradation process of the copolymer proceeded in two steps. Mechanism of copolymer biodegradation in vivo was bulk degradation. The gel could well administrate the release of TU in a sustained way without significant burst features. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3800–3808, 2013     

Investigations on porous PLA composite scaffolds with amphiphilic block PLA‐b‐PEG to enhance the carrying property for hydrophilic drugs of excess dose

To address concern of the dispersion property of hydrophilic drugs of excess dose loaded in a hydrophobic poly(lactic acid) (PLA) matrix, this work developed a PLA and PLA‐b‐polyethylene glycol (PEG) composite scaffold ( ) and studied its carrier properties for aspirin as a model hydrophilic drug. The porous functional scaffolds were prepared from PLA and PLA‐b‐PEG solutions with the dose of 5, 10, and 15 wt % aspirin preloaded. The products and control samples of pure PLA with the same loading amount for comparison were characterized by scanning electron microscopy and X‐ray diffraction to examine the miscibility and porous structure. Rapid degradations in a strongly basic solution were performed to determine the actual loading amount and the encapsulation ratio. The in vitro release in phosphate buffer saline (PBS) at 37.5 °C indicated that the addition of amphiphilic block polymer may efficiently enhance the dispersion property and stabilize the release of hydrophilic drugs, especially with a high loading dose. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44489.     

In vitro hydrolysis and magnesium release of poly(d,l‐lactide‐co‐glycolide)‐based composites containing bioresorbable glasses and magnesium hydroxide

Magnesium is important for both bone growth and cartilage formation. However, the postoperative intake of antibiotics such as quinolones may cause a reduction in magnesium levels in tissue. The addition of magnesium to scaffolds may therefore be beneficial for the regeneration of osteochondral defects. In this study, porous composite scaffolds were produced by gas foaming of poly(d ,l ‐lactide‐co‐glycolide) (PLGA) rods with magnesium‐containing bioresorbable glasses and magnesium hydroxide as fillers. The in vitro hydrolytical degradation of the composite scaffolds in Tris buffer was followed over a 10‐week period. Mg²⁺ was released in a controlled manner from the scaffolds with varying release profiles between the different materials. Higher glass content resulted in a reduced mass loss compared to scaffolds with lower glass content. As a result of the foaming method, the scaffolds shrank initially, without evidence that the addition of hydrophilic fillers would decrease the initial shrinkage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42646.     

Antimicrobial cytocompatible pentaerythritol triacrylate‐co‐trimethylolpropane composite scaffolds for orthopaedic implants

As of 2010, 5.3 million orthopedic surgeries are performed each year, and this number is expected to increase to 6.2 million by 2020. On average, 27.7% of all orthopedic surgeries result in infection which often leads to osteomyelitis and the loss of supporting bone. In this study, we describe two synthetic bone grafts, or augmentation methods, for a biodegradable, silver nanoparticle (SNPs) containing antimicrobial scaffolds composed of pentaerythritol triacrylate‐co‐trimethylolpropane tris (3‐mercaptopropionate) (PETA) and hydroxyapatite (HA). This osteoinductive and degradable material is designed to stimulate proliferation of bone progenitor cells, and provide controlled release of antimicrobial components. The first method, denoted as the “incorporating method,” involves dissolving SNPs in ethanol, butanol, or isopropanol and directly incorporating the particles into the scaffold prior to polymerization. The second method, “coating method,” involves submerging fabricated scaffolds into their respective SNPs‐solution and mixing for 24 h. The coating method allowed better distribution and release of SNPs from the surface of the composites when exposed to extracellular media. The in vitro release of silver for both methods was quantified by inductively coupled plasma optical emission spectroscopy (ICP‐OES). The scaffolds made by means of the coating method showed increased release of silver with respect to time; no silver leached from the scaffolds formed by the incorporating method. Use of Alamar Blue assay demonstrated that the SNPs incorporation did not affect cell viability when tested with hASCs. The scaffolds formed by the coating method inhibited the proliferation of Staphylococcus aureus 99.5% and Escherichia coli by 99.9% within 24 h. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41099.     

The use of poly (ε‐caprolactone) to enhance the mechanical strength of porous Si‐substituted carbonate apatite

Poly(ε‐caprolactone) (PCL)/silicon‐substituted carbonate apatite (Si‐CO3Ap) composite derived from the interconnected porous Si‐CO3Ap reinforced with molten PCL was prepared. PCL was used to improve the mechanical properties of a porous apatite by a simple polymer infiltration method, in which the molten PCL was deposited through the interconnected channel of porous Si‐CO3Ap. The PCL covered and penetrated into the pores of the Si‐CO3Ap to form an excellent physical interaction with Si‐CO3Ap leading to a significant increase in diametral tensile strength from 0.23 MPa to a maximum of 2.04 MPa. The Si‐CO3Ap/PCL composite has a porosity of about 50–60% and an interconnected porous structure, with pore sizes of 50–150 μm which are necessary for bone tissue formation. These results could pave the way for producing a porous, structured biocomposite which could be used for bone replacement. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of chitosan derivative with dual‐antibacterial functional groups and its antibacterial activity

The O‐fumaryl ester (OFTMCS) of N,N,N‐trimethyl chitosan (TMCS) has been synthesized as a water‐soluble chitosan (CS) derivative bearing dual‐functional groups, with the aim of discovering novel CS derivatives with good water solubility and enhanced the antibacterial activity compared with unmodified CS. OFTMCS was characterized by FT‐IR, ¹³C NMR, XPS, XRD and Zeta potential analyses. The XPS results indicated that the degree of substitution (DS) on the C₂‐NH₂ group of the CS was 0.78, and that the DS on its C₆‐OH group was 0.31. The TGA results showed that the thermal stability of OFTMCS was lower than that of unmodified CS. The antibacterial activities of OFTMCS were investigated by assessing the mortality rates of the representative Gram‐positive and Gram‐negative bacteria Staphylococcus aureus and Escherichia coli, respectively. The results indicated that OFTMCS exhibited superior antibacterial activity to CS at a lower dosage. The synthesis of CS derivatives bearing dual‐functional groups could therefore be used as a promising strategy to enhance the antibacterial activity of CS. The antimicrobial mechanism of action of OFTMCS was discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42663.     

Core–shell PVA/gelatin nanofibrous scaffolds using co‐solvent,aqueous electrospinning: Toward a green approach

Electrospinning (ES) of gelatin often requires cytotoxic organic solvents or acidic environments, which deteriorate cell recognition sites. In this study, aqueous, non‐toxic, co‐solvent ES was performed to obtain core–shell poly(vinyl alcohol) (PVA)/gelatin nanofiber scaffolds. Effects of the core/shell feed rate ratio (FRR) were investigated on a morphological and mechanical basis. PVA:gelatin ratio of 1:4 was the limiting ratio for specific voltage and electrode distance parameters to obtain uniform fibers. Core–shell bead‐free structures were obtained at 8% PVA and gelatin aqueous solutions. A mean diameter of 280 nm was obtained for 1:1 FRR at 15 kV and 15 cm of electrode distance. Crosslinking resulted in slight improvement in tensile strengths and severe decrease in ductility. Fourier transform infrared spectra revealed retention and improvement of stable secondary structures of gelatin after ES. The scaffolds almost degraded more than 60% in 14 days. Based on the results, present scaffolds hold great promise as suitable candidates for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46582.     

Silver nanoparticle incorporated poly(l‐lactide‐co‐glycolide) nanofibers: Evaluation of their biocompatibility and antibacterial properties

The objective of this work is the fabrication of poly(l ‐lactide‐co‐glycolide) or PLGA (with LA/GA ratios of 50/50 and 75/25) nanofibers containing silver nanoparticles (AgNPs) by the method of electrospinning. The incorporation of AgNPs in PLGA was carried out in three different concentrations (1, 3, 6 w/w %).The electrospun nanofibers were evaluated for their morphology by scanning electron microscopy and their fiber diameters ranged between 487 and 781 nm. Integration of AgNPs within the fibers was verified by spectroscopy studies, while the mechanical properties of the developed fibers were found comparable to the mechanical properties of the human skin. Proliferation of human dermal fibroblasts (HDF) demonstrated minimal cytotoxicity on fibers containing 1 wt % and 3 wt % of AgNPs, while 6 wt % of AgNPs inhibited cell proliferation. Antimicrobial activity was studied using three different strains of Gram‐positive and Gram‐negative bacteria. Results of the HDF proliferation and antimicrobial studies showed that the electrospun PLGA75/25 containing 3 wt % AgNP can function as a suitable substrate for wound dressing, compared to the other scaffolds of this study. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42686.     

Elaboration of small‐diameter vascular prostheses—Selection of appropriate sterilisation method

The aim of study is the elaboration of semi‐biodegradable, multilayered tubular structures as substitutes for the reconstruction of small diameter vascular prostheses (<6 mm). The inert external layer of the prostheses will be fabricated via the melt electrospinning of poly (l ‐lactide‐co‐glycolide) (PLGA). The middle layer will be constructed from polypropylene (PP); the first prototype will be produced via melt electrospinning and the second using the melt blowing technique. The general aim of this stage of the research is the selection of a sterilisation technique that is appropriate for semi‐biodegradable, multilayered tubular structures. For this purpose, single tubular structures created via the melt electrospinning of PLGA or PP and melt blown tubular structures of PP were elaborated. The influence of steam, ethylene‐oxide (EO), and radiation sterilisation techniques on the elaborated microstructure of tubular structures was analyzed during this study. The effect of each sterilisation technique was evaluated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy analysis (SEM/EDS). The changes in average molecular weight (M_w) and crystallinity index (CI) of the PLGA tubular structures after EO and steam sterilisation were evaluated. The EO and steam sterilisation resulted in the complete destruction of PLGA tubular structures. Only the radiation sterilisation (accelerated electrons) did not influence on PLGA tubular structures morphology as well as thermal and chemical properties. FTIR and SEM/EDS analysis indicated that no changes in the chemical properties of PP tubular structures after each sterilisation occurred. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40812.     

Preparation,characterization, and properties of modified barium sulfate nanoparticles/polyethylene nanocomposites as T‐shaped copper intrauterine devices

To improve the mechanical properties and shelf‐life of barium sulfate nanoparticles (BaSO₄‐NPs)/polyethylene (PE) composites, which are used as the scaffold of T‐shaped copper intrauterine devices (Cu‐IUDs) in the clinic, an Al coupling agent was used to modify BaSO₄‐NPs. The influence of the Al coupling agent on the microstructures, properties, and shelf‐life of the nanocomposites were investigated. The results showed that: (1) a chemical reaction occurred between the Al coupling agent and the hydroxyl groups adsorbed by BaSO₄‐NPs. (2) BaSO₄‐NPs modified by the Al coupling agent dispersed in the PE matrix were much better than unmodified NPs. The interface bonding between modified NPs and the PE matrix was better than unmodified NPs. (3) the maximum tensile strength of nanocomposites containing modified NPs was 11.87 MPa, flexural strength was 6.61 MPa, and the elongation rate was 66.78%. (4) After an accelerated aging experiment, the tensile strength of the nanocomposites only decreased 5–15%. All of these results indicate that m‐BaSO₄‐NPs/PE nanocomposites are more clinically useful than unmodified nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40393.     

Characterization and mechanical properties of ultraviolet stimuli‐responsive functionalized cellulose nanocrystal alginate composites

The poor mechanical properties of alginate when exposed to aqueous solution have been a problem plaguing researchers within the biomedical field. In order to be able to improve the mechanical properties in a systematic manner functionalized cellulose nanocrystals (CNCs) were added to alginate and UV‐induced crosslinked following an azo‐initiated free radical polymerization. CNCs were functionalized with 4‐pentenoic acid (PA‐g‐CNCs) using a simple, environmentally friendly solvent‐free esterification. The dimensional and crystallinity properties of PA‐g‐CNCs remained unchanged following esterification. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and ¹³C nuclear magnetic resonance indicated that 4‐pentenoic acid was present on the surface of CNCs through bulk analysis. These PA‐g‐CNCs were then used in the creation of composites with an azo‐initiator to induce UV‐dependent crosslinking for the improvement of the mechanical properties of alginate. It was shown that the properties of alginate can be enhanced with the addition of functionalized CNCs to nanocomposites in mechanical testing in wet and dry conditions. These results suggest that the addition of PA‐g‐CNCs and crosslinking by UV‐dependent free radical polymerization improves the performance of alginate when tested in dry conditions, but without any apparent dependence to azo‐initiated crosslinking when exposed to water in regards to mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45857.     

Microwave‐assisted synthesis of chitosan biguanidine hydrochloride and its antioxidant activity in vitro

Chitosan biguanidine hydrochloride (CSGH) was synthesized by guanidinylation of chitosan hydrochloride (CSH) under microwave irradiation and characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and element analysis. The antioxidant activity of CSGH was evaluated by both chemical and cellular methods. The results showed that CSGH was better than CSH but slightly inferior to ascorbic acid (Vc) for scavenging 2,2‐diphenyl‐1‐picryl‐hydrazyl (DPPH) free radicals, and the DPPH? scavenging ability of CSGH was dose‐dependent. However, cell experiments indicated CSGH had a superior repairing effect on oxidatively damaged cells. The intervention of CSGH could excellently recover the cell morphology, decrease the level of malondialdehyde, and enhance the activity of superoxide dismutase and glutathione peroxidase. CSGH could be a potential antioxidant reagent, and its antioxidant activity was reflected not only in scavenging the free radicals but also in regulating the oxidation/antioxidation balance of damaged cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43570.     

Improvement of surface hydrophilicity,water uptake,biodegradability, and cytocompatibility through the incorporation of chitosan oligosaccharide into poly(l‐lactide)

Poly(l ‐lactide) (PLLA)‐based biocomposites incorporated with different amounts of chitosan oligosaccharide (COS) were developed through solvent‐casting method. Then, the physical–chemical properties, surface morphology, hydrophilicity, water uptake, biodegradability, and biocompatibility of the COS/PLLA composites were investigated. Fourier transform infrared and X‐ray diffraction results showed that strong hydrogen‐bonding interactions were presented between the COS and PLLA components. Scanning electron microscope and atomic force microscope images revealed that COS physically attached on the PLLA surface enhanced the formation of the surface seepage network, which led to the improvement of the surface biological features. A gradual rise in the level of hydrophilicity, water uptake, and degradation rate in phosphate buffered saline solution were found on increasing COS content in the COS/PLLA composites, which may provide effective support for cell adhesion and proliferation. Further, the results of cell experiments also suggested that the COS/PLLA composites had better cytocompatibility compared with PLLA. Thus, the COS/PLLA composites may have the great potential to be used for soft and bone tissue repair. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45724.     

Preparation and characterization of mPEG‐g‐α‐zein biohybrid micelles as a nano‐carrier

A new kind of block copolymer micelles methoxy polyethylene glycol (mPEG) grafted α‐zein protein (mPEG‐g‐α‐zein) was synthesized. The chemical composition of mPEG‐g‐α‐zein was identified with the help of FT‐IR and ¹H‐NMR. The biohybrid polymer can self‐assemble into spherical core–shell nanoparticles in aqueous solution. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to investigate the self‐assembled morphology of mPEG‐g‐α‐zein. Dynamic light scattering (DLS) results showed that the particle size of mPEG‐g‐α‐zein was about 90 nm. Moreover, the nanoparticles had a very low critical micelle concentration value with only 0.02 mg/mL. Then, the anticancer drug curcumin (CUR) was encapsulated into the biohybrid polymer micelles. The in vitro drug release profile showed a zero‐order release of CUR up to 12 h at 37°C. Cell viability studies revealed that the mPEG‐g‐α‐zein polymer exhibited low cytotoxicity for HepG2 cells (human hepatoma cells). Consequently, the mPEG‐g‐α‐zein micelles can be used as a potential nano‐carrier to encapsulate hydrophobic drugs and nutrients. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42555.     

Oxidation resistance and abrasive wear resistance of vitamin E stabilized radiation crosslinked ultra‐high molecular weight polyethylene

The effect of gamma radiation on the oxidation and wear resistance of ultra‐high molecular weight polyethylene (UHMWPE) has been extensively studied since these properties are critical for the longevity of UHMWPE components of total joint replacement prostheses. While gamma radiation increases wear resistance of UHMWPE, the free radical generated in the lamellar regions by radiation must be stabilized before oxidative degradation occurs as the polymer ages. Initially, post‐radiation melting conducted to quench free radicals but this treatment also decreases its mechanical properties. Recently, it has been replaced by incorporation of Vitamin E into UHMWPE to combat oxidative degradation. In this study, we assessed wear resistance of Vitamin E stabilized UHMWPE under abrasive wear conditions and oxidation resistance by shelf‐aging irradiated components for 2 years. Equilibrium swelling experiments showed that Vitamin E decreased crosslink density, which affected wear resistance, but oxidation resistance was better preserved with increasing concentration of Vitamin E. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44125.     

Tunable multifunctional tissue engineering scaffolds composed of three‐component polyampholyte polymers

Resistance to nonspecific protein adsorption and the capability to provide targeted bioactive signals are essential qualities for implantable biomaterials. The development of materials that combine these multifunctional characteristics and tunable mechanical properties has been a target in the tissue engineering field over the last decade. This study is the first to demonstrate that polyampholyte hydrogels prepared with equimolar quantities of positively charged and negatively charged monomer subunits from multiple monomer compositions have great potential to address these needs. The hydrogels were synthesized with positively charged [2‐(acryloyloxy)ethyl] trimethylammonium chloride and different monomer ratios of the negatively charged 2‐carboxyethyl acrylate and 3‐sulfopropyl methacrylate monomers. The physical and chemical properties of the hydrogels were fully characterized, including swelling, hydration, mechanical strength, and chemical composition, and the fouling resistance of the hydrogels was demonstrated using enzyme‐linked immunosorbent assays. Additionally, the capability of the hydrogels to facilitate protein conjugation via EDC/NHS conjugation chemistry was assessed. The results clearly demonstrate that the polyampholyte hydrogels have a range of tunable mechanical strength based on the monomer subunits, while maintaining their excellent nonfouling properties. Additionally, high levels of conjugated protein were achieved for all of the monomer combinations investigated. Therefore, the broadly applicable multifunctional properties of polyampholyte hydrogels and their tunable mechanical properties clearly demonstrate the potential of these materials for tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43985.     

Compressive properties and creep resistance of a novel,porous, semidegradable poly(vinyl alcohol)/poly(lactic‐co‐glycolic acid) scaffold for articular cartilage repair

Tissue engineering for articular cartilage repair has shown success in ensuring the integration of neocartilage with surrounding natural tissue, but the rapid restoration of biomechanical functions remains a significant challenge. The poly(vinyl alcohol) (PVA) hydrogel is regarded as a potential articular cartilage replacement for its fair mechanical strength, whereas its lack of bioactivity limits its utility. To obtain a scaffold possessing expected bioactivity and initial mechanical properties, we herein report a novel salt‐leaching technique to fabricate a porous PVA hydrogel simultaneously embedded with poly(lactic‐co‐glycolic acid) (PLGA) microspheres. Through the investigation of environmental scanning electron microscopy, we found that the porous PVA/PLGA scaffold was successfully manufactured. The compression and creep properties were also comprehensively studied before and after cell culturing. The relationship between the compressive modulus and strain ratio of the porous PVA/PLGA scaffold showed significant nonlinear behavior. The elastic compressive modulus was influenced a little by the porogen content, whereas it went higher with a higher PLGA microsphere content. The cell‐cultured scaffolds presented higher compressive moduli than the initial ones. The creep resistance of the cell‐cultured scaffolds was much better than that of the initial ones. In all, this new scaffold is a promising material for articular cartilage repair. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40311.