Search

Mesenchymal stem cells (MSCs) have attracted great interest in the field of regenerative medicine, particularly in bone regeneration. Osteogenic differentiation from MSCs is regulated by various environmental factors including hormones, growth factors, chemicals and physical cues from biomaterials. We present the use of electroactive degradable copolymers to guide the osteogenic differentiation from bone marrow derived MSCs (BMSCs). The biodegradable conductive copolymers based on polylactide and tunable contents of the aniline oligomer were synthesized by ring opening polymerization and free radical polymerization, and subsequent functionalization with the aniline tetramer. Electroactive nanofibrous scaffolds were created via a thermally induced phase separation technique. The cell culture of BMSCs and MC3T3-E1 cells on electroactive copolymers showed that these copolymers were cytocompatible and the proliferation for both cells was significantly enhanced. Osteogenic differentiation from BMSCs on the electroactive copolymers was promoted compared to polylactide in terms of gene expression and von Kossa staining. Furthermore, protein adsorption on the electroactive copolymer surface was greatly increased, and this may contribute to the enhanced proliferation and differentiation of BMSCs. This is the first report about degradable electroactive polymers directing osteogenic differentiation from BMSCs and the results indicated that electroactive degradable polymers have great potential for application in bone regeneration.

Electrically conductive hydrogels have great potential for biomedical applications. However, they usually exhibited poor mechanical properties. We present a simple approach to prepare injectable conductive interpenetrating polymer network (IPN) hydrogels with enhanced mechanical properties. The in situ forming IPN conductive hydrogels were based on gelatin-graft-polyaniline and carboxymethyl-chitosan, which were crosslinked with oxidized dextran via Schiff base at physiological conditions. Storage modulus of the injectable conductive IPN hydrogels was greatly increased. Gelation time, swelling ratio, pore size and conductivity of these injectable hydrogels were adjusted by polyaniline content. Electroactivity of the hydrogels was studied by UV-vis and cyclic voltammetry. Cytocompatibility of the hydrogels was investigated by cell adhesion and proliferation of C2C12 myoblasts and adipose-derived mesenchymal stem cells. The in vivo biocompatibility of the hydrogels was confirmed by H&E staining. These injectable conductive hydrogels with good mechanical properties and biocompatibility as bioactive biomaterials have great potential for drug delivery and tissue engineering.

Cytocompatible electrically conducting hydrogels based on amphoteric carboxymethyl chitosan (CMCS) and aniline oligomers with bioactive molecule delivery properties were presented. A series of conductive CMCS hydrogels with different aniline pentamer (AP) content were synthesized by a one-pot reaction with the combination of grafting and crosslinking reaction via glutaraldehyde. The conductivities of the swollen hydrogels are between 1.14 × 10−4 and 4.23 × 10−4 S/cm by tuning the AP content. Swelling ratio was controlled by the AP content and crosslinking degree of the hydrogels. The hydrogels showed absorption capacity of diclofenac sodium (DCS) as a model molecule and released DCS in a controlled manner. Morphologies and mechanical properties of the hydrogels were characterized by SEM and rheometer, respectively. The biocompatibility of the hydrogels was confirmed by C2C12 myoblast cells using Live/Dead assay and Alamar blue assay. These conducting hydrogels with controlled release capacity as bioactive scaffolds have potential application for tissue regeneration.

Electroactive injectable degradable hydrogels have great potential as bioactive scaffolds for tissue regeneration. We present the development of a series of in situ forming biodegradable electroactive hydrogels which were synthesized by in situ crosslinking of gelatin-graft-polyaniline (GP) by genipin at body temperature. The chemical structure and electroactivity of the GP co-polymers was confirmed. The formation of in situ hydrogels was demonstrated by the test tube inversion method and rheology measurement. Gelation time, swelling ratio and degradation rate of the hydrogels were controlled by the polyaniline content and genipin content. The conductivity of the hydrogels in the swollen state increased with increasing the polyaniline content in the materials. Interestingly, the hydrogels exhibited a linear release profile of in situ encapsulated diclofenac sodium. The non-cytotoxicity of the hydrogels was confirmed via cell adhesion and proliferation by using bone marrow mesenchymal stem cells and rat C2C12 myoblast cells. These in situ formed degradable electroactive hydrogels represent a new class of biomaterials and as biomimetic scaffolds they have great potential for sophisticated tissue engineering, such as bone, muscle and neural regeneration.

Fabrication of functional nanofibrous biomimetic scaffolds for tissue regeneration remains a challenge. This work demonstrates that functional nanofibrous scaffolds were fabricated from blends of polylactide with other functional polymers by a thermally induced phase separation (TIPS) technique, here exemplified by the fabrication of electroactive nanofibrous scaffolds from the blends of polylactide and an electroactive degradable tetraaniline-polylactide-tetraaniline (TPT) block copolymer by TIPS. The TPT copolymer was synthesized by coupling reaction between the carboxyl-capped tetraaniline and polylactide. The chemical structure, electroactivity, thermal properties and mechanical properties of TPT and polylactide/TPT blend films were characterized. The copolymer blends were fabricated into electroactive nanofibrous scaffolds by TIPS. The effect of aniline tetramer content, polymer concentration and phase separation temperature on the diameter of nanofibers was investigated. The adhesion and proliferation of C2C12 myoblast cells and protein adsorption on the electroactive biodegradable substrates were evaluated, and the results show that the electroactive materials are nontoxic and could enhance the C2C12 cell proliferation without electrical stimulation, and adsorbed more proteins compared to polylactide. The electrical stimulation on the electroactive substrates significantly increased the cell proliferation of C2C12 myoblasts. This work opens the way to fabricate functional nanofibrous scaffolds from the blends of polylactide and other functional polymers by TIPS.