Mechanically-Compliant Bioelectronic Interfaces through Fatigue-Resistant Conducting Polymer Hydrogel Coating.

Because of their distinct electrochemical and mechanical properties, conducting polymer hydrogels have been widely exploited as soft, wet, and conducting coatings for conventional metallic electrodes, providing mechanically compliant interfaces and mitigating foreign body responses. However, the long-term viability of these hydrogel coatings is hindered by concerns regarding fatigue crack propagation and/or delamination caused by repetitive volumetric expansion/shrinkage during long-term electrical interfacing. This study reports a general yet reliable approach to achieving a fatigue-resistant conducting polymer hydrogel coating on conventional metallic bioelectrodes by engineering nanocrystalline domains at the interface between the hydrogel and metallic substrates. It demonstrates the efficacy of this robust, biocompatible, and fatigue-resistant conducting hydrogel coating in cardiac pacing, showcasing its ability to effectively reduce the pacing threshold voltage and enhance the long-term reliability of electric stimulation. This study findings highlight the potential of its approach as a promising design and fabrication strategy for the next generation of seamless bioelectronic interfaces.

Electrospun compliant heparinized elastic vascular graft for improving the patency after implantation.

The low patency rate after artificial blood vessel replacement is mainly due to the ineffective use of anticoagulant factors and the mismatch of mechanical compliance after transplantation. Electrospun nanofibers with biomimetic extracellular matrix three-dimensional structure and tunable mechanical strength are excellent carriers for heparin. In this work, we have designed and synthesized a series of biodegradable poly(ester-ether-urethane)ureas (BEPU), following compound with optimized constant concentration of heparin by homogeneous emulsion blending, then spun into the hybrid BEPU/heparin nanofibers tubular graft for replacing rats' abdominal aorta in situ for comprehensive performance evaluation. The results in vitro demonstrated that the electrospun L-PEUUH (LDI-based PEUU with heparin) vascular graft was of regular microstructure, optimum surface wettability, matched mechanical properties, reliable cytocompatibility, and strongest endothelialization in situ. Replacement of resected abdominal artery with the L-PEUUH vascular graft in rat showed that the graft was capable of homogeneous hybrid heparin and significantly promoted the stabilization of vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs), as well as stabilizing the blood microenvironment. This research demonstrates the L-PEUUH vascular graft with substantial patency, indicating their potential for injured vascular healing.

Ultraviolet irradiation assisted liquid phase deposited titanium dioxide (TiO2)-incorporated into phytic acid coating on magnesium for slowing-down biodegradation and improving osteo-compatibility.

It remains challenging to build up a multifunctional coating onto biodegradable magnesium (Mg) for biomedical use. In this study, a small amount of titanium dioxide (TiO2) has been incorporated in situ into phytic acid (PA) coating when it was chemically deposited on Mg substrate targeted to biodegradable implant applications. Ultraviolet (UV) irradiation was utilized in the liquid phase deposition of TiO2 to improve the quality of coating (PA&TiO2-UV). This PA&TiO2-UV coating was compact, thicker and more hydrophilic compared with sole PA or TiO2 coating. The PA&TiO2-UV coated Mg presented a seven times lower electrochemical corrosion current density as well as significantly slower in vitro degradation rate up to 500 h in phosphate buffer saline as compared to the direct PA coated Mg. In addition, the UV irradiation showed remarkably to promote the MC3T3-E1 pre-osteoblast cells adhesion and proliferation especially after 7 days of culture. Further, the PA&TiO2-UV coating adhered more firmly on Mg substrate after 90° bending than the other coatings, indicating a better mechanical compliance on Mg substrate. These results make this PA&TiO2-UV complex coating bodes well for biodegradation slowing-down, osteo-compatible as well as mechanical compliant modification of Mg for orthopedic implants applications.