Fabrication and characterization of polycaprolactone/chitosan/graphene quantum dots nanocomposite scaffolds with potential application in neural tissue engineering

Abstract

The ability to develop a polymeric scaffold with suitable electrical conductivity for an ideal nerve tissue engineering scaffold has been a persistent challenge for researchers. In this study, five nanocomposite scaffolds based on polycaprolactone (PCL), a synthetic polymer providing mechanical strength, natural biocompatible chitosan, and graphene quantum dots (GQDs) to enhance conductivity, were fabricated via electrospinning, a technique known for producing thin, uniformly aligned fibers. The scaffolds were characterized structurally using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), confirming uniform distribution and significant impact of GQDs on fiber structure. Scanning electron microscopy (SEM) and fluorescence microscopy revealed a substantial reduction in fiber diameter by approximately 70 and the presence of GQDs along the fibers. Electrical testing showed that increasing GQD content from 0.5 to 1 wt notably decreased electrical resistance (from similar to 1883 to 133 Omega), enhancing conductivity. Degradation studies in PBS over two months demonstrated an increase in degradation rate proportional to GQD content, with some scaffolds exhibiting up to 60 degradation. Mechanical tensile testing indicated improved strength and elastic modulus with 0.5 to 1 wt GQDs, whereas higher contents caused brittleness and strength reduction. Biological evaluation using PC12 cells showed a 4-7 increase in cell viability upon adding 0.5 to 2 wt GQDs, while 4 wt induced cytotoxicity. Considering the combined biological, physical, and mechanical results, scaffolds S-2 and S-3 emerged as the best candidates for electrically conductive and biocompatible scaffolds suitable for peripheral nerve tissue engineering. These findings highlight the promising potential of these nanocomposites for nerve tissue repair applications.