Aerosol Jet® printing of bioconductive AuNPs micropatterns supporting Schwann cell Alignment

Conductive and biocompatible (micro)structures have attracted considerable interest in bioelectronic systems, tissue engineering, and cell-instructive interfaces. However, the reliable fabrication of bioconductive microstructures with high resolution, excellent electrical performance, and good biocompatibility remains a current biofabrication challenge, which requires the synergistic advancement of functionalized materials and their related production process. In this study, Aerosol Jet® Printing (AJ®P) is proposed as a promising direct writing approach towards fabricating bioconductive microstructures. A systematic investigation was conducted on gold nanoparticles (AuNPs) conductive patterns, focusing on the effects of key AJ®P parameters, including nozzle diameter, carrier gas flow rate (CG), and focus ratio (Rf), on printed linewidth (Lw). CG was identified as the dominant factor governing Lw, with a strong coupling effect between CG and Rf. By optimising printing parameters, a minimum Lw of 16.3±0.2 μm was achieved with high reproducibility. Electrical characterisation revealed that increasing the number of printed layers significantly reduced resistance, reaching a minimum of 6.8 ± 0.4 Ω due to enhanced microstructural connectivity. The biocompatibility of AuNPs coatings was evaluated by culturing human Dental Pulp Stem cells differentiated Schwann cells (hDPSC-SCs) on the coating. The results demonstrated that hDPSC-SCs displayed good adhesion, proliferation and maintained their phenotype. On AJ®P-fabricated 100/160 μm AuNPs micropatterns, the cell density on the AuNPs tracks was about 4 times higher than that on the adjacent glass regions, indicating a pronounced preferential adhesion of hDPSC-SCs to the conductive microtracks. Furthermore, on the 40/160 μm AuNP micropatterns, up to 93% of hDPSC-SCs were aligned along the printing direction, demonstrating a strong contact-guidance effect. These results demonstrate that the AuNPs microtracks provided effective guidance, promoting both cell adhesion and alignment. Overall, this study demonstrates the feasibility of AJ®P for the high-resolution fabrication of bioconductive AuNP micropatterns. The findings provide a manufacturing foundation for the application of metal-based conductive microstructures in bioelectronic interfaces and cell-instructive culture systems, and offer valuable insights for the future development of more advanced neural tissue engineering platforms.