Self-assembled gel tubes, filaments and 3D-printing with in situ metal nanoparticle formation and enhanced stem cell growth

This paper reports simple strategies to fabricate self-assembled artificial tubular and filamentous systems from a low molecular weight gelator (LMWG). In the first strategy, tubular ‘core–shell’ gel structures based on the dibenzylidenesorbitol-based LMWG DBS-CONHNH(2) were made in combination with the polymer gelator (PG) calcium alginate. In the second approach, gel filaments based on DBS-CONHNH(2) alone were prepared by wet spinning at elevated concentrations using a ‘solvent-switch’ approach. The higher concentrations used in wet-spinning prevent the need for a supporting PG. Furthermore, this can be extended into a 3D-printing method, with the printed LMWG objects showing excellent stability for at least a week in water. The LMWG retains its unique ability for in situ precious metal reduction, yielding Au nanoparticles (AuNPs) within the tubes and filaments when they are exposed to AuCl(3) solutions. Since the gel filaments have a higher loading of DBS-CONHNH(2), they can be loaded with significantly more AuNPs. Cytotoxicity and viability studies on human mesenchymal stem cells show that the DBS-CONHNH(2) and DBS-CONHNH(2)/alginate hybrid gels loaded with AuNPs are biocompatible, with the presence of AuNPs enhancing stem cell metabolism. Taken together, these results indicate that DBS-CONHNH(2) can be shaped and 3D-printed, and has considerable potential for use in tissue engineering applications.