Spatially-resolved soft materials for controlled release - hybrid hydrogels combining a robust photo-activated...

Hybrid hydrogels based on self-assembling low-molecular-weight gelator (LMWG) DBS-CONHNH₂ (DBS = 1,3;2,4-dibenzylidene-d-sorbitol) and crosslinked polymer gelator (PG) PEGDM (poly(ethyleneglycol) dimethacrylate) are reported, and an active pharmaceutical ingredient (naproxen, NPX) is incorporated. The use of PEGDM as PG enhances the mechanical stiffness of the hybrid gel (G' increases from 400 to 4500 Pa) - the LMWG enhances its stability to very high frequency. Use of DBS-CONHNH₂ as LMWG enables interactions with NPX and hence allows pH-mediated NPX release - the PG network is largely orthogonal and only interferes to a limited extent. Use of photo-activated PEGDM as PG enables spatially-resolved photo-patterning of robust hybrid gel domains within a preformed LMWG network - the presence of the LMWG enhances the spatial resolution. The photo-patterned multi-domain gel retains pH-mediated NPX release properties and directionally releases NPX into a compartment of higher pH. The two components within these hybrid PG/LMWG hydrogels therefore act largely independently of one another, although they do modify each others properties in subtle ways. Hybrid hydrogels capable of spatially controlled unidirectional release have potential applications in tissue engineering and drug-delivery.