Control of chemical release in hydrogel microvalve array for localized chemical stimulations

Abstract

Chemical stimulation is considered as one of the most promising therapeutic solutions for degenerated retina due to its ability to mimic a natural chemical signaling pathway. However, the majority of demonstrated platforms actuate chemicals using bulky external setups. Hence, developing high-resolution chemical release platforms with remote-controlled actuation mechanism is of great interest to the next generation of chemical prosthetics. Moreover, the effectiveness of chemical stimulation depends on several parameters, such as the chemical dosage, pulse duration, and spread radius. Therefore, to engineer the chemical release profile, the actuation mechanism of these localized chemical release platforms needs to be thoroughly studied to facilitate modifications. In this study, we have presented a high-resolution chemical release platform based on a macroporous silicon membrane structure. Chemical release ports defined in the membrane pores can be remotely actuated through thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel with near-infrared (NIR) light. As plasmonic heating elements, gold nanorod (GNR) was incorporated within PNIPAAm hydrogel. The pore size of the hydrogel was tuned by varying tetrahydrofuran content in the hydrogel polymerization solution. We have shown that the chemical release properties through membrane pores can be controlled as required using this approach. This insight can be used to engineer the relevant chemical release parameters, thereby creating an efficient chemical stimulation platform.