Visible-light-induced hyaluronate hydrogel for soft tissue fillers.

Hyaluronic acid (HA) is widely used as a filler owing to its excellent biocompatibility and biodegradability. However, commercial HA-based filler products have some limitations and can cause side effects due to the presence of residual chemical crosslinking agents. In this study, tyramine (Tyr) was introduced into HA to impart photocrosslinking ability to HA, and a photocrosslinked hydrogel was formed using a less toxic vitamin B2 derivative as a photoinitiator. For injection, an injectable filler was prepared by converting the photocrosslinked hydrogel to a microgel form. The crosslinking of the tyramine-modified HA (HA-Tyr) hydrogel, which can be applied as a soft tissue filler, increased with an increase in the irradiation time, and the crosslinked hydrogel showed excellent mechanical strength, elastic recovery rate, and injectability. It also showed non-cytotoxicity and cell proliferation behavior in fibroblasts. Therefore, injectable HA hydrogels have great potential as an alternative to conventional commercial dermal fillers.