Photodegradable Tissue-Adhesive Hydrogels

Hydrogels for wound management and tissue gluing have to adhere to tissue for a given time scale and then disappear, either by removal from the skin or by slow degradation in applications inside the body. Advanced wound management materials also envision the encapsulation of therapeutic drugs or cells to support the natural healing process. The design of hydrogels that can fulfill all these properties with minimal chemical complexity, a stringent condition to favor transfer into a real medical device, is challenging. Herein, we present a hydrogel design with moderate structural complexity that fulfills a number of relevant properties for wound dressing: it can form in situ and encapsulate cells, it can adhere to tissue, and it can be degraded on demand by light exposure under cytocompatible conditions. The hydrogels are based on starPEG macromers terminated with catechol groups as crosslinking units and contain intercalated photocleavable triazole nitrobenzyl groups. Hydrogels are formed under mild conditions (HEPES buffer with 9-18 mM of sodium periodate as oxidant) and are compatible with encapsulated cells. Upon light-irradiation, the cleavage of the nitrobenzyl group mediates depolymerization, which enables on-demand release of cells or debonding from tissue. The molecular design and obtained properties are interesting for the development of advanced wound dressings and cell therapies, and expand the range of functionality of current alternatives.