Highly Reactive Thiol‐Norbornene Photo‐Click Hydrogels: Toward Improved Processability

In the present work, gelatin type B is modified with highly reactive norbornene functionalities (Gel‐NB) following a one‐pot synthesis approach to enable subsequent thiol–ene photo‐click crosslinking. The modification strategy displays close control over the amount of introduced functionalities. Additionally, Gel‐NB exhibits considerably improved processing capabilities in terms of two‐photon polymerization when benchmarked to earlier‐reported crosslinkable gelatin derivatives (e.g., gelatin‐methacrylamide (Gel‐MOD) and gelatin‐methacrylamide‐aminoethylmethacrylate (Gel‐MOD‐AEMA)). The improvement is especially apparent in terms of minimally required laser power (20 mW vs ≥60 mW (Gel‐MOD) vs ≥40 mW (Gel‐MOD‐AEMA) at 100 mm s −1 scan speed) and processable concentration range (≥5 w/v% vs ≥10 w/v% (Gel‐MOD/Gel‐MOD‐AEMA)). Furthermore, the proposed functionalization scheme maintains the excellent biocompatibility and cell interactivity of gelatin. Additionally, the norbornene functionalities have potential for straightforward postprocessing “thiol–ene” surface grafting of active molecules. As a consequence, a very promising material toward tissue engineering applications and more specifically, biofabrication, is presented.