(A) Photo-crosslinking reaction underlying the polymerization of styrene groups after blue visible light irradiation (BVLI, energy) in the presence of carboxylated camphorquinone (CQ) with oxygen free radical release. (B) Water-soluble carbodiimide (WSC) was added to the gelatin molecules to initiate strong crosslinking between the amino groups of rhBDNF, rhNT-3, laminin and fibronectin with carboxyl groups of gelatin molecules. (White arrow; shorter triple helix gelatin subunits formed by two α1 and one α2 chains). =O, primary oxygen electron transfer; R–H, organic compound (4VBA) hydrogen donors; ●, free radical; R●, active free radical capable of initiating photopolymerization; X, monomer.