Fig. 6

The lysozyme-activated drug-eluting CL is illustrated as follows: (a) The process begins by synthesizing drug-loaded ND-nanogels through the cross-linking of PEI-coated NDs (nanodiamonds) and partially N-acetylated chitosan in the presence of timolol maleate. These ND-nanogels containing the drug are then embedded in a hydrogel and cast into CLs that are responsive to enzymes. (b) When exposed to the lacrimal fluid containing lysozyme, the N-acetylated chitosan present in the ND-nanogels is cleaved by the enzyme. This enzymatic cleavage leads to the degradation of the ND-nanogels, resulting in the release of the encapsulated timolol maleate. Importantly, the CLs remain intact throughout this process. This schematic illustration demonstrates the mechanism by which the lysozyme-activated drug-eluting CL operates, where the presence of lysozyme triggers the controlled release of the drug while maintaining the integrity of the lens [76]