PEGylated gold nanoparticles promoted rapid macromolecular chain-end transformation and formation of injectable hydrogels
Azide-alkyne click cycloaddition, and Michael addition reactions are useful for the synthesis and modification of biologically relevant macromolecules. Promotion of these reactions at the macromolecular chain-ends and backbone has been achieved by the gold [Au-(PEG-SH)n] nanoparticles (NPs) stabilized with multi-thiol-functional poly(ethylene glycol) containing tertiary amine in its backbone. The Au NPs successfully activate electron rich alkynes, and acrylates functionalities of macromolecules at low substrate concentration leading to the enhancement of reaction rate. The Au NPs successfully accelerate the gelation rate of reactive prepolymers leading to the rapid formation of injectable hydrogels with improved modulus. Grafting density (chains/nm2) of the stabilizer onto the Au NPs surface plays a crucial role towards the activity of the NPs. Conversion of chain-ends functionality and gelation rate increase with decreasing grafting density. High grafting density lowers the activity of the Au NPs through blocking the active metal surface. The developed Au NPs may be potential agent for the rapid preparation of biologically relevant macromolecular entities.