Click-Chemistry Based Functionalization of Biomolecules and Biopolymers Using a Thermo-Responsive Smart Catalyst

In this paper, we report the convenient application of the Click reaction to collagen and bovine serum albumin (BSA) using a thermoresponsive catalyst we recently developed. The catalyst's thermoresponsive nature allows for its facile removal from the reaction medium by simply raising the temperature. The Click reaction was performed in aqueous solution and on surfaces using a self-assembled monolayer formation technique after appropriate functionalization of the collagen or BSA. Successful functionalization and Click reactions were confirmed through analysis by XPS, solid-state NMR spectroscopy (¹³C, ¹⁵N, and ²⁹Si), IR spectroscopy, and microscopy. For instance, the characteristic azide signal in FTIR and the ²⁹Si solid-state NMR spectrum confirmed the initial functionalization step. XPS, solid-state NMR, and microscopy validated the Click reaction on both BSA and collagen. Notably, the ¹⁵N solid-state NMR data provided compelling evidence of triazole formation after the Click reaction.