Kinetic Aspects of Enzyme-Mediated Evolution of Highly Luminescent Meta Silver Nanoclusters

The proteolysis of human serum albumin (HSA) templated Ag nanoclusters (NCs) induced by trypsin digestion reveals that photoluminescence (PL) intensity of the blue emitting Ag:HSA NCs exhibits a decremental behavior. The unique aspect of this study is the gradual evolution of a new red emission band characterized by an enhanced quantum yield (QY) of similar to 28% and a lifetime similar to 80 ns in contrast to the parent blue-emitting Ag:HSA NCs (QY = 16% and lifetime similar to 7.4 ns). The decay and growth PL kinetics of Ag NCs upon trypsin digestion have been used to unravel the process of destabilization of the Ag:HSA NCs and the simultaneous formation of the meta AgTp NCs as evidenced from MALDI-TOF spectra. Our fluorescence correlation spectroscopy (FCS) data substantiate the evolution of larger sized Ag NCs due to enzymatic digestion which thereby results in a slower translational diffusion rate as a consequence of their increasing hydrodynamic diameters.