Green Synthesis of a Gold Nanoparticle–Nanocluster Composite Nanostructures Using Trypsin as Linking and Reducing Agents

Abstract

We report a green synthesis of novel gold nanoparticle–nanocluster composite nanostructures directly using trypsin as linking and reducing agents. Size exclusion chromatography (SEC) and transmission electron microscopy (TEM) reveals that the as-prepared gold nanocomposite (gold nanoparticles-trypsins-nanoclusters, GNPs-Trys-GNCs) is composed of GNPs (gold nanoparticles) with an average diameter of 5.5 nm and the GNCs (gold nanoclusters, about 1 nm)-embedded trypsins (Trys-GNCs), which are attached to the surface of the GNPs. The specific amino acids in the trypsin molecule, like cysteine, methionine, and tyrosine, combined with the unique spatial structures, enable trypsins to bind and reduce the AuCl4– ions, simultaneously forming GNPs and GNCs in one-pot synthesis. Similar to pure GNPs, the GNPs-Trys-GNCs nanocomposite also exhibits an intense surface plasmon resonance (SPR) absorbance at 520 nm. However, it shows an obvious different optical property in the interaction with Pb2+ ions. In the presence ...