Photoluminescence Mechanisms of Dual-Emission Fluorescent Silver Nanoclusters Fabricated by Human Hemoglobin Template: From Oxidation- and Aggregation-Induced Emission Enhancement to Targeted Drug Delivery and Cell Imaging

A novel fundamental understanding of the features of mechanism for the synthesis of luminescent silver nanoclusters (AgNCs) in human hemoglobin (Hb) as capping/reducing agents is presented based upon simultaneous size transition and fluorescence enhancement phenomena  The interesting features consist of both NC core oxidation and aggregation-induced emission (AIE) attributed to ligand-to-metal charge transfer (LMCT) or ligand-to-metal–metal charge transfer (LMMCT) from Ag(I)-Hb complexes (through oxygen, nitrogen, and sulfur atoms of Hb residues donation to the Ag(I) ions) forming Ag(0)@Ag(I)–Hb core–shell NCs, the origin and consequence being a dual emission/single excitation nanosystem with large stocks shift and high quantum yield obtained even at high temperature which is a challenging subject,  is not reported until now. The bioconjugation of hyaluronic acid (HA) onto surfaces of an Hb layer (HA/AgNCs) produced a biocompatible platform with a doxorubicin drug (DOX) as DOX/HA/AgNCs for specific imagin...