Protein-stabilized bimetallic Au/Ag nanoclusters as fluorescent reporters: Synthesis, characterization and their interactions with biocolloids
Árpád Turcsányi, Ditta Ungor, Marek Wojnicki, Edit Csapó
Abstract
Fabrication protocol of bovine serum albumin-(BSA) and lysozyme-(LYZ) stabilized gold/silver bimetallic nanoclusters (Au/Ag NCs) have been reported via optimization of the protein/metal ion ratios, metal concentration, pH and incubation time. No other reducing and stabilizing compounds were used to produce these nanoclusters at room temperature. Incorporation of small quantities of silver (∼3–10 w%) into the gold core substantially changed the optical features such as the enhancing of the quantum yield and blue shifting of the emission wavelength compared to their purely gold-based derivatives. Applicability of the BSA- and LYZ-directed Au/Ag NCs having intense fluorescence at above ∼ 600 nm as potential fluorescent reporters (FRs) has been studied by examining their interactions with chitosan/hyaluronic acid (Chit/HyA)-based colloidal drug delivery particles. It was found that, in contrast to the monometallic derivatives, our bimetallic NCs, prepared at room temperature and stabilized with larger amounts of proteins, exhibit a much higher degree of stability during interaction with biocolloids. The results are confirmed by fluorescence measurements in addition to light scattering studies, since the aggregation-induced emission is not observed dominantly, as clearly confirmed for Au-based NCs. Utilizing the alloying process and the milder preparation conditions can be a promising route to the synthesis of noble metal NCs-based FRs in biomedical field.