Regulating the nanostructure of composite nanoparticles is essential for making them suitable for various applications. In general, the chemical reduction method is employed for preparing metal nanoparticles in the liquid phase. However, complicated techniques are required to control the nanostructure during particle synthesis. The evaporation/condensation method is used for synthesizing nanoparticles in the vapor-phase. Although this method produces impurity-free particles without aggregation, very few studies have been carried out on the synthesis of composite particles in the vapor-phase. In this study, we synthesized composite nanoparticles in the vapor-phase by using the evaporation/condensation method. The results showed that bimetallic nanoparticles are produced by this method. Moreover, it was indicated that the nanostructure of the synthesized nanoparticles is influenced by the order of the electric furnace with different temperatures.
The conjugation of biomolecules, such as protein, sugar, and DNA, with metal nanoparticles is an important technique for bioassay and biomaterial preparation. In this study, we aim to enzymatically immobilize a functional peptide on gold nanoparticles (AuNPs) using a single-step reaction. We used tyrosinase, a catechol oxidase, to immobilize an enzymatic peptide. We performed immobilization experiments of a fluorescent compound-linked caspase-3 substrate peptide using tyrosinase on chitosan-coated AuNPs. Peptides were effectively immobilized onto the AuNPs depending on the presence of tyrosine within the sequence, which suggests the DOPA-quinone produced from tyrosine, via tyrosinase, is connected to the chitosan amino group. Although fluorescent emission from the immobilized capase-3 substrate was quenched by AuNPs, fluorescence intensity recovery occurred due to the addition of caspase-3. Thus, we were able to easily prepare functional AuNPs that can be used for a caspase-3 activity assay. Our results indicate that the tyrosinase-mediated peptide link to chitosan-coated particles is a useful technique for preparing functionalized nanoparticles.
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