Abstract
The utilization of the core-shell composite nanoparticles as nano-sensing system to detect biomolecules has received much attention. In this study, SiO2/Au core-shell nanoparticles immobilized with urease as nano-sensing system to detect urea was fabricated. The monodisperse silica colloids were first obtained by hydrolytic sol-gel method. The particle surfaces were then covered with gold shell by the reduction of chloroauric acid in the presence of sodium citrate. Moreover, urease and FITC were further immobilized on the gold surface by self-assembled monolayer method. The developed core-shell biosensors showed high reproducibility, and the relative standard deviation was lower than 10 %. A good analytical performance with dynamic range of 3-4 orders of magnitude with the detection limit of lower than 1.1x10-2 μM was observed. In addition, the detection of heavy metals using the core-shell biosensors was also performed.