Growth-sensitive gold nanoshells precursor nanocomposites for the detection of l-DOPA and tyrosinase activity

In the present work, we have developed a novel nanocomposite-based method for the detection of l-DOPA and tyrosinase (TR) activity. This was accomplished by growth-sensitive gold nanoshells (GNSs) precursor nanocomposites (SiO2/GNPs II) and the formation process of GNSs. l-DOPA can reduce AuCl4− to Au0, depositing on the surface of SiO2/GNPs II and mediating the enlargement of gold nanoparticles (GNPs). Here, the preadsorbed GNPs on SiO2/GNPs II serve as nucleation sites for Au0 deposition. As the concentration of l-DOPA increases, the surface coverage of resultant gold on silica cores increases accordingly until continuous GNSs are formed. In this growth procedure, the spectra changes in wavelength correlate well with the concentration of l-DOPA, which indicates that this nanocomposite is a good nanoprobe for detecting l-DOPA. Because TR can catalyze the hydroxylation of l-tyrosine to form l-DOPA, this approach can also be employed to analyze the activity of TR, which possesses vast clinical and food industrial importance.