Protein-directed synthesis of highly monodispersed, spherical gold nanoparticles and their applications in multidimensional sensing

An in-situ reduction method has been reported to prepare gold nanoparticles (GNPs) of 40–110 nm by using the green reducing agents of proteins, which are activated by H 2 O 2 and the superoxide anion ( ). The protein of collagen turns HAuCl 4 to the aqueous Au(I) ainions, which are further reduced by other proteins to be highly monodispersed and spherical GNPs of different sizes. The GNPs reduced by different proteins are found to be with the exposed {100} facets, the distinctive UV-vis absorption spectra and various colors (See Fig. 1 ). By means of extracting the color responses, such as red, green and blue (RGB) alterations, an in-situ reduction method-based multidimensional sensing platform is fabricated in the process of GNPs synthesis. Without further modification of GNPs, nine common proteins are found to be well detected and discriminated at different concentrations. Moreover, this sensing platform also demonstrates great potentials in qualitative and semiquantitative analysis on the individuals of these proteins with high sensitivity. Furthermore, the validation of this multidimensional sensing platform has been carried out by analysis on the spiked proteins in human urine and the target proteins in complex matrix (e.g. lysozyme in human tear). ( a ) Schematic illustration of an in-situ reduction method to synthesize monodispersed and spherical GNPs by using proteins, the reducing power of which activated by H 2 O 2 and the superoxide anion ( ). ( b ) The distinctive colors of as-synthesized GNPs reduced by different proteins.