Gold nanoparticle multilayer films based on surfactant films as a template: Preparation, characterization, and application

Silver-decorated aligned CNT arrays as SERS substrates by high temperature annealing

A feasible way to synthesize a surface-enhanced Raman scattering (SERS) substrate has been developed, where Ag nanoparticles (AgNPs) of different size and morphology are assembled on the surface and sidewalls of the aligned carbon nanotube (CNT) arrays via magnetron sputtering and high-temperature annealing. Our results show that the optimized substrate is performed by annealing temperature at 450 °C for 30 min. The state of the obtained AgNPs makes a significant contribution to the high sensitivity of SERS to R6G molecules, and the substrate has an enhancement factor (EF) on the order of ~10¹⁰. Meanwhile, the Ag/CNT arrays keep a good reproducibility with the average RSD values being less than 0.01 for all major Raman peaks. The temporal stability of our substrates has been also appeared, which indicates that the Ag/CNT arrays can be used as stable substrates for the production of enhanced SERS signals for up to three months under ambient conditions.

Au-nanoparticles as an electrochemical sensing platform for aptamer-thrombin interaction

A novel electrochemical method for the detection of bioaffinity interactions based on a gold-nanoparticles sensing platform and on the usage of stripping voltammetry technique was developed. The oxidation of gold surface (resulted in gold oxide formation) upon polarization served as a basis for analytical response. As a model, thrombin-thrombin binding aptamer couple was chosen. The aptamer was immobilized on a screen-printed electrode modified with gold-nanoparticles by avidin-biotin technology. Cathodic peak area was found proportional to thrombin quantity specifically adsorbed onto electrode surface. Sigmoid calibration curve as is typical for immunoassay was obtained, with thrombin detection limit of 10(-9)M. Linear range corresponds from 10(-8) to 10(-5)M thrombin concentration or 2 x 10(-14) to 2 x 10(-11)mol/electrode (R=0.996). Binding of thrombin to an aptamer has also been detected using the ferricyanide/ferrocyanide redox couple as electrochemical indicator.