Departamento de Química Analítica e Ingeniería Química, Facultad de Química, Edificio Polivalente, Universidad de Alcalá, Ctra. Madrid-Barcelona km 33,600, 28871 Alcalá de Henares, Madrid, Spain
Abstract:
Localized surface plasmon resonance (LSPR) is one of the most remarkable features of gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs). Due to these inherent optical properties, colloidal solutions of Au and Ag NPs have high extinction coefficients and different colour in the visible region of the spectrum when they are well-spaced in comparison with when they are aggregated. Therefore, a well-designed chemical interaction between the analyte and NPs surroundings leads to a change of colour (red to blue for Au NPs and yellow to brown for Ag NPs from well-spaced to aggregated ones, respectively) allowing the visual detection of the target analyte.