Formation and Collapse of Fluorescent Gels by Gold Nanoparticles

In this article the formation and collapse of fluorescent gels made using bovine serum albumin (BSA) and chloroauric acid (HAuCl₄) is demonstrated. The formation of gels depends upon the concentration of BSA. The formation of the gels is associated with electrostatic interaction between chloroauric acid and BSA. The collapse of the gel is attributed to the reduction of gold as nanoparticles. The gels collapse without any external agents. The gels were characterized using SEM, FTIR, Rheometer, and XRD. The effect of aging upon the gels showed that in time all the gels turned into dark viscous liquid. Particle size distributions showed that higher concentrations of proteins showed inhomogeneous particle sizes indicating that the rate of reduction of gold depended upon the concentration of the proteins. The gels were tested for their abilities to be used for encapsulation of drugs using Rhodamine. Gels of cylindrical shapes of ∼2.5 cm in length and 2 cm in diameter were made using this technique. A model is proposed for the formation and the collapse of the gel.