Gold Nanoparticle-Loaded Silica Nanospheres for Sensitive and Selective Electrochemical Detection of Bisphenol A.

In this work, silica nanospheres were used as support for gold nanoparticles and applied for bisphenol A electrochemical detection. The development of new silica-supported materials has attracted increasing attention in the scientific world. One approach of interest is using silica nanospheres as support for gold nanoparticles. These materials have a variety of applications in several areas, such as electrochemical sensors. The obtained materials were characterized by solid-state UV-vis spectroscopy, electron microscopy, X-ray diffraction, and electrochemical techniques. The electrode modified with AuSiO2700/CHI/Pt was applied as an electrochemical sensor for BPA, presenting an oxidation potential of 0.842 V and a higher peak current among the tested materials. The AuSiO2700/CHI/Pt electrode showed a logarithmic response for the detection of BPA in the range of 1-1000 nmol L-1, with a calculated detection limit of 7.75 nmol L-1 and a quantification limit of 25.8 nmol L-1. Thus, the electrode AuSiO2700/CHI/Pt was presented as a promising alternative to an electrochemical sensor in the detection of BPA.

Antibacterial effects and ibuprofen release potential using chitosan microspheres loaded with silver nanoparticles.

The wide use of chitosan microspheres in pharmaceutical applications, mainly in the controlled release of drugs and as a bactericidal agent, has been widely reported in the literature. However, these important biomaterial applications with multifunctionality is still scarce. In this study, epichlorohydrin-crosslinked chitosan microspheres were prepared and evaluated for Ag+ adsorption and formation of silver nanoparticles. The hybrid material obtained was used to antibacterial activity and controlled drug release. The optimal pH for adsorption of Ag+ ions in aqueous medium was pH 5-7; the best fit was the Langmuir model; the optimal time for maximum adsorption was 10 h. The highest release of the drug occured at neutral pH of the intestinal fluids and remained constant for 6 h. Silver ion microspheres demonstrated activity against E. coli and S. aureus. The concentration of ibuprofen incorporated in the chitosan microspheres was 7.9 × 10-3 mol L-1 and in the microspheres with AgNPs the concentration was 1.8 × 10-2 mol L-1. The microspheres with AgNPs released more drug (77%) than the material without AgNPs.