Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

QSAR models using a large diverse set of estrogens

Abstract: Endocrine disruptors (EDs) have a variety of adverse effects in humans and animals. About 58,000 chemicals, most having little safety data, must be tested in a group of tiered assays. As assays will take years, it is important to develop rapid methods to help in priority setting. For application to large data sets, we have developed an integrated system that contains sequential four phases to predict the ability of chemicals to bind to the estrogen receptor (ER), a prevalent mechanism for estrogenic EDs. Here we report the results of evaluating two types of QSAR models for inclusion in phase III to quantitatively predict chemical binding to the ER. Our data set for the relative binding affinities (RBAs) to the ER consists of 130 chemicals covering a wide range of structural diversity and a 6 orders of magnitude spread of RBAs. CoMFA and HQSAR models were constructed and compared for performance. The CoMFA model had a r2 = 0.91 and a q2LOO = 0.66. HQSAR showed reduced performance compared to CoMFA with r2 = 0.76 and q2LOO = 0.59. A number of parameters were examined to improve the CoMFA model. Of these, a phenol indicator increased the q2LOO to 0.71. When up to 50% of the chemicals were left out in the leave-N-out cross-validation, the q2 remained significant. Finally, the models were tested by using two test sets; the q2pred for these were 0.71 and 0.62, a significant result which demonstrates the utility of the CoMFA model for predicting the RBAs of chemicals not included in the training set. If used in conjunction with phases I and II, which reduced the size of the data set dramatically by eliminating most inactive chemicals, the current CoMFA model (phase III) can be used to predict the RBA of chemicals with sufficient accuracy and to provide quantitative information for priority setting.

Synthesis and Characterization of Antibacterial Ag−SiO2 Nanocomposite

Abstract: In order to increase antibacterial abilities and avoid aggregation of Ag nanoparticles, Ag−SiO2 nanocomposites were studied to achieve hybrid structure. SiO2 nanoparticles synthesized by the Stober method served as seeds for immobilization of Ag. The chemical binding structure and morphology of Ag−SiO2 nanocomposites and SiO2 nanoparticles were investigated with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The antibacterial properties of Ag−SiO2 nanocomposites were examined with disk diffusion assay and minimum inhibitory concentration (MIC). Results showed that Ag nanoparticles are homogeneously formed on the surface of SiO2 nanoparticles without aggregation and showed excellent antibacterial abilities.