4-Iodophenylboronic Acid Stabilized Gold Cluster as a New Fluorescent Chemosensor for Saccharides Based on Excimer Emission Quenching.

4-iodophenylboronic acid (IPBA) ligated luminescent gold cluster was synthesized by mixing an aqueous solution of IBPA and polyvinylpyrrolidone stabilized gold cluster (Au:PVP) in water at room temperature through chemisorption of iodine on gold nano surface. Transmission Electron microscopy (TEM) and matrix assisted laser desorption ionization (MALDI) analysis revealed that the size of these Au-clusters (1.4±0.2 nm) remain unchanged without any noticeable aggregation during synthesis. Owing to the formation of excimer between aryl moieties grafted over Au surface, the cluster exhibit strong emission peak at 335 nm. This luminescent gold cluster is used for sensing different saccharides in water at physiological pH through quenching of excimer emission peak. This strong excimer emission is significantly quenched in presence of saccharides through interaction with boronic acid moieties. The selectivity for different saccharides follows the order: fructose > galactose > maltose > glucose ~ ribose > sorbitol with hight affinity for fructose (KSV = 1.54 × 104 M-1) with Limit of Detection (LOD) of 100 µM.

Effect of Commonly Consumed Beverages on Microhardness of Two Types of Composites.

OBJECTIVE: The objective of the present in vitro study was to assess the influence of commonly consumed beverages on the microhardness of microhybrid and nanofilled composite resins. MATERIALS AND METHODS: Two hundred and forty cylindrical specimens were produced using circular aluminum molds of an internal diameter of 10 mm and a thickness of 2 mm, 120 samples each from microhybrid composite (Filtek Z250, 3M, ESPE, USA) and nanofilled composite (filtek Z250, 3M, ESPE, USA). They were divided into 4 subgroups of 30 specimens each. These specimens were immersed in distilled water, tea, coffee, and cola drink, respectively. Microhardness was calculated using Vickers microhardness tester (MMT-X7 Matsuzawa, Japan). Data were statistically analyzed using paired t-test and one-way analysis of variance (ANOVA) using Tukey's correction was used for multiple subgroup comparison. RESULTS: Microhardness of both the composites reduced after immersing in different beverages compared to water. Nanofilled composites showed more change in microhardness than microhybrid composite. Cola caused a significant reduction in microhardness followed by coffee, tea, and water. CONCLUSION: The beverages used have negative effects on the hardness of both the type of composites. The surface microhardness of nanofilled composite is significantly reduced when immersed in carbonated beverages like cola. HOW TO CITE THIS ARTICLE: Barve D, Dave PN, Gulve MN, et al. Effect of Commonly Consumed Beverages on Microhardness of Two Types of Composites. Int J Clin Pediatr Dent 2020;13(6):663-667.