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.

Azeotropic mixture used for development and validation of Lornoxicam in bulk and its tablet dosage form by spectrophotometric method.

A novel, safe, economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water:methanol: 60:40, v/v) for the quantitative determination of Lornoxicam, a practically water-insoluble drug. Hence, Lornoxicam stock solution was prepared in Azeoptropic mixture. Lornoxicam showed maximum absorbance at 383 nm. Beer's law was obeyed in the concentration range 4-24 µg/mL with regression coefficient of 0.999. The method was validated in terms of linearity (R2=0.999), precision (CV for intra-day and inter-day was 0.28-0.68 and 0.12-0.92, respectively), accuracy (98.03-100.59% w/w) and specificity. This method is simple, precise, accurate, sensitive and reproducible and can be used for the routine quality control testing of the marketed formulations.