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This critical review summarizes recent developments in the preparation and application of lithium catalysts/initiators such as, alkyl lithium, alkoxy lithium and bimetallic lithium compounds for ring-opening polymerization (ROP). The ROP of cyclic esters, cyclic carbonates, cyclo-silazanes, cyclo-silanes, cyclo-siloxanes, cyclo-carboxylate, cyclic phosphirene and quinodimethanes are covered in this review. The present paper emphasizes the polymerization kinetics and the control exhibited by the different types of lithium initiators/catalysts. For the cases where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the mechanistic studies of the catalysts/initiators are provided. Furthermore, this review also focuses on the synthesis of block copolymers and graft copolymers by ROP principle. The topics covered in this review regarding lithium compounds toward ROP will be of interest to inorganic, organic and organometallic chemists, material, polymer and catalytic scientists due to its unique mode of activation as compared to transition and inner transition-metals. In addition, use of these compounds in catalysis is steadily growing, because of the complementary reactivity toward ROP as compared to other metals. Finally, some aspects and opportunities which may be of interest in the future are suggested (143 references).

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Graphene oxide (GO) and functionalized carboxylic graphene oxide (COOH-GO) were successfully synthesized by modified Hummer’s technique. The prepared GO and COOH-GO was characterized successfully by UV-Visible Spectroscopy, Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction, Raman spectroscopy, Scanning electron microscopy (SEM)& Zeta potential. The removal of U(VI) heavy metal comparative study was done by using Graphite, GO & COOH-GO and the removal were confirmed by using LED fluorimeter. The effect of pH of medium, contact time, adsorbent dose, initial concentration of U(VI) were examined for the removal of U(VI). The extent of U(VI) removal has been found to be in the order of COOH-GO >GO> graphite. The U(VI) removal maximum efficiency was observed ~96% observed at pH 4.5. The higher removal efficiency is attributed to the higher negative surface charge of COOH-GO (zeta potential:-39.9 mV) in comparison to zeta potential of GO (-28.9 mV) &graphite (-21.6 mV).

This study comprises a convenient, rapid and very sensitive method for the determination of bovine serum albumin (BSA). The technique is based on fluorescence resonance energy transfer (FRET) between Rhodamine‐6G (R6G) acting as donor and gold nanoparticles (AuNPs) acting as acceptors. This method takes advantage of AuNPs that have high quenching efficiency, therefore the absorption spectra range shifts from 521 to 635 nm when aggregation of the AuNPs takes place. Furthermore, when R6G was electrostatically self‐adsorbed to the citrate‐stabilized AuNPs surface the fluorescence intensity was quenched. After addition of BSA, the fluorescence intensity of the R6G recovered as BSA induced aggregation of the AuNPs and the adsorbed R6G was released to the solution. The recovery of intensity displays a linear relationship with BSA concentration over the range from 0.8 × 10−11 M to 5.6 × 10−11 M. The detection limit for BSA was found to be 4.58 × 10−11 M. The proposed method exhibited rapid analysis with high selectivity for BSA determination in human urine, blood and serum samples.

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