0000000000324863
AUTHOR
Muhammad Sher
showing 7 related works from this author
Fabrication, characterization, thermal stability and nanoassemblies of novel pullulan-aspirin conjugates
2017
Abstract Present study deals with homogeneous and one-pot synthesis of novel macromolecular prodrugs (MPDs) of aspirin onto naturally occurring hydrophilic biopolymer pullulan. Pullulan-aspirin conjugates were synthesized by using green carboxylic acid activating reagent 1,1′-carbonyldiimidazole (CDI). The aspirin was first reacted with CDI to prepare aspirin-imidazolide at RT for 24 h which in situ reacted with pre-dissolved pullulan and the reaction preceded further for 24 h at 80 °C under nitrogen. Degree of substitution (DS 0.32–0.40) of aspirin onto pullulan was calculated from 1H NMR spectroscopy. Spectroscopic techniques confirmed the high covalent drug loading and purity. Thermal an…
Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater.
2015
Abstract Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium (Cd) from spiked high-hardness groundwater (GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by 1 H NMR spectroscopy. Pullulan succinate (Pull-Suc) was converted into the sodium salt (Pull-Suc-Na). The effect of contact time (5–200 min) and pH (2–8) on Cd-uptake by the sorbent (Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water (DW) and GW solution, respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents sugge…
An efficient esterification of pullulan using carboxylic acid anhydrides activated with iodine
2010
Received August 9, 2009Accepted January 12, 2010Published online February 11, 2010Acylation of alcohols (esterification) with anhydride is an important and routinely utilizedtransformation in organic synthesis. Iodine is a cheap and one of the most powerful anhy-dride activating agents for the esterification of alcohols. Therefore, an efficient and cost ef-fective method was developed for the acylation of pullulan polysaccharide by using differentacid anhydrides activated with iodine. A series of organo-soluble pullulan esters were suc-cessfully synthesized, purified and characterized. Under solvent free conditions, it was feasi-ble to fabricate pullulan nonaacetate and pullulan stearate. A…
HPMC-salicylate conjugates as macromolecular prodrugs: Design, characterization, and nano-rods formation
2009
The design, characterization, and nano-rods formation of hydroxypropylmethylcellulose (HPMC)-salicylate conjugates as macromolecular prodrugs, was described. HPMC, obtained from Zhejiang Zhongbao Imp and Exp Corp, was dried under vacuum at 110°C for 8 hr. Nanoparticles were prepared using dialysis process in which 170 mg of HPMC-salicylate sample was dissolved in 5 mL of purified DMSO and was dialyzed against distilled water for 4 days. HPMC-salicylic acid conjugates reveal the absence of sulfur in all of the samples showing that there is no introduction to tosylate groups either covalently bounded or as an impurity.
An efficient acetylation of dextran using in situ activated acetic anhydride with iodine
2010
A facile, efficient, cost-effective and solvent-free acetylation method has been developed for the acetylation of dextran. Dextran acetates were successfully synthesized using different molar ratios of acetic anhydride in the presence of iodine as a catalyst without the use of any solvent. The reactions were realized at 50?C for 3 h under stirring and nitrogen. This efficient method yielded highly pure and organosoluble dextran esters. The reaction appears highly effective for obtaining higher degrees of substitution (DS) with great efficiency. Under solvent-free conditions, dextran triacetates were efficiently synthesized. It was also observed that the molar ratio can easily control the DS…
Design, characterization and evaluation of hydroxyethylcellulose based novel regenerable supersorbent for heavy metal ions uptake and competitive ads…
2017
Abstract Hydroxyethylcellulose succinate-Na (HEC-Suc-Na) was designed and evaluated for removal of some heavy metal ions from aqueous solution. Pristine sorbent HEC-Suc-Na was thoroughly characterized by FTIR and solid-state CP/MAS 13C NMR spectroscopy, SEM-EDS and zero point charge analyses. Langmuir isotherm, pseudo second order kinetic and ion exchange models provided best fit to the experimental data of sorption of metal ions. Maximum sorption capacities of supersorbent HEC-Suc-Na for sorption of heavy metal ions from aqueous solution as calculated by Langmuir isotherm model were found to be 1000, 909.09, 666.6, 588 and 500 mg g−1 for Pb(II), Cr(VI), Co(II), Cu(II) and Ni(II), respectiv…
SARS-CoV-2 infection and venous thromboembolism after surgery: an international prospective cohort study
2021
SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 da…