Studies on non-gelatinous & thermo-responsive chitosan with the N-isopropylacrylamide by RAFT methodology for control release of levofloxacin.

The non-gelatinous and thermo-responsive properties were introduced in chitosan by incorporating the chain of poly(N-isopropylacrylamide) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To achieve this, the reaction was carried out at 80 °C by modifying the chitosan(CS) with RAFT agent as a macroinitiator (CS-RAFT), where the amine group of CS was protected with phthalic anhydride and then reacted with 4-cyano-4-[(dodecyl sulfanyl thiocarbonyl)sulfanyl]-pentanoic acid (CDSTSP) to form CS-RAFT agent. Further, the addition of NIPAAm chains onto CS-RAFT was carried out in N,N'-dimethylformamide (DMF) solvent by using 2,2'-azobisisobutyronitrile (AIBN) as an initiator in N2 atmosphere. The controlled addition of NIPAAm chains on to CS was confirmed by 1H NMR spectroscopy, further, a kinetic study was performed to get the characteristic features of the RAFT reaction. The product was characterized by 1H NMR, FT-IR, UV-Visible spectroscopy, XRD, SEM, and TGA analyses. The product in aqueous solution showed LCST at 2.0 mg/mL on 33 ± 0.1 °C. Further, beads were prepared with the sodium alginate and loaded the water-soluble levofloxacin drug (60% w/w loading was achieved). The drug delivery process was studied in-vitro at 37 ± 0.1 °C & pH 7.4, which shown controlled release of drug up to 32 h and it was 71% of the loaded levofloxacin.

l-Alanine induced thermally stable self-healing guar gum hydrogel as potential drug vehicle for sustained release of hydrophilic drug.

A simple approach for preparing self-healable guar gum-graft-acrylic acid (GG-PAA) hydrogel using l-alanine as a cross-linking agent was introduced for the first time. It drastically modifies the mechanical strength of the hydrogel to G' = 90,570 Pa. Thus, a series of guar gum (GG) based hydrogel was synthesized by varying the concentration of l-alanine from 0.4 to 1% w/v. The hydrogel was characterized by different analytical techniques such as FTIR, HRSEM etc. The mechanical strength of the hydrogel was investigated by rheology analysis and it was observed in terms of storage and loss modulus i.e. G' & G'', respectively. Maximum G' & G'' (90,560 Pa & 60,820 Pa) were observed when 1 wt% of l-alanine was used as a cross-linking agent. This GG based hydrogel have shown excellent swelling i.e. up to 3350%, which indicates its porous network. The synthesized hydrogel has been identified as a controlled drug delivery gel, which releases 98% of the highly water-soluble loaded drug in 140 h.

Development of graft copolymer of carboxymethylcellulose and N-vinylcaprolactam towards strong antioxidant and antibacterial polymeric materials.

The present paper reports graft copolymerization of N-vinylcaprolactam (NVCL) onto carboxymethylcellulose (CMC) using tert-butyl hydroperoxide (TBHP) initiator in N2 atmosphere. The grafting was found to be highest when concentrations of CMC, NVCL and TBHP were 6.25×10-2gdm-3, 10×10-3moldm-3 and 20×10-5moldm-3 respectively. The graft copolymer (CMC-g-PNVCL-1) was characterized by FTIR, 1HNMR, SEM, AFM, XRD and TGA analysis. The antioxidant activity of the graft copolymer was found to be higher (3.81%) than CMC and slightly less (5.47%) than the standard one (butylated hydroxytoluene, BHT). The hydroxyl radical scavenging activity of graft copolymer was found to be slightly less (13.69%) than CMC and more (44.20%) than the BHT. The hydrogen peroxide scavenging activity of graft copolymer was observed to be less (20.42%) than CMC and 53.34% less than BHT. The superoxide scavenging activity of graft copolymer was greater than the both. Compared to CMC the graft copolymer has shown greater antibacterial activity against S. aureus, Proteus vulgaris and S. typhi bacteria and less against Klebsiellapneumonia and Salmonella typhimurium.