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Title: Biopolymer based stimuli responsive blend hydrogels: synthesis, characterization and applications in biomedicine
Authors: Rasool, Atta
Keywords: Physical Sciences
Issue Date: 2020
Publisher: University of the Punjab , Lahore
Abstract: Stimuli responsive hydrogel blends based on biopolymers and synthetic polymers by using a nontoxic silane crosslinker due to its acceptance in biomaterials have been developed in the present study. Different biopolymers i.e. chitosan, CG and Alginates were used to produce stimuli responsive hydrogels. Chitosan (CS) and poly (N-vinyl-2- pyrrolidone) (PVP) had attained hydrogel properties in the presence of 74% neutralized PAA (PAA) that can be exploited for wound healing applications. CS based hydrogel was also prepared with synthetic polymer PVP using aminopropyle triethoxy silane (APTES) as a cross linker. Kappa carrageenan (CG) was used to prepare hydrogel having novel compositions with poly (vinyl alcohol) (PVA), and APTES as a crosslinker. The formulation of the CG based hydrogel was also done that was based on biopolymers (CG and sodium Alginate (ALG)), synthetic polymer, and poly ((ethylene glycol) (PEG)). FT-IR spectra confirmed the presence of all functional groups of the biopolymers and synthetic monomeric units as they were in individual components, and after the developed interactions in the hydrogels due to hydrogen bonding. Thermal analysis explained that the hydrogel samples are thermally more stable than individual CS and PVP. The hydrogel samples containing more crosslinker (TAP 32) were also thermally more stable. Similarly, for CG based hydrogels, amount of crosslinker and molar mass of PEG controls the stability of sample, as illustrated from their TGA, the hydrogels (AP40 and GAP 60) were more stable. Antimicrobial analysis revealed that all the samples showed antibacterial activity against E. coli. Whereas, CG based hydrogels samples showed strong antibacterial activity against S. aureus and a little against E. coli. ix The in vitro biodegradation analysis of the all the hydrogels were performed to confirm their degradation. All the samples were found biodegradable and these prepared hydrogel samples were supposed to be broken down by various enzymes into small chain polysaccharides, which further broke down into the metabolic pathways. The CS based hydrogels showed enhanced responsive swelling behaviour against different media depending upon the amount of PVP. The % swelling in water was decreased with increase in the amount of PVP. The hydrogel sample (T6 PVP 0.5) showed the highest swelling (8988 %). The most considerable swelling behaviour was observed against pH, as they manifested low swelling at acidic pH and high swelling at neutral pH while at pH 8, prominent values were obtained. In other series, the maximum swelling (4386%) was observed for TAP 32 in distilled water while swelling was decreased when concentration of ions was increased. The values of diffusion exponent (n) were less than 0.5, so it was Quasi-Fickian diffusion for all the hydrogel samples. The hydrogel had maximum swelling at pH 2 buffer and it decreased with increase in pH. The statistical parameters such as R 2 for Zero order, Higuchi, Hixson, Korsmeyer- Peppas and Baker-Lonsdale were close to unity (0.9649, 0.9818, 0.9865, 0.9786, and 0.8785), whereas, for 1 st order model its value was low i.e. 0.7966 Swelling behaviour of CG based hydrogel was studied under different conditions of pH and electrolytic aqueous media. The most efficient swelling result (200 %) was observed by the sample containing low fraction of crosslinker (AP 5) or high molar mass of PEG (GAP 60) had maximum range of swelling (910 %) right after 90 min. The statistical parameters such as R 2 for Zero order, 1 st Order, Higuchi, x Hixson, Korsmeyer-Peppas and Baker-Lonsdale are (0.9876, 0.9590, 0.9377, 0.9461, 0.9655 and 0.7763) close to unity and are within acceptable range for fitting. This distinctive behaviour of CS based hydrogels with PAA and its biocompatibility made them pertinent for drug delivery and its release profile as examined spectrophotometrically using silver sulfadiazine (antibiotic for burn wounds) showed 91.2% of drug release over a period of 1 h in a phosphate buffer saline (PBS) in a consistent and controlled manner. This eccentric pH sensitive swelling behaviour of 2 nd series of CS/PVP hydrogels made them apropos for drug delivery of cefixime analyzed spectrophotometrically at 288 nm (λ max). It showed 81.6% of drug release over a period of 12 h in a simulated intestinal fluid (SIF) in a consistent and controlled manner CG based hydrogel samples were used to study in-vitro release of a model drug (cephradine) in SIF. This release account of the cephradine demonstrated that the release of the drug increased as the time and pH increased and reached its maximum amount 84.4%at pH 8 after 6 h. The formulation (CG/PEG/ALG) was employed to load the drug, lidocaine; GAP 15 was used for the study of release behaviour and for drug loading. The in vitro release mechanism of the prepared hydrogels loaded with lidocaine showed 20 % of lidocaine release for 2 h. A persistent release (83.33%) of remaining lidocaine after 6 h was observed in PBS.
Gov't Doc #: 20714
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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