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Application of Bioresponsive Polymers in Drug Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Manisha Lalan, Deepti Jani, Pratiksha Trivedi, Deepa H. Patel
Electro-responsive drug release from electro-conductive hydrogels was explored from semi-interpenetrating networks containing a blend of poly[ethyleneimine) and 1-vinylimidazole polymer as the novel electro-active species. The semi-interpenetrating networks are systems comprised of poly(acrylic acid) (PAA) and poly(vinyl alcohol). It was observed in the study that the relative ratios of the two polymers in the blend markedly influenced the degree of electro-responsive drug release and the matrix resilience of the hydrogels. The absence of an electric field resulted in low fluctuation flexibility and thus a highly stable molecular architecture. The use of an electric-stimulus offers versatility in usage of stimulus in terms of the duration of electric pulses, intervals between pulses, magnitude of current, etc. This gives an opportunity for precise control over the changes in physical structure. A number of polymers may be used as electroactive polymers like polypyrrole, polythiophene, polydimethylsiloxane, poly(methyl methacrylate), poly(3,4-ethylene dioxythiophene) and polyvinyl alcohol. These polymers have characteristic redox properties which render them semiconducting in nature and allow controlled ionic transport through the polymeric membrane. They allow for drug transport in the presence of an electric field only where they become resilient in nature and the drug release ceases in its absence. They may be used for continuous, pulsed, triggered drug delivery applications [9].
Design, synthesis and characterization of enzyme-analogue-built polymer catalysts as artificial hydrolases
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Divya Mathew, Benny Thomas, Karakkattu Subrahmanian Devaky
The first report on substrate analogue imprinted chymotrypsin mimic was announced by Leonhardt and Mosbach in 1987 [46]. Imidazole residues were employed to hydrolyze amino acid p-nitrophenyl esters. A pyridine derivative of the amino acid- picolinyl-N-Boc protected amino acid- was used as the substrate analogue template molecule. The functional monomer 5-vinylimidazole and the template picolinyl-N-Boc protected amino acid were coordinated by Co(II) ions using CoCl2.6H2O in the pre-polymerization step. Then on copolymerization in presence of the crosslinker divinylbenzene (DVB), followed by removal of the template and Co (II) ions resulted in an esterase MIP (Figure 8). The incorporation of catalytic groups is responsible for the substrate specificity and catalytic activity within the imprinted cavities. The esterase MIP exhibited a 5- to 7-fold rate enhancement in the hydrolysis of Boc-Met (or Leu)-p-nitrophenyl ester over the control polymer esterase CP with statistically distributed imidazole groups. Nevertheless, the template molecule was not a TSA but an analogue of the substrate, which was likely the cause of the polymers rather low rate enhancement.