Journal of Colloid and Interface Science, Vol.505, 1111-1117, 2017
Deamidation of pseudopeptidic molecular hydrogelators and its application to controlled release
Hypothesis: The incorporation of a succinic acid-derived moiety in amino acid derivatives would favor an intramolecular catalysis of a deamidation reaction. Such reaction would permit controlled disassembly of molecular hydrogelators and the use of the hydrogels for controlled release of actives. Experimental: Low molecular weight hydrogelators containing a succinic acid-derived moiety were prepared by conventional organic synthesis procedures. Hydrogels were examined by electron microscopy and H-1 NMR studies were carried out to evaluate the solubility in water of the hydrogelators and the deamidation reaction. Liberation of Rose Bengal entrapped in the hydrogels was monitored by UV-Vis spectroscopy. Findings: Molecular hydrogels formed by pseudopeptidic derivatives of L-valine suffer a thermal deamidation reaction, leading to partial disassembly. The succinic acid-derived moiety present in the gelators is responsible of intramolecular catalysis of a deamidation reaction. Such neighboring group effect is reminiscent of biochemical processes such as protein deamidation and self-excision of inteins. It has been found that the thermodynamic equilibrium of the deamidation reaction is regulated by the efficiency of hydrogelation. As a proof of concept, the thermally promoted deamidation is applied to controlled release of Rose Bengal. (C) 2017 Elsevier Inc. All rights reserved.