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E.Krisch, B. Gyarmati, D. Barczikai, V. Lapeyre, B.A. Szilágyi, V. Ravaine, A. Szilágyi

European Polymer Journal 105 (2018) 459–468

Redox and pH responsive hydrogels were synthesized, which can serve as matrices for smart drug deliveryRedox and pH responsive hydrogels were synthesized, which can serve as matrices for smart drug deliverysystems exploiting the redox and pH gradients in the human body. Water soluble thiolated poly(aspartic acid), abiocompatible synthetic polymer, enables us to cross-link in water with a non-cleavable cross-linker, poly(ethylene glycol) diglycidyl ether. The permanent cross-linker establishes stable polymer hydrogels regardless ofthe redox environment, thus the gels swell but do not dissolve upon redox stimuli. The reversible response uponredox stimulus was induced by thiol-disulphide transformation inside the hydrogel. The degree of swelling andthe stiffness of the macroscopic hydrogels were controlled by their chemical composition including thiol contentand cross-linking ratio as well as the redox state of the hydrogels. The degree of swelling of the hydrogels showedstrong pH dependence due to the polyelectrolyte nature of the polymer network. Release of a macromolecularmodel drug was considerably faster in reducing than in oxidising environment, which indicates the potential useof the synthesized hydrogels as redox responsive drug delivery systems. Nanogels were prepared in water-in-oilemulsion and displayed redox-responsive properties. The hydrodynamic diameter of the nanogels strongly increasedupon the cleavage of the disulphide linkages in reducing solution without the disruption of the gels.

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