Ionotropic alginate hydrogels are versatile materials for a wide range of applications. Their biocompatibility and biodegradability have made them perfect candidates for biomedical applications such as tissue engineering and drug...
The high porosity of calcium alginate hydrogels was controlled by its treatment with polyvinyl alcohol followed by cross-linking with diboronic acids, which blocks larger pores in calcium alginate. Low molecular weight (11−31 kDa) polyvinyl alcohol selectively diffuses into larger pores of calcium alginate hydrogels, and the subsequent cross-linking with 1,3-benzenediboronic acid is highly efficient, providing stoichiometry of one 1,3benzenediboronic acid per four OH groups of polyvinyl alcohol. Cross-linking blocks larger pores in calcium alginate hydrogels, decreasing leaching of model bovine serum albumin, insulin, and myoglobin proteins physically entrapped in calcium alginate hydrogels by 20−30 fold. Internal pore blockage was confirmed by scanning electron microscopy and surface pore closure by liquid atomic force microscopy.
Alginate
hydrogel thin films of different compositions were electrochemically
produced at an electrode surface, and their interfacial reactions
were studied for biomolecule release. Nanozyme catalytic species represented
by Au nanoparticles were used to trigger biomolecule release from an Fe3+-cross-linked alginate hydrogel film upon receiving a glucose signal.
The oxidase-mimicking reaction catalyzed by Au nanoparticles resulted
in the production of H2O2, which yielded free
radicals through a Fenton-type reaction in the presence of iron cations.
The generated free radicals resulted in degradation/dissolution of
the alginate matrix and stimulated the release of entrapped DNA molecules.
The systematic study addressed the issues of the uncontrolled leakage
of the DNA molecules from alginate hydrogel and demonstrated the signal-triggered
DNA release in systems with various configurations, ranging from a
simple addition of H2O2 to the bulk solution
to the in situ production of H2O2 by the nanozyme coentrapped in the alginate film. The present study
adds an additional feature to the multioperational functions of nanozymes,
representing their use in signal-controlled biomolecule-releasing
systems.
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