Synthesis and characterization of 4-formylphenylboronic acid cross-linked chitosan hydrogel with dual action: Glucose-sensitivity and controlled insulin release

The number of people affected by diabetes mellitus is increasing globally in each year. A cause of elevated blood glucose levels can result from a lack of insulin or insufficient utilization of produced insulin. However, diabetes, a metabolic disorder is a serious chronic disease and an acute public health problem. Glucose-sensitive hydrogels that have 3D network structure can act in response to glucose and garners immense attention in biomedical appliance especially for drug delivery. Herein, a novel, glucose- and pH-responsive intelligent hydrogel encompassing chitosan cross-linked to 4-formylphenylboronic acid is prepared via dynamical reversible chemical bonds (imine) between chitosan and 4-formylphenylboronic acid with potential of controlled release of insulin. The characteristic features of such hydrogels are confirmed by Fourier transformed infrared (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and swelling ratio. Of these, the glucose-sensitive polymeric carrier (hydrogel) based on 4-formylphenylboronic acid has the advantages of enhanced stability, long-term storage, reversible response to glucose with high entrapment efficiency and controlled drug release into the physiological condition. In this paper, chitosan cross-linked with 4-formylphenylboronic acid, comprising the realization of Schiff base bearing (–C=N–) linkage, leads to the generation of a hydrogel which works better than normal phenylboronic acid (PBA) under physiological setting. The ensuing outcome implies that the glucose-susceptible hydrogel has prospective appliance as a glucose-receptive matter for insulin transport.