(165n) Characteristics of Electrically Responsive Ferrocene-Conjugated Chitosan/Alginate Hydrogel for Biomedical Application

Pathogenic infection as the most frequent complication of chronic wounds has become a global healthcare challenge because of the impairment of the healing process and the risks for amputations and mortality. The spatiotemporal release of therapeutics from wound dressings is highly desirable in order to manage wound treatment. The aim of this study is to obtain and characterize an electro-responsive ferrocene-chitosan/alginate polyelectrolyte complex (PEC) hydrogel that can be used as a smart wound dressing. First, chitosan/alginate PEC hydrogel was obtained as a control and characterized in terms of chemical properties and drug release kinetics. Natural chitosan (CHI) was chemically conjugated with ferrocene (Fc) moieties to create Fc-CHI. The Fc-CHI was interacted with alginate (ALG) to form Fc-CHI/ALG PEC through electrostatic interaction. The turbidity test was performed to find the optimum ratio between the Fc-CHI and ALG, thus the stoichiometric PEC hydrogel. The PEC hydrogel was characterized by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), in addition to the swelling behavior and gel content tests. Comparative analysis of the ATR-FTIR spectra of CHI, Fc-CHI, ALG, and their mixtures indicated the formation of a polyelectrolyte complex. The SEM images showed the porosity of the PEC. The EDS analysis proved the incorporation of the Fc into the CHI by the appearance of the Fc peaks in the analysis. The PEC hydrogel showed a comparative swelling percentage to be 4400% and also showed excellent stability. To demonstrate the drug delivery potential of the developed PEC-based wound dressing, fluorescence (FITC) and FITC-Dextran were used as model drugs. First, the drug loading and release kinetics of the PEC were studied in solution. In 3 days, about 83% and 61% were released of the FITC, and FITC-Dextran, respectively in PBS solution. Secondly, the drug release properties on the phantom skin surface (agarose gel) were investigated using a custom-made electrical stimulus setup incorporated with fluorescence microscopy. The release of the model drugs on the surface was tested in passive (no electrical stimulus) and active (with electrical stimulus) manners. The PEC hydrogels showed an electro responsivity represented by increasing the intensity of the model drugs that diffused through the agarose gel under the electric stimulus. The diffusion coefficients for different drug models were estimated by analyzing images obtained after a time series of acquisition. Based on the results, the developed Fc-CHI/ALG PEC hydrogel is prone to be an enhanced drug release upon the electrical stimulus, compared to the CHI/ALG PEC hydrogel, indicating the presence of Fc may be able to increase the electro-osmosis pressure followed by the spontaneous drug release. The developed PEC hydrogel may be integrated with the bioelectronic devices.