A chitosan composite with a vertical array of pore channels is fabricated via an electrophoretic deposition (EPD) technique. The composite consists of chitosan and polyethylene glycol, as well as nanoparticles of silver oxide and silver. The formation of hydrogen bubbles during EPD renders a localized increase of hydroxyl ions that engenders the precipitation of chitosan. In addition, chemical interactions among the constituents facilitate the establishment of vertical channels occupied by hydrogen bubbles that leads to the unique honeycomb-like microstructure; a composite with a porosity of 84%, channel diameter of 488 μm, and channel length of 2 mm. The chitosan composite demonstrates an impressive water uptake of 2100% and a two-stage slow release of silver. In mass transport analysis, both Disperse Red 13 and ZnO powders show a much enhanced transport rate over that of commercial gauze. Due to its excellent structural integrity and channel independence, the chitosan composite is evaluated in a passive suction mode for an adhesive force of 9.8 N (0.56 N cm −2 ). The chitosan composite is flexible and is able to maintain sufficient adhesive force toward objects with different surface curvatures.
Chitosan is considered to be a natural polymer for promising applications in drug delivery, wound dressing/healing, biocompatible coating, and tissue engineering. Since the chitosan is known for bio-compatibility, non-toxicity, anti-bacterial ability, and low cost, there has been increasing interest to leverage the unique characteristics of chitosan to fabricate bio-composites for specific bio-medical purposes. In this work, we demonstrate a facile synthetic approach to fabricate composite hydrogels consisting of chitosan, poly(3,4-ethylenedioxythiophene (PEDOT), and iridium oxide (IrO2) nanoparticles. Our synthesis step entails a potentiostatic mode that enables electrophoresis and water electrolysis simultaneously to produce free-standing conductive hydrogels with high porosity. Materials characterization of the as-synthesized composite hydrogels confirm reasonable electric conductivity and impressive anti-bacterial performance. In addition, structural and compositional analysis such as SEM, EDX, XPS, and Raman spectroscopy are conducted. From in-vitro tests of fibroblast cells, we observe that the application of electrical signals accelerates the growth rate, and the resulting current responses are contingent on the magnitude of cell proliferation. Our composite hydrogels combine both electrical stimulation and detection functionality, desirable attributes for potential use in wound healing application.
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