ABSTRACT
Electrical stimulation has emerged as a cornerstone technique in the rapidly evolving field of biomedical engineering, particularly within the realms of tissue engineering and regenerative medicine. It facilitates cell growth, proliferation, and differentiation, thereby advancing the development of accurate tissue models and enhancing drug-testing methodologies. Conductive hydrogels, which enable the conduction of microcurrents in 3D in vitro cultures, are central to this advancement. The integration of high-electroconductive nanomaterials, such as graphene oxide (GO), into hydrogels has revolutionized their mechanical and conductivity properties. Here, we introduce a novel electrostimulation assay utilizing a hybrid hydrogel composed of methacryloyl-modified small intestine submucosa (SIS) dECM (SISMA), chitosan methacrylate (ChiMA), and GO-polyethylene glycol (GO-PEG) in a 3D in vitro culture within a hypoxic environment of umbilical cord blood cells (UCBCs). Results not only demonstrate significant cell proliferation within 3D constructs exposed to microcurrents and early growth factors but also highlight the hybrid hydrogel's physiochemical prowess through comprehensive rheological, morphological, and conductivity analyses. Further experiments will focus on identifying the regulatory pathways of cells subjected to electrical stimulation.
ABSTRACT
Polypyrrole (PPy) is a promising material for the fabrication of flexible energy storage devices and much research has been published. However, no statistical tools have been used to relate PPy synthesis conditions to its energy storage performance, considering not only the main synthesis factors but also their interactions. In this work, we use a factorial design of experiments to evaluate the influence of two electropolymerization methods and three synthesis parameters on the energy storage capacity of PPy coatings. The polymers were characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and scanning electron microscopy (SEM). Statistical tests showed that ClO4 --doped PPy exhibits higher capacitances than p-toluenesulfonate (pTS)-doped PPy, with a maximum capacitance of 353.75 ± 1.6 F g-1 at 1 A g-1. However, the pTS-doped PPy had better cycling stability, losing only 10% of its original energy storage capability after 5000 charge-discharge cycles at 1 A g-1. The best energy densities and power densities were 49.1 ± 0.2 Wh kg-1 and 2297 ± 15 W kg-1 (ClO4 --doped PPy) and 47.8 ± 1.5 Wh kg-1 and 2191 ± 91 W kg-1 (pTS-doped PPy), respectively, which indicates that through statistical tools, the optimal synthesis conditions are refined to take advantage of the energy storage properties of this polymer.