An Insight into Ionic Conductivity of Polyaniline Thin Films

Advancements in stimulation therapies for peripheral nerve regeneration

Soft-tissue injuries affecting muscles, nerves, vasculature, tendons, and ligaments often diminish the quality of life due to pain, loss of function, and financial burdens. Both natural healing and surgical interventions can result in scarring, which potentially may impede functional recovery and lead to persistent pain. Scar tissue, characterized by a highly disorganized fibrotic extracellular matrix, may serve as a physical barrier to regeneration and drug delivery. While approaches such as drugs, biomaterials, cells, external stimulation, and other physical forces show promise in mitigating scarring and promoting regenerative healing, their implementation remains limited and challenging. Ultrasound, laser, electrical, and magnetic forms of external stimulation have been utilized to promote soft tissue as well as neural tissue regeneration. After stimulation, neural tissues experience increased proliferation of Schwann cells, secretion of neurotropic factors, production of myelin, and growth of vasculature, all aimed at supporting axon regeneration and innervation. Yet, the outcomes of healing vary depending on the pathophysiology of the damaged nerve, the timing of stimulation following injury, and the specific parameters of stimulation employed. Increased treatment intensity and duration have been noted to hinder the healing process by inducing tissue damage. These stimulation modalities, either alone or in combination with nerve guidance conduits and scaffolds, have been demonstrated to promote healing. However, the literature currently lacks a detailed understanding of the stimulation parameters used for nerve healing applications. In this article, we aim to address this gap by summarizing existing reports and providing an overview of stimulation parameters alongside their associated healing outcomes.

Mitigating Lithium Dissolution and Polysulfide Shuttle Effect Phenomena Using a Polymer Composite Layer Coating on the Anode in Lithium-Sulfur Batteries

To mitigate lithium dissolution and polysulfide shuttle effect phenomena in high-energy lithium sulfur batteries (LISBs), a conductive, flexible, and easily modified polymer composite layer was applied on the anode. The polymer composite layer included polyaniline and functionalized graphite. The electrochemical behavior of LISBs was studied by galvanostatic charge/discharge tests from 1.7 to 2.8 V up to 90 cycles and via COMSOL Multiphysics simulation software. No apparent overcharge occurred during the charge state, which suggests that the shuttle effect of polysulfides was effectively prevented. The COMSOL Multiphysics simulation provided a venue for optimal prediction of the ideal concentration and properties of the polymer composite layer to be used in the LISBs. The testing and simulation results determined that the polymer composite layer diminished the amount of lithium polysulfide species and decreased the amount of dissolved lithium ions in the LISBs. In addition, the charge/discharge rate of up to 2.0 C with a cycle life of 90 cycles was achieved. The knowledge acquired in this study was important not only for the design of efficient new electrode materials, but also for understanding the effect of the polymer composite layer on the electrochemical cycle stability.

Strategic Electrochemical Determination of Nitrate over Polyaniline/Multi-Walled Carbon Nanotubes-Gum Arabic Architecture

Significant agricultural and industrial activities necessitate the regular monitoring of nitrate (NO₃^-) ions levels in feed and groundwater. The current comparative study discloses an innovative user-friendly electrochemical approach for the determination of NO₃^- over polyaniline (PAni)-based modified electrodes. The electrochemical sensors concocted with PAni, multi-walled carbon nanotubes (CNT), and gum arabic (GA). The unique electrode material GA@PAni-CNT was synthesized by facile one-pot catalytic polymerization of aniline (Ani) with FeCl₃/H₂O₂ in the presence of CNT and GA as integral components. As revealed by cyclic voltammetry (CV), the anchoring/retention of NO₃^- followed by reduction is proposed to occur when a GA@PAni-CNT electrode is immersed in phosphate buffer electrolyte containing NO₃^- that eventually results in a significantly higher redox activity of the GA@PAni-CNT electrode upon potential scan. The mechanism of NO₃^- anchoring may be associated with the non-redox transition of leucomeraldine salt (LS) into emeraldine salt (ES) and the generation of nitrite (NO₂^-) ions. As a result, the oxidation current produced by CV for redox transition of ES ↔ pernigraniline (PN) was ~9 times of that obtained with GA@PAni-CNT electrode and phosphate buffer electrolyte, thus achieving indirect NO₃^- voltammetric determination of the GA@PAni-CNT electrode. The prepared GA@PAni-CNT electrode displayed a higher charge transfer ability as compared to that of PAni-CNT and PAni electrodes. The optimum square wave voltammetric (SWV) response resulted in two linear concentration ranges of 1-10 (R² = 0.9995) and 15-50 µM (R² = 0.9988) with a detection limit of 0.42 µM, which is significantly lower. The GA@PAni-CNT electrode demonstrated the best detection, sensitivity, and performance among the investigated electrodes for indirect voltammetric determination of NO₃^- that portrayed the possibility of utilizing GA-stabilized PAni and CNT nanocomposite materials in additional electrochemical sensing applications.

Self-doped conducting polymers in biomedical engineering: Synthesis, characterization, current applications and perspectives

Recent studies willingly agree that conducting polymers (CPs) are attractive materials for biomedical engineering purposes, mainly because of their unique physicochemical characteristics combining electrical conductivity and high biocompatibility. Nevertheless, the applicability of CPs is restricted by their limited stability under physiological conditions, associated with a decrease in electrical conductivity upon dedoping. Accordingly, modifying chemical structure of CPs to exhibit a self-doping effect seems to be an appealing approach aimed to enhance their functionality. The aim of this review is to provide a current state-of-the-art in the research concerning self-doped CPs, particularly those with potential biomedical applications. After presenting a library of available structure modifications, we describe their physicochemical characteristics, focusing on achievable conductivities, electrochemical, optical and mechanical behaviour, as well as biological properties. To highlight high applicability of self-doped CPs in biomedical engineering, we elaborate on biomedical areas benefiting most from using this type of conducting materials.

Large Deflection Analysis of Peripherally Fixed Circular Membranes Subjected to Liquid Weight Loading: A Refined Design Theory of Membrane Deflection-Based Rain Gauges

The anticipated use of elastic membranes for deflection-based rain gauges has provided an impetus for this paper to revisit the large deflection problem of a peripherally fixed circular membrane subjected to liquid weight loading, a statics problem when the fluid–structure interaction of membrane and liquid reaches static equilibrium. The closed-form solution of this statics problem of fluid–structure interaction is necessary for the design of such membrane deflection-based rain gauges, while the existing closed-form solution, due to the use of the small rotation angle assumption of the membrane, cannot meet the design requirements for computational accuracy. In this paper, the problem under consideration is reformulated by giving up the small rotation angle assumption, which gives rise to a new and somewhat intractable nonlinear integro-differential equation of the governing out-of-plane equilibrium. The power series method has played an irreplaceable role in analytically solving membrane equations involving both integral and differential operations, and a new and more refined closed-form solution without the small rotation angle assumption is finally presented. Numerical examples conducted show that the new and more refined closed-form solution presented has satisfactory convergence, and the effect of giving up the small rotation angle assumption is also investigated numerically. The application of the closed-form solution presented in designing such membrane deflection-based rain gauges is illustrated, and the reliability of the new and more refined closed-form solution presented was confirmed by conducting a confirmatory experiment.

Self Standing Mats of Blended Polyaniline Produced by Electrospinning

Conducting nanofibers of polyaniline (PANI) doped with camphor-10-sulfonic acid (HCSA) and blended with different polymers, such as polymethyl methacrylate (PMMA) and polyvinyl acetate (PVAc), have been fabricated using the electrospinning technique. Scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) were utilized to characterize the morphology and the thermal stability of PANI-blended fibers. An extensive study was performed to understand the copolymer influence on both the structural and surface properties of the realized conductive thin films. Samples main electrical characteristics, as conductivity, specific capacitance and electrochemical performances were tested. The better mats were obtained with the use of PVAc copolymer, which showed a conductivity value two orders of magnitude higher than the PMMA system. Aiming at further improving the electrochemical features of these blended mats, hybrid fibers based on PANI/PVAc/graphene oxide and PANI/PVAc/iron oxide were also produced and characterized. The obtained mats were potentially addressed to numerous practical fields, including sensors, health applications, smart devices and multifunctional textile materials.