Electro-assisted assembly of conductive polymer and soft hydrogel into core-shell hybrids

Soft hydrogels have become an important class of materials for mimicking and interfacing biological soft tissues with potential applications in drug delivery, tissue engineering and bioelectronics. Creative methods for integrating hydrogels with other materials such as organic conductors are highly desired. Here, we describe the single-step electrosynthesis of PEDOT/alginate into core-shell hybrid structures via an electrochemical-chemical-chemical mechanism. Using a pulsed electropolymerisation protocol, we generated PEDOT in either oxidized or reduced form. By-products of this electrochemical step trigger the chemical reactions for the concomitant assembly of alginate hydrogels. Characterization evidences that PEDOT (core) and alginate (shell) compartments form an electrochemically integrated interface. During growth, both can be loaded with useful cargo. We loaded a negatively charged small molecule and investigated passive and electroactive release mechanisms from the two compartments. Our electro-assisted assembly/crosslinking of integrated PEDOT/alginate hybrids contributes a promising approach to the design of functional interfaces for applications in controlled release and soft electronics

Óxidos Mistos de Al2O3/ZrO2 como Inibidores de Corrosão do Aço SAE 1020

<p class="orbitalabstract"><span>This paper describes the use of Al₂O₃/ZrO₂ mixed oxides synthesized by sol-gel process with different amounts of ZrO₂ (5%, 10%, 15% and 20% by mass) in the Al₂O₃ matrix and different temperatures of calcination, such as interesting inhibitor materials of corrosive processes of SAE 1020 steel. The materials were characterized by Infrared Spectroscopy Fourier Transform (FTIR) and X-Ray Diffraction (XRD) techniques. FTIR spectra show the typical Al-O and Zr-O bonds vibrations in the mixed oxides. The XRD patterns of the samples calcined at 800 °C and 1000 °C shows the ZrO₂ tetragonal and γ-Al₂O₃face-centered cubic (FCC) phases. The corrosion tests showed that the SAE 1020 steel covered with mixed oxides have an anodic passive region, thereby inhibiting the corrosive processes on the metal surface. Furthermore, the found values for steel coated with mixed oxide synthesized indicate a decrease in corrosion potentials (E_cor) and corrosion current (i_cor). With respect to different samples of mixed oxides, the sample with 20 % of ZrO₂ in the Al₂O₃ matrix proved to be the best inhibitor of steel corrosion, with the lowest values of corrosion potential and corrosion current, - 1.32 V and 0.31 μA cm^-2, respectively.</span></p

Electrochemically Driven Assembly of Chitosan Hydrogels on PEDOT Surfaces

Abstract Hydrogels are attracting interest in the field of bioelectronics due to their ability to serve as coatings on electrodes, improving the electrochemical interface, addressing the mechanical mismatch, and offering potential for localized drug or cell delivery. Challenges persist in integrating hydrogels with electrodes typically composed of metals and/or organic semiconductors. Here, an electrochemically driven method is introduced for direct growth of chitosan hydrogels onto poly(3,4‐ethylenedioxythiophene) (PEDOT) surfaces. The growth of ionic gelation chitosan is triggered by electrical release of a specific dopant, tripolyphosphate (TPP), from PEDOT. As a result, chitosan hydrogels grow directly from the PEDOT surface and firmly attach to it. Although this process temporarily reduces PEDOT to the benzoid structure, its unique electroactivity allows for reversible conversion to the quinoid structure after chitosan hydrogel assembly. Once assembled, the chitosan hydrogel coating can be further functionalized. The introduction of covalent cross‐links and incorporation of additional interpenetrating polymer networks (IPNs) are explored. Electrochemical characterization reveals that an interface with favorable properties is formed between PEDOT and ionic‐covalent chitosan, functionalized with a PEDOT IPN. The electroactivity of the proposed method surpasses any other PEDOT/chitosan system reported in the literature. These results underscore the potential of this material for bioelectronics applications