Cell Viability Assessment of PEDOT Conducting Polymer-Coated Microneedles for Skin Sampling.

Recently, transdermal monitoring and drug delivery have gained much interest, owing to the introduction of the minimally invasive microneedle (MN) device. The advancement of electroactive MNs electrically assisted in the capture of biomarkers or the triggering of drug release. Recent works have combined conducting polymers (CPs) onto MNs owing to the soft nature of the polymers and their tunable ionic and electronic conductivity. Though CPs are reported to work safely in the body, their biocompatibility in the skin has been insufficiently investigated. Furthermore, during electrical biasing of CPs, they undergo reduction or oxidation, which in practical terms leads to release/exchange of ions, which could pose biological risks. This work investigates the viability and proliferation of skin cells upon exposure to an electrochemically biased MN pair comprising two differently doped poly(3,4-ethylenedioxy-thiophene) (PEDOT) polymers that have been designed for skin sampling use. The impact of biasing on human keratinocytes and dermal fibroblasts was determined at different initial cell seeding densities and incubation periods. Indirect testing was employed, whereby the culture media was first exposed to PEDOTs prior to the addition of this extract to cells. In all conditions, both unbiased and biased PEDOT extracts showed no cytotoxicity, but the viability and proliferation of cells cultured at a low cell seeding density were lower than those of the control after 48 h of incubation.

PEDOT coated microneedles towards electrochemically assisted skin sampling.

Skin sampling is a diagnostic procedure based on the analysis of extracted skin tissues and/or the observation of biomarkers in bodily fluids. Sampling using microneedles (MNs) that minimize invasiveness is gaining attention over conventional biopsy/blood lancet. In this study, new MNs for electrochemically assisted skin sampling are reported, specifically tailored for combined skin tissue biopsy and interstitial fluid (ISF) extraction. To overcome risks associated with using metal MNs, a highly electroactive, mechanically flexible, and biocompatible organic conducting polymer (CP) coated onto plastic is chosen as an alternative. Two different variants of doped poly(3,4-ethylenedioxythiophene) are coated on polymethyl methacrylate and used in combination as a MN pair with subsequent testing via a variety of electrochemical techniques to (i) give real-time information of the MN penetration depth into the skin, and (ii) yield new information on various salts present in the ISF. The MN skin sampler shows the ability to extract ions from the hydrated excised skin as a step towards in vivo ISF extraction. The presence of ions was analyzed using X-ray photoelectron spectroscopy. This added chemical information in conjunction with the existing biomarker analysis increases opportunity for disease/condition detection. For example, in the case of psoriasis, information about salt in the skin is invaluable in combination with pathogenic gene expression for diagnosis.

Understanding PEDOT doped with tosylate.

Now in their 5th decade of research and development, conducting polymers represent an interesting class of materials to underpin new wearable or conformable electronic devices. Of particular interest over the years has been poly(3,4-ethylenedioxythiophene), commonly known as PEDOT, owing to its ease of fabrication and relative stability under typical ambient conditions. Understanding PEDOT from a variety of fundamental and applied perspectives is important for how it can be enhanced, modified, functionalised, and/or processed for use in commercial products. This feature article highlights the contribution of the research team at the University of South Australia led by Professor Evans, and their collaborators, putting their work into the broader context of conducting polymer research and application. This review focuses on the vapour synthesis of PEDOT doped with the tosylate anion, the benefits of controlling its morphology/structure during synthesis, and its application as an active material interacting with secondary anions in sensors, energy devices and drug delivery.