PEDOT coated microneedles towards electrochemically assisted skin sampling

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Materials for biology and medicine, 2023-06, Vol.11 (22), p.521-531
• Main Authors: Ajmal Mokhtar, Siti Musliha, Yamada, Miko, Prow, Tarl W, Moore, Mark, Strudwick, Xanthe L, Evans, Drew R
• Format: Article
• Language: English
• Subjects: Biocompatibility; Biomarkers; Biopsy; Body fluids; Bridged Bicyclo Compounds, Heterocyclic; Coatings; Conducting polymers; Electrochemistry; Gene expression; In vivo methods and tests; Invasiveness; Ions; Needles; Penetration depth; Photoelectron spectroscopy; Photoelectrons; Plastics; Polymers; Polymethyl methacrylate; Polymethylmethacrylate; Psoriasis; Samplers; Sampling; Skin; Skin diseases
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/d3tb00485f

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. Electrochemically active microneedles are formed from plastic coated with PEDOT. A pair of these form a skin sampler and evaluated in the hydrated excised skin. This provides additional information on the interstitial fluid extracted from the skin.