Recent advances in the aqueous applications of PEDOT

Abstract

Water is ubiquitous in life - from making up the majority of the Earth's surface (by area) to over half of the human body (by weight). It stands to reason that materials are likely to contact water at some point during their lifetime. In the specific case of sensors however, there is a need to consider materials that display stable function while immersed in aqueous applications. This mini-review will discuss the most recent advances (2018 to 2021) in the application of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) in aqueous environments. At its heart, the use of PEDOT in aqueous applications relies on nanoscale understanding and/or nanoengineered structures and properties. This enables their use in water-based settings such as within the human body or buried in agricultural soils.

Fig. 1. Scanning electron microscopy micrographs showing hippocampal cultures grown on PEDOT:PSS layers. (A) Lower magnification micrographs display that qualitatively the size of neuronal network is comparable between undoped PEDOT:PSS and PEDOT:PSS 3% EG. (B) Higher magnification micrographs show the healthy morphology of single neurons grown on the different substrates. Reproduced with permission from ref. . CC BY 4.0.

Fig. 2. TEM images of the regenerated nerve (A), the thickness of the regenerated nerve (B) (standard error, n = 30, ***p < 0.001), immunohistochemistry staining of CD31 (C), and toluidine blue staining (D) of the regenerated nerve slice in chitin-p (ChT-p), chitin-2%PEDOT-p (ChT-PEDOT-p), and autograft group, respectively. The red arrow is indicated as vessels. The amplitude of compound motor action potential (CMAP) index of the normal side compared with experiment side (E). Nerve conducting velocity curve (F) and corresponded statistics (G) (standard error, n ≥ 3, ***p < 0.001, **p < 0.01, *p < 0.05). All testifications were conducted on the postoperative rats after 20 weeks. Reprinted with permission from ref. . Copyright 2021 American Chemical Society.

Fig. 3. Examples of PEDOT used in plants. (a) Louisiana iris plant from which the leaf was extracted. (b) Cross sectional image of the leaf with PEDOT:PSS in the conduits which turns the conduits dark in color. (c) Chemical structure of PEDOT:PSS used as conducting polymer to construct conducting wires inside the leaves. Reproduced with permission from ref. . CC BY-NC 3.0.

Fig. 4. Selectivity experiments using cationic and anionic dyes accompanied by UV-vis spectra of (a) mixture of MO and MB dyes, (b) mixture of MO and RB dyes, (c) mixture of MO and TB dyes, (d) mixture of MO and CR dyes and (e) mixture of MO and IC dyes. Reprinted with permission from ref. . Copyright 2020 Elsevier.