Conducting polymer-based sensors for food and drug analysis

Abstract

Conducting polymers (CPs) are a category of polymeric materials with conjugated main chains. The characteristic electrical and optical properties of CPs can be fine-tuned through controlling the doping states of CPs. Because of their long-term stability in water, CPs have been demonstrated as electroactive biointerfaces and electrode materials especially in aqueous environments. Serving as multifunctional interfaces and organic electrodes for the integration bioelectronics and devices, CPs have been studied and applied in various biological applications. This paper provides a review of conducting polymer-based electrochemical sensors, particularly those used in biological fields. General conducting polymers and derivatives and their main electrochemical sensing platforms with different design of devices are introduced. Cyclic voltammetry, differential pulse voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and quartz crystal microbalance methods and their features are then explored as detection methods for the analysis of drugs and food. To enhance the sensitivity and lower the detection limit of sensing platforms, various CP-based nanocomposites have been designed and developed. Although the electrodes made of CP-based nanocomposites usually outperform those made of pristine CPs, more systematic studies are required to provide insights into the design of nanocomposite-based electrodes. More applications of CP-based sensors for advanced food and drug analyses are expected.

Fig. 1

(a) Chemical structures of common conducting polymers. Examples of doping states of (b) PA and (c) PEDOT.

Fig. 2

The application of conducting polymer biosensor in food and drug analysis.

Fig. 3

Examples of labeled biosensors: (a) detection of Lactate (Reprinted with permission from ref [8]. Copyright 2020 American Chemical Society); (b) detection of breast cancer susceptibility gene (Reprinted with permission from ref [25]. Copyright 2017 American Chemical Society) and label-free biosensors: (c) detection of calmodulin (Reprinted with permission from ref [26]. Copyright 2020 American Chemical Society); (d) detection of DA (Reprinted with permission from ref [48]. Copyright 2016 American Chemical Society); (e) detection of H₂O₂ (Reprinted with permission from ref [53]. Copyright 2018 American Chemical Society); (f) detection of oxidants (Reprinted with permission from ref [54]. Copyright 2019 American Chemical Society).

Fig. 4

Five types of commonly used detection methods: (a) cyclic voltammetry (CV); (b) differential pulse voltammetry (DPV); (c) chronoamperometry (CA); (d) electrochemical impedance spectroscopy (EIS); (e) quartz crystal microbalance (QCM).