Electrochemical biosensors for pathogen detection

Abstract

Recent advances in electrochemical biosensors for pathogen detection are reviewed. Electrochemical biosensors for pathogen detection are broadly reviewed in terms of transduction elements, biorecognition elements, electrochemical techniques, and biosensor performance. Transduction elements are discussed in terms of electrode material and form factor. Biorecognition elements for pathogen detection, including antibodies, aptamers, and imprinted polymers, are discussed in terms of availability, production, and immobilization approach. Emerging areas of electrochemical biosensor design are reviewed, including electrode modification and transducer integration. Measurement formats for pathogen detection are classified in terms of sample preparation and secondary binding steps. Applications of electrochemical biosensors for the detection of pathogens in food and water safety, medical diagnostics, environmental monitoring, and bio-threat applications are highlighted. Future directions and challenges of electrochemical biosensors for pathogen detection are discussed, including wearable and conformal biosensors, detection of plant pathogens, multiplexed detection, reusable biosensors for process monitoring applications, and low-cost, disposable biosensors.

Keywords: Bio-threat; Biosensors; COVID-19; Electrochemical; Food safety; Medical diagnostics; Pathogen quantification; Virus detection; Water safety.

Fig. 1

Components and measurement formats associated with electrochemical biosensors for pathogen detection.

Fig. 2

a) Trend in pathogens detected by electrochemical biosensors since 2005 based on the data shown in Table 1, Table 2. b) Common matrices associated with the various pathogen detection applications.

Fig. 3

Emerging transduction approaches associated with electrochemical biosensors for pathogen detection. a) A nanostructured Au microelectrode array with high curvature (De Luna et al. 2017). b) Cell-imprinted polymer (CIP) with ‘artificial’ biorecognition elements for detection of E. coli using electrochemical impedance spectroscopy (EIS) and the Fe(CN)₆^3-/4- redox probe (Jafari et al. 2019).

Fig. 4

Measurement settings associated with electrochemical biosensor-based multiplexed pathogen detection. a) Microfluidic device with an interdigitated Au microelectrode array for continuous measurement of S. typhimurium (Dastider et al. 2015). b) Conjugated nanoparticles with two different biorecognition elements for E. coli and V. cholerae detection via voltammetry using Fe(CN)₆^3-/4- (Li et al. 2017). c) Schematic of a microfluidic device with two separate spatial regions of biorecognition elements for E. coli and S. aureus (Tian et al. 2016).

Fig. 5

Typical responses associated with the common electrochemical methods used for pathogen detection. a) Cyclic voltammetry (CV) data using Fe(CN)₆^3-/4- for varying concentrations of E. coli (Güner et al. 2017). b) Differential pulse voltammetry (DPV) data using Fe(CN)₆^3-/4- for varying concentrations of S. aureus (Bhardwaj et al. 2017). c) Electrochemical impedance spectroscopy (EIS) in 100 mM LiClO₄ solution in the form of a Nyquist plot and corresponding equivalent circuit model associated with biorecognition element immobilization and detection of S. typhimurium (Sheikhzadeh et al. 2016). d) Conductometry data for varying concentrations of B. subtilis (Yoo et al. 2017).

Fig. 6

Highlight of secondary binding and signal amplification approaches utilized in electrochemical biosensor-based pathogen detection. a) Four amplification approaches associated with the secondary binding of enzyme-labeled secondary antibodies: (A) electron transfer mediation; (B) nanostructuring of surface for increased rate of charge transfer kinetics; (C) conversion of electrochemically inactive substrate into a detectable electroactive product; (D) catalysis of oxidation of glucose for production of hydrogen peroxide for electrochemical detection (Kokkinos et al. 2016). b) Signal amplification via non-selective binding of AuNPs to bound bacterial target (E. coli) (Wan et al. 2016).

Fig. 7

State-of-the-art developments in electrochemical biosensors for pathogens. a) Low-cost, flexible, disposable screen-printed carbon electrodes (Afonso et al. 2016). b) Free-standing graphene electrodes (Wang et al. 2013). c) Paper-based substrates for pathogen detection using electrochemical methods (Bhardwaj et al. 2017). d) Wearable wireless bacterial biosensor for tooth enamel (Mannoor et al. 2012). e) Smartphone-enabled signal processing for field-based environmental monitoring (Jiang et al. 2014).