Electrochemical diagnostics of infectious viral diseases: Trends and challenges.

Infectious diseases caused by viruses can elevate up to undesired pandemic conditions affecting the global population and normal life function. These in turn impact the established world economy, create jobless situations, physical, mental, emotional stress, and challenge the human survival. Therefore, timely detection, treatment, isolation and prevention of spreading the pandemic infectious diseases not beyond the originated town is critical to avoid global impairment of life (e.g., Corona virus disease - 2019, COVID-19). The objective of this review article is to emphasize the recent advancements in the electrochemical diagnostics of twelve life-threatening viruses namely - COVID-19, Middle east respiratory syndrome (MERS), Severe acute respiratory syndrome (SARS), Influenza, Hepatitis, Human immunodeficiency virus (HIV), Human papilloma virus (HPV), Zika virus, Herpes simplex virus, Chikungunya, Dengue, and Rotavirus. This review describes the design, principle, underlying rationale, receptor, and mechanistic aspects of sensor systems reported for such viruses. Electrochemical sensor systems which comprised either antibody or aptamers or direct/mediated electron transfer in the recognition matrix were explicitly segregated into separate sub-sections for critical comparison. This review emphasizes the current challenges involved in translating laboratory research to real-world device applications, future prospects and commercialization aspects of electrochemical diagnostic devices for virus detection. The background and overall progress provided in this review are expected to be insightful to the researchers in sensor field and facilitate the design and fabrication of electrochemical sensors for life-threatening viruses with broader applicability to any desired pathogens.

Polymer scaffold layers of screen-printed electrodes for homogeneous deposition of silver nanoparticles: application to the amperometric detection of hydrogen peroxide.

A method is described for electrochemical oxidation of polymers on the surface of screen-printed electrodes (SPCE). These act as scaffold layers for homogeneous deposition of silver nanoparticles (AgNPs). Hexamethylenediamine (HMDA) and poly(ethylene glycol) were immobilized on the SPCE surface via electrochemical oxidation. AgNPs were then electrodeposited on the scaffolds on the SPCE. This type of different carbon chain containing materials like PEG and HMDA act as big tunnels for electron mobility and are useful for the homogenous deposition of AgNPs on the SPCE surface without agglomeration. The resulting sensor was applied to the determination of hydrogen peroxide (H2O2) as a model analyte. It is found to display favorable catalytic and conductive properties towards the reduction of H2O2. Cyclic voltammetry and amperometry revealed that the modified electrode performs better than other modified SPCEs. Best operated at a potential of around -0.61 V (vs Ag|AgCl), the amperometric response is linear in the 10-180 µM H2O2 concentration range and the detection limit is 1.5 µM. The sensor is stable and reproducible. The resultant sensor was appplied to toothpaste analysis, and good recovery values were gained. Graphical abstractSchematic representation of electropolymerization of poly(ethylene glycol) and hexamethylenediamine scaffold layers on screen-printed electrodes for homogeneous electrodeposition of silver nanoparticles. This electrode was applied for the amperometric determination of hydrogen peroxide.

Silver nanoparticles impregnated chitosan layered carbon nanotube as sensor interface for electrochemical detection of clopidogrel in-vitro.

Continuous periodical monitoring of clopidogrel in physiological body fluids is indispensable in medical diagnosis of heart ailments and cardiovascular diseases. A highly sensitive electrochemical sensor has been fabricated with silver nanoparticles embedded chitosan-carbon nanotube hybrid composite (AgChit-CNT) as sensor interface for detection of the important anti-platelet drug, clopidogrel (CLP). Synthesized AgChit-CNT nanocomposite is examined by x-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy for its chemical and structural characteristics. Crystalline silver nanoparticles of about 35 nm are well distributed in the composite and have formed continuous chain like linkages with CNTs all throughout. Electrochemical responses of the fabricated AgChit-CNT nanocomposite electrode for the determination of CLP have been examined by cyclic voltammetry and electrochemical impedance spectroscopy. The nanoAg patterned CNT nanocomposite interface acts as an excellent electron transfer mediator towards the oxidation of clopidogrel. Electrochemical determination of CLP was investigated by differential pulse voltammetry (DPV) and amperometric analysis under optimized conditions. The limit of detection by DPV and amperometry were 30 nM and 10 nM, respectively, and the time of the analysis is as low as 10 s. Practical applicability for determination in artificially prepared urine and pharmaceutical formulation has been examined with good recovery limits of 95.2 to 102.6%.