Low-interference and sensitive electrochemical detection of glucose and lactate using boron-doped diamond electrode and electron mediator menadione

To minimize background interference in electrochemical enzymatic biosensors employing electron mediators, it is essential for the electrochemical oxidation of electroactive interfering species (ISs), such as ascorbic acid (AA), to proceed slowly, and for the redox reactions between electron mediators and ISs to occur at a low rate. In this study, we introduce a novel combination of a working electrode and an electron mediator that effectively mitigates interference effects. Compared to commonly used electrodes such as Au, glassy carbon, and indium tin oxide (ITO), boron-doped diamond (BDD) electrodes demonstrate significantly lower anodic current (i.e., lower background levels) in the presence of AA. Additionally, menadione (MD) exhibits notably slower reactivity with AA compared to other electron mediators such as Ru(NH3)63+, 4-amino-1-naphthol, and 1,4-naphthoquinone, primarily due to the lower formal potential of MD compared to AA. This synergistic combination of BDD electrode and MD is effectively applied in three biosensors: (i) glucose detection using electrochemical-enzymatic (EN) redox cycling, (ii) glucose detection using electrochemical-enzymatic-enzymatic (ENN) redox cycling, and (iii) lactate detection using ENN redox cycling. Our developed approach significantly outperforms the combination of ITO electrode and MD in minimizing IS interference. Glucose in artificial serum can be detected with detection limits of ~ 20 μM and ~ 3 μM in EN and ENN redox cycling, respectively. Furthermore, lactate in human serum can be detected with a detection limit of ~ 30 μM. This study demonstrates sensitive glucose and lactate detection with minimal interference, eliminating the need for (bio)chemical agents to remove interfering species.

Rapid detection of vaccinia virus using biofunctionalized fiber-optic ball-tip biosensors

In this work, we present the development and biofunctionalization of a fiber-optic ball-resonator biosensor for the real-time detection of vaccinia poxvirus. We fabricated several ball-tip resonators, functionalized through a silanization process to immobilize two bioreceptors: the monoclonal anti-L1R antibody targeting the L1R protein, and the polyclonal rabbit serum antibodies targeting the whole vaccinia virus (VV) pathogen. Experimental measurements were carried out to detect VV in concentrations from 103 to 108 plaque-forming units (PFU), with a limit of detection of around 1.7-4.3 × 103 PFU and a log-quadratic pattern, with a response up to 5 × 10-4 RIU (refractive index units). The specificity was assessed against herpes simplex virus, used as a non-specific control, with the best results obtained with anti-L1R monoclonal antibodies, and through the detection of vaccinia virus/herpes simplex-1 combination. The obtained results provide a real-time viral recognition with a label-free sensing platform, having rapid response and ease of manufacturing, and paving the road to the seamless detection of poxviruses affecting different human and animal species using optical fibers.

Addressing the Silent Spread of Monkeypox Disease with Advanced Analytical Tools

Monkeypox disease is caused by a virus which belongs to the orthopoxvirus genus of the poxviridae family. This disease has recently spread out to several non-endemic countries. While some cases have been linked to travel from endemic regions, more recent infections are thought to have spread in the community without any travel links, raising the risks of a wider outbreak. This state of public health represents a highly unusual event which requires urgent surveillance. In this context, the opportunities and technological challenges of current bio/chemical sensors, nanomaterials, nanomaterial characterization instruments, and artificially intelligent biosystems collectively called "advanced analytical tools" are reviewed here, which will allow early detection, characterization, and inhibition of the monkeypox virus (MPXV) in the community and limit its expansion from endemic to pandemic. A summary of background information is also provided from biological and epidemiological perspective of monkeypox to support the scientific case for its holistic management using advanced analytical tools.

Robotic APTamer-Enabled Electrochemical Reader (RAPTER) System for Automated Aptamer-Mediated Electrochemical Analysis

Electrochemical aptamer-based (E-AB) sensors using conformational change-induced electron transfer kinetics are sensitive, reagent-less, and cost-effective tools for molecular sensing. Current advances in this technology can allow continuous drug pharmacokinetic monitoring in living animals (Dauphin-Ducharme et al., ACS Sens 4(10):2832-2837, 2019; Idili et al., Chem Sci 10(35):8164-8170, 2019), as well as automated analysis of hormone pulsatility (Liang et al., Nat Commun 10(1):852, 2019). In this chapter, we provide the methodology for an automated E-AB conformational change-based robotic sensing platform. By using an open-source programmable robotic system, this method can be adapted to a wide range of experimental scenarios.

A comprehensive review on current COVID-19 detection methods: From lab care to point of care diagnosis

Without a doubt, the current global pandemic affects all walks of our life. It affected almost every age group all over the world with a disease named COVID-19, declared as a global pandemic by WHO in early 2020. Due to the high transmission and moderate mortality rate of this virus, it is also regarded as the panic-zone virus. This potentially deadly virus has pointed up the significance of COVID-19 research. Due to the rapid transmission of COVID-19, early detection is very crucial. Presently, there are different conventional techniques are available for coronavirus detection like CT-scan, PCR, Sequencing, CRISPR, ELISA, LFA, LAMP. The urgent need for rapid, accurate, and cost-effective detection and the requirement to cut off shortcomings of traditional detection methods, make scientists realize to advance new technologies. Biosensors are one of the reliable platforms for accurate, early diagnosis. In this article, we have pointed recent diagnosis approaches for COVID-19. The review includes basic virology of SARS-CoV-2 mainly clinical and pathological features. We have also briefly discussed different types of biosensors, their working principles, and current advancement for COVID-19 detection and prevention.

DT-Diaphorase as a Bifunctional Enzyme Label That Allows Rapid Enzymatic Amplification and Electrochemical Redox Cycling

The most common enzyme labels in enzyme-linked immunosorbent assays are alkaline phosphatase and horseradish peroxidase, which, however, have some limitations for use in electrochemical immunosensors. This Article reports that the small and thermostable DT-diaphorase (DT-D) and electrochemically inactive 4-nitroso-1-naphthol (4-NO-1-N) can be used as a bifunctional enzyme label and a rapidly reacting substrate, respectively, for electrochemical immunosensors. This enzyme-substrate combination allows high signal amplification via rapid enzymatic amplification and electrochemical redox cycling. DT-D can convert an electrochemically inactive nitroso or nitro compound into an electrochemically active amine compound, which can then be involved in electrochemical-chemical (EC) and electrochemical-enzymatic (EN) redox cycling. Six nitroso and nitro compounds are tested in terms of signal-to-background ratio. Among them, 4-NO-1-N exhibits the highest signal-to-background ratio. The electrochemical immunosensor using DT-D and 4-NO-1-N detects parathyroid hormone (PTH) in phosphate-buffered saline containing bovine serum albumin over a wide range of concentrations with a low detection limit of 2 pg/mL. When the PTH concentration in clinical serum samples is measured using the developed immunosensor, the calculated concentrations are in good agreement with the concentrations obtained using a commercial instrument. Thus, the use of DT-D as an enzyme label is highly promising for sensitive electrochemical detection and point-of-care testing.

A highly sensitive and simply operated protease sensor toward point-of-care testing

The sensor is based on (i) low nonspecific adsorption and (ii) electrochemical–chemical redox cycling.