Electrochemical biosensor for the evaluation of monoclonal antibodies targeting the N protein of SARS-CoV-2 virus

Biomarker Detection in the Wastewater Phantom

Research trends are focused on developing solutions that monitor public health utilizing sewage surveillance, as wastewater can provide valuable information on the presence of specific biomarkers. Such information can serve as an indication of immune response at the community level, delivering a noninvasive measure of e.g., vaccination effectiveness. In this paper, we present an optical wastewater phantom fabrication, characterization, and comparison to real wastewater samples. Raman spectroscopy was used for the investigation of the molecular compositions of treated wastewater and artificial wastewater phantoms, and the refractometer to investigate refractive index values dependence on temperature. Selected biomarkers concentrations (10-6 to 10-1 mg/mL) were added to the validated phantoms. The selective detection of SARS-CoV-2 immunoglobulin G (IgG) was achieved through specific surface modification of the fiber-optic probe, allowing only targeted biomarkers to attach and influence the measurement signal. Successful detection of 10-6 mg/mL IgG concentration in the wastewater phantom was achieved within 5 min.

Design of immunoassay based biosensor platforms for SARS-CoV-2 detection using highly specific monoclonal antibodies

The global expand of SARS-CoV-2 has highlighted the importance of early and rapid detection to control the spread of a pandemic. In this study, specific and high-affinity monoclonal antibodies (mAbs) were developed against the conserved nucleocapsid protein of the virus among variants. Appropriate antibody pairs were selected to develop a lateral flow immunoassay (LFIA) and an unconventional application of an amperometric biosensor using unmodified screen-printed electrodes and external magnetic bead preparation. In the study, the LFIA we developed detected the SARS-CoV-2 virus at 104 PFU/mL, while the amperometric biosensor enabled sensitive detection of inactivated SARS-CoV-2 with an LOD of 5.5 PFU/mL. After validating the developed systems, it is considered that the mAbs we have obtained will enable the sensitive and selective detection of SARS-CoV-2 in LFIA and amperometric immunosensor platforms for clinical diagnosis.

Nanomaterials-based electrochemical biosensors for diagnosis of COVID-19

Since the outbreak of corona virus disease 2019 (COVID-19), this pandemic has caused severe death and infection worldwide. Owing to its strong infectivity, long incubation period, and nonspecific symptoms, the early diagnosis is essential to reduce risk of the severe illness. The electrochemical biosensor, as a fast and sensitive technique for quantitative analysis of body fluids, has been widely studied to diagnose different biomarkers caused at different infective stages of COVID-19 virus (SARS-CoV-2). Recently, many reports have proved that nanomaterials with special architectures and size effects can effectively promote the biosensing performance on the COVID-19 diagnosis, there are few comprehensive summary reports yet. Therefore, in this review, we will pay efforts on recent progress of advanced nanomaterials-facilitated electrochemical biosensors for the COVID-19 detections. The process of SARS-CoV-2 infection in humans will be briefly described, as well as summarizing the types of sensors that should be designed for different infection processes. Emphasis will be supplied to various functional nanomaterials which dominate the biosensing performance for comparison, expecting to provide a rational guidance on the material selection of biosensor construction for people. Finally, we will conclude the perspective on the design of superior nanomaterials-based biosensors facing the unknown virus in future.

A new strategy based on a cascade amplification strategy biosensor for on-site eDNA detection and outbreak warning of crown-of-thorns starfish

Population outbreaks of the crown-of-thorns starfish (COTS) seriously threaten the sustainability of coral reef ecosystems. However, traditional ecological monitoring techniques cannot provide early warning before the outbreaks, thus preventing timely intervention. Therefore, there is an urgent need for a more accurate and faster technology to predict the outbreaks of COTS. In this work, we developed an electrochemical biosensor based on a programmed catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) cyclic amplification strategy for sensitive and selective detection of COTS environmental DNA (eDNA) in water bodies. This biosensor exhibited excellent electrochemical characteristics, including a low limit of detection (LOD = 18.4 fM), low limit of quantification (LOQ = 41.1 fM), and wide linear range (50 fM - 10 nM). The biosensing technology successfully allowed the detection of COTS eDNA in the aquarium environment, and the results also demonstrated a significant correlation between eDNA concentration and COTS number (r = 0.990; P < 0.001). The reliability and accuracy of the biosensor results have been further validated through comparison with digital droplet PCR (ddPCR). Moreover, the applicability and accuracy of the biosensor were reconfirmed in field tests at the COTS outbreak site in the South China Sea, which has shown potential application in dynamically monitoring the larvae before the COTS outbreak. Therefore, this efficient electrochemical biosensing technology offers a new solution for on-site monitoring and early warning of the COTS outbreak.