Electrochemical immunoassay for detection of hepatitis C virus core antigen using electrode modified with Pt-decorated single-walled carbon nanotubes

Reducing hepatitis C diagnostic disparities with a fully automated deep learning-enabled microfluidic system for HCV antigen detection

Viral hepatitis remains a major global health issue, with chronic hepatitis B (HBV) and hepatitis C (HCV) causing approximately 1 million deaths annually, primarily due to liver cancer and cirrhosis. More than 1.5 million people contract HCV each year, disproportionately affecting vulnerable populations, including American Indians and Alaska Natives (AI/AN). While direct-acting antivirals (DAAs) are highly effective, timely and accurate HCV diagnosis remains a challenge, particularly in resource-limited settings. The current two-step HCV testing process is costly and time-intensive, often leading to patient loss before treatment. Point-of-care (POC) HCV antigen (Ag) testing offers a promising alternative, but no FDA-approved test meets the required sensitivity and specificity. To address this, we developed a fully automated, smartphone-based POC HCV Ag assay using platinum nanoparticles, deep learning image processing, and microfluidics. With an overall accuracy of 94.59%, this cost-effective, portable device has the potential to reduce HCV-related health disparities, particularly among AI/AN populations, improving accessibility and equity in care.

Disposable and sensitive electrochemical magneto-immunosensor for point-of-care HCV diagnostics: Targeting HCVcAg, the active viremia biomarker, in patient samples

Early detection of hepatitis C virus (HCV) infection is crucial for eliminating this silent killer, especially in resource-limited settings. HCV core antigen (HCVcAg) represents a promising alternative to the current "gold standard" HCV RNA assays as an active viremia biomarker. Herein, a highly sensitive electrochemical magneto-immunosensor for the HCVcAg was developed. The biosensing strategy involved capturing HCVcAg using antibody-coated magnetic beads, followed by a sandwich immunoassay before electrochemical detection on disposable screen-printed electrodes. To achieve signal amplification and consequent enhanced sensitivity, the antigen-antibody reaction was detected with a biotinylated polyclonal antibody subsequently labelled with a streptavidin poly horseradish peroxidase conjugate followed by amperometric detection via a hydroquinone/hydrogen peroxide system. The developed biosensor exhibited a cathodic current variation directly proportional to the HCVcAg concentration over a wide range (0.1-500 ng/mL), with a detection limit of 10 pg/mL. Moreover, it successfully discriminated healthy control human plasma samples from HCVcAg-spiked samples, showed no interference from endogenous plasma constituents or cross-reactivity with other viruses tested, and possessed excellent percentage recoveries of HCVcAg (≥92.83%), demonstrating high specificity. The proposed bioplatform remained stable for at least ten days and showed excellent clinical performance in detecting HCVcAg across a cohort of thirty-six plasma and serum samples from active hepatitis C cases, and healthy individuals, with results matching those previously obtained using clinically validated qPCR and serological testing. In summary, this biosensor provides a simple, rapid and economic alternative to other available techniques such as ELISA and qPCR for early diagnosis of HCV infection.

Bioreceptors' immobilization by hydrogen bonding interactions and differential pulse voltammetry for completely label-free electrochemical biosensors

Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46-12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication.

Current advances in Hepatitis C diagnostics

Nearly 60 million people worldwide are infected with Hepatitis C Virus (HCV), a bloodborne pathogen which leads to liver cirrhosis and increases the risk of hepatocellular carcinoma. Those with limited access to healthcare resources, such as injection drug users and people in low- and middle-income countries, carry the highest burden. The current diagnostic algorithm for HCV is slow and costly, leading to a significant barrier in diagnosis and treatment for those most at risk from HCV. There remains no available vaccine for HCV, and infection is often asymptomatic until significant cirrhosis has occurred, which makes screening incredibly important to prevent liver damage and transmission. Recent investigation has sought to address these issues through improvements in various aspects of the diagnostic procedure, using methods such as isothermal amplification techniques for viral RNA amplification, the use of viral protein as an analyte, and the incorporation of streamlined, self-contained testing systems to reduce administrative skill requirements. This review provides a comprehensive overview of current commercial standards and novel improvements in HCV diagnostics, as well as a framework for future integration of these improvements to develop a one-step diagnostic that meets the needs of those most affected.

Nucleic acid-based electrochemical biosensors

Colorectal cancer, breast cancer, oxidative DNA damage, and viral infections are all significant and major health threats to human health, presenting substantial challenges in early diagnosis. In this regard, a wide range of nucleic acid-based electrochemical platforms have been widely employed as point-of-care diagnostics in health care and biosensing technologies. This review focuses on biosensor design strategies, underlying principles involved in the development of advanced electrochemical genosensing devices, approaches for immobilizing DNA on electrode surfaces, as well as their utility in early disease diagnosis, with a particular emphasis on cancer, leukaemia, oxidative DNA damage, and viral pathogen detection. Notably, the role of biorecognition elements and nanointerfaces employed in the design and development of advanced electrochemical genosensors for recognizing biomarkers related to colorectal cancer, breast cancer, leukaemia, oxidative DNA damage, and viral pathogens has been extensively reviewed. Finally, challenges associated with the fabrication of nucleic acid-based biosensors to achieve high sensitivity, selectivity, a wide detection range, and a low detection limit have been addressed. We believe that this review will provide valuable information for scientists and bioengineers interested in gaining a deeper understanding of the fabrication and functionality of nucleic acid-based electrochemical biosensors for biomedical diagnostic applications.

Toward the early diagnosis of tuberculosis: A gold particle-decorated graphene-modified paper-based electrochemical biosensor for Hsp16.3 detection

Tuberculosis (TB) currently remains a major life-threatening disease as it can be fatal if not treated properly or in a timely manner. Herein, we first describe a disposable and cost-effective paper-based electrochemical biosensor based on a gold particle-decorated carboxyl graphene (AuPs/GCOOH)-modified electrode for detecting heat shock protein (Hsp16.3), which is a specific biomarker indicating the onset of TB infection. The device pattern was first engineered to facilitate detection procedures and printed on low-cost filter paper to create hydrophobic and hydrophilic regions using a wax printing technique. Immunoassays proceeded in a half-sandwich format because it is a reagent-less approach and requires no labeling step. The fabrication of the immunosensor began with GCOOH drop casting, the electrochemical deposition of AuPs, and the establishment of a biorecognition layer against Hsp16.3 utilizing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS)-sulfo standard chemistry. The appearance of Hsp16.3 resulted in a substantial decrease in the electrochemical signal response of the redox probe employed [Fe (CN)6]3-/4- due to the created immunocomplexes that possess insulation properties. GCOOH enables direct antibody immobilization, and AuPs enhance the electrochemical properties of the sensor. This proposed immunosensor, while requiring only a miniscule sample volume (5 μL), achieved superior performance in terms of the limit of detection, measuring at 0.01 ng/mL. Our platform was confirmed to be highly specific to Hsp16.3 and can rapidly detect TB-infected sera without necessitating any pre-enrichment (20 min), making it an alternative and particularly suitable for the early diagnosis of TB in resource-scarce countries.

Paper as smart support for bioreceptor immobilization in electrochemical paper-based devices

The use of paper as a smart support in the field of electrochemical sensors has been largely improved over the last 15 years, driven by its outstanding features such as foldability and porosity, which enable the design of reagent and equipment-free multi-analysis devices. Furthermore, the easy surface engineering of paper has been used to immobilize different bioreceptors, through physical adsorption, covalent bonding, and electrochemical polymerization, boosting the fine customization of the analytical performances of paper-based biosensors. In this review, we focused on the strategies to engineer the surface of the paper for the immobilization of (bio)recognition elements (eg., enzymes, antibodies, DNA, molecularly imprinted polymers) with the overriding goal to develop accurate and reliable paper-based electrochemical biosensors. Furthermore, we highlighted how to take advantage of paper for designing smart configurations by integrating different analytical processes in an eco-designed analytical tool, starting from the immobilization of the (bio)receptor and the reagents, through a designed sample flow along the device, until the analyte detection.

The Advancement of Nanomaterials for the Detection of Hepatitis B Virus and Hepatitis C Virus

Viral hepatitis is a global health concern mostly caused by hepatitis B virus (HBV) and hepatitis C virus (HCV). The late diagnosis and delayed treatment of HBV and HCV infections can cause irreversible liver damage and the occurrence of cirrhosis and hepatocellular carcinoma. Detecting the presence and activity of HBV and HCV is the cornerstone of the diagnosis and management of related diseases. However, the traditional method shows limitations. The utilization of nanomaterials has been of great significance in the advancement of virus detection technologies due to their unique mechanical, electrical, and optical properties. Here, we categorized and illustrated the novel approaches used for the diagnosis of HBV and HCV.

Decadal Journey of CNT-Based Analytical Biosensing Platforms in the Detection of Human Viruses

It has been proven that viral infections pose a serious hazard to humans and also affect social health, including morbidity and mental suffering, as illustrated by the COVID-19 pandemic. The early detection and isolation of virally infected people are, thus, required to control the spread of viruses. Due to the outstanding and unparalleled properties of nanomaterials, numerous biosensors were developed for the early detection of viral diseases via sensitive, minimally invasive, and simple procedures. To that aim, viral detection technologies based on carbon nanotubes (CNTs) are being developed as viable alternatives to existing diagnostic approaches. This article summarizes the advancements in CNT-based biosensors since the last decade in the detection of different human viruses, namely, SARS-CoV-2, dengue, influenza, human immunodeficiency virus (HIV), and hepatitis. Finally, the shortcomings and benefits of CNT-based biosensors for the detection of viruses are outlined and discussed.