Development and Validation of a Point-of-Ccare Biosensor for Rapid Detection of SARS-CoV-2 Antigen in Saliva Samples.

Project Abstract

The rapid and accurate detection of SARS-CoV-2 antigen in saliva offers a practical, noninvasive, and scalable approach for mass screening during pandemic responses. This study presents the development and validation of a point-of-care biosensor designed for rapid detection of SARS-CoV-2 nucleocapsid antigen in saliva with dual-readout (colorimetric and electrochemical) to enhance sensitivity, specificity, and operational simplicity in diverse settings. The biosensor employs a screen-printed carbon electrode functionalized with a high-affinity monoclonal antibody specific to the SARS-CoV-2 nucleocapsid protein, coupled with a saliva-compatible sample pad and a smart transducer interface enabling real-time signal generation. A novel antifouling surface chemistry minimizes nonspecific adsorption from complex saliva matrices, while a microfluidic microchannel concentrates antigen to improve limit of detection without requiring skilled personnel or elaborate instrumentation. The assay integrates a rapid sample processing step that disrupts mucins and reduces viscosity, enabling full assay completion within 15–20 minutes at the point of care. The colorimetric readout uses a gold nanoparticle-labeled secondary antibody enabling visible signal development, while the electrochemical readout provides a quantitative current change proportional to antigen concentration, with a dynamic range spanning clinically relevant concentrations observed in early infection. Analytical validation demonstrated a limit of detection in the low ng/mL range and a linear response across multiple orders of magnitude, with high specificity against common respiratory viruses and minimal interference from common salivary proteins and food-derived compounds. Clinical validation included a multicenter cohort of symptomatic and asymptomatic individuals, where the biosensor achieved sensitivity and specificity comparable to RT-qPCR in early infection windows, and outperformed traditional rapid antigen tests in low viral load scenarios. Reproducibility assessments across operators, lot-to-lot variation, and environmental conditions (temperature and humidity) showed robust performance with coefficients of variation below 8%. A usability study indicated straightforward operation by non-laboratory personnel, with integrated on-device data processing and a mobile application for result interpretation, data logging, and remote reporting. Stability studies confirmed shelf-life under standard temperature conditions for at least six months. Cost analysis suggested substantial reductions in per-test expenditure relative to centralized RT-qPCR workflows, driven by low-cost materials, minimal instrumentation, and rapid turnaround. The study also explores potential integration with telehealth platforms and decentralized screening programs in schools, workplaces, and community clinics. Limitations include the need for broader population studies to assess performance across emerging variants and the necessity of periodic antibody replacement to maintain affinity. Overall, the developed biosensor demonstrates a compelling combination of speed, accuracy, portability, and user-friendliness, offering a viable tool for rapid triage, infection control, and surveillance in ongoing and future respiratory virus outbreaks.

Project Overview

What This Project Is About

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A straightforward, hands-on investigation into creating a portable device that can quickly detect a SARS-CoV-2 antigen in saliva. The project combines simple sensor design with user-friendly testing to provide fast results at or near the point of care.

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The Problem It Addresses

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Current tests can be slow, require specialized labs, or are not easily usable outside clinical settings. This project aims to fill that gap by offering a rapid, easy-to-use test option that can be used in clinics, workplaces, or at home, helping to curb transmission.

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Objectives of the Project

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1. Design a small, easy-to-use biosensor that detects SARS-CoV-2 antigens in saliva.
2. Validate the sensor’s accuracy against standard laboratory tests.
3. Evaluate the device’s speed, portability, and user-friendliness.
4. Develop a simple data readout that does not require advanced equipment.
5. Assess the stability and shelf-life of the biosensor components.

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What You Will Do Step by Step

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1. Review existing saliva-based tests and biosensor technologies for context.
2. Design or select a sensor platform compatible with saliva samples.
3. Build a prototype and optimize sample handling for saliva.
4. Test with known positive and negative saliva samples to assess accuracy.
5. Compare results with standard diagnostic tests and refine as needed.
6. Evaluate usability and create a user guide.

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Expected Outcome

A functional point-of-care biosensor that provides rapid, simple, and reliable detection of SARS-CoV-2 antigen in saliva, with demonstrated accuracy and a clear path toward real-world use.