Journal Article

Development and Optimization of a Cost-Effective Electrochemical Immunosensor for Rapid COVID-19 Diagnosis

Leal, Daiane Martins, Ferreira, Lucas Franco, Martins, Helen Rodrigues, Pereira, Arnaldo César, Souza, Fernando de Jesus, de Oliveira, Danilo Bretas, Ferreira, Zirlane Coelho, Rocha-Vieira, Etel, Lima, Thaís Machado

2025

Overview

The coronavirus disease (COVID-19) pandemic has created an urgent need for rapid, accurate, and cost-effective diagnostic tools. In this study, an economical electrochemical immunosensor for the rapid diagnosis of COVID-19 was developed and optimized based on charge transfer resistance (Rct) values obtained by electrochemical impedance spectroscopy (EIS) from the interaction between antibodies (anti-SARS-CoV-2) immobilized as a bioreceptor and the virus (SARS-CoV-2). The sensor uses modified pencil graphite electrodes (PGE) coated with poly(4-hydroxybenzoic acid), anti-SARS-CoV-2, and silver nanoparticles. The immobilization of anti-SARS-CoV-2 antibodies was optimized at a concentration of 1:250 for 30 min, followed by blocking the surface with 0.01% bovine serum albumin for 10 min. The optimal conditions for virus detection in clinical samples were a 1:10 dilution with a response time of 20 min. The immunosensor responded linearly in the range of 0.2–2.5 × 106 particles/μL. From the relationship between the obtained signal and the concentration of the analyzed sample, the limit of detection (LOD) and limit of quantification (LOQ) obtained were 1.21 × 106 and 4.04 × 106 particles/μL, respectively. The device did not cross-react with other viruses, including Influenza A and B, HIV, and Vaccinia virus. The relative standard deviation (RSD) of the six immunosensors prepared using the shared-pool sample was 3.87. Decreases of 22.3% and 12.4% were observed in the response values of the ten immunosensors stored at 25 °C and 4.0 °C, respectively. The sensor provides timely and accurate results with high sensitivity and specificity, offering a cost-effective alternative to the existing diagnostic methods.

• Publisher: MDPI AG,MDPI
• Subject: 4-hydroxybenzoic acid / Analysis / Antibodies / Antibodies, Immobilized / Antigens / Biosensing Techniques - economics / Biosensing Techniques - instrumentation / Biosensing Techniques - methods / Biosensing Techniques - standards / Biosensors / Bovine serum albumin / Charge transfer / Coronaviruses / Cost effectiveness / COVID-19 / COVID-19 - diagnosis / COVID-19 diagnostic tests / Diagnosis / Dilution / Economic aspects / Electrochemical impedance spectroscopy / electrochemical platforms / Electrochemistry / Electrochemistry - economics / Electrochemistry - instrumentation / Electrochemistry - methods / Electrodes / Electrons / electropolymerization / Graphite / Graphite - chemistry / Health aspects / Humans / Immobilization / Immunosensors / Influenza A / Medical research / Metal Nanoparticles - chemistry / Mucus - virology / Nanoparticles / Optimization / p-Hydroxybenzoic acid / Pandemics / pencil graphite electrodes / Polymers / Potassium / Rapid Diagnostic Tests - economics / Rapid Diagnostic Tests - instrumentation / Rapid Diagnostic Tests - methods / Rapid Diagnostic Tests - standards / Reproducibility of Results / SARS-CoV-2 / Sensitivity and Specificity / Sensors / Serum albumin / Severe acute respiratory syndrome coronavirus 2 / Silver / Sodium / Spectroscopy / Spectrum analysis / Viral antibodies / Viral diseases / Viruses