Development of Safe and Sensitive Electrochemical Aptasensor for Active Tuberculosis Diagnosis

Abstract

Tuberculosis (TB), the leading cause of infectious disease mortality, mainly occurs in developing countries; however, its diagnosis still relies on conventional methods that are expensive or inaccurate and require infectious sputum samples. Here, we propose a safe, cost-effective and accurate electrochemical biosensor for TB diagnosis that directly detects the circulating biomarker CFP10 in serum with a gold electrode-based system. We selected an ssDNA aptamer that specifically binds to the CFP10 protein (Kd = 92.8 nM) and used ferri/ferrocyanide and methylene blue as label-free redox coupled agents for the electrochemical signal by fabricating the gold electrode modified with MB-bound aptamer. The developed sensor could be used to successfully quantify CFP10 within short turnaround time of 1 h in buffer and serum-spiked conditions with markedly low detection limits of 3.25 fM and 6.92 fM, respectively. Clinical application using 72 non-infectious serum samples from healthy controls and patients with active TB showed sensitivity of 64.58%, specificity of 95.83%, and accuracy of 86.81%. Additionally, the signal intensities of the sensor increased with the acid-fast bacillus indices of the sample, indicating that they could be used to determine the severity of TB. As a result, this novel and low-cost aptamer-based electrochemical sensor has the potential to be used for the early-stage exclusion and treatment of patients with active TB in resource-limited countries while avoiding the risk of infection by using non-infectious serum samples.