Ye, Xiu-AnXiu-AnYeLin, Shu-HongShu-HongLinChen, Liang-YuLiang-YuChenLi, Jie-RenJie-RenLiChiu, Hsiang-WeiHsiang-WeiChiuPan, Sheng-WeiSheng-WeiPanFeng, Jia-YihJia-YihFengSHYH-CHYANG LUOHo, Mei-LinMei-LinHo2025-07-072025-07-072025-08https://www.scopus.com/record/display.uri?eid=2-s2.0-105007525332&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/730609Pulmonary tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), necessitates early diagnosis for effective patient care. Despite advancements in TB diagnostics, there remains an urgent need to discover innovative non-sputum-based methods to detect Mtb-specific antigens for TB patient identification. We have developed a polymer-based electrochemical biosensor for detecting an Mtb-specific antigen, the 6-kDa early secreted antigenic target (ESAT-6), in blood. Using a gold electrode (Au), the biosensor is created by electropolymerizing poly(3,4-ethylene dioxythiophene) with carboxyl groups (PEDOT-COOH), which is activated with 3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide (EDC-NHS), conjugated with an ESAT-6 polyclonal antibody (Ab), treated with bovine serum albumin (BSA) to block non-specific binding, forming BSA/Ab-EDC-NHS/PEDOT-COOH/Au. Using differential pulse voltammetry measurements, the electrode demonstrated an excellent linear response (R2 = 0.99) for ESAT-6 detection across a concentration range of 24.2 pM (0.81 ng/mL) to 50 nM (1.69 μg/mL), with a low detection limit of 1.39 pM (0.047 ng/mL) and a rapid detection time of under 4 min. This biosensor for ESAT-6 detection effectively distinguished pulmonary TB patients from healthy individuals, achieving 95.0 % sensitivity and 100 % specificity at a cut-off value of 97.0 ng/mL. It demonstrated a diagnostic accuracy of 97.1 %, outperforming the 82.9 % achieved by a commercial ELISA kit. Moreover, biosensor-detected ESAT-6 levels were significantly higher in smear-positive TB patients compared to the smear-negative group (p = 0.014), whereas ELISA-based detection showed no significant difference (p = 0.197). In conclusion, the PEDOT-COOH biosensor enables rapid and effective detection of plasma ESAT-6, facilitates TB diagnosis, and correlates with Mtb bacterial burden, highlighting its potential for disease monitoring.Early secreted antigenic target 6-kDa (ESAT-6)Electrochemical biosensorPEDOT-COOH-based materialPlasmaTuberculosisjournal article10.1016/j.sbsr.2025.100816