Au Nanoparticle-Based Disposable Electrochemical Sensor for Detection of Leptospirosis in Clinical Samples
Kannan Sapna, J. Sonia, Yoon‐Bo Shim, A. B. Arun, K. Sudhakara Prasad
Abstract
Leptospirosis is a worldwide zoonotic disease causing major health problems in tropical areas. A point-of-care test that is accurate for early diagnosis of leptospirosis is, thus, imperative and the need of the hour. Herein, we demonstrate the development of a disposable immunosensor based on gold nanoparticle (AuNp)-modified paper electrodes (PPEs) with carbon nanotube-labeled monoclonal anti-LipL32 (e-LipL32) for simple, rapid, and sensitive determination of Leptospira in clinical samples. The immunosensor was constructed on AuNp-decorated PPEs immobilized with self-assembled monolayers of glutathione for the incorporation of monoclonal antibodies specific to the leptospiral major outer membrane protein, LipL32. The e-LipL32 sensor was further characterized with scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical techniques for demonstrating the robust formation of the sensor. The sensor exhibited a wide linear range up to 1 μg/mL with an unprecedented low limit of detection of 348 fg/mL compared to the reported leptospirosis sensors to date. The sensor displayed acceptable precision, reproducibility, and long-term stability for LipL32 detection. Further, e-LipL32 was validated with 20 patient samples suspected of leptospirosis, including other febrile illnesses along with the gold standard macroscopic agglutination test, culture, IgM enzyme-linked immunosorbent assay, and IgM spot test. Based on the boxplot analysis of 20 patient samples, an average peak current above 9.8 μA was classified as positive for leptospirosis. Compared to commercial diagnostic tools, our sensor provides rapid results and offers an alternative, specific, and sensitive method for early diagnosis of leptospirosis.