Au Nanoparticle-Based Disposable Electrochemical Sensor for Detection of Leptospirosis in Clinical Samples

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.

Diagnosis of Neglected Tropical Zoonotic Disease, Leptospirosis in a Clinical Sample Using a Photothermal Immunosensor

“…By utilizing the CNT’s photothermal effect, the biomarker was quantified using temperature change, enabling higher sensitivity without color interference, as opposed to conventional colorimetric detection. The detection limit of the photothermal sensor was higher than those of the electrochemical method and fluorescence method used in our previous works. ,, Unlike electrochemical and colorimetric methods, the photothermal sensor requires no sophisticated instruments and no technical expertise to execute the experiment and can complete the assay in a minimal amount of time. As a proof-of-concept study, the photothermal platform showed high selectivity toward leptospiral biomarker detection in clinical samples with a low LOD.…”

“…In resource-limited environments, the aforementioned procedures are ineffective for diagnosing leptospirosis. 33 Therefore, point-of-care diagnostic tools need to emphasize portability, sensitivity, specificity, minimum turnaround time, ease of use, and affordability to meet the need. 1 Recently, numerous immunoassays have been developed based on different mechanisms.…”

“…Among all of the above-mentioned techniques, MAT is the gold standard for the diagnosis of leptospirosis. In resource-limited environments, the aforementioned procedures are ineffective for diagnosing leptospirosis . Therefore, point-of-care diagnostic tools need to emphasize portability, sensitivity, specificity, minimum turnaround time, ease of use, and affordability to meet the need …”

Recent Progress of Covalent Organic Frameworks Applied in Electrochemical Sensors

“…In comparison to SPME and chromatography, COF-based electrochemical sensors have higher sensitivity, and in comparison to luminescent and colorimetric sensing, The working electrode plays an important role in the qualitative and quantitative detection performance of the sensor. Many advanced materials have been applied to prepare the working electrodes of electrochemical sensors, mainly including graphene, 64 carbon nanotubes (CNTs), 65 quantum dots (QDs), 66 metal nanoparticles (NPs), 67 metal oxides, 68 conductive polymers (CPs), 69 biomolecules, 70 enzyme, 71 black phosphorus, 72 Mxene, 73 polyoxometalates (POMs), 74 Perovskite, 75 MOFs, 76 COFs, 77 and so on. Compared with other materials, COFs possess excellent structural diversity, enabling them to be fine-tuned to meet specific sensing requirements.…”

Dual Linear Range Laser-Induced Graphene-Based Sensor for 4-Nitrophenol Detection in Water

“…These properties, along with its low cost compared to other materials, make it a viable option for electrochemical sensors . Earlier efforts for electrochemical detection of 4-NP using graphene-based material as sensors have been made with different nanomaterials. − Metal nanoparticles such as gold and silver have been used with reduced graphene oxide (rGO). For example, Tang et al demonstrated a facile method of rGO and gold nanocomposite fabrication for the electrochemical detection of 4-NP .…”