Polyaniline-gold nanoparticle-based biosensor targeting miR-21-5p for early diagnosis of leptospirosis
4 affiliations
- 1Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, 620 024 Tamil Nadu India
- 2Electrodics and Electrocatalysis (EEC) Division, CSIR – Central Electrochemical Research Institute (CSIR – CECRI), Karaikudi, 630003 Tamil Nadu India
- 3Lincoln Memorial University, College of Veterinary Medicine, Harrogate, TN 37752 USA
- 4Department of Neuroscience, Rowan-Virtua School of Osteopathic Medicine, Rowan University, Stratford, NJ 08084 USA
Abstract
Blood-based disease diagnosis facilitates the early-stage detection of leptospirosis because leptospires were present in the blood in the first 5 to 10 days after exposure. We present a sensor employing polyaniline (PANI) and gold nanoparticles (AuNPs) for the specific detection of miR-21-5p in individuals with leptospirosis. The electropolymerization of PANI on glassy carbon electrodes (GCEs) creates a porous and durable coating that remains stable over extended periods without mechanical damage. To enhance the biosensor’s performance, we functionalized the sensor surface with gold nanoparticles through electrodeposition, which facilitated an electroactive surface and selective binding of the thiolated probe. Our data confirmed that the thiolated DNA probe (anti-miRNA-21) exhibits a higher affinity for the target miRNA-21 and serum samples from individuals with leptospirosis compared to non-complementary sequences and healthy serum samples. The biosensor demonstrated remarkable sensitivity with a detection range spanning from 1 aM to 50 nM, boasting a limit of detection (LOD) of 1 aM and a limit of quantification (LOQ) of 4.59 aM. This represents an unprecedented achievement in ultra-low-level miRNA-based biosensors for diagnosing leptospirosis. Early-stage disease detection is crucial for effective disease management and timely treatment. Such an approach holds promise for point-of-care testing in remote settings to facilitate the early diagnosis of leptospirosis.
Graphical abstract:
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00216-026-06754-1.
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BibTeX
@article{bothammal2026polyanilinegold,
title = {{Polyaniline-gold nanoparticle-based biosensor targeting miR-21-5p for early diagnosis of leptospirosis}},
author = {Palanisamy Bothammal and Singarayan Michelraj and Ashutosh Verma and Ganesh Venkatachalam and Kalimuthusamy Natarajaseenivasan},
journal = {Analytical and Bioanalytical Chemistry},
year = {2026},
month = aug,
doi = {10.1007/s00216-026-06754-1},
url = {https://doi.org/10.1007/s00216-026-06754-1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Polyaniline-gold nanoparticle-based biosensor targeting miR-21-5p for early diagnosis of leptospirosis
AU - Palanisamy Bothammal
AU - Singarayan Michelraj
AU - Ashutosh Verma
AU - Ganesh Venkatachalam
AU - Kalimuthusamy Natarajaseenivasan
PY - 2026
DA - 2026/08/25
JO - Analytical and Bioanalytical Chemistry
DO - 10.1007/s00216-026-06754-1
UR - https://doi.org/10.1007/s00216-026-06754-1
AB - Blood-based disease diagnosis facilitates the early-stage detection of leptospirosis because leptospires were present in the blood in the first 5 to 10 days after exposure. We present a sensor employing polyaniline (PANI) and gold nanoparticles (AuNPs) for the specific detection of miR-21-5p in individuals with leptospirosis. The electropolymerization of PANI on glassy carbon electrodes (GCEs) creates a porous and durable coating that remains stable over extended periods without mechanical damage. To enhance the biosensor’s performance, we functionalized the sensor surface with gold nanoparticles through electrodeposition, which facilitated an electroactive surface and selective binding of the thiolated probe. Our data confirmed that the thiolated DNA probe (anti-miRNA-21) exhibits a higher affinity for the target miRNA-21 and serum samples from individuals with leptospirosis compared to non-complementary sequences and healthy serum samples. The biosensor demonstrated remarkable sensitivity with a detection range spanning from 1 aM to 50 nM, boasting a limit of detection (LOD) of 1 aM and a limit of quantification (LOQ) of 4.59 aM. This represents an unprecedented achievement in ultra-low-level miRNA-based biosensors for diagnosing leptospirosis. Early-stage disease detection is crucial for effective disease management and timely treatment. Such an approach holds promise for point-of-care testing in remote settings to facilitate the early diagnosis of leptospirosis. Graphical abstract: Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00216-026-06754-1.
SN - 1618-2642
SN - 1618-2650
ER -