基于碳点的免标记吸光度平台实现大肠杆菌DNA快速检测

• Article
• Open access
• Published: 26 October 2026

• Huyen Ngo Thi¹,
• Nguyen Le Phan²,
• Michael Kraft^3,4,
• Son Hai Nguyen⁵ &
• …
• Mai Thi Tran  ORCID: orcid.org/0000-0002-7993-5735^1,6 

Scientific Reports (2026) Cite this article

We’re sharing this article early to provide faster access to peer-reviewed, accepted research. It is citable and carries a permanent DOI. This version is subject to further edits and will be replaced automatically by the final Version of Record. All legal disclaimers apply.

Abstract

Reliable DNA-based detection of Escherichia coli is essential for monitoring bacterial contamination in food, water, and environmental samples. In this work, we developed a label-free and amplification-free UV-Vis absorbance biosensor using carbon dots (Cdots) as optical transducers for the detection of E. coli DNA. Cdots synthesized from chitosan, citric acid, and thiourea were functionalized with NH₂-terminated DNA probes through carbodiimide-mediated covalent coupling, enabling stable attachment of amine-modified DNA probes to carboxyl-containing Cdots. Among the tested probe configurations, NH₂-BL21 produced the strongest optical response, with a maximum absorbance change of 31.6%, highlighting the importance of both probe sequence and terminal functionalization in enhancing sensor performance. The optimized biosensor exhibited excellent linearity over the 200–2000 fM range, with an R² of 0.9992, a limit of detection of 147.53 fM, and a limit of quantification of 491.76 fM. In addition, the sensor exhibited sequence-dependent recognition and preferential selectivity toward the tested E. coli DNA target, while its response remained statistically unchanged over four weeks of storage, demonstrating short-term stability under the tested conditions. Mechanistic analysis suggests that the absorbance response reflects multiple hybridization-induced interfacial and optical effects, including increased nucleic-acid absorption near 258 nm and possible contributions from changes in surface charge, the local dielectric environment, particle organization, and light scattering. This label-free and amplification-free absorbance strategy provides a potentially accessible platform for E. coli DNA detection. However, matrix-specific calibration and further validation are required before practical environmental or food-safety deployment.

Acknowledgements

This work was supported by VLIR-UOS under grant number VN2025SIN484A101, awarded to Michael Kraft and Mai Thi Tran.

Funding

This work was supported by VLIR-UOS under grant number VN2025SIN484A101, awarded to Michael Kraft and Mai Thi Tran.

Author information

Authors and Affiliations

1. College of Engineering and Computer Science, VinUniversity, Hanoi, Vietnam

   Huyen Ngo Thi & Mai Thi Tran

2. Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA, 92093, USA

   Nguyen Le Phan

3. Department of Electrical Engineering (ESAT), Micro- and Nanosystems (MNS), KU Leuven, Leuven, 3000, Belgium

   Michael Kraft

4. Leuven Institute for Micro and Nanoscale Integration (LIMNI), Leuven, 3000, Belgium

   Michael Kraft

5. School of Mechanical Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam

   Son Hai Nguyen

6. VinUni-Illinois Smart Health Center, VinUniversity, Hanoi, Vietnam

   Mai Thi Tran

Authors

1. Huyen Ngo Thi
2. Nguyen Le Phan
3. Michael Kraft
4. Son Hai Nguyen
5. Mai Thi Tran

Corresponding authors

Correspondence to Michael Kraft, Son Hai Nguyen or Mai Thi Tran.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and permissions

About this article

Cite this article

Thi, H.N., Phan, N.L., Kraft, M. et al. Development of a simple and robust absorbance-based carbon dot platform for rapid escherichia coli DNA detection. Sci Rep (2026). https://doi.org/10.1038/s41598-026-77766-1

Download citation

• Received: 04 June 2026

• Accepted: 22 October 2026

• Published: 26 October 2026

• DOI: https://doi.org/10.1038/s41598-026-77766-1