Development of a simple and robust absorbance-based carbon dot platform for rapid escherichia coli DNA detection
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 NH ₂ -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, NH ₂ -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 R ² 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.
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BibTeX
@article{thi2026development,
title = {{Development of a simple and robust absorbance-based carbon dot platform for rapid escherichia coli DNA detection}},
author = {Huyen Ngo Thi and Nguyen Le Phan and Michael Kraft and Son Hai Nguyen and Mai Thi Tran},
journal = {Scientific Reports},
year = {2026},
month = oct,
doi = {10.1038/s41598-026-77766-1},
url = {https://www.nature.com/articles/s41598-026-77766-1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Development of a simple and robust absorbance-based carbon dot platform for rapid escherichia coli DNA detection
AU - Huyen Ngo Thi
AU - Nguyen Le Phan
AU - Michael Kraft
AU - Son Hai Nguyen
AU - Mai Thi Tran
PY - 2026
DA - 2026/10/26
JO - Scientific Reports
DO - 10.1038/s41598-026-77766-1
UR - https://www.nature.com/articles/s41598-026-77766-1
AB - 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 NH ₂ -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, NH ₂ -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 R ² 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.
SN - 2045-2322
ER -