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Enclosure-Free Smartphone Detection of Enrofloxacin Using an AlphaFold-Engineered Nanobody Biosensor with Active
Guoqiang Li1, Lin Wei1, Qifan Sun1
1State Key Laboratory of Marine Food Processing & Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266100, China.
Analytical Chemistry
|June 3, 2026
Summary
This study introduces a novel nanobody biosensor for detecting enrofloxacin (ENR) using smartphone imaging. Active illumination and multidimensional color analysis significantly improve detection stability and sensitivity for on-site food safety testing.
Area of Science:
- Analytical Chemistry
- Biosensor Technology
- Molecular Engineering
Background:
- Smartphone colorimetric assays offer potential for on-site analysis but face challenges with ambient light interference and low sensitivity.
- Conventional methods often require controlled environments, limiting their field applicability.
Purpose of the Study:
- To develop an interference-resistant, enclosure-free smartphone-based biosensor for enrofloxacin (ENR) detection.
- To enhance assay sensitivity and stability using active illumination and multidimensional color analysis.
Main Methods:
- An AlphaFold-engineered nanobody biosensor was developed for ENR detection.
- Active-illumination imaging was integrated with smartphone-based multidimensional color analysis (RGB, HSV, CIELAB).
- Data fusion techniques were employed to enhance readout sensitivity and discrimination of color changes.
Main Results:
- Active illumination stabilized the coefficient of variation to 8-10% under variable lighting, a significant improvement over 66-97% without it.
- The biosensor achieved a limit of detection (LOD) of 2.93 ng/mL for ENR, reduced to 1.91 ng/mL with fused parameters (Senh), a 34.8% sensitivity enhancement.
- The assay demonstrated reliable performance in spiked marine fish samples, indicating on-site applicability.
Conclusions:
- The developed strategy effectively minimizes environmental interference through active illumination.
- Multidimensional color analysis and data fusion significantly enhance readout sensitivity for portable biosensing applications.
- This approach offers a promising solution for adaptable and robust on-site detection of contaminants.
