ORIGINAL RESEARCH article
Front. Bioeng. Biotechnol.
Sec. Biosensors and Biomolecular Electronics
Separation and Detection of Gram-Negative Bacteria via Vancomycin-Functionalized Magnetic Beads and Aminopeptidase Test Strips
Provisionally accepted
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou, China
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Gram-negative bacteria are key pathogens causing food contamination and animal diseases (such as bovine mastitis), and they are prone to developing multidrug resistance, necessitating rapid and sensitive detection technologies. Using an antibiotic affinity strategy, this study developed a novel method for detecting Gram-negative bacteria by combining vancomycin-functionalized magnetic beads (Van-MBs) with aminopeptidase test strips. Vancomycin, which binds exclusively to D-alanyl-D-alanine (D-Ala-D-Ala) on the cell wall of Gram-positive bacteria, is used by Van-MBs to capture Gram-positive bacteria from the sample. After magnetic separation, the supernatant containing Gram-negative bacteria is retained. This supernatant reacts with aminopeptidase test strips, utilizing the enzyme's unique properties as a Gram-negative enzyme. Visual detection is made possible by the enzyme's catalysis of the chromogenic substrate, which produces a yellow signal. Using raw milk as a representative sample, validation showed that the approach achieves a detection limit of 10¹ CFU/mL in about 100 minutes. This approach is quick, sensitive, and visual, and it doesn't require complicated equipment. It also offers useful technical support for safe food production, early animal disease detection, and sensible antibiotic administration.
Keywords: biosensor, vancomycin-functionalized magnetic beads, aminopeptidase test, Gram-Negative Bacteria, Point-of-care-testing, Milk contamination
Received: 25 Sep 2025; Accepted: 05 Nov 2025.
Copyright: © 2025 Xu, Zhu, Bai, Li, Ge, Yang, Liu, Qin, Li and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jian-Yong Li, lijy1971@163.com
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