Smartphone-assisted biosensor based on broom-like bacteria-specific magnetic enrichment platform for colorimetric detection of Listeria monocytogenes

• Published in: Journal of hazardous materials 2023-10, Vol.459, p.132250-132250, Article 132250
• Main Authors: Xiao, Fangbin, Li, Weiqiang, Wang, Zhixing, Xu, Qian, Song, Yang, Huang, Jin, Bai, Xuekun, Xu, Hengyi
• Format: Article
• Language: English
• Subjects: Antibiotic-affinity strategy; biosensors; Colorimetric detection; colorimetry; detection limit; human health; Listeria monocytogenes; magnetic materials; Magnetic nanoparticles; magnetic separation; magnetism; microbial detection; nanoparticles; Nanosensor; Nanozyme
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.132250

Pathogenic bacteria contamination poses a major threat to human health. The detection of low-abundance bacteria in complex samples has always been a knotty problem, and high-sensitivity bacterial detection remains challenging. In this work, a novel magnetic platform with high enrichment efficiency for L. monocytogenes was developed. The magnetic platform was designed by branched polyglutamic acid-mediated indirect coupling of cefepime on magnetic nanoparticles (Cefe-PGA-MNPs), and the specific enrichment of low-abundance L. monocytogenes in real samples was achieved by an external magnet, with a capture efficiency over 90%. A controllable and highly active platinum-palladium nanozyme was synthesized and further introduced in the magnetic nanoplatform for the construction of enzymatic colorimetric biosensor. The total detection time for L. monocytogenes was within 100 min. The colorimetric signals generated by labelled nanozyme were corresponding to different concentrations of L. monocytogenes, with a limit of detection (LOD) of 3.1 × 101 CFU/mL, and high reliability and accuracy (with a recovery rate ranging from 96.5% to 116.4%) in the test of real samples. The concept of the developed method is applicable to various fields of biosensing that rely on magnetic separation platforms. [Display omitted] •Broom-like magnetic platform captured > 90% of L. monocytogenes in real samples.•Size-controlled PdPt nanozyme demonstrated superior catalytic activity than HRP.•A signal acquisition and analysis system based on smartphone was established.•The LOD of L. monocytogenes was 3.1 × 101 CFU/mL.