Researchers develop smartphone sensor for on-site detection of E. coli in milk
An article in the Journal of Diary Science shows researchers from the Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin in China created a smartphone-based colorimetric aptasensor, which was an efficient tool for the detection of E. coli O157:H7 in milk.
Effective testing tools for E. coli O157:H7 can prevent outbreaks of foodborne illness.
The scientists developed the aptasensor using functionalized gold nanoparticles (GNP) and multi-walled carbon nanotubes (MWCNT) for monitoring E. coli O157:H7 in milk.
The maximum absorption peak of GNP bonded with aptamer (Apt) generated evident transformation from 518 to 524 nm. The excess GNP-Apt was removed by functionalized MWCNT magnetized with carbonyl iron powder (CIP) and hybridized with a DNA probe, whereas the GNP-Apt immobilized on E. coli O157:H7 remained in the system.
In the presence of a high-salt solution, the GNP-Apt that captured E. coli O157:H7 remained red, but the free GNP-Apt aggregated and appeared blue.
The chromogenic results were analyzed by a smartphone-based colorimetric device that was fabricated using acrylic plates, a light-emitting diode, and a mobile power pack.
The researchers said the aptasensor exhibited good reproducibility and no cross-reaction for other bacteria. A concentration of 8.43 × 103 cfu/mL of E. coli O157:H7 could be tested in pure culture, and 5.24 × 102 cfu/mL of E. coli O157:H7 could be detected in artificially contaminated milk after one hour of incubation.
Journal of Dairy Science
A novel smartphone-based colorimetric aptasensor for on-site detection of Escherichia coli O157:H7 in milk
Tao Yang, Zhenghui Wang, Yang Song, Xinyan Yang, Sihan Chen, Shiqian Fu, Xue Qin, Wei Zhang, Chaoxin Man, Yujun Jiang