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