A novel smartphone-based colorimetric aptasensor for on-site detection of Escherichia coli O157:H7 in milk

Effective testing tools for Escherichia coli O157:H7 can prevent outbreaks of foodborne illness. In this paper, a smartphone-based colorimetric aptasensor was developed using functionalized gold nanoparticles (GNP) and multi-walled carbon nanotubes (MWCNT) monitoring E. in milk. The maximum absorption peak GNP bonded with aptamer (Apt) generated evident transformation from 518 to 524 nm. excess GNP-Apt removed by MWCNT magnetized carbonyl iron powder (CIP) hybridized DNA probe, whereas the immobilized on remained system. presence high-salt solution, that captured red, but free aggregated appeared blue. chromogenic results were analyzed device fabricated acrylic plates, light-emitting diode, mobile power pack. To our knowledge, first attempt use employing capture coupled separation MWCNT@CIP probe detect O157:H7. exhibited good reproducibility no cross-reaction other bacteria. A concentration 8.43 × 103 cfu/mL could be tested pure culture, 5.24 102 detected artificially contaminated milk after 1 h incubation. Therefore, an efficient tool detection