A point-of-care detection platform for Escherichia coli O157:H7 by integration of smartphone and the structural colour of photonic microsphere.

• A label-free smartphone-based detection platform for pathogenic bacteria was established. • The SPM modified with aptamer could specifically capture target bacteria. • The structural color change of SPM can report the concentration of bacteria with smartphone. • Gold nanoparticles and silver staining can enhance the signal/noise ratio of the detection system. • The method showed a wide linear detection range, low LOD and high specificity for target bacteria. A smartphone-based sensitive, rapid, label-free and high-throughput detection platform for Escherichia coli O157:H7 was established. The specific recognition capability of this platform was dependent of the aptamer modified on the silica photonic microsphere (SPM), whose structural colour was utilized for the quantification of the target bacterium. Gold nanoparticles and silver staining technique were employed to improve the sensitivity of the detection platform. Such smartphone-based detection platform gave a wide linear detection range of 102 ∼ 108 CFU/mL with a low limit of detection (LOD) of 68 CFU/mL and high specificity for Escherichia coli O157:H7. Moreover, the recovery rates of the detection method were measured in the range of 99 ∼ 108% in the milk, pork and purified water samples. Furthermore, the developed detection platform did not require complex sample pretreatment and could be easily manipulated, displaying great application potential in the fields of food safety, environmental monitoring and disease diagnosis. [ABSTRACT FROM AUTHOR]