A smartphone-integrated paper sensing system for fluorescent and colorimetric dual-channel detection of foodborne pathogenic bacteria

• DOI: 10.1007/s00216-019-02208-z
• Publication Date: 2020-01-03T23:02:17Z
• Authors: Chengnan Wang; Xia Gao; Shuo Wang; Yaqing Liu
• Keywords: Paper; Bacteria; Reproducibility of Results; Biosensing Techniques; 01 natural sciences; 0104 chemical sciences; 3. Good health; Systems Integration; Spectrometry, Fluorescence; Food Microbiology; Colorimetry; Spectrophotometry, Ultraviolet; Smartphone; Fluorescent Dyes

Infections caused by foodborne microorganisms are a great threat to the global environment and public healthcare today. Thus, rapid, portable and sensitive assays that can realize the identification of foodborne bacteria are highly desired. In this study, a smart fluorescent and colorimetric dual-readout sensing system has been established for simple and rapid E. coli determination by utilizing the Cu2+-triggered oxidation of o-phenylenediamine (OPD). Initially, Cu2+ can oxidize OPD to OPDox, resulting in an orange-yellow fluorescence and visible pale-yellow color. However, E. coli can effectively reduce Cu2+ into Cu+, inhibiting the Cu2+-triggered oxidation of OPD to OPDox. Consequently, the introduction of E. coli can turn off both the fluorescence and the UV-vis absorbance signals of the OPD-Cu2+ system, illustrating an original mechanism for fluorescent and colorimetric dual-channel detection of E. coli. Moreover, a filter paper-based visual sensor was built and coupled with OPD-Cu2+ solution under the assistance of a UV lamp. The as-prepared sensor can detect E. coli quantitatively with the help of a typical smartphone color-scanning application (APP). Thus, this study offers a valid dual-mode assay for sensitive and on-site visible detection of E. coli, guaranteeing the reliability of the results and is more attractive for practical use. Graphical Abstract Schematic illustration of the smartphone-integrated sensing system for fluorescent and colorimetric dual-channel detection of E. coli based on the Cu2+-OPD system.