Cotton thread-based multi-channel photothermal biosensor for simultaneous detection of multiple microRNAs

The abnormal expression of microRNAs (miRNAs) is associated with various diseases. Developing simple and portable methods for sensitive, rapid and simultaneous detection of multiple miRNAs is critical to achieve accurate and timely diagnosis. Herein, a cotton thread-based multi-channel photothermal biosensor was proposed for simultaneous detection of three breast cancer-related miRNAs including miRNA-10b, miRNA-27a and miRNA-let-7a. Three cotton thread-based channels with one input were designed and the capture probes for detecting different miRNAs were immobilized on the test zones of the corresponding channels. Cu_2-xS nanostrings prepared on the basis of hybridization chain reaction (HCR) were taken as the photothermal agents for signal transduction and amplification. The formation of a sandwich structure among the capture probe, target miRNA, and Cu_2-xS nanostrings led to the accumulation of the Cu_2-xS nanostrings on the test zones and transformed the concentration of miRNA into temperature signal under 808 nm laser irradiation. The temperature changes were quantified by a portable thermal camera and directly reflected the concentration of miRNAs. Under the optimal conditions, the developed multi-channel photothermal biosensor showed excellent specificity and sensitivity with the detection limits of 37 pM, 38 pM and 38 pM for miRNA-10b, miRNA-27a and miRNA-let-7a, respectively. Furthermore, a simultaneous detection of the three miRNAs in cell lysates were achieved and the results were in accordance with that obtained by the quantitative reverse transcription polymerase chain reaction (qRT-PCR), indicating its excellent capacity for practical applications. The developed biosensor provided an important tool for analysis of multiple targets and showed great potential in clinical diagnosis.