A smartphone-assisted dual-mode sensor for synchronous detection of Microcystin-LR in environmental water via Temperature-Multicolour dual signals.

BACKGROUND: The direct reading of a signal is one of the essential requirements for field testing. However, quantitative analysis based on a single signal is prone to false positives and false negatives, compromising monitoring reliability. Therefore, there is an urgent need for a method that can enhance the reliability of detection achieved through simple quantitative signal readings. In this work, a temperature-multicolour dual-mode sensor was fabricated based on the localized surface plasmon resonance and photothermal effects of gold nanorods (Au NRs) to enable synchronous dual-signal detection of microcystin-LR (MC-LR) in environmental water.

RESULTS: The proposed sensor offers the advantages of sensitive, synchronous, and simple dual-signal reading with the aid of a smartphone equipped with an infrared temperature probe. Both the temperature signal (ΔT) and the multicolour signal (R/G) exhibit strong linear correlations with the concentration of MC-LR. To evaluate the sensor's environmental monitoring performance, environmental water samples from different areas were analysed. Compared with the commercial enzyme-linked immunosorbent assay method, the proposed sensor achieved a lower limit of detection and produced comparable results using only signal readings obtained with a smartphone equipped with an infrared temperature probe, without the need for additional professional equipment. Moreover, excellent recoveries were obtained in the detection of spiked environmental water samples.

SIGNIFICANCE: Two independent signals can be used to validate each other, thereby improving the reliability of detection. Therefore, the proposed smartphone-assisted temperature-multicolour dual-mode sensor shows strong potential for point-of-care testing, particularly in water quality monitoring.