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The development of immobilization method of a chemoprobe on solid support without sacrificing its good original performance in homogeneous solution is a tricky problem. Herein, we make use of the transparent agarose hydrogel with semi-wet property which provided appropriate microenvironment to immobilize the chemoprobe and maintained its original performance to develop an excellent smartphone-enabled colorimetric platform. As a proof of concept, the sensing platform was fabricated with agarose hydrogel that captured diethylaminoethyldextran chloride (DEAE-dextran) and dithiothreitol modified copper nanoclusters (Cu NCs) as a fluorescence probe. Benefiting from the aggregation-induced emission (AIE) effect and confinement effect of hydrogel, the fluorescence quantum yield (QY) of Cu NCs hydrogel is three times higher than that of Cu NCs. Moreover, sensitively detection of Cr(VI) can be realized in the concentration range of 0.07–38.00 μM based on the amplified fluorescence probe. The outstanding analysis performance for Cr(VI) is also achieved when Cu NCs hydrogel was directly immobilized on paper as a smartphone-enabled colorimetric platform, indicating that our strategy can promote the further development of the application of hydrogel materials. [Display omitted] • An AIE-active copper nanoclusters (Cu NCs) functionalized hydrogel was prepared. • The amplified fluorescent detection of Cr(VI) by Cu NCs hydrogel was achieved. • Cu NCs hydrogel as a smartphone-enabled colorimetric platform showed an outstanding performance of detecting Cr(VI). • Smartphone-enabled colorimetric platform can realize instrument-free, portable and on-site detection of Cr(VI). [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-in-one signal sensing probe is designed for the determination of PMS. • The multisignal output guarantees more accurate monitoring of the PMS. • A conventional chromogenic substrate realizes the output of multiple signals. • Such a strategy improves the probe's reliability, sensitivity and adaptability. The extensive applications of peroxymonosulfate (PMS) in the field of environmental pollutant treatment based on advanced oxidation processes (AOPs) have prompted a high demand for advances in the probe ranging from improving their performances to strengthening their practicalities. Here, a multisignal-output probe of PMS was achieved by the unconventional application of traditional chromogenic system, 3,3′,5,5′-tetramethylbenzidine with Co2+ ions (Co2+-TMB). It works on the trace Co2+-catalyzed specific conversion of a colorless TMB into a blue oxidation product (oxTMB) with PMS as the oxidizing agent, accompanied by the enhanced absorption value of oxTMB at 652 nm and decreased fluorescence intensity of TMB at 405 nm. The change of color was directly observed. The combination of a hydrogel with a colorimetric platform favors the real-time and convenient sensing of PMS in the concentration range of 0.98 to 130.29 μM. A good linear relationship between the PMS concentration and both the absorption and fluorescence intensity was obtained with an r 2 value of 0.999, and a detection limit of 0.03 μM for fluorescence and 0.11 μM for spectrometry. Such a multisignal output probe with the advantages of simplicity, convenience, high sensitivity and stability improves the reliability and practical adaptability. This study successfully applied a valuable strategy for sensing PMS, and verified its availability in detecting the residual quantity of PMS in pollutant water treated by AOPs and PMS concentrations in actual water samples with peroxydisulfate (PDS). [ABSTRACT FROM AUTHOR]