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Apart from environmental implications, the extreme toxicity of cyanide can lead to sudden human death upon prolonged exposure to it. Hence, rapid and low-level on-site detection of cyanide has earned paramount significance in the present era. Therefore, an AIEE active and piezofluorochromic Schiff base (probe 2) was synthesized which exhibited highly selective fluorescence enhancement based nanoscale (LOD; 6.17 nM) detection of CN−. The interaction mode was attributed to the deprotonation of the probe by the cyanide that was confirmed through 1H NMR titration, pH, theoretical studies, and switchable fluorescence response upon the addition of HCl. Advantageously, probe 2 displayed solid and vapor phase recognition of cyanide which is the first of its kind as far as we know. The excellent sensing potential of the probe was satisfactorily applied for the detection of cyanide in food, natural soil, and industrial wastewater. Additionally, probe 2 showed an immediate colorimetric response towards cyanide which was favorably integrated through a smartphone. Finally, the switchable fluorescence response of the probe was used to design an INHIBIT logic gate. Therefore, the multifunctional probe 2 displayed excellent practical potential for cyanide detection which was the ultimate goal of our work. [ABSTRACT FROM AUTHOR]

We report benzo[ghi]perylene (BzP) and coronene (Cron) as multimode fluorescent probes for accurate monitoring and direct visualization of monomer–micelle transitions in surfactants for the first time. The probe molecules formed self-assembled nanoparticles in an aqueous solution and displayed strong aggregation-enhanced excimer emission (AEEE). During the process of surfactant monomer–micelle transition, the probe nanoparticles dissolved, and the observation of excimer–monomer emission transition clearly indicated the formation of micelles. The ratiometric changes in excimer–monomer emission (IE/IM) were used for the precise determination of critical micelle concentration (CMC) of various surfactants. The monomer–micelle transition process was directly observed under a UV lamp, and the visual determination of CMC became possible. The CMC value determination using the excimer/monomer ratio (IE/IM), UV-vis, lifetime and visual assessment clearly suggests that BzP and Cron are excellent multimode probes for monitoring the micelle structural transitions of amphiphiles. [ABSTRACT FROM AUTHOR]

Benzo[ghi]perylene and coronene were used as ratiometric fluorescent probes to monitor microenvironment changes and monomer-micelle transition for the first time. The perturbations in vibronic bands in the emission spectra of probes displayed microenvironment sensing behavior in various solvents and surfactants. The monomer–micelle transitions of anionic, cationic and neutral surfactants were monitored by changes in the ratios of vibronic band intensities. Clear CMC values were obtained, which is an advantage over the conventional probes such as pyrene with clear CMC values sometimes difficult to obtain due to less steep changes of S-shaped plots. They revealed a redshift in emission which offers a good substitute in situations where the fluorescence of pyrene and the background fluorescence of the assay mixture interfere with each other. BzP exhibited reverse behavior in the perturbations of vibronic band intensities in anionic SDS and SLS relative to cationic and non-ionic surfactants, which was not observed when pyrene was used. In addition, the vibronic band ratios of BzP are thermally more stable than those of pyrene, which is advantageous since strict assay temperature control may not be necessary. These probes are thus helpful for various applications in the areas of sensing and interface science. [ABSTRACT FROM AUTHOR]

We exploit a real-time perylene probe fluorescence turn-on method to detect acetylcholinesterase (AChE) activity through the selective decomposition of MnO2 nanosheets. The surface of the MnO2 nanosheets is negatively charged. The perylene probe (P-4C+) has four positively charged quaternary ammonium groups. When mixed together, P-4C+ attached to the surface of the MnO2 nanosheets through electrostatic attractive interactions. The fluorescence of P-4C+ was effectively quenched by the MnO2 nanosheets. Acetylthiocholine (ATCh) could be hydrolyzed to thiocholine by AChE. Thiocholine is a reducing agent. It could reduce MnO2 nanosheets to Mn2+ and thus trigger the decomposition of the MnO2 nanosheets. As a result, P-4C+ was released and the fluorescence of P-4C+ was restored. The AChE inhibitor restrained the catalytic activity of AChE and resulted in a reduced fluorescence recovery of P-4C+. Our assay method is simple and selective, with low toxicity and better biocompatibility, which would facilitate biological and biomedical applications associated with AChE activity. [ABSTRACT FROM AUTHOR]

A cancer cell specific aptamer was labeled with an aggregation-induced emission (AIE) probe for the first time. Using it as a light-up bioprobe, a specific cancer cell detection method is developed. [ABSTRACT FROM AUTHOR]

A novel fluorescence turn-on strategy based on Au nanoparticles and a perylene probe for the sensing of Hg2+ ions has been developed. It was observed that a perylene probe could be adsorbed onto the surface of Au NPs through strong electrostatic and hydrophobic interactions. Its fluorescence was efficiently quenched by the Au nanoparticles. However, in the presence of Hg2+ and NaBH4, Hg2+ was reduced and an Au/Hg amalgam was formed on the surface of the Au nanoparticles. The perylene probe could hardly be adsorbed and quenched by the Au/Hg amalgam. A turn on fluorescence signal was therefore detected. The assay is quite sensitive, and 5 nM Hg2+ could be easily detected. It is also very selective, a number of metal ions were tested and no noticeable interference was observed. The assay was also successfully applied for the determination of Hg2+ in lake water samples. A simple, fast, inexpensive, highly sensitive and selective Hg2+ sensing strategy is therefore established. [ABSTRACT FROM AUTHOR]

A novel fluorescence turn-on strategy for glucose sensing is demonstrated. The fluorescence of a perylene probe could be quenched by the silver nanoparticles (Ag NPs). The Ag NPs could be etched by H2O2 generated from the enzymatic oxidation of glucose. And efficient probe fluorescence recovery was detected. [ABSTRACT FROM AUTHOR]