It is critical to design a novel and simple bifunctional sensor for the selective and sensitive detection of ions in an aqueous media in environmental samples. As a result, in this study, tetraphenylethene hydrazinecarbothioamide (TPE-PVA), known as probe 1, was successfully synthesized and characterized as having impressive photophysical phenomena such as aggregation-induced emission (AIE) and mechanochromic properties by applying mechanical force to the solid of probe 1. The emission of the solid of probe 1 changed from turquoise blue to lemon yellow after grinding, from lemon yellow to parakeet green after annealing at 160 °C, and to arctic blue after fuming with DCM. Such characteristics could lead to a variety of applications in several fields. The probe was implemented and demonstrated remarkable selectivity and sensitivity toward mercury(II) and silver(I) ions by substantially switching off emission over other cations. Following an extensive photophysical analysis, it was discovered that detection limits (LOD) as low as 0.18344 and 0.2384 μg mL –1 for Hg 2+ and Ag + , respectively, are possible with a quantum yield (Φ) of 2.26. Probe 1 was also explored as a Hg 2+ and Ag + paper strip-based sensor and kit for practical use. The binding mechanisms of probe 1 (TPE-PVA) with Hg 2+ and Ag + were confirmed by 1 H NMR titration. These results could lead to the development of reliable onsite Hg 2+ and Ag + fluorescent probes in the future.

The development of a novel uncomplicated sensor for sensitive and selective detection in biomedical analysis is necessary. This study demonstrates the preparation of nitrogen-doped carbon dots (NC dots) via hydrothermal synthesis as a naked eye fluorescent probe for selective and sensitive detection of dopamine (DA). The successful synthesis of NC dots was confirmed using various microscopic and spectroscopic techniques. In addition, NC-dot-incorporated gel strips were prepared through a simple approach for naked eye detection of dopamine. The linear range for detection of dopamine was 2−20 μg/mL with a detection limit as low as 1.97 μg/mL. Moreover, NC dots showed a low toxicity toward HeLa cells, demonstrating their relevance in multicolor cell imaging. The developed probe was also utilized for quantitative determination of dopamine in a commercial pharmaceutical sample with adequate results.

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