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In this study, carbonized polymer dots (CPDs) were first proposed for the quantitative detection of chlortetracycline (CTC) based on aggregation induced emission. CPDs were synthesized by a one-step hydrothermal assay using polyethylene imine as the sole precursor. CPDs showed bright blue fluorescence under UV light (λEx 350 nm and λEm 465 nm), with a quantum yield of 14.58%. There was a significant fluorescence enhancement for the CPDs + CTC system. When the concentration of CTC increased, the fluorescence color of CPDs displayed a significant change from bright blue to dark blue with the maximum emission shifting from 465 nm to 430 nm. Furthermore, the lifetime of CPDs + CTC increased from 7.12 ns to 11.26 ns, an increment of 4.14 ns, which was ascribed to the aggregation induced emission of CTC in the presence of CPDs. There was a good linear response between the fluorescence intensity of CPDs and the concentration of CTC from 0.1 μM to 120 μM with a limit of detection of 40 nM. Therefore, an excellent fluorescence probe was successfully prepared for the detection of CTC and its application in real samples was confirmed. [ABSTRACT FROM AUTHOR]

It was the first time to report the aggregation induced emission (AIE) of acetaldehyde (AA) on the surface of carbonized polymer dots (CPDs) with the auxiliary of Tb3+. Based on the AIE of AA, a turn-off–on fluorescence method was established for AA detection using the porous CPDs-Tb3+ system. The one-pot hydrothermal method was used to obtain CPDs, using milk and polyethyleneimine (PEI) as precursors. In the presence of Tb3+, CPDs aggregated immediately and even forming precipitate, and the fluorescence intensity decreased obviously. AA can effectively embed on the surface of CPDs-Tb3+ due to the porous structure. AA displayed obviously blue fluorescence with excitation wavelength at 370 nm (emission peak at 460 nm), while there was no fluorescence peak when excited at 460 nm. In the CPDs-Tb3+ solution, AA exhibits obvious fluorescence enhancement effect (λex 460 nm, λem 545 nm). And then, AA can be determined by the turn-off–on system based on the linear relationship between fluorescence enhancement and the concentration of AA ranging from 0.04 mM to 42.48 mM. The limit of detection (LOD) was 0.02 mM. The turn-off–on system was successfully applied to determine AA in wine samples. The strategy may be exploited to monitor AA in more drinking or foodstuff samples. [ABSTRACT FROM AUTHOR]

It was the first time to report the aggregation induced emission (AIE) of acetaldehyde (AA) on the surface of carbonized polymer dots (CPDs) with the auxiliary of Tb3+. Based on the AIE of AA, a turn-off–on fluorescence method was established for AA detection using the porous CPDs-Tb3+ system. The one-pot hydrothermal method was used to obtain CPDs, using milk and polyethyleneimine (PEI) as precursors. In the presence of Tb3+, CPDs aggregated immediately and even forming precipitate, and the fluorescence intensity decreased obviously. AA can effectively embed on the surface of CPDs-Tb3+ due to the porous structure. AA displayed obviously blue fluorescence with excitation wavelength at 370 nm (emission peak at 460 nm), while there was no fluorescence peak when excited at 460 nm. In the CPDs-Tb3+ solution, AA exhibits obvious fluorescence enhancement effect (λex 460 nm, λem 545 nm). And then, AA can be determined by the turn-off–on system based on the linear relationship between fluorescence enhancement and the concentration of AA ranging from 0.04 mM to 42.48 mM. The limit of detection (LOD) was 0.02 mM. The turn-off–on system was successfully applied to determine AA in wine samples. The strategy may be exploited to monitor AA in more drinking or foodstuff samples. [ABSTRACT FROM AUTHOR]

In this work, a fluorescence method was developed for selective detection of Ag + in the presence of Cd 2+ , Hg 2+ , and Cu 2+ based on gold nanoclusters (AuNCs). That is, bovine serum albumin (BSA) templated AuNCs with double emission peaks were synthesized using BSA as a protective agent. AuNCs with uniform distribution and average size between 2.0 and 2.2 nm were synthesized using a green and simple method, and showed bright orange-red fluorescence under ultraviolet light. AuNCs have two emission peaks at 450 nm and 630 nm with an excitation wavelength of 365 nm. Under alkaline conditions, Cd 2+ can combine with the surface sulfhydryl groups of BSA-AuNCs to form Cd-S bonds, which cause AuNCs to aggregate, resulting in an increase in fluorescence intensity at 630 nm. Conversely, due to the d 10 -d 10 metal affinity interaction, the addition of Hg 2+ can reduce the fluorescence peak at 630 nm. Ag + was reduced to Ag 0 by gold nuclei in AuNCs, forming a stable hybrid Au@ AgNCs species with blue-shifted and enhanced fluorescence. Finally, the paramagnetic behavior of Cu 2+ combined with BSA causes the excited electrons of the gold cluster to lose their energy via ISC, eventually leading to simultaneous quenching of the two emission peaks. The results show that the limit of detection (LOD) of Ag + , Hg 2+ , Cd 2+ and Cu 2+ is 1.19 μM, 3.39 μM, 1.83 μM and 5.95 μM, respectively., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)