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Three cationic surfactants labeled as APS-8 ((Z)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N,N-dimethyl-N-octylbenzenaminium bromide), APS-12 ((E)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl-N,N-dimethylbenzenaminiumbromide), and APS-16 ((E)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl-N,N-dimethylbenzenaminium bromide) were opportunely synthesized in order to study the effect of the hydrocarbon chain length on the process of micellization in mixed surfactant systems. The critical micelle concentration (CMC) values of binary mixtures containing APS-x (x = 8, 12, 16) and a conventional cationic surfactant (cetyltrimethylammonium bromide, CTAB) were retrieved by using surface tension measurements. The behavior of the mixed systems has been analyzed in the light of Rubingh's regular solution theory. In particular, two parameters describing respectively the interactions at the air/water interface and in the micellar phase were obtained for each system. Results show that micellization and adsorption properties of the mixed systems depend on the hydrophobic chain length and on the interaction of APS-x with CTAB. Furthermore, applying the regular solution theory (RST) to the experimental data allowed obtaining the interaction parameter of the mixed micelles (β) and the air–water interface (βσ). Results indicate an attractive interaction between the micelles and reveal a synergistic effect between the two components of the mixtures both in micelles and at the interface. The activity coefficients and the experimental CMC values in micelles indicate synergism less than as well as at the interface. [ABSTRACT FROM AUTHOR]

The design of multifunctional sensors based on biocompatible hybrid materials consisting of conjugated polythiophene-quantum dots for multiple environmental pollutants is a promising strategy for the development of new monitoring technologies. Herein, we present a new approach for the "on–off–on" sensing of Hg2+ and triacetone triperoxide (TATP) based on amphiphilic polythiophene-coated CdTe QDs (PQDs, PLQY ∼78%). The emission of the PQDs is quenched by Hg2+ ions via electron transfer interactions. Based on the strong interaction between TATP and Hg2+ ions, the addition of TATP to the PQD-Hg2+ complex results in a remarkable recovery of the PQD emission. Under the optimized conditions, the PQD sensor shows a good linear response to Hg2+ and TATP with detection limits of 7.4 nM and 0.055 mg L−1, respectively. Furthermore, the "on–off–on" sensor demonstrates good biocompatibility, high stability, and excellent selectivity in the presence of other metal ions and common explosives. Importantly, the proposed method can be used to determine the level of Hg2+ and TATP in environmental water samples. [ABSTRACT FROM AUTHOR]

The design of multifunctional sensors based on biocompatible hybrid materials consisting of conjugated polythiophene-quantum dots for multiple environmental pollutants is a promising strategy for the development of new monitoring technologies. Herein, we present a new approach for the "on-off-on" sensing of Hg 2+ and triacetone triperoxide (TATP) based on amphiphilic polythiophene-coated CdTe QDs (PQDs, PLQY ∼78%). The emission of the PQDs is quenched by Hg 2+ ions via electron transfer interactions. Based on the strong interaction between TATP and Hg 2+ ions, the addition of TATP to the PQD-Hg 2+ complex results in a remarkable recovery of the PQD emission. Under the optimized conditions, the PQD sensor shows a good linear response to Hg 2+ and TATP with detection limits of 7.4 nM and 0.055 mg L -1 , respectively. Furthermore, the "on-off-on" sensor demonstrates good biocompatibility, high stability, and excellent selectivity in the presence of other metal ions and common explosives. Importantly, the proposed method can be used to determine the level of Hg 2+ and TATP in environmental water samples.