Protamine gold nanoclusters - based fluorescence turn-on sensor for rapid determination of Trinitrotoluene (TNT)

A facile and sensitive hexahomotrioxacalix[3]arene-based fluorescent sensor for the detection of trace amounts of 2,4,6-trinitrophenol

Nitroaromatic compounds are common explosives and toxic pollutants, the selective and sensitive detection of which is of great importance. Herein, a facile and sensitive fluorescent sensor L was constructed for the sensing of TNP based on the hexahomotrioxacalix[3]arene skeleton. The fluorescence emission of L was drastically quenched in the presence of 2,4,6-trinitrophenol (TNP), while other tested NACs, metal ions, and anions induced negligible changes. Under the optimized conditions, the spectroscopic studies revealed that L exhibited extremely sensitive and selective TNP recognition, with a detection limit of 9.17 × 10-7 M and a quenching constant of 2.44 × 104 M-1. The sensitivity of sensor L for TNP was attributed to the formation of a ground-state charge-transfer complex and an inner filter effect, which also contributed to the special selectivity of the sensor among the various nitroaromatic analogues. Compared with previous reports, L can serve as a highly efficient sensor for the sensing of TNP and can be employed over a wide pH range of 2 to 12. Sensor L was effectively used to quantify TNP in real water and soil samples. Additionally, fluorescent test strips were also developed for visual and rapid detection of TNP in both the solution and vapour phases.

Histidine-capped copper nanoclusters for in situ amplified fluorescence monitoring of doxycycline through inner filter effect

There is a significant need to accurately measure doxycycline concentrations in view of the adverse effects of an overdose on human health. A fluorescence (FL) detection method was adopted and copper nanoclusters (CuNCs) were synthesized using chemical reduction technology. Based on FL quenching with doxycycline, the prepared CuNCs were used to explore a fluorescent nanoprobe for doxycycline detection. In an optimal sensing environment, this FL nanosensor was sensitive and selective in doxycycline sensing and displayed a linear relationship in the range 0.5-200 μM with a detection limit of 0.092 μΜ. A characterization test demonstrated that CuNCs offered active functional groups for identifying doxycycline using electrostatic interaction and hydrogen bonds. Static quenching and the inner filter effect (IFE) resulted in weakness in the FL of His@CuNCs with doxycycline with great efficiency. This suggested nanosensor was revealed to be a functional model for simple and rapid detection of doxycycline in real samples with very pleasing accuracy.

Application of aza-BODIPY as a Nitroaromatic Sensor

Nitroaromatic explosive detection with high sensitivity and selectivity is requisite for civilian and military safety and the ecosystem. In this study, aza boron dipyrromethene (aza-BODIPY) dye was selected as a fluorescent-based chemosensor against nitroaromatic compounds (NACs) including 2,4,6-trinitrophenol (picric acid, TNP), 2,4,6-trinitrotoluene (TNT), and 2,4-dinitrotoluene (DNT). This dye molecule exhibits sharp fluorescent behavior with high quantum yields beyond the near-infrared region (NIR) and is considered as a potential candidate for the detection of NACs. O'Shea's approach was used to synthesize tetraphenyl-conjugated aza-BODIPY molecules. Quenching of fluorescence emission of aza-BODIPY at 668 nm after the exposure to NACs was investigated under acetonitrile-water and acetonitrile-ethanol solvent conditions. The quenching responses and its mechanism were examined by considering the Stern-Volmer relationship Stern-Volmer constants (K_sv) for TNP (in water), TNP (in ethanol), TNT, and DNT, which are predicted to be 1420, 1215, 1364, and 968 M^-1, respectively, all of which are sufficiently above the limit of detection (LOD) values. Thus, the present study opens up the possibility of the usage of aza-BODIPY molecules as a low-cost, light-weight sensor for the detection of NAC explosives.