Identification Of Cu2 Research Articles

Mediated self-assembled gold nanoclusters with mesoporous silica particles to boost fluorescence for enhanced on-site monitoring of organophosphate pesticides

Accurate detection of organophosphate pesticides (OPs) is paramount for ensuring food safety. Dendritic mesoporous silica sphere was employed to confine gold nanoclusters (AuNCs@dmSiO2) to ameliorate fluorescent property of AuNCs. A AuNCs@dmSiO2-based fluorescent method was developed for OPs sensing. Identification of Cu2+ by AuNCs quenched AuNCs@dmSiO2 fluorescence. Interaction between Cu2+ and generated thiocholine in catalysis of acetylcholinesterase (AChE) caused fluorescence enhancement. OPs, an inhibitor of AChE, suppressed thiocholine production to cause fluorescence quenching. Based on fluorescent variation, a fluorescent method was proposed for OPs by selecting paraoxon as a model within range of 0.05–25.0 ng/mL with a limit of detection (LOD) of 0.032 ng/mL. Besides, a portable test swab was prepared for on-site monitoring OP paraoxon with a smartphone-based 3D-printing portable device with a LOD of 0.65 ng/mL. This work is highlighted by the inspiration of designing highly fluorescent AuNCs, and the provision of a viable avenue for OPs-related food analysis.

A novel triaminopyridine fluorescent probe based on AIE effect with high selectivity under solvent shielding effect

A new fluorescent probe TPA-DAP with aggregation-induced emission (AIE) characteristic based on 2,6-pyridinedicarboxylic acid was synthesized for the detection of paramagnetic ions (Cu2+, Co2+, Ni2+). In the DMF/PBS (5:95, v/v, pH = 7.40) solvent mixture, the fluorescence intensity exhibited a notable enhancement of over 3-fold when compared to DMF alone. Concurrently, fluorescence quenching phenomena were observed in the presence of Cu2+, Co2+, and Ni2+, with corresponding detection limits measured at 56.4 nM, 22.4 nM, and 26.5 nM, respectively. These detection limits were found to be lower than the prescribed thresholds for Cu2+ in Class I groundwater and Co2+, Ni2+ in Class III groundwater, multi-functional detection was possible. The coordination constants were 9.07 × 105, 3.63 × 105 and 5.69 × 105, respectively. However, in the DMSO system, the probe will be highly selective in the presence of solvent shielding effects. The probe showed more than 10-fold enhancement of fluorescence intensity in DMSO/Tris-HCl (5:95, v/v, pH = 7.00) compared to DMSO and specific detection of Cu2+ with a detection limit of 36.7 nM and a coordination constant of 4.35 × 105, and was cyclically detectable in the presence of EDTA. TPA-DAP was applied for the detection of Cu2+ in actual water samples and showed good biocompatibility and recyclability, making it suitable for water testing and test paper experiments, and also for a wide range of applications in the identification of Cu2+, Co2+, Ni2+ and other bioassays in cells and zebrafish. Solvents could be selected according to actual test requirements.

Bispyrene/surfactant assemblies as fluorescent sensor platform: detection and identification of Cu2+ and Co2+ in aqueous solution

A cationic bis-pyrene derivative was prepared and its assemblies with anionic surfactant to function as fluorescent sensor platforms for heavy metal ions in aqueous solution were evaluated. Optical spectroscopy measurements illustrated that both UV-vis absorption and fluorescence emission spectra of bis-pyrene could be well enhanced in the assemblies with the anionic surfactant, SDS. Moreover, fluorescence quenching studies revealed that the sensitivity of bis-pyrene/SDS assemblies is highly dependent on the concentration of SDS. The optimized sensor platform exhibited not only a high sensitivity towards both Cu2+ and Co2+ in aqueous solution with detection limits lower than 100 nM but also a high selectivity towards these two metal ions over a series of divalent metal ions including Ba2+, Ca2+, Hg2+, Mg2+, Ni2+, Pb2+, Zn2+, Cd2+, and Fe3+. The high sensitivity was demonstrated to be due to the electrostatic interaction between the metal cations and the anionic surfactants, which dramatically increases the local concentration of metal ions in the near vicinity of pyrene moieties. Moreover, the metal ion target could be identified by addition of glycine to the quenched system, where a dramatic turn-on fluorescence was observed for the Cu2+-quenched system whereas a further turn-off fluorescence was found for the Co2+-quenched system. Furthermore, the recovery of Cu2+-quenched fluorescence could be utilized to provide a turn-on fluorescence sensor for neutral amino acids.