Photoluminescence Sensing of Soluble Lead in Children's Crayons Using Perovskite Nanocrystal In Situ Growth on an Aluminum Hydroxide Layer.

In this study, a fluorescence sensing approach for lead ion (Pb2+) was developed using in situ growth of methylamine lead bromine (MAPbBr3) perovskite on an aluminum hydroxide (Al(OH)3) thin layer. The Al(OH)3 thin layer could be obtained on a glass slide by liquid phase deposition and is of a large specific surface area and insoluble in water. After sulfhydryl functionalization, the Al(OH)3 thin layer reveals effective adsorption and excellent enrichment ability to Pb2+ and is additionally used as the substrate for the in situ growth of lead halogen perovskite. The fluorescence sensing of Pb2+ could be realized by the fluorescence intensity of lead halogen perovskite on the Al(OH)3 layer. The linear relationship between the fluorescence intensity and the concentration of Pb2+ was found in the range from 80 to 1500 mg/kg. The detection limit of Pb2+ is found to be 40 mg/kg, which is lower than the maximum permission of lead residue in student products (90 mg/kg) stipulated by the National Standard of the People's Republic of China (GB21027-2020). After being grinded and pre-treated, soluble lead in watercolor paint and crayon samples can be extracted by the sulfhydryl functionalization Al(OH)3 layer, then lead halogen perovskite can be generated in situ on the layer to achieve the fluorescence sensing for the determination of soluble lead in the samples.

Design of competition nanoreactor with shell-isolated colloidal plasmonic nanomaterials for quantitative sensor platform.

Shell-isolated colloid plasmonic nanomaterials-based nanoreactor is a well-established platform widely applied in catalyst or Surface Enhanced Raman Scattering (SERS) sensors. The potentials versatility of nanoreactor platform is mainly implemented by the well-defined and tailorable structure of colloid plasmonic nanomaterials. Currently, a competitive conjugative-mediated nanoreactor is introduced to determine glucose with SERS. Glucose-conjugating nanoreactor, as convertors of the sensors, are constructed by coordinated deposition colloidal gold nanoparticles with sodium nitroprusside framework (Au@SNF) and covalently bonded 4-mercaptopyridine (4-Mpy) with self-assembly strategy. The nanoreactor contained the signal-amplifier Au@SNF NPs, conjugative-mediated signal receiver 4-Mpy, and signal internal standard molecular CN-. In addition to well-defined morphology and functionality, conjugative-mediated and internal standards method are also employed to benefit the nanoreactor. The two-parameter strategy significantly improves the signal indication and correction. Using this proposed platform, the competitive-mediated nanoreactor provides a quantitative SERS detection of glucose, and extends the applicability of SERS in more complicated and reproducibility analysis. Meanwhile, the nanoreactor based sensors also exhibited better properties to detect glucose in various food samples and bio-samples which provided strongly appliance for glucose sensors.

A taurine-functionalized 3D graphene-based foam for electrochemical determination of hydrogen peroxide.

We present a synthesis approach of taurine-functionalized graphene foam (a-NSGF) using hydrothermal reduction, freeze-drying and high temperature annealing. The higher temperature in annealing allowed the N/S atoms of taurine enter into the graphene lattice, which improves its electrocatalytic activity greatly. The a-NSGF consisting of taurine that modified into 3D layers of graphene and endow is of the rapid sensitive to hydrogen peroxide (H2O2). The electrode using a-NSGF modification reveals highly sensitive and stable towards the concentration change of H2O2 due to the stable 3D structure and good electrical conductivity of a-NSGF. A linear correlation between H2O2 concentration and the electrochemical signal is found to be in a range from 1.5 to 300 µM and the correlation coefficient is R2 = 0.999. The modified electrode has been applied in the determination of H2O2 in rain samples and the results have been compared with the China National Standard Method. The recoveries range from 94.6% to 106.7%. These results show that the proposed sensor is promising for the development of novel electrochemical sensing for H2O2 determination.