Cyanine dye-assembled composite upconversion nanoparticles for the sensing and cell imaging of nitrite based on a single particle imaging method.

In this work, a single particle imaging method based on the total internal reflection (TIR) imaging platform for the sensing and cell imaging of nitrite (NO2-) in the near-infrared region using cyanine dye-assembled composite upconversion nanoparticles (UCNPs) was developed. The NaYF4:Yb,Tm@NaGdF4 UCNPs were synthesized as energy donors, and the cyanine dye IR-798 was prepared as an energy acceptor. Since the absorption spectrum of the cyanine dye IR-798 and the luminescence spectrum of upconversion nanoparticles overlapped effectively, IR-798 quenched the luminescence of the UCNPs. When NO2- was added to the cyanine dye-assembled composite upconversion nanoparticle system, NO2- destroyed the conjugate structure of IR-798, so that the luminous intensity of UCNPs could be restored. Based on the mechanism, a quantitative image analysis with high sensitivity, low sample usage, and fast response time using the TIR single particle imaging platform was developed to determine the content of nitrite in human serum samples. In addition, the UCNPs-IR-798 probe was applied to image the exogenous NO2- content in HeLa living cells based on the single particle imaging platform.

A hybrid boronate affinity probe for the selective detection of cis-diol containing compounds in tea beverages.

UiO-66-NH2 nanocomposite was post-modified with 4-mercaptophenylboronic acid (MPBA) by the method of in situ hybridization reaction. The hybrid boronate affinity material UiO-NH2 @P (TEPIC-co-MPBA) was characterized by scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. The material was applied as fluorescent probe for the detection of cis-diol containing compounds based on the boronate affinity mechanism, and exhibited high specific selectively. The proposed method exhibited good linearity for the detection of catechol in the range of 0.50 to 8.00 µg ml-1 . The detection limit was 0.13 µg ml-1 . The tactic was successfully applied to analyze the total polyphenols in tea beverages for catechol, and relative recovery was in 98.86-106.00%. Therefore, this work provided a promising strategy for the recognition of cis-diol containing compounds.