Cu(II)-Mediated aerobic oxidative synthesis of sulfonated chromeno[4,3-c]pyrazol-4(2H)-ones.

Herein, starting with propiolates and sulfonyl hydrazides, we developed a concise and facile synthesis of 2-sulfonylated chromeno [4,3-c]pyrazol-4(2H)-ones or 2,5-dihydro-4H-pyrazolo[4,3-c]quinolin-4-ones via Cu(II)-promoted oxidative cascade C-C/C-N bond formation. This protocol has the advantages of atom economy and good functional group tolerance. The primary mechanism studies indicate that the reaction involves a free-radical process as well as terminal alkyne C-H activation.

Detection of glycoprotein through fluorescent boronic acid-based molecularly imprinted polymer.

A novel strategy based on the fluorescent molecularly imprinted polymers (FMIP) for specific recognition and sensitive sensing glycoprotein from biological samples was developed. The FMIP prepared by introducing a fluorescent boronic acid quinoline-based on the PGMA/EDMA bead surface and assembled a glycoprotein molecularly imprinted polymer using surface imprinting technology. The resultant material showed specific recognition to model glycoprotein. At the same time, the change of fluorescence caused by the amount of model glycoprotein could achieve quantitative determination. The method provided a good linear relationship of the concentrations of HRP in the range of 0.05-1 µM, and the detection limit was 0.02 µM. It is 10 times lower than the previous fluorescence nanosensor for glycoprotein. The established method combined the desired selectivity of molecularly imprinted polymers and high sensitivity of fluorescence spectroscopy. The influence of background impurities could be effectively eliminated. The outstanding features guarantee that it can be successfully applied to detect glycoprotein from biological samples under physiological conditions.

Spectroscopic quantification of 5-hydroxymethylcytosine in genomic DNA using boric acid-functionalized nano-microsphere fluorescent probes.

5-hydroxymethylcytosine (5hmC) is the sixth base of DNA. It is involved in active DNA demethylation and can be a marker of diseases such as cancer. In this study, we developed a simple and sensitive 2-(4-boronophenyl)quinoline-4-carboxylic acid modified poly (glycidyl methacrylate (PBAQA-PGMA) fluorescent probe to detect the 5hmC content of genomic DNA based on T4 ß-glucosyltransferase-catalyzed glucosylation of 5hmC. The fluorescence-enhanced intensity recorded from the DNA sample was proportional to its 5-hydroxymethylcytosine content and could be quantified by fluorescence spectrophotometry. The developed probe showed good detection sensitivity and selectivity and a good linear relationship between the fluorescence intensity and the concentration of 5 hmC within a 0-100nM range. Compared with other fluorescence detection methods, this method not only could determine trace amounts of 5 hmC from genomic DNA but also could eliminate the interference of fluorescent dyes and the need for purification. It also could avoid multiple labeling. Because the PBAQA-PGMA probe could enrich the content of glycosyl-5-hydroxymethyl-2-deoxycytidine from a complex ground substance, it will broaden the linear detection range and improve sensitivity. The limit of detection was calculated to be 0.167nM after enrichment. Furthermore, the method was successfully used to detect 5-hydroxymethylcytosine from mouse tissues.

A ratiometric fluorescence RRE RNA-targeted assay for a new fluorescence ligand.

The Rev protein regulates HIV-1 gene expression. Small ligands that bind to the Rev response element (RRE) RNA would inhibit Rev function and suppress HIV-1 replication. A novel ratiometric fluorescence assay was applied in the present study to monitor ligand-RNA interactions by using red-emitting CdTe quantum dots (QDs) coated with silica as a reference. A small fluorescence ligand, ICR 191, was found to interact with RRE at the Rev binding site and compete with the Rev peptide. After adding red-emitting QDs to the interaction system, it was observed that ICR 191 did not fluoresce upon the addition of RRE, and fluorescence recovered when ICR 191 was displaced by a Rev model peptide, whereas the fluorescence of QDs remained constant. Furthermore, variations in the fluorescence ratios between ICR 191 and QDs were exploited to characterize the interactions of Rev with two known antagonists, neomycin B and tobramycin, by using RRE RNA with ICR 191 as a fluorescence indicator. Together, our results demonstrated that ratiometric fluorescence-based nanotechnology applications can be used for ligand-RNA interaction assays. This ICR 191-RRE RNA interaction assay can potentially be developed to build a screening model for assessing antagonists of the Rev binding element in RRE.