Research Progress of Small Molecule Fluorescent Probes for Detecting Hypochlorite

Hypochlorous acid (HOCl) generates from the reaction between hydrogen peroxide and chloride ions via myeloperoxidase (MPO)-mediated in vivo. As very important reactive oxygen species (ROS), hypochlorous acid (HOCl)/hypochlorite (OCl−) play a crucial role in a variety of physiological and pathological processes. However, excessive or misplaced production of HOCl/OCl− can cause variety of tissue damage and human diseases. Therefore, rapid, sensitive, and selective detection of OCl− is very important. In recent years, the fluorescent probe method for detecting hypochlorous acid has been developed rapidly due to its simple operation, low toxicity, high sensitivity, and high selectivity. In this review, the progress of recently discovered fluorescent probes for the detection of hypochlorous acid was summarized with the aim to provide useful information for further design of better fluorescent probes.

The Fluidization Effect of a Bilayer Membrane on a Fatty Acid Vesicle by a Detergent

A bicelle, which is a bilayer molecular assembly, can be prepared by fluidizing a vesicle in the presence of a detergent. We investigated the effect of two different detergents, 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxypropane sulfonate (CHAPSO) and Triton X-100 (TX), on the formation of a bicelle from a vesicle containing oleic acid (OA) and the detergent molecules. The fluidization effect of the detergent was evaluated using the membrane packing density, which we measured using the fluorescent probe method with Laurdan, in conjunction with transmission electron microscopy to examine the morphology of the prepared bilayer molecular assemblies. As a result, it was discovered that the OA/CHAPSO system could form a heterogeneous phase with the highest packing density, implying that CHAPSO was the better detergent for a bicelle preparation, whereas the OA/TX system formed a disordered phase with the lowest packing density.

Exploratory development of PCR-fluorescent probes in rapid detection of mutations associated with extensively drug-resistant tuberculosis

Background The diagnosis and treatment of drug resistant tuberculosis (TB) especially multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis are the critical and difficult factors in the prevention and control of tuberculosis. The development of rapid molecular diagnostic tools become more and more significant to improve the cure rate, decrease the risk of recurrence and death rate. Currently, molecular mechanisms of drug resistance and major drug-resistant genes of Mycobacterium tuberculosis (MTB) have been analyzed and elucidated. We put into use PCR-fluorescent probes to detect the mutation gene associated with XDR-TB and evaluate the clinical value of PCR-fluorescent probes. Methods The molecular species identification of 900 sputum specimens was performed with the use of PCR-fluorescent probe method, wherein the mutations of the drug resistance genes including rpoB, katG, inhA, embB, rpsL, rrs and gyrA were detected, and the conventional drug susceptibility testing(DST)and PCR-directed sequencing(PCR-DS) was carried out as control. Results Among the 900 positive sputum specimens, the result of DST demonstrated that there were 501 strains of rifampicin-resistance, 451 strains of isoniazid-resistance, 293 strains of quinolone-resistance, 425 strains of streptomycin-resistance, 235 strains of ethambutol-resistance, and 204 strains of Amikacin-resistance. 427(47.44%) strains were MDR-TB. 146 (16.22%) strains were XDR-TB. The mutations of the rpoB, katG, inhA, embB, rpsL, rrs, and gyrA genes were detected in 751 of 900 specimens of MTB by PCR-fluorescent probe method, and the detection rate of drug resistance was 751/900 (83.44%). No mutant genes were detected in the other 149 specimens. Compared with DST, the mutant detection rate of rpoB, katG/inhA, rpsL, rrs, embB, and gyrA of six drugs (RIF,INH,SM,AM,EMB,FQs) were larger than 88%, five of six drugs were larger than 90% except for SM༈88.11%༉. The MDR mutant gene types were found in 398 specimens (42.22%), and XDR mutant gene types were found in 137 specimens (15.22%). PCR-DS was also employed and confirmed the PCR-fluorescent probe method with the accordance rate of 100%. Conclusion The PCR-fluorescent probe method is simple and rapid in detection of genotypes of XDR-TB and is worthy to be applied in the hospital.

Study on Non-Selective Photocatalytic Degradation of Organic Dyes in Presence of Hollow CdS Nanospheres

In this study, template method was applied to synthesize CdS hollow nanospheres via sonochemical method. The morphology, size of the nanospheres and crystal structure of the synthesized hollow CdS were characterized. The results showed that the hollow CdS nanospheres formed have pure cubic sphalerite structure and exhibit good monodispersity and size uniformity. The photocatalytic activity of the samples was evaluated by the decoloration of Rhodamine B (RhB), Methylene Blue (MB) and Methyl Orange (MO) aqueous solution under UV-vis light irradiation. The results indicated the hollow CdS had a good photocatalytic activity and show little selectivity of attack and are able to oxidize various organic pollutants. Moreover, the results of hydroxyl radical (•OH) detection using fluorescent probe method was in accordance with the RhB decolorization efficiency, which the •OH is likely to be the main active species responsible for dye degradation.

Supramolecular Interaction of Gliclazide with Cucurbit[7]uril and its Analytical Application

Gliclazide (GLZ) is non-fluorescent in aqueous solution. This property makes its determination through direct fluorescent methods impossible. Palmatine (PAL) exhibits very weak fluorescence emissions in aqueous solution. However, in acidic media at room temperature, PAL can react with cucurbit[7]uril (CB[7]) to form a stable complex and the fluorescence intensity of the complex is greatly enhanced. Dramatic quenching of the fluorescence intensity of the CB[7]–PAL complex was observed with the addition of GLZ. The competing reactions and the supramolecular interaction mechanisms between GLZ and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, 1H NMR spectroscopy, and molecular modelling calculations. The association constants of the complexes formed between the host and the guest were determined. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity was developed to determine GLZ in its pharmaceutical dosage forms and in human plasma with good precision and accuracy. The linear range of the method was from 0.003 to 2.100 μg mL–1. The limit of detection was 0.001 μg mL–1. This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

The preparation of phosphorylcholine-containing poly(Llactide) nanoparticles with solvent evaporation method

Phosphorylcholine-containing poly(L-lactide) (PLLA-PC) is a kind of amphiphilic copolymer synthesized with L-lactide (LLA) as monomer and glycerophosphorylcholine as ring-opening reagent. In this paper, self-assembly nanoparticles of PLLA-PC were prepared with solvent evaporation method. The factors that affected the properties and stability of nanoparticles were investigated. Transmission electron microscope (TEM) indicated that PLLA-PC nanoparticles presented typical core/shell structure. The critical micelle concentration (CMC) was determined with fluorescent probe method. The results showed that the CMCs were quite low (< 1×10-3 g/l) and were dependent on LLA units in the copolymer. The size of the nanoparticles was detected by dynamic light scattering (DLS). The results indicated that the size could be affected by LLA units, the amount of solvent and water in the preparation process. On the other hand, the obtained nanoparticles were stable while being stored at 4 °C, and hardly changed over the dilution with water, which was of great importance in venous injection. The solubility of clofazimine was better in aqueous solution of PLLA-PC nanoparticles than in pure water. This preliminary study suggested that PLLA-PC nanoparticles had a great potential as delivery system for hydrophobic drug.

The interaction of PVP complexes of gossypol and its derivatives with an artificial membrane lipid matrix

In this paper, we present the results of a study on the membrane-active properties of gossypol, its derivatives and their polyvinylpyrrolidone complexes as assessed by differential scanning calorimetry and by the fluorescent probe method. The latter revealed the change in polarization of the incident radiation caused by the action of the polyphenol on the artificial membrane lipid matrix.