Photoguided Shape Deformation of Azobenzene-Containing Polymer Microparticles.

Here we present the generation of uniform microparticles with tunable diameters from azobenzene-based homopolymer by combining the microfluidics technique and emulsion-solvent evaporation route. In addition, the photoinduced deformation behavior of these microspheres, irradiated by a linearly polarized beam with different irradiation time and direction, are systemically studied. The deformation process through real time optical microscope observation can be investigated, benefiting from the uniform and microscaled size of the polymer particles. These results indicate that the deformation degree characterized by relative variation of the long axial for the particles can be controlled by the irradiation time. Moreover, elongated particles with tunable aspect ratio or tilted shape can be generated by manipulating the irradiation direction and/or time. Interestingly, the shape transformation kinetics displays a significant dependence on initial size of the polymer particle. In addition, the shape transformation of the polymer particle can lead to the variation of the orientation and distribution of the encapsulated anisotropic gold nanorods.

Determination of phthalate esters in polyvinyl chloride infusion bag by stir bar sorptive extraction combined with GC.

A novel, efficient, and sensitive stir bar sorptive extraction method coupled with GC for the detection of four kinds of phthalate esters in plasticized polyvinyl chloride infusion bag has been developed and validated. Some experimental parameters including stirring speed, stirring time, pH value, salt concentration, desorption mode, desorption solvents, and desorption time were investigated and optimized. Under optimum condition, the validated assay was found to be linear (r > 0.9945) and LODs were between 1.07 and 2.67 ng for the four analytes. The method exhibited excellent precision with RSD varied from 4.5 to 6.1% (n = 5). The recoveries of the four phthalate esters at two different concentrations ranged from 80.5 to 93.4%. The results showed that the validated method could meet the need of determination of targets and was successfully applied to the analysis of phthalate esters in real samples.

Structural changes in the oral microbiome of the adolescent patients with moderate or severe dental fluorosis.

Dental fluorosis is a very prevalent endemic disease. Although oral microbiome has been reported to correlate with different oral diseases, there appears to be an absence of research recognizing any relationship between the severity of dental fluorosis and the oral microbiome. To this end, we investigated the changes in oral microbial community structure and identified bacterial species associated with moderate and severe dental fluorosis. Salivary samples of 42 individuals, assigned into Healthy (N = 9), Mild (N = 14) and Moderate/Severe (M&S, N = 19), were investigated using the V4 region of 16S rRNA gene. The oral microbial community structure based on Bray Curtis and Weighted Unifrac were significantly changed in the M&S group compared with both of Healthy and Mild. As the predominant phyla, Firmicutes and Bacteroidetes showed variation in the relative abundance among groups. The Firmicutes/Bacteroidetes (F/B) ratio was significantly higher in the M&S group. LEfSe analysis was used to identify differentially represented taxa at the species level. Several genera such as Streptococcus mitis, Gemella parahaemolysans, Lactococcus lactis, and Fusobacterium nucleatum, were significantly more abundant in patients with moderate/severe dental fluorosis, while Prevotella melaninogenica and Schaalia odontolytica were enriched in the Healthy group. In conclusion, our study indicates oral microbiome shift in patients with moderate/severe dental fluorosis. We identified several differentially represented bacterial species enriched in moderate and severe fluorosis. Findings from this study suggests that the roles of these bacteria in oral health and related diseases warrant more consideration in patients with moderate and severe fluorosis.

Folate-polyethyleneimine functionalized mesoporous carbon nanoparticles for enhancing oral bioavailability of paclitaxel.

Polymer-functionalized carbon nanoparticles hold great promise for their use in enhancing the oral absorption of drugs with poor oral bioavailability. And since the abundant expression of folate receptors in intestinal tract, folic acid (FA) modified uniform mesoporous carbon spheres (UMCS) was used to improve oral absorption of paclitaxel, a chemotherapeutic drug with poor oral bioavailability. In this research, folate-polyethyleneimine (FA-PEI) was grafted onto acid-treated uniform mesoporous carbon spheres through one-step electrostatic attraction. PTX was loaded into mesopores of nanoparticles through solvent evaporation, present as amorphous. The release of PTX from the FA-PEI-UMCS nanoparticles exhibited an initial rapid release, followed by a sustained release. And release rate could be regulated by changing amount of FA-PEI complex on the UMCS. The uptake of PTX-encapsulated nanoparticles was studied exploiting Caco-2 cells as an in vitro model. The results of confocal microscopy and flow cytometry demonstrated that folate functionalization enhanced internalization of nanoparticles by the cells. Moreover, PTX loaded in FA-PEI-UMCS nanoparticles resulted in a 5.37-fold increase in apparent permeability (Papp) across Caco-2 cell monolayers compared to Taxol(®). And the in vivo results showed that FA-PEI-UMCS nanoparticles did not only improve the oral bioavailability of PTX, but also decrease the gastrointestinal toxicity of PTX. In conclusion, the FA-PEI-UMCS nanoparticles might be a potentially applicable system to improve oral absorption of drugs with poor oral bioavailability.

A UFLC-MS/MS method coupled with one-step protein precipitation for determination of docetaxel in rat plasma: comparative pharmacokinetic study of modified nanostructured lipid carrier.

A rapid, simple and sensitive ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method coupled with one-step protein precipitation procedure has been developed and validated for the pharmacokinetic study of docetaxel in rat plasma to investigate the influence of polyethylene glycol (PEG) molecular weights (chain length) using in the modified formulations. Separation was achieved on a Venusil MP C18 column (100 mm × 2.1 mm, 3.0 µm) with a mobile phase consisting of methanol-water, and the total running time was 3.5min. The standard curve was linear over the range of 5-5000 ng/mL, with lower limits of quantification (LLOQ) of 5 ng/mL. The method was shown to be reliable and reproducible with intra-day precision below 10.7%, inter-day precision below 11.2%, accuracy within ±5.2%, and mean extraction recovery of 84.6-90.2%. The validated method was successfully applied to the comparative pharmacokinetic study of docetaxel in rat plasma after intravenous administration of docetaxel-loaded nanostructured lipid carrier modified by copolymers consisting of series of PEG molecular weights (2000, 4000, 10,000 Da), respectively. The results indicated that PEG-4000 possessed a better and longer circulation effect, which made the modified formulation one of the promising suspensions for the delivery of docetaxel in cancer.

Pharmacokinetics and tissue distribution of docetaxel by liquid chromatography-mass spectrometry: evaluation of folate receptor-targeting amphiphilic copolymer modified nanostructured lipid carrier.

A novel amphiphilic copolymer, folate-poly(PEG-cyanoacrylate-co-cholesteryl cyanoacrylate) (FA-PEG-PCHL) was synthesized to modify docetaxel-loaded nanostructured lipid carrier to lead to a long blood circulating effect and targeting ability for the delivery of antitumor drug in cancer. To investigate the characteristics of modified docetaxel-loaded nanostructured lipid carrier in vivo, a liquid chromatography-mass spectrometry method was developed and validated for the determination of docetaxel in rat plasma and tumor-bearing mouse tissue samples. The biosamples were extracted by liquid-liquid extraction method with ether and separated on a C(18) column (150 mm×4.6 mm, 5 µm) using a mobile phase consisting of methanol-0.01% formic acid water (82:18, v/v). The standard curves were linear over the ranges of 0.01-4.0 µg/mL for plasma and 0.02-8.0 µg/g for tissue samples, respectively. The validated method was successfully applied to the pharmacokinetic study in rat plasma and tissue distribution study in mouse tissues of docetaxel after an intravenous administration of docetaxel injection (DTX injection), docetaxel-loaded nanostructured lipid carrier (DTX-NLC) and FA-PEG-PCHL-modified docetaxel-loaded nanostructured lipid carrier (FA-DTX-NLC), respectively. The results indicated that the FA-DTX-NLC led to significant differences in pharmacokinetic profile and tissue distribution. Nanostructured lipid carrier modified by FA-PEG-PCHL could be one of the promising suspensions for the delivery of docetaxel in cancer.