A high-throughput and simultaneous determination of combretastatin A-4 phosphate and its metabolites in human plasma using HPLC-MS/MS: Application to a clinical pharmacokinetic study.

To investigate the clinical pharmacokinetics of CA4P, a high-throughput high-performance liquid chromatography-tandem mass spectrometry assay with an identical positive electrospray ionization (ESI) mode was developed for the simultaneous determination of CA4P, its active metabolite CA4, and CA4 glucuronide in human plasma. CA4P and CA4 were easier to protonate in positive ESI mode, whereas CA4G was reported to produce deprotonated ion in negative ESI mode. Because the baseline separation of CA4P and CA4G could not be achieved, using MS positive/negative ion switching is not feasible. In this study, an abundant ammonium adduct ion of CA4G in ESI+ was observed as an ideal precursor ion. The final precursor/product transition pairs chosen for CA4P, CA4, and CA4G were at m/z 397/350, 317/286, and 510/317, respectively. To the best of our knowledge, it is the first report on the simultaneous quantification of CA4P, CA4, and CA4G in biological samples. The proposed method was validated, which showed a wide linear dynamic range, high selectivity and sensitivity, good repeatability, and a short run time. Compared with the literatures, the lower limits of quantification were five- and two-fold more sensitive for CA4G and CA4, respectively. Therefore, this method was successfully applied to the pharmacokinetic study of CA4P in phase I clinical trial.

Two kinds of lateral flow immunoassays based on multifunctional magnetic prussian blue nanoenzyme and colloidal gold for the detection of 38 ß-agonists in swine urine and pork.

Herein, novel multifunctional magnetic prussian blue nanoenzymes (MPBNs) and colloidal gold (CG) were synthesized and used to develop two kinds of lateral flow immunoassays (LFIAs) for the detection of 38 ß-agonists. Since MPBNs has a unique three-in-one function of colorimetric magnetic catalytic activities, the signal intensity and coupling ratio are 2 and 8-fold higher than that of the CG. The cut-off values of the CG-LFIA and MPBNs-LFIA for swine urine and pork are 5/5 and 0.3/0.5 µg/kg, the limits of detection are 0.19/0.29 and 0.02/0.03 µg/kg, respectively. The sensitivity of MPBNs-LFIA is 10-fold higher than that of CG-LFIA, and up to 200-fold higher than that of the reported LFIAs. The recoveries of the LFIAs are 80.0%-116.7%, with coefficients of variation of 1.4%-14.3%. Our study proved that the MPBNs have more advantages than CG, and can offer a promising signal label for ultrasensitive immunoassay techniques.

Developing an ultrasensitive immunochromatographic assay for authentication of an emergent fraud aminopyrine in herbal tea.

Aminopyrine is a nonsteroidal anti-inflammatory drug only for medical purposes, however, it has been illegally added in traditional Chinese herbal teas for fraud activity recently. In this study, a specific antibody against aminopyrine with IC50 of 3.00 ng/mL was obtained for the first time by a rational hapten design. Furthermore, an ultrasensitive gold nanoparticles immunochromatographic assay (AuNPs-ICA) for determination of aminopyrine based on a portable reader was firstly developed, with cut-off value of 100.00 ng/mL, limit of detection (LOD) of 4.80 ng/mL and limit of quantification (LOQ) of 5.71 ng/mL for herbal tea, respectively. The recovery rates ranged from 93.21 % to 105.61 %, with inter-assay coefficient of variation (CV) from 1.08 % to 3.82 %. Additionally, 24 blind samples were examined simultaneously by AuNPs-ICA and LC-MS/MS, demonstrating a good consistency for each other. The proposed AuNPs-ICA is an ultrasensitive and reliable tool for on-site surveillance screening of fraud additives in herbal tea.

Ultrasensitive Magnetic Assisted Lateral Flow Immunoassay Based on Chiral Monoclonal Antibody against R-(-)-Salbutamol of Broad-Specificity for 38 ß-Agonists Detection in Swine Urine and Pork.

Screening for ″zero tolerance″ ß-agonists requires broad-specificity and sensitivity methods. Herein, R-(-)-salbutamol (SAL) is chirally separated and designed as a hapten, and a monoclonal antibody (mAb) was first prepared with an IC50 of 0.27 ng/mL, which can recognize 38 ß-agonists simultaneously. The broad-specificity of chiral mAb was explored by molecular simulation technology. Magnetic nanoparticles (MNPs) were then synthesized and applied as a signal tracer to develop a lateral flow immunoassay (LFIA). The limits of detection of MNPs-LFIA for SAL in swine urine and pork were 0.05 and 0.09 µg/kg, which was (2-125)-fold lower than that of the reported LFIAs. The recoveries were between 95.8 and 116.7%, with the coefficient of variation from 2.7 to 15.4%. Parallel analysis of 44 samples by commercial ELISA kits confirmed the reliability. Therefore, our work not only provides a broad-specificity and ultrasensitive method for ß-agonists but also suggests that chirality is the new general theory that guided the rational hapten design.

Effect of folic acid on the postharvest physiology of broccoli during storage.

The objective of the present study was to explore the effect of folic acid on the postharvest physiology of broccoli placed in storage. Broccoli heads were immersed in 5 mg L-1 folic acid for 10 min, then stored at 20 ± 1 °C for 4 days. Results indicated that the postharvest treatment of broccoli with folic acid decreased the rate of flower opening and yellowing, inhibited weight loss, reduced the level of respiration, as well as ethylene generation. Folic acid-treated broccoli maintained their level of chlorophyll, total soluble solids, vitamin C, total phenolics, flavonoids, glucosinolate, and folic acid. Treated broccoli also exhibited reduced accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS). Concomitantly, antioxidant enzyme activity and corresponding gene expression were also enhanced. In contrast, chlorophyll-degrading enzyme gene expression was suppressed. These results indicated that folic acid treatment of broccoli could be used to prolong shelf-life.

Hydrothermal formation of N/Ti3+ codoped multiphasic (brookite-anatase-rutile) TiO2 heterojunctions with enhanced visible light driven photocatalytic performance.

Mixed phased TiO2 catalysts codoped with N and Ti3+ have been successfully synthesized using a low-temperature, one step hydrothermal method using TiN as the precursor. The as prepared samples were studied for their crystalline structure, morphology, composition, and optical properties using various analytical techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). It was observed that N and Ti3+ codoped TiO2 samples having mixed phases of brookite, anatase and rutile could be obtained at a wide range of hydrothermal time durations ranging from 24 h to 72 h. The as-prepared samples exhibit a distinct red shift, suggesting that N and Ti3+ codoping significantly enhances the optical absorption characteristics of TiO2. The photocatalytic activity of the prepared samples was studied using methylene blue and colorless resorcinol dyes. The prepared samples demonstrated good photocatalytic activity because of their excellent mixed phase crystalline structures and an increase in the threshold wavelength response. The mechanism of the photocatalytic degradation reaction was also studied. This work provides a novel strategy to fabricate and extend the visible light response of TiO2, which facilitates their application in the environment remediation and energy conversion.

Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.