Development of a highly efficient in-tube solid-phase microextraction system coupled with UHPLC-MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.

Hydroxyl polycyclic aromatic hydrocarbons are considered active mutagenic and carcinogenic substances and are found in extremely low levels (ng/g) in biological samples. As a result, their determination in urine and blood samples is challenging, and a sensitive and effective method for the analysis of trace hydroxyl polycyclic aromatic hydrocarbons in complex biological matrices is required. In this work, a novel macroporous in-tube solid-phase microextraction monolith was prepared via a thiol-yne click reaction, and a highly efficient analytical method based on in-tube solid-phase microextraction coupled with UHPLC-MS/MS was developed to determine hydroxyl polycyclic aromatic hydrocarbons with low detection limits of 0.137-11.0 ng/L in complex biological samples. Four hydroxyl polycyclic aromatic hydrocarbons, namely, 2-hydroxyanthraquinone, 1-hydroxypyrene, 1,8-dihydroxyanthraquinone, and 6-hydroxychrysene, were determined in the urine samples of smokers, non-smokers, and whole blood samples of mice. Satisfactory recoveries were achieved in the range of 83.1-113% with relative standard deviations of 3.2-9.7%. It was found that implementation of the macroporous monolith gave a highly efficient approach for enriching trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.

Silver Nanoparticle-Functionalised Nitrogen-Doped Carbon Quantum Dots for the Highly Efficient Determination of Uric Acid.

The fabrication of efficient fluorescent probes that possess an excellent sensitivity and selectivity for uric acid is highly desirable and challenging. In this study, composites of silver nanoparticles (AgNPs) wrapped with nitrogen-doped carbon quantum dots (N-CQDs) were synthesised utilising N-CQDs as the reducing and stabilising agents in a single reaction with AgNO3. The morphology and structure, absorption properties, functional groups, and fluorescence properties were characterised by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, fluorescence spectroscopy, and X-ray diffraction spectroscopy. In addition, we developed a novel method based on AgNPs/N-CQDs for the detection of uric acid using the enzymatic reaction of uric acid oxidase. The fluorescence enhancement of the AgNPs/N-CQDs composite was linear (R2 = 0.9971) in the range of 2.0-60 µmol/L, and gave a detection limit of 0.53 µmol/L. Trace uric acid was successfully determined in real serum samples from the serum of 10 healthy candidates and 10 gout patients, and the results were consistent with those recorded by Qianxinan Prefecture People's Hospital. These results indicate that the developed AgNP/N-CQD system can provide a universal platform for detecting the multispecies ratio fluorescence of H2O2 generation in other biological systems.

Covalently bonded aptamer-functionalised magnetic mesoporous carbon for high-efficiency chloramphenicol detection.

A novel aptamer-modified magnetic mesoporous carbon was prepared to develop a specific and sensitive magnetic solid-phase extraction method through combination with ultra-high performance liquid chromatography-tandem mass spectrometry for the analysis chloramphenicol in complex samples. More specifically, the chloramphenicol aptamer-modified Mg/Al layered double hydroxide magnetic mesoporous carbon was employed as a novel magnetic solid-phase extraction sorbent for analyte enrichment and sample clean-up. The extraction solvent, extraction time, desorption solvent, and desorption time were investigated. It was found that the mesoporous structure and aptamer-based affinity interactions resulted in acceptable selective recognition and a good chemical stability toward trace amounts of chloramphenicol. Upon combination with the ultra-high performance liquid chromatography-tandem mass spectrometry technique, a specific and sensitive recognition method was developed with a low limit of detection (0.94 pmol/L, S/N = 3) for chloramphenicol analysis. The developed method was successfully employed for the determination of chloramphenicol in complex serum, milk powders, fish and chicken samples, giving recoveries of 87.0-107% with relative standard deviations of 3.1-9.7%.

Screening antiproliferative drug for breast cancer from bisbenzylisoquinoline alkaloid tetrandrine and fangchinoline derivatives by targeting BLM helicase.

BACKGROUND: The high expression of BLM (Bloom syndrome) helicase in tumors involves its strong association with cell expansion. Bisbenzylisoquinoline alkaloids own an antitumor property and have developed as candidates for anticancer drugs. This paper aimed to screen potential antiproliferative small molecules from 12 small molecules (the derivatives of bisbenzylisoquinoline alkaloids tetrandrine and fangchinoline) by targeting BLM642-1290 helicase. Then we explore the inhibitory mechanism of those small molecules on proliferation of MDA-MB-435 breast cancer cells. METHODS: Fluorescence polarization technique was used to screen small molecules which inhibited the DNA binding and unwinding of BLM642-1290 helicase. The effects of positive small molecules on the ATPase and conformation of BLM642-1290 helicase were studied by the malachite green-phosphate ammonium molybdate colorimetry and ultraviolet spectral scanning, respectively. The effects of positive small molecules on growth of MDA-MB-435 cells were studied by MTT method, colony formation and cell counting method. The mRNA and protein levels of BLM helicase in the MDA-MB-435 cells after positive small molecule treatments were examined by RT-PCR and ELISA, respectively. RESULTS: The compound HJNO (a tetrandrine derivative) was screened out which inhibited the DNA binding, unwinding and ATPase of BLM642-1290 helicase. That HJNO could bind BLM642-1290helicase to change its conformationcontribute to inhibiting the DNA binding, ATPase and DNA unwinding of BLM642-1290 helicase. In addition, HJNO showed its inhibiting the growth of MDA-MB-435 cells. The values of IC50 after drug treatments for 24 h, 48 h and 72 h were 19.9 µmol/L, 4.1 µmol/L and 10.9 µmol/L, respectively. The mRNA and protein levels of BLM helicase in MDA-MB-435 cells increased after HJNO treatment. Those showed a significant difference (P < 0.05) compared with negative control when the concentrations of HJNO were 5 µmol/L and 10 µmol/L, which might contribute to HJNO inhibiting the DNA binding, ATPase and DNA unwinding of BLM helicase. CONCLUSION: The small molecule HJNO was screened out by targeting BLM642-1290 helicase. And it showed an inhibition on MDA-MB-435 breast cancer cells expansion.

Bisbenzylisoquinoline alkaloid fangchinoline derivative HY-2 inhibits breast cancer cells by suppressing BLM DNA helicase.

The high expression of BLM (Bloom syndrome) DNA helicase in tumors involves its strong association with cell expansion. Bisbenzylisoquinoline alkaloids own an antitumor property and have developed as candidates for anticancer drugs. This paper aimed to study the antitumor effect of fangchinoline derivative HY-2 by targeting BLM642-1290 DNA helicase, and then explore its inhibitory mechanism on proliferation of MDA-MB-435 breast cancer cells. We confirmed that the mRNA and protein levels of BLM DNA helicase in breast cancer were higher than those in normal tissues. HY-2 could inhibit the DNA binding, ATPase and DNA unwinding of BLM642-1290 DNA helicase with enzymatic assay. HY-2 could also inhibit the DNA unwinding of DNA helicase in cells. In addition, HY-2 showed an inhibiting the MDA-MB-435, MDA-MB-231, MDA-MB-436 breast cancer cells expansion. The mRNA and protein levels of BLM DNA helicase in MDA-MB-435 cells increased after HY-2 treatment, which might contribute to HY-2 inhibiting the DNA binding, ATPase and DNA unwinding of BLM DNA helicase. The mechanism of HY-2 inhibition on BLM DNA helicase was further confirmed with the effect of HY-2 on the ultraviolet spectrogram of BLM642-1290 DNA helicase and Molecular dynamics simulation of the interacting between HY-2 and BLM640-1291 DNA helicase. Our study provided some valuable clues for the exploration of HY-2 in the living body and developing it as an anticancer drug.

Determination of six parabens in biological samples by magnetic solid-phase extraction with magnetic mesoporous carbon adsorbent and UHPLC-MS/MS.

Although parabens are useful due to their antiseptic properties, their widespread use has caused concerns regarding their potential toxicological effects. In this study, a novel magnetic solid-phase extraction combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (MSPE-UHPLC-MS/MS) was developed, based on ordered magnetic mesoporous carbon (MMC), for paraben analysis. The MMC was prepared by soft-template synthesis, with a unique pore structure and a highly specific surface response, indicating potential as an excellent adsorbent. Several parameters affecting the paraben extraction efficiency were investigated and a novel method for paraben analysis in serum and urine samples using MSPE-UHPLCMS/MS was developed. The concentrations of methylparaben, ethylparaben, isopropylparaben, and propylparaben in these samples were 0.0380-4.36, 0.460-9.65, 0.0118-0.770, and 0.0363-0.641 µg/L, respectively, whereas isobutylparaben and butylparaben were not detected. Furthermore, satisfactory recoveries of 76.4-121% with relative standard deviations (n = 5) of 1.9-8.6% were obtained. Therefore, the developed MSPE-UHPLC-MS/MS method was efficient, highly sensitive, and reliable for analysing parabens in complex biological samples.

A substantial increase of analytical throughput in capillary electrophoresis throughput by separation-interrupted sequential injections.

How to further improve the throughput of capillary electrophoresis (CE) is a fascinating question. Herein an idea to substantially increase the throughput of CE has been proposed together with theory and experimental demonstration. The key is to introduce samples for CE, one after another, by a short suspension of voltage application, which was hence termed separation-interrupted sequential injections (Sisi). The idea was demonstrated to be feasible on a laboratory-built CE instrument coupled with tandem C4D (contactless capacitively-coupled conductivity) detectors. At least 50 injections of a testing sample (mixture of NH4+, K+, Ca2+, Na+ and Mg2+) were successfully separated in only a single run. The separation took 145 min in total, equivalent to 2.9 min per analysis which is only 21% of that of normal CE. Quantification of the separated ions was performed, with a limit of detection of 1.1-2.6 µM, a limit of quantification of 3.2-8.9 µM, and a linear range up to 1000 µM (R2 > 0.99). The recovery was between 88% and 112% measured by spiking standards into samples at low, middle and high levels. The real applicability of Sisi-CE was evaluated by direct injection and analysis of 45 mineral water samples also in a single run. Its clinical application potential was demonstrated by high throughput assay of the calcium and zinc gluconate oral solution formula, and the blood potassium of hyperkalemia and hypokalemia from patients with renal failure disease. This method can be extended to other applications such as omics studies through the use of more suitable detectors. The theory proposed may also be applicable to other high throughput methods.

A stable version of capillary electrophoresis for determining human hemoglobin chains aiming at the screening and diagnosis of thalassemia.

As a fast, high-performance and cost-effective separation technique, capillary electrophoresis (CE) is applicable to the screening and diagnosis of diseases such as thalassemia. However, it is often not preferred due to its unrepeatable and/or irreproducible migration times. Herein, we propose a stable version of CE that uses migration charge density instead of the migration time to plot the electropherogram. The peak position is now independent of the applied voltage or current and the capillary geometry and is also insensitive to temperature. Its applicability was demonstrated in the quantitative analysis of human hemoglobin. On a laboratory-built device, with a running buffer simply consisting of 3.0 M acetic acid and 0.1% (w/v) hydroxyethyl cellulose, it allows a direct injection of whole blood samples and all the concerned globin chains, α, ß, Aγ and Gγ can be well separated in 15 minutes. The resolution of α/ß, ß/Aγ, and Aγ/Gγ reached 4.4, 3.1 and 5.3, respectively. The intra- and inter-day precisions for the peak position based on the migration charge densities were below 0.6%. Its diagnostic applicability was validated in the analysis of several real blood samples from newborns, children and adults, and its capacity was demonstrated to screen and define the type of thalassemia.

The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II).

Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a fluorescence quantum yield of 11% and superior water solubility and fluorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the fluorescence of the CQDs in a specific and sensitive manner, we developed a method for the detection of Hg2+ using this fluorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50-20 µM, with an excellent coefficient of determination (R 2 = 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.