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Identification and quantification of chemical DNA modifications provide essential information on genomic DNA changes, for example, epigenetic modifications and abnormal DNA lesions. In this vein, it requires to digest genomic DNA strands into single nucleosides, facilitating the mass spectrometry analysis. However, rapid digestion of such supramacromolecule DNA of several millions Daltons (molecular weight) into single nucleosides remains very challenging. Here, we constructed an immobilized benzonase capillary bioreactor and further tandemly coupled with immobilized snake venom phosphodiesterase and alkaline phosphatase capillary bioreactor to form a novel three-enzyme cascade bioreactor (BenzoSAC bioreactor). In these constructions, the chosen enzymes were immobilized onto synthetic porous capillary silica monoliths. With the tailor-made porous structure and high immobilized capacity and high digestion rate of benzonase, genomic DNA of >99.5% can be digested into single nucleosides within only 10 min when passing through the BenzoSAC bioreactor by microinjection pump. In contrast, traditional digestion requires 8–24 h. By offline coupling this benzoSAC bioreactor with liquid chromatography-tandem mass spectrometry, we detected 5-hydroxymethylcytosine, a major oxidation product of the epigenetically crucial 5-methylcytosine, in genomic DNA isolated from ladder cancer (T24) cells. The newly synthesized BenzoSAC bioreactor and the proposed mass spectrometry detection are promising for fast identification and analysis of structural modifications in DNA.

Human beings do not produce ascorbic acid (AA) and acquire AA through the sodium vitamin C transporters (SVCTs). Changes in the expression or function of SVCT proteins may be associated with human diseases. In this regard, imaging of SVCTs in living cells is important. However, the options for live-cell labelling of SVCTs were very limited. In this work, we synthesized a new small-molecule fluorescent probe RB–A–Vc, and demonstrated its application in selectively visualizing SVCTs in living cells. This probe features visible excitation and emission profiles, can easily enter into membranes, has high selectivity for SVCTs, and can monitor up-regulation or down-regulation of SVCT expression in living cells. We emphasize that this small-molecule probe is suitable for subcellular localization of SVCTs in living cells. This study provides a useful tool for simultaneously monitoring the level and distribution of intracellular SVCTs, which is probably more useful for evaluating the changes induced by external stimulations. We propose that this probe for SVCT imaging and the corresponding method could be applied to other cell lines, tissues, and species.

Bisphenols (BPs) are potential endocrine-disrupting chemicals that may adversely affect human health and wildlife. The complexity of matrix encountered in real-world samples renders screening of trace BPs a formidable challenge. The present study highlighted the potential of molecularly imprinted solid-phase extraction (MISPE) for selective detection of trace bisphenols and their halogenated analogues in surface water. The template bleeding was observed at parts-per-billion levels, deteriorating the accuracy and precision of BPs quantification. To surmount this problem, a dummy MISPE strategy was proposed, in which bisphenol E (BPE) was selected as a dummy template for molecularly imprinted polymer (MIP) synthesis. Coupling this MISPE strategy with chromatographic analysis, a dummy MISPE-HPLC method was established. The linearity, precision, limit of detection (LOD) and recovery were then validated. The linearity of the calibration curve for each BP was observed over the range of 20–2000 ng L−1(r> 0.998). LOD for each bisphenol was measured as low as 2.5–5.0 ng L−1. This technique was applied to simultaneous screening of BPs in the Qinghe River, and five bisphenols were found within the concentration range of 0–224 ng L−1in river samples. The designed dummy MIP was superior to the commercial sorbents with regard to the selectivity, cross-reactivity, matrix removal efficiency and reusability. These merits enabled the applications of dummy MISPE for selective extraction and sensitive screening of BPs in environmental water samples. This method also provided a promising tool for monitoring the occurrence, distribution and fate of BPs in surface water.

An on‐line SPE–HPLC method, using a monolithic poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (poly(GMA‐EDMA)) based weak cation‐exchange (WCX) column, was developed for simultaneous determination of α1‐adrenergic receptor antagonists in human plasma. The monolithic WCX column was prepared by anin‐situ polymerization protocol and modified stepwise with ethylenediamine and chloroacetic acid. On connecting this column to an injection valve, an on‐line SPE protocol could be established for removal of matrices (mainly proteins and lipids) and preconcentration of four α1‐adrenergic receptor antagonists in human plasma. This method was validated and then used for determination of terazosin, alfuzosin, prazosin, and doxazosin in clinical plasma samples. For all analytes, each calibration curve was found to be linear over a range of 0.005–5 μg/mL (R>0.997), and the limit of detection for each analyte was 0.5 ng/mL. Recovery (> 80%) and precision (RSD <15%) for inter‐ and intra‐day assay were tested at three concentration levels of each analyte and showed acceptable results for quantitative assay. Real samples from hypertensive patients were monitored and results were in agreement with those of the conventional liquid–liquid extraction‐HPLC method. Furthermore, due to its good permeability and biocompatibility, the monolithic WCX sorbent could be reused more than 300 times. The proposed method was especially appropriate for multi‐analyte monitoring in plasma samples.