Electrochemical preconcentration of metals using mercury film electrodes followed by electrothermal vaporization into an inductively coupled plasma and determination by atomic emission spectrometry

Advances in the Antagonism of Epigallocatechin-3-gallate in the Treatment of Digestive Tract Tumors

Due to changes in the dietary structure of individuals, the incidence of digestive tract tumors has increased significantly in recent years, causing a serious threat to the life and health of patients. This has in turn led to an increase in cancer prevention research. Many studies have shown that epigallocatechin-3-gallate (EGCG), an active ingredient in green tea, is in direct contact with the digestive tract upon ingestion, which allows it to elicit a significant antagonizing effect on digestive tract tumors. The main results of EGCG treatment include the prevention of tumor development in the digestive tract and the induction of cell cycle arrest and apoptosis. EGCG can be orally administered, is safe, and combats other resistances. The synergistic use of cancer drugs can promote the efficacy and reduce the anti-allergic properties of drugs, and is thus, favored in medical research. EGCG, however, currently possesses several shortcomings such as poor stability and low bioavailability, and its clinical application prospects need further development. In this paper, we have systematically summarized the research progress on the ability of EGCG to antagonize the activity and mechanism of action of digestive tract tumors, to achieve prevention, alleviation, delay, and even treat human gastrointestinal tract tumors via exogenous dietary EGCG supplementation or the development of new drugs containing EGCG.

Facile Ag-Film Based Surface Enhanced Raman Spectroscopy Using DNA Molecular Switch for Ultra-Sensitive Mercury Ions Detection

Heavy metal pollution has long been the focus of attention because of its serious threat to human health and the environment. Surface enhanced Raman spectroscopy (SERS) has shown great potential for metal detection owing to many advantages, including, requiring fewer samples, its minimal damage to specimen, and its high sensitivity. In this work, we proposed a simple and distinctive method, based on SERS, using facile silver film (Ag-film) combined with a DNA molecular switch, which allowed for the highly specific detection of heavy metal mercury ions (Hg²⁺). When in the presence of Hg²⁺ ions, the signals from Raman probes attach to single-stranded DNA, which will be dramatically enhanced due to the specific structural change of DNA strands-resulting from the interaction between Hg²⁺ ions and DNA bases. This SERS sensor could achieve an ultralow limit of detection (1.35 × 10^-15 M) for Hg²⁺ detection. In addition, we applied this SERS sensor to detect Hg²⁺ in real blood samples. The results suggested that this SERS platform could be a promising alternative tool for Hg²⁺ detection in clinical, environmental, and food inspection.

Highly sensitive SERS sensor for mercury ions based on the catalytic reaction of mercury ion decorated Ag nanoparticles

Schematic diagram of the SERS sensing mechanism for mercury ions by a catalytic oxidation reaction.

Post-elution concentration of (188)Re by an electrochemical method

High specific activity (188)Re required for nuclear medicine is mostly obtained from (188)W/(188)Re generators. As the parent radionuclide (188)W is of low specific activity (<185 GBq/g), a relatively large volume of 0.9% saline is required for the elution of (188)Re. Post-elution concentration is needed in order to increase the radioactive concentration of the eluted (188)Re. An electrochemical procedure to concentrate (188)Re suitable for the preparation of radiopharmaceuticals is developed. (188)Re eluted from an alumina generator could be concentrated approximately 100 fold, and it could be used to label DMSA and HEDP with >98% yield.

Zirconia-coated graphite adsorption bar micro-extraction combined with ETV-ICP-MS for the determination of trace amounts of Cd, Hg and Pb in environmental and biological samples

In this work, a new and simple micro-extraction method termed graphite adsorption bar micro-extraction was developed, for the first time, for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) determination of trace Cd, Hg and Pb. In this method, the graphite bar was first coated with zirconia and then inserted into the sample solution for extraction. The graphite bar enriched with the analytes was inserted directly into a graphite tube, and subsequently analyzed by ETV-ICP-MS according to an established temperature program. The experimental parameters, which had influence on the extraction and vaporization, were systematically investigated and the optimal experimental conditions were established. Under the optimized conditions, the detection limits of the method were 0.05, 0.42 and 0.06 pg/ml for Cd, Hg and Pb and the relative standard deviations (RSDs) for 11 replicates at the 0.1 ng/ml level were 7.4, 8.2 and 7.7%, respectively. The proposed method was successfully applied to the determination of trace Cd, Hg and Pb in environmental and biological samples. The results of the experiments indicate that the method has a high enrichment factor and sample utilization efficiency. Furthermore, the method is fast and environment-friendly.

Anodic stripping voltammetry combined on-line with inductively coupled plasma-MS via a direct-injection high-efficiency nebulizer

A direct-injection high-efficiency nebulizer (DIHEN) is used to couple a thin-layer electrochemical flow cell on-line with an ICP-mass spectrometer to perform anodic stripping voltammetry (ASV) at a thin mercury film followed by subsequent ICPMS measurements for the stripped metal analytes. The resultant hyphenated technique (ASV-DIHEN-ICPMS) is capable of analyzing select heavy metals present at ultratrace levels (down to low-ppt to sub-ppt levels) that are lower than the detection limits obtained by conventional ICPMS. In addition to its good analytical performance, the technique offers other attractive features such as the ability to eliminate detrimental matrix effects that can compromise ICPMS analyses and the possibility of probing electrode reactions involving trace amounts metal species with ICPMS. For conducting ASV on-line with ICPMS, the DIHEN was found to be more advantageous than the microconcentric nebulizer in terms of minimizing memory effects and potential artifacts caused by the erosion of the Hg film into the flowing solution stream. Compared to a direct injection nebulizer (DIN), the DIHEN was easier to operate. Moreover, its simpler design and the lack of back pressure from the DIHEN capillary made it more compatible with coupling to the thin-layer electrochemical cell than a DIN system.