Yinfa Ma

Toxicity of Cerium Oxide Nanoparticles in Human Lung Cancer Cells

With the fast development of nanotechnology, the nanomaterials start to cause people’s attention for potential toxic effect. In this paper, the cytotoxicity and oxidative stress caused by 20-nm cerium oxide (CeO2) nanoparticles in cultured human lung cancer cells was investigated. The sulforhodamine B method was employed to assess cell viability after exposure to 3.5, 10.5, and 23.3 μg/ml of CeO2 nanoparticles for 24, 48, and 72 h. Cell viability decreased significantly as a function of nanoparticle dose and exposure time. Indicators of oxidative stress and cytotoxicity, including total reactive oxygen species, glutathione, malondialdehyde, α-tocopherol, and lactate dehydrogenase, were quantitatively assessed. It is concluded from the results that free radicals generated by exposure to 3.5 to 23.3 μg/ml CeO2 nanoparticles produce significant oxidative stress in the cells, as reflected by reduced glutathione and α-tocopherol levels; the toxic effects of CeO2 nanoparticles are dose dependent and time dependent; elevated oxidative stress increases the production of malondialdehyde and lactate dehydrogenase, which are indicators of lipid peroxidation and cell membrane damage, respectively.

Investigation of Pharmaceuticals in Missouri Natural and Drinking Water Using High Performance Liquid Chromatography-Tandem Mass Spectrometry

A comprehensive method has been developed and validated in two different water matrices for the analysis of 16 pharmaceutical compounds using solid phase extraction (SPE) of water samples, followed by liquid chromatography coupled with tandem mass spectrometry. These 16 compounds include antibiotics, hormones, analgesics, stimulants, antiepileptics, and X-ray contrast media. Method detection limits (MDLs) that were determined in both reagent water and municipal tap water ranged from 0.1 to 9.9 ng/L. Recoveries for most of the compounds were comparable to those obtained using U.S. EPA methods. Treated and untreated water samples were collected from 31 different water treatment facilities across Missouri, in both winter and summer seasons, and analyzed to assess the 16 pharmaceutical compounds. The results showed that the highest pharmaceutical concentrations in untreated water were caffeine, ibuprofen, and acetaminophen, at concentrations of 224, 77.2, and 70 ng/L, respectively. Concentrations of pharmaceuticals were generally higher during the winter months, as compared to those in the summer due, presumably, to smaller water quantities in the winter, even though pharmaceutical loadings into the receiving waters were similar for both seasons.

A fast capillary electrophoresis method for separation and quantification of modified nucleosides in urinary samples.

Modified nucleosides are formed at the post-transcriptional stage by chemical modification of normal nucleosides within the ribonucleic acid (RNA). These modified nucleosides cannot be reutilized or further degraded, but they are excreted in the urine as intact molecules. The elevated levels of modified nucleosides in the urine samples have served as potential cancer biomarkers in many studies. Although different analytical techniques have been reported for determining nucleosides levels, they are practically difficult to use as a routine tool for early cancer screening. In this paper, a novel method was developed to separate and quantify 10 nucleosides--adenosine, cytidine, guanosine, uridine, inosine, xanthosine, pseudouridine, N(2)-methylguanosine, 1-methyladenosine, and N(2),N(2)-dimethylguanosine--in urine samples using capillary electrophoresis with an ultraviolet (UV) detector (abbreviated as CE-UV) at a wavelength of 254 nm. A 50 microm (i.d.) x 38 cm (effective length) fused silica capillary was used for the separation, and a borate-phosphate buffer containing 25 mM cetyltrimethylammonium bromide (CTAB) at pH 9.50 was used as a background electrolyte. The separation was performed at 15 kV under reverse polarity and completed within 10 min. The linear range of the analytes was 5.0-500 micromol/L, and the limit of detection was <2.0 micromol/L. The effects of pH, buffer concentrations, CTAB concentration, and the operation voltages on the separation and quantification of the modified nucleosides were also investigated. The technique developed in this study is much simpler and faster, compared to previous studies, and can be used to quantify modified nucleosides in urine samples.

Comprehensive profiling of isoflavones, phytosterols, tocopherols, minerals, crude protein, lipid, and sugar during soybean (Glycine max) germination.

Isoflavone, phytosterol, tocopherol, mineral, protein, lipid, and sugar contents of soybeans were analyzed during 7-day germination with or without exposure to light. The levels of phytosterols and tocopherols increased significantly during the 3 day germination. Although malonyl glycosides were the predominant forms of isoflavones in soybean seeds, 77% of malonyl daidzin and 30% of malonyl genistin were converted to corresponding daidzin, daidzein, genistin, and genistein during the germination period. Slight decreases in malonal glycidin and malonyl glycidin concentrations were also observed while the total molar concentration of isoflavones remained constant. An increase of approximately 4% in the protein level was accompanied by a 5-6% reduction in the carbohydrate and lipid contents after the 7-day germination. Mineral (Ca, Cr, Fe, Zn Cu, K, Mg, Mn) levels did not vary much during germination, and the presence of light during germination had only a little, if any, effect on the levels of the micro- and macronutrients in soybeans.

Quantitative determination of sarcosine and related compounds in urinary samples by liquid chromatography with tandem mass spectrometry.

The current prostate cancer (PCa) diagnosis, based on the blood prostate-specific antigen (PSA) level measurement, is not a precise science. The widely used PSA biomarker for PCa has poor sensitivity and specificity and often leads to false-negative and false-positive test results. Recently, sarcosine, proline, kynurenine, uracil, and glycerol 3-phosphate were found in higher concentrations in metastatic prostate cancer urine samples. By measuring all five of these metabolites, doctors may be better able to diagnose prostate cancer with high accuracy. However, there is no method reported for simultaneous detection of these compounds in urine samples. In this study, a novel method was developed to separate and quantify six urinary metabolites including creatinine in urine samples by using liquid chromatography/tandem mass spectrometry. Chromatographic separations of the analytes were carried out using a phenyl-hexyl column with 0.1% formic acid in water and acetonitrile, respectively, under a gradient program. The six metabolites were detected in the multiple reaction monitoring modes with the ESI-positive mode. The linear range of the analytes was from 0.003 to 40 μmol/L. The limit of detection was from 0.05 to 4 nmol/L, and the limit of quantification ranged from 3 to 20 nmol/L. The factors affecting the separation and quantification of the six metabolites, such as mobile-phase and MS conditions, were also investigated. The technique developed in this study is simple, fast, sensitive, and selective. It can be used for quantifying these six metabolites in urine samples for potential early cancer screening.

Indirect photometric detection of polyamines in biological samples separated by high-performance capillary electrophoresis

A rapid separation of polyamines and some related amino acids in cultured tumor cells by high-performance capillary zone electrophoresis with indirect photometric detection is demonstrated. 60 cm x 75 microns I.D. fused-silica capillary was used for the separation and quinine sulfate was used as a background electrolyte (BGE). Several polyamines (putrescine, spermidine and spermine), amino acids (lysine, arginine, histidine) and simple cations (K+, Na+) were easily separated in less than 10 min. Using the indirect photometric detection method, femtomole amounts of polyamines extracted from the tumor cells were detected from nanoliter injection volumes, and the signal response was linear over two orders of magnitude.

Cytotoxicity and cell membrane depolarization induced by aluminum oxide nanoparticles in human lung epithelial cells A549

The cytotoxicity of 13 and 22 nm aluminum oxide (Al2O3) nanoparticles was investigated in cultured human bronchoalveolar carcinoma-derived cells (A549) and compared with 20 nm CeO2 and 40 nm TiO2 nanoparticles as positive and negative control, respectively. Exposure to both Al2O3 nanoparticles for 24 h at 10 and 25 µg mL−1 doses significantly decreased cell viability compared with control. However, the cytotoxicity of 13 and 22 nm Al2O3 nanoparticles had no difference at 5–25 µg mL−1 dose range. The cytotoxicity of both Al2O3 nanoparticles were higher than negative control TiO2 nanoparticles but lower than positive control CeO2 nanoparticles (TiO2 < Al2O3 < CeO2). A real-time single cell imaging system was employed to study the cell membrane potential change caused by Al2O3 and CeO2 nanoparticles using a membrane potential sensitive fluorescent probe DiBAC4(3). Exposure to the 13 nm Al2O3 nanoparticles resulted in more significant depolarization than the 30 nm Al2O3 particles. On the other hand, the 20 nm CeO2 particles, the most toxic, caused less significant depolarization than both the 13 and 22 nm Al2O3. Factors such as exposure duration, surface chemistry, and other mechanisms may contribute differently between cytotoxicity and membrane depolarization.

More Sensitive Way to Determine Iron using an Iron(II)-1,10-phenanthroline Complex and Capillary Electrophoresis

Iron is one of the major metal species of concern in many samples, such as in serum, foods, drinking waters, etc. In this paper, we present a more sensitive way to determine the iron concentration in water solutions by using an iron(II)-1,10-phenanthroline complexing system with high-performance capillary electrophoresis, and have applied this method to the determination of the levels of iron in serum samples. The technique uses ammonium acetate-acetic acid (50 mM NH4Ac-HAc, pH 5.0) as a running buffer, and the detection wavelength is set at 270 nm instead of 508 nm. This new approach enhances the molar absorbance of the Fe(II)-1,10-phenanthroline complex by about eight-fold compared with that obtained at 508 nm. By combining the larger light output of the deuterium (D2) lamp and the lower noise level at 270 nm, the sensitivity was improved at least twenty-fold compared to that at 508 nm. The detection limit for iron(II) is lower than 5 x 10(-9) M, which has never been reached by reported spectrophotometric methods or with the recently published HPCE method. The effects of pH, buffer concentration and operation voltages on the sensitivity and resolution are also discussed. The signal response is linear over two orders of magnitude (r2 = 0.995) and the iron recovery for samples reached 99-101%. The technique described here is much more sensitive, fast and simple and is suitable for determining trace amounts of iron in biological, food, water and other samples.

High-efficiency DNA separation by capillary electrophoresis in a polymer solution with ultralow viscosity.

The viscosities of some polymer solutions for DNA separation in capillary electrophoresis are generally very high, which makes them hard to pump into the capillaries. We have developed a novel sieving buffer, based on low-molecular-weight hydroxypropylmethylcellulose, to separate DNA fragments. The viscosity of this sieving matrix was at least 1 order of magnitude lower than that of traditional buffers with similar sieving effect. The influence of additives such as urea and mannitol was investigated. It was found that the double-stranded DNA (ds DNA) fragments began to denature in 3.5 M urea, and 7 M urea can denature the ds DNA completely. The presence of mannitol will decrease the overlap threshold of the polymer solution (the concentration at which the polymer molecules begin to entangle with each other), which makes it possible to separate DNA fragments in a polymer solution of relatively low concentration. The influence of the electrical field was also investigated, and it was found that the mobility of DNA fragments up to 2000 bp in length did not change greatly with different electric fields. This phenomenon implies that the DNA fragments at this range do not change their conformation with the increase of electric field as was previously believed. The possible mechanism for the separation of DNA fragments is also discussed.

Oxidative removal of selected endocrine-disruptors and pharmaceuticals in drinking water treatment systems, and identification of degradation products of triclosan

The potential occurrences of endocrine-disrupting compounds (EDCs), as well as pharmaceuticals, are considered to be emerging environmental problems due to their persistence and continuous input into the aquatic ecosystem, even at only trace concentrations. This study systematically investigated the oxidative removal of eight specially selected ECDs and pharmaceuticals by comparing their relative reactivity as a function of different oxidative treatment processes (i.e., free chlorine, ozone, monochloramine, and permanganate) under various pH conditions. For the oxidative removal study, EDC and pharmaceutical standards were spiked into both deionized water and natural water, followed by treatment using common oxidants at typical water treatment concentrations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for identification and quantification. The removal efficiency of the EDCs and pharmaceuticals varied significantly between oxidation processes. Free chlorine, permanganate, and ozone treatments were all highly effective at the elimination of triclosan and estrone, while they were not effective for removing ibuprofen, iopromide, and clofibric acid. Monochloramine (at a dose of 3mg/L) was mostly ineffective in eliminating any of the selected EDCs and pharmaceuticals under the tested conditions. pH also played an important role in the removal efficiency of the EDCs and pharmaceuticals during free chlorine, permanganate, and ozone treatments. Additionally, the study identified the oxidation products of triclosan by permanganate, and 2,4-dichlorophenol was identified as the major oxidation product of triclosan by permanganate in drinking water system treatment. Furthermore, 2,4-dichlorophenol was further degradated to 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol and/or 5,6-dichloro-2-(2,4-dichlorophenoxy)phenol. The kinetics for this reaction indicated that the reaction was first order in the drinking water system.