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[Gd@C82(OH)22]n particles (22 nm in a saline solution) of a dose level as low as 10(-7) mol/kg exhibit a very high antineoplastic efficiency ( approximately 60%) in mice. A dose increment of 1 x 10(-7) mol/kg increases the tumor inhibition rate 26%. [Gd@C82(OH)22]n particles have a strong capacity to improve immunity and interfere with tumor invasion in normal muscle cells, nearly without toxicity in vivo and in vitro. Unlike conventional antineoplastic chemicals, the high antitumor efficiency of nanoparticles is not due to toxic effects to cells because they do not kill the tumor cells directly and only about 0.05% of the used dose is found in the tumor tissues. Results suggest that fullerene derivatives with proper surface modifications and sizes may help realize the dream of tumor chemotherapeutics of high-efficacy and low-toxicity.

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The present study was carried out to solve the problems of long washout time and non-linear calibration curves encountered in mercury analysis using inductively coupled plasma mass spectrometry. Comparisons of the washing efficiency for different reagents to eliminate the mercury memory effect were made. Of all the selected washing reagents, mercapto reagents such as 2-mercaptoethanol and L-cysteine could efficiently clean the instrument. Taking the toxicity and odor of mercaptoalkanol into account, L-cysteine was preferred as the most suitable washing reagent and was added into the standard and sample solutions. A good linear calibration curve was obtained with the correlation coefficient of 0.9999. The detetion limit for addition of L-cysteine was 0.024 mg l À1 . Addition of 0.18% L-cysteine into the sample solution also facilitates the washout of mercury even using deionized water. The recoveries of mercury in certified reference materials, i.e. human hair and dogfish muscle, were 97.2% and 98.3%, respectively, when using 0.18% L-cysteine in the sample solutions.

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Phosphorylation of histone protein H2AX on serine 139 (gamma-H2AX) occurs at sites flanking DNA double-stranded breaks (DSBs) and can provide a measure of the number of DSBs within a cell. We describe a flow cytometry-based method optimized to measure gamma-H2AX in nonfixed mononuclear blood cells as well as in cultured cells, which is more sensitive and involves less steps compared with protocols involving fixed cells. This method can be used to monitor induction of gamma-H2AX in mononuclear cells from cancer patients undergoing radiotherapy and for detection of gamma-H2AX throughout the cell cycle in cultured cells. The method is based on the fact that H2AX like other histone proteins are retained in the nucleus when cells are lysed at physiological salt concentrations. Cells are therefore added without fixation to a solution containing detergent to lyse the cells along with a fluorescein isothiocyanate-labeled monoclonal gamma-H2AX antibody, DNA staining dye and blocking agents. The stained nuclei can be analyzed by flow cytometry to monitor the level of gamma-H2AX to determine the level of DSBs and DNA content and to determine the cell cycle stage. The omission of fixation simplifies staining and enhances the sensitivity. This protocol can be completed within 4-6 h.

Manufactured fullerene nanoparticles easily enter into cells and hence have been rapidly developed for biomedical uses. However, it is generally unknown which route the nanoparticles undergo when crossing cell membranes and where they localize to the intracellular compartments. Herein we have used both microscopic imaging and biological techniques to explore the processes of [C(60)(C(COOH)(2))(2)](n) nanoparticles across cellular membranes and their intracellular translocation in 3T3 L1 and RH-35 living cells. The fullerene nanoparticles are quickly internalized by the cells and then routed to the cytoplasm with punctate localization. Upon entering the cell, they are synchronized to lysosome-like vesicles. The [C(60)(C(COOH)(2))(2)](n) nanoparticles entering cells are mainly via endocytosis with time-, temperature- and energy-dependent manners. The cellular uptake of [C(60)(C(COOH)(2))(2)](n) nanoparticles was found to be clathrin-mediated but not caveolae-mediated endocytosis. The endocytosis mechanism and the subcellular target location provide key information for the better understanding and predicting of the biomedical function of fullerene nanoparticles inside cells.

Amorphous calcium phosphate often forms as a precursor phase in a solution at sufficiently high supersaturation and pH, and then transforms to the thermodynamically stable hydroxyapatite. The chemical composition, structure, and property of the amorphous phase are dependent on the structure of its composing clusters. Based on the results from the measurements of in situ Ca K-edge X-ray near-edge structure and ex situ X-ray diffraction, as well as the concomitant pH change in the reaction process, here we propose an improved model for the structure of “Posner’s cluster” and identify the three types of reactions that lead to the formation of amorphous calcium phosphate and its subsequent transition to crystalline hydroxyapatite.