Determination Of Chromium In Cells Based On Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Chromium plays an irreplaceable role in the life system,and excess or deficiency of chromium will cause various kinds of disease.The exploration of metal chromium in the life system is useful for revealing its functions and process of physiological or pathological in organisms.In this study,a protocol of matrix-matched external standard method-laser ablation inductively coupled plasma mass spectrometry(MES-LA-ICP-MS)was developed to quantify the chromium content in the gel.Firstly,a series of matrix-matched standards were prepared by mixing 12%acrylamide-bisacrylamide solution with a certain amount of potassium dichromate solution,and then the method was evaluated.The relative standard deviation of this method was less than 16%(n=300),the correlation coefficient of LA-ICP-MS quantitative calibration curve is 0.9805,and the chromium detection limits of method and instrument give 2.22 μg g-1 and 2.72 μg g-1 respectively.The experiment explored the signal intensity showed a regular change with the increase of the spot size and the chromium content in the size range of 2-10 μm laser spot.The gel sample was ablated with a spot size of 4 μm,and its mapping by LA-ICP-MS is consistent with the gel topography.In order to better understand the transport and ability to bind to proteins of heavy metal chromium,MCF-7 cells were used as an in vitro cell model,and high-throughput metallomics analysis was used to determine metal chromium in cells.The effect of chromium on the proliferation of MCF-7 cells were firstly investigated by MTT assay to determine the incubation concentration of Cr(VI)for MCF-7 cells.Whole proteins after the MCF-7 cells incubated with chromium were extracted by ice bath shaking and then were separated by polyacrylamide gel electrophoresis(denaturing and non-denaturing electrophoresis).The gels were stained with Coomassie Brilliant Blue G250 and destained with sodium chloride solution,after those,they were made into dry gels,and the electrophoresis strips obtained by the two electrophoresis methods were respectively detected by LA-ICP-MS.Line scan analysis revealed one chromium-containing protein band through denaturing electrophoresis and two protein bands are detected by the non-denaturing electrophoresis.In the final experiment,LA-ICP-MS is used to measure and image the chromium in individual cells.