Detection And Targeted Imaging Of Sialic Acid And Amino Acids In Tumor Cells

Sialic acid is located at the end of glycoproteins in tumor cell and its significant up-regulation is a common feature of cell malignant transformation and tumor progression,hence monitoring its content changes can provide an available indicator of early detection and cancer diagnosis;basic amino acids are the basic structural units of natural proteins,and their abnormal changes will lead to metabolic disorders.Therefore,the detection of amino acids is widely used in many fields such as biochemistry and clinical medicine,and it is of great significance to establish analytical methods of amino acids.The main works are as follows:1.A sensitive and selective analysis method for sialic acid is set up the cells with complicated matrix.Firstly,the adsorption principle between boric acid and sialic acid with varying pH was explored.It was found that,unlike general cis-diol molecules,sialic acid has the highest affinity for boric acid at pH=4.0,and almost nothing at pH=1.5.Then the boric acid functionalized magnetic material Fe₃O₄@PBA was synthesized,the sialic acid was adsorbed at pH=4.0 and eluted at pH=1.5 according to the pH-dependent adsorption principle.Hence an analysis method was established combining SPE（solid phase extraction）and HPLC for enrichment,quantitative determination and cell imaging of sialic acid in HepG2 and Hela tumor cells.As a result,it showed that the content of sialic acid in the two tumor cells is different.The method has excellent selectivity,high adsorption efficiency,fast adsorption and elution time,pure water system without any organic solvent,and is suitable for the analysis of sialic acid in complex biological samples.2.A sialic acid molecularly imprinted polymers are prepared,with the advantages of simple synthesis,fast mass transfer and convenient magnetic separation.According to the pH dependent principle for boric acid and sialic acid,the pH=1.5 acidic aqueous solution,that is template elution solvent,can avoid not only template leakage,but also the complex elution process and organic solvents.Finally,sialic acid molecularly imprinted polymer was applied to the determination of sialic acid in transferrin.3.Abnormal changes of amino acid in cells reflect the abnormalities in cellular metabolism.Hence an analysis method of eleven basic amino acid has been established with phenyl isothiocyanate（PITC）pre-column derivatization and is applied to the determination of free amino acids in cells.The result showed that when the gold nanomaterials were incubated with cells,the content of free amino acid decreased significantly,and the higher the concentration of the gold materials,the more obvious degradation happened,therefore,the toxicity of gold nanomaterials was revealed.