Detection Of H₂O₂ By Functionalized Halloysite Nanotubes And Cell Killing By Combination Of DNA And Photosensitizer

It is important to develop new biological function materials and to study their application in biochemical analysis and clinical treatment.In this paper,detection of glucose and the fluorescence imaging of intracellular hydrogen peroxide?H₂O₂?were carried out based on the detection of H₂O₂ by the fluorescein-modified halloysite nanotubes?HNTs-PA?.The DNA-photosensitizer composite was firstly prepared and applied to photodynamic therapy of cell.The main contents are as follows:1.A simple and sensitive method for the detection of glucose was developed by utilizing HNTs.HNTs-PA,a complex that binds PA to HNTs by esterification.Because of boric acid's fluorescence quenching effect on fluorescein,fluorescein in HNTs-PA will not produce fluorescence.While H₂O₂ is able to oxidize the borate bond,leading to the release of the fluorescein from the surface of the HNTs and the fluorescence of fluorescein will be recovered.Under the action of glucose oxidase,the glucose can generate H₂O₂ that can be detected by HNTs-PA.Therefore,a new method for the detection of glucose by HNTs-PA was proposed with the detection limit of 0.114 ?M.Meanwhile,the content of glucose in serum samples was detected by this method with satisfactory result.This method extended the application of HNTs and provided a new idea for the detection of biologically active substances such as glucose,amino acids,and proteases that produce H₂O₂ during the reaction.2.Based on the fluorescence properties of HNTs-PA,HNTs-PA was applied to the fluorescence imaging of intracellular H₂O₂.A specific fluorescent dye of mitochondria was used to locate the mitochondria.It was found that the fluorescence of fluorescein was mostly focused on the mitochondria,indicating that H₂O₂ was mainly from mitochondria.This study can provide theoretical basis for HNTs-PA application in intracellular H₂O₂ imaging analysis and the HNTs-based drug delivery and cell therapy.3.The photosensitizer Chlorin e6?Ce6?-modified DNA hybrid was prepared to study its photodynamic activity for cell killing.First,a long chain DNA was obtained by rolling circle amplification reaction.Based on the chelating effect between Gd3+ ions and carboxyl groups and phosphates,Ce6 was directly bound to the phosphate-containing DNA,allowing the DNA to load a large number of Ce6 molecules.Through endocytosis,the DNA-Ce6 composite enter into the cells when incubated with cells.In the 664 nm light irradiation,Ce6 could produce reactive oxygen species?ROS?,which efficiently killed cell.The method is simple,low cost,high loading drug efficiency of DNA,and provides a new strategy for cell photodynamic therapy.