Study On The Ability Of Modified-Chitosan To Absorb Heavy Metals And Deliver SiRNA

Chitosan(CS)has a promising application in environmental and medical fields,but its dispersion in aqueous solution is poor,which limits the application of chitosan to some extent.Therefore,the modification of chitosan is of great significance.Among them,nano-chitosan is used as an effective carrier for gene or drug delivery.In this study,two kinds of modified chitosan,Arg-CS and Lys-CS,were prepared by Arg and Lys modification of low molecular weight chitosan(LMWCS),and the effects of Arg and Lys modification on heavy metal absorption were investigated.Since Arg-CS was found to belong to nanorod by further identification,the ability of Arg-CS to deliver si RNA was further investigated.The specific study consists of the following three parts:1.Preparation and identification of Arg-CS and Lys-CSAmide bonds or ester bonds were formed by amide reaction linking the carboxyl groups in Arg and Lys to the amino group in C₂ or the hydroxyl in C₆of CS,preparing Arg-CS and Lys-CS by covalently cross-linking the Arg and Lys to the CS molecules.The FTIR results showed that Arg and Lys were successfully covalently attached to the CS,respectively.The results of ¹H spectrum analysis showed that the substituting degree of Arg in Arg-CS was21.28%and the molecular weight is 9033.14 Da;while those of Lys-CS were21.07%(for Lys-CS₁)and 16.70%(for Lys-CS₂),with the molecular weight8758.19 Da and 8497.24 Da,respectively.The results of atomic force microscopy and transmission electron microscopy showed that Arg-CS was nanorod with13 nm in particle size and 78.56 nm in length.2.The study on the ability of Arg-Chitosan and Lys-Chitosan to absorb Cd²⁺and Pb²⁺The results of flame atomic absorption spectrometry showed that the unit absorption capacity of Arg-CS and Lys-CS to Cd²⁺was greater than those of CS,with the number of 0.110 mmol/g and 0.090 mmol/g,respectively.Within the range of experimental concentrations(1.25,2.50 and 5.00 mg/m L),a gradual increasing trend in the unit absorption capacity to Cd²⁺was observed as the absorbing material increased.The unit absorption capacity of Arg-CS and Lys-CS to Pb²⁺was also stronger than that of CS,reaching 0.172 mmol/g and 0.055 mmol/g,respectively.3.Study on the ability of Arg-CS to delivery si RNAFirst,the ability of Arg-CS to wrap si RNA was investigated by agarose retardation experiment.Then,the effects of Arg-CS on the viability of 293T and L1210 cells were tested by MTT experiments.Finally,the ability of Arg-CS to deliver si RNA into 293T and L1210 cells was investigated.The results showed gel retardation duing to si RNAs wrapping by Arg-CS;Arg-CS concentrations below 0.8?g/m L were safe for 293T and L1210 cells;si RNAs to Rhoa and Rhoc were able to be delivered into 293T and L1210 cells by Arg-CS.