NMR Study On The Structure Of Some Chitosan Complexes

This dissertation is organized in two parts:Part 1:NMR Studies on the Interaction between Chitosan and 1-HydroxybenzotriazoleThe interaction between Chitosan(CS) and 1-Hydroxybenzotriazole (HOBt) wasstudied by ¹H NMR spectroscopy,NMR diffusion measurement,and solid statehigh-resolution ¹³C NMR spectroscopy.CS and HOBt were found to be able to formorganic complex,and the main binding force is hydrogen-bond interaction.Theassociation constant of CS/HOBt complex was calculated from the self-diffusioncoefficients of HOBt.CS/HOBt system would be efficient in chemical modificationof CS without the use of acids or organic solvents.Part 2:Preparation and NMR Study of CS-g-mPEG/DNA ComplexesWater-soluble Chitosan was prepared by functionalizing with poy(ethyleneglycol) methyl ether(mPEG) at the ammo and hydroxyl groups via a single reaction ina CS/HOBt aqueous system.The product was characterized by NMR,IR etc.TheCS-g-mPEG was complexed with DNA at various CS-g-mPEG/DNA(N/P) chargeratios and the resulting complexes was characterized by IR,gel retardation,dynamiclight scattering,solid state NMR ³¹P DD/MAS spectra and ¹³C CP/MAS spectra todetermine the complex formation and the interaction between CS-g-mPEG and DNA.The results indicated that:The solubility of CS was improved to 50mg/mlH₂Othrough functionizing with mPEG and the ¹H spin-diffusion NMR experiments with¹³C detection showed their good compatibility;the CS-g-mPEG/DNA complex was formed at higher charge ratio(N/P>10).In the ³¹P DD/MAS spectra,the chemical shiftof the phosphate group of DNA was found to be dependent on the charge ratio.Thesame phenomenon was got in the ¹³C CP/MAS spectra.Both of these results indicatethat higher the charge ratio,then better the compatibility of the system.