| 1. Interaction behaviors between chitosan and hemoglobinThe interaction between chitosan and hemoglobin (Hb) and the effects of chitosan on Hb behaviors are studied by the methods of UV-Vis and fluorescence spectroscopies, circular dichroism, rheometer, dynamic and static light scattering. The average molecular weight of chitosan in this thesis is 9.8×104g?mol?1. The average polymerization degree of the chitosan is about 6.1×102. Chitosan can obviously associate with Hb to form protein-chitosan complexes using hydrogen bonding, hydrophobic and electrostatic interactions. The complexes can affect microstructural behaviors of Hb. The addition of chitosan makes the intrinsic UV-Vis absorption of Hb increase and leads to the decrease of the fluorescence intensities of Hb. When pH is 3.0 and 4.0, the distances between the first association site of chitosan with 214-tryptophan residue in Hb are about 5.473nm and 5.616nm, respectively. Theα-helix of Hb can be drawn and changed intoβ-sheet with the increase of chitosan concentration.2. Solubilization effect of chitosan on acyclovirThe solubility of insoluble or the less-soluble drugs (acyclovir) can be improved through hydrophilic and hydrophobic properties and hydrogen bond in chitosan and acycolvir can be prepared in the form of liquid reagent for easy to use. With the increase of chitosan concentration (0.4g/l-4.0g/l), the solubility is obviously improved (1.91×10-3mol/L-5.56×10-3mol/L). The microenvironment polarity measurement shows that acyclovir is solubilized and located in the network structure of chitosan. It not only increases the solubility and stability of acyclovir in the solvent, but also extends the release time of drug to achieve the aim of sustained release.3. Interactions and effects among chitosan, hemoglobin and acyclovirBoth chitosan and acyclovir have influences on Hb behaviors. In hemoglobin/acyclovir/H2O system, the changing trends of Hb behaviors are similar to those in hemoglobin/H2O system with the increase of chitosan content. However, the interactions between chitosan and Hb are greater than those between acyclovir and Hb. The former interactions lead to the dissociation of acyclovir from Hb and the increase of free acyclovir concentration, which can control drug release process and improve the efficacy of drug.4. Interactions between chitosan and fuchsinThe interactions between acid fuchsin and chitosan are in detail studied by UV–Vis spectrum, FT-IR spectroscopy, differential scanning calorimetry and microenvironment polarity measurement. The adsorption capability of acid fuchsin on chitosan decreases with the increase of pH. Acid fuchsin has two kinds of isomers (II and III). The increase of pH leads to the structure transformation from isomer II (coloured) to isomer III (colourless). The existence of chitosan increases the color transformation of the solution from mauve to pink. The adsorption of acid fuchsin on chitosan almost obeys the Freundlich isotherm model in the given scope of chitosan concentration. The increase of chitosan content results in the decrease of the adsorption efficiency. 5. Interactions and effects among chitosan, hemoglobin and fuchsinThe interactions and the effects among chitosan, acid fuchsin and Hb are studied by UV-Vis and fluorescence spectroscopies, circular dichroism. The hydrogen bonding and hydrophobic interaction existing between acid fuchsin and hemoglobin lead to the structure transformation from metHb to hemichrome. The transformation can decrease the capacity of containing oxygen of Hb. The addition of acid fuchsin gradually makes peptide chain of Hb spread and tryptophan and tyrosine residues exposed. A small amount of chitosan has some protections on the Hb behaviors in acid fuchsin/Hb system. The interactions between chitosan and Hb are greater than those between acid fuchsin and Hb. |
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