The Aggregation And Application Of Chitosan/surfactant

The amphiphilic molecules can self-assemble into a variety of ordered association structures through intermolecular interactions under a certain condition.Although the structure is diverse,the performance is relatively simple.On the one hand,the stability of the association structure can be enhanced,and on the other hand,some unique properties of amphiphilic molecules can be imparted to expand their applications by introducing biological macromolecules into the association structure of the amphiphilic molecules.In this paper,the macromolecule chitosan with good biological properties and common edible foods were used to build the gel system,and the change of gel structure and the change of performance under different factors were explored by means of rheology.The surface properties and interactions of the chitosan/surfactant system were studied by surface tension method when the chitosan was introduced into the surfactant system.Finally,the biological properties of chitosan/surfactant system were explored through in vitro simulated release experiments and cell survival experiments.1.IntroductionIn the early stage of the experiment,the literature on chitosan and surfactants was first consulted,and the literature on chitosan/chitosan/chitosan hydrogel and chitosan lyotropic liquid crystal was briefly reviewed.It is found that chitosan hydrogel system has a good application prospect as a drug delivery system,but the defects such as poor self-solubility of chitosan limit its in-depth application.This outer shell polysaccharide macromolecule will interfere with the traditional surfactant association structure.It has a certain impact,thus expanding its application.Therefore,we chose food acid and chitosan to prepare the gel system and studied the influence of different factors on its structural properties on the basis of the original work of the laboratory.We used chitosan to introduce Tween 80,Brij 97 and other surfactants and studied the effect of macromolecular chitosan on the performance of surfactant system.2.Effect of food acid components on the performance of gel systemsIn this chapter,the phase behavior of the sol-gel system formed by chitosan and different food acids(tartaric acid,citric acid,malic acid,and lactic acid)was first studied by phase diagram method.Then,the rheological method was used to study the effect of chitosan content and food acid type on chitosan food acid system.The experimental results show that:(1)During the dissolution of chitosan,food acids can provide a good protonation environment,providing conditions for the formation of hydrogels.(2)The increase of chitosan content will cause food acid molecules and chitosan chains to intertwine to promote the formation of gel system.(3)The critical stress values of the four food acid systems exceed 100 Pa,and the composite modulus G* increases with the increase of chitosan content.(4)When the chitosan content was 12 % and 13 %,the composite modulus of the lactic acid system exceeded 1000 Pa,while other systems did not exceed 1000 Pa.(5)With the change of shear rate,two different stress processes occur in the chitosan gel system.When the shear rate is low,the chitosan molecules will begin to align and appear orientation,and the new structure gradually form.As the shear rate increases,the architecture tends to stabilize and begins to act in reverse.3.Effects of temperature on Food Acid/Chitosan GelIn this chapter,the influence of temperature on the chitosan gel system was studied by means of rheology and it was analyzed using a mathematical model.The results show that:(1)The interaction between chitosan molecules is more important than that of small molecule acids in the process of gel formation.With the increase of temperature,small molecules of chitosan have gradually appeared.Segmental motion and molecular centroid motion.(2)The lactic acid/chitosan system is different from the other three food acid systems.During the formation of the gel,the lactic acid molecular monomer also forms self-aggregation,which accelerates the formation of the gel system.(3)The results of continuous temperature scan appear,and the valley of complex viscosity appears later than the peak of internal friction.This corresponds to the hysteresis effect of the gel system,the strain lags behind the stress.(4)The Williams–Landel–Ferry(WLF)model and the Arrhenius model were established to quantitatively analyze the small molecule motion and centroid motion of the chitosan molecular fragment at the time of temperature change,linking the entire temperature range.(5)Steady-state rheology at different temperatures indicates the fluid nature of the food acid system.Tartaric acid,citric acid,and malic acid,at temperatures below 318 K,will exhibit Newtonian platforms as the shear rate increases,followed by shearing.Dilution behavior,when the temperature is higher than 318 K,shear dilution occurs in the lower shear rate range.In contrast,the temperature sensitivity of lactic acid is stronger,and the phenomenon of overall shear dilution has already appeared at 310 K.4.Surface properties and biological applications of chitosan/surfactant blend componentsIn this chapter,the surface tension method was used to study the interaction of chitosan/surfactant mixed system.Secondly,the in vitro release and biocompatibility of chitosan/surfactant mixed system was studied.The experimental results show that:(1)The introduction of surfactant into chitosan will participate in the micelle core formation and adsorption of surfactant molecules,thereby reducing the surface activity of the system.(2)The interaction force ?m indicates that the chitosan and the surfactant molecules are attracted to each other.The difference is that the Brij 97 has a different hydrophobic structure from the Tween 80,which leads to the interaction of the chitosan/Brij 97 system.Weaker.(3)For the lyotropic liquid crystal system,the introduction of chitosan,through intertwining and bonding of the chitosan molecular chains,makes the original liquid crystal system structure more stable,both slowing down the initial release rate and affecting the final release.rate.(4)MTT experiments showed that the growth of cells cultured with chitosan/surfactant system was good,indicating that the system has good biocompatibility.