The Effects Of Amino Acids On The Self-aggregation Behavior Of Octenylsuccinated Oat ?-glucan Micelles And Its Mechanisms

Nowadays,in the context of the food industry,polymer micelles with a core-shell structure came into being in order to solve the problem that the application of hydrophobic functional substances are limited due to their low water solubility.Among them,the hydrophobically modified polysaccharide-based amphiphilic micelles have gradually attracted researchers' attention due to their advantages of good self-assembly characteristics and structural stability.Inspired by the currently mature hydrophobic octenylsuccinate modified starch products,octenylsuccinated oat ?-glucan obtained by modifying ?-glucan with octenyl succinic anhydrides groups.The amphiphilic octenylsuccinated oat ?-glucan can form micelles with typical core-shell structure by hydrophobic interaction in aqueous solution,which has been proven to possess good curcumin loading capacity and significant solubilization functionality.Unlike block copolymers,the micellar structure of OS?G is looser.Hence,OS?G is easily affected by both its own nature and environmental factors,and is more vulnerable to the impact of food processing conditions as well.Meanwhile,since the monomer molecules and micelles are in both thermodynamic and kinetic equilibrium during the formation of OS?G micelles,the coexisting food ingredients and the environmental conditions.These external factors not only can easily affect the formation and stability of OS?G micelles(OS?G-Ms),but also restrict the performance of loading micelles.Amino acids are considered as the model compounds of the basic biological macromolecules,proteins,in some specific aspects.Studying the characteristics of self-aggregation behavior and stability mechanisms of OS?G-Ms in different amino acids aqueous solutions contributes to its further practical applications.Based on this,amino acids are taken as representatives of food ingredients in this article,the main research contents are as follows: the influence of amino acids on the formation of OS?G micelles;the influence of environmental factors,such as p H and temperature on the formation of OS?G micelles in the presence of amino acids,as well as the effect of environmental factors on the curcumin-loaded OS?G micelles with amino acids in order to reveal the impact and mechanism of both amino acids and the environmental conditions on the formation of OS?G micelles,and to further explore their effects on the loaded micelles.The results of research will ultimately provide a theoretical basis for the construction of an “efficient and stable” loaded micelle in food ingredients coexistence system.The main results obtained are as follows:(1)By measuring the influence of 13 common amino acids on the critical micelle concentration,particle size,polydispersity coefficient and Zeta potential of OS?G micelles,which revealed the rules and the molecular essence of the impact of amino acids on OS?G micelle formation was.The results show that the hydrophobic and acidic amino acids are conducive to OS?G micellization,while hydrophilic and basic amino acids are not and lead to an increase in the particle size of OS?G micelles.Correspondingly,the hydrophobic and acidic amino acids cause their shrinkage,and the particle size of OS?G micelles decrease as the hydrophobicity of amino acids increases.Furthermore,the influence of amino acids on the formation of OS?G micelles is closely related to the degree of dissociation,polarity,hydrophobicity and properties of the side chain of amino acids themselves,which is also subject to the environmental factors of the system.(2)By determining the critical micelle concentration,particle size,PDI,Zeta potential and surface tension of OS?G micelles under 7 hydrophobic amino acids addition at different p H(3,6,10)and temperatures(298.15 K,313.15 K,328.15 K,343.15 K,358.15 K)to further reveals the influence of the nature of properties of amino acids and the environmental conditions on OS?G micelles as well as their molecular nature.For each amino acid,as the p H value increases,the CMC,particle size,and Zeta potential of OS?G micelles all show an increasing trend,mainly due to p H-induced dissociation of amino acids,which further affected these relevant parameter and charge density of OS?G micelles by electrostatic interactions.For most amino acids(except Glu),as temperature increases,the CMC of OS?G micelles shows a “U-shaped” change trend,while the particle size and Zeta potential generally show a parabolic change trend as the result of the impact of temperatures on the hydrophobic interaction.(3)By measuring the effect of five hydrophobic amino acids on structure of curcumin-loaded OS?G micelles(particle size,PDI,Zeta potential)and surface tension,the effect of amino acids on curcumin-loaded micelle structure was revealed.The addition of Cysteine,Alanine,and Serine resulted in a reduction in the particle size of the curcumin-loaded OS?G micelles compared with the curcumin-loaded OS?G micelles without the presence of amino acids was found.Meanwhile,the addition of Serine increased the PDI and Zeta potentials of curcumin-loaded OS?G micelles,while the addition of Isoleucine and Phenylalanine caused the opposite trend of the particle size,PDI and Zeta potential of curcumin-loaded OS?G micelles to the above.In summary,the influence of amino acids on OS?G micelles and curcumin-loaded OS?G micelles is dominated by multiple factors,which are closely related to the nature,structure of amino acids and environmental conditions of the system.