Molecular Dynamics Simulation On The Series Of Triton X Non-ionic Surfactant Molecules

The aggregation structures of Triton X(TX)amphiphilic molecules in aqueous solution play an important role in determining various properties and applications of surfactant solutions.In this thesis,the properties of micelles formed by TX-5,TX-114 and TX-100 molecules with different poly(ethylene oxide)(PEO)chain lengths in TX series of nonionic surfactants are studied via molecular dynamics(MD)simulations.The structural characteristics of three micelles are analyzed at the molecular level,including the shape and size of micelles,the solvent accessible surface area,the radial distribution function,the micelle configuration and the hydration numbers.The effects of different PEO chain lengths on their aggregation behaviors in aqueous solutions are emphatically studied.With the increase of PEO chain length,micelle size and solvent accessible surface area also increase.The distribution probabilities of polar head oxygen atoms on the surface of TX-100 micelle are higher than those in TX-5 and TX-114 micelles.In particular,the tail quaternary carbon atoms in hydrophobic region are mainly located at micelle exterior.For TX-5,TX-114 and TX-100 micelles,the interactions between micelles and water molecules are also quite different.These structures and comparisons at the molecular level contribute to further understand the aggregation and applications of TX series surfactants.Because the TX series non-ionic surfactants have low toxicity,high cost effectiveness and simple production,they have been widely used in pharmaceutical field.Therefore,on the basis of TX micellar research,the mechanism of TX micelles as drug delivery carriers(DDV)to solubilize non-steroidal anti-inflammatory drugs(NSAIDs)is further studied.The selected NSAIDs are meloxicam and celecoxib,and the effects of solubilizing drug molecules on the structural characteristics of three micelles and their interactions are mainly studied.Results show that meloxicam have no significant effect on the shape of TX-5 micelle,but increases the ellipsoidal degree of TX-114 and TX-100 micelles.After solubilizing celecoxib,the ellipsoidal degrees of three TX micelles all increase.Meloxicam hardly has effect on the size of each micelle,while celecoxib reduces the size of all three micelles to some extents.In addition,the binding modes between two drug molecules and each micelle are different.Among them,TX-5 micelle bind most closely to meloxicam.The interactions between two drug molecules and water molecules are also significantly different,the hydration number and hydrogen bond number of selected atoms are different in the three systems.In addition to the aggregate structure in bulk phase,the structural properties and interfacial behaviors of TX-5,TX-114 and TX-100 molecules at the air-water interface are also investigated in this thesis.The results of density profiles show that polar O atoms of three TX molecules are all on the water surface,and the entire TX molecule is almost parallel to the water surface.The results of the order parameters show that the order parameters of the three TX molecules on the interface are basically similar and relatively ordered.The TX-100 molecule has the highest value of gauche defects.The changing trends of hydration numbers for s TX molecules at the air-water interface are similar to those in micelle and the hydration numbers of PEO chain has obvious zigzag trend.This thesis provides the reference for further development of TX family micelles and surfactant molecules in pharmaceutical and commodity applications.Overall,the research in this paper has certain reference significance for the application of TX series non-ionic surfactants in related fields.In addition,the molecular dynamics simulation method used in this paper clearly displays the microscopic conformation of the aggregate structure,further demonstrating the important applications of this method in fields such as chemistry and biology.