Multi-scale Simulations And Calculations On Biocompatibility Of Boron Nitride Nanomaterials

In recent years,with the continuous development of the field of biomedical materials,researchers have made a lot of experiments and explorations on the possibilities of some nanomaterials in biomedicine applications.Graphene,graphene oxide,carbon nanotubes and other carbon-based nanomaterials first aroused the imagination of researchers.These carbon-based nanomaterials have been extensively tested in the field of medical materials applications.Boron nitride nanomaterials have high thermal conductivity and excellent mechanical property.Compared with graphene,boron nitride nanomaterials also have extraordinary properties in other aspects,such as good chemical stability,extremely high oxidation resistance and excellent electrical insulation.These good unique properties may offer boron nitride nanomaterials broad application prospects as biological materials.There have been many experiments on boron nitride nanomaterials of the possible applications in drug delivery,antibacterial effects,and tissue engineering.However,the understanding of the related theoretical mechanisms of the complex interactions in organisms is still very limited.Nowadays,there have also been many experimental work about what effect on the changes in the physical properties to the boron nitride nanomaterials biocompatibility,such as size,surface area,etc.However,the research about curvature,the physical quantity is very little.And the conclusions explored by experimental means have also appeared to be different.Here,a new path was taken.The research method of theoretical calculation was selected.The effect of the change of the physical quantity of the curvature of boron nitride nanomaterials on the biocompatibility of boron nitride nanomaterials was carried out an in-depth microscopic investigation.It was expected to explain and predict the micro-theoretical mechanism from the calculation results and analysis of the effect of boron nitride nanomaterials on biomolecules,the change of the interaction bond and the change of energy.In this paper,three theoretical calculation methods were selected in the calculation method.The calculation accuracy of these three theoretical methods is constantly changing,and it is better step by step.The first one is molecular dynamics simulation method based on the molecular scale.The advantage of using this method is that the dynamic process of the interaction between boron nitride nanomaterials and biomolecules can be observed,So a preliminary judgment whether there is any interaction between the two molecules can be made.But the information obtained in this way is relatively preliminary.Using the second one,tight-binding density functional method,we can explore in more detail at the subatomic level on the key binding region generated during the molecular dynamic simulations.This method can not only guarantee a certain calculation accuracy,but also has greater tolerance for calculating the number of atoms than the density functional method.The third method is a method combining molecular mechanics and quantum mechanics.The calculation accuracy can achieve to the level of quantum mechanics.So that the calculation results are not only further upgraded in calculation accuracy,And it can avoid the defect of DFTB method in order to expand the number of calculation atoms to reduce the calculation accuracy.In addition,this method is a proof and supplement to the second calculation method that ensuring the accuracy and credibility of research conclusionsHere,the biological application of boron nitride nanomaterials was studied through three multi-scale simulation methods.The work contents and conclusions include1.Using Molecular Dynamics(MD)simulation method.Placing the boron nitride nanosheets and boron nitride nanotubes of different curvatures and chicken vitamin head protein HP35 in an aqueous solution and made simulations for at least 50 ns.Through the observation of the binding process,the calculation of the RMSD value,the analysis of the secondary structure and the change of hydrogen bonds in the protein,and the energy change between the boron nitride and the protein.Finally,it was concluded that the binding strength of boron nitride nanotubes and proteins increases with the decrease of its curvature.The structure of the protein develops from complete to incomplete with the declining of boron nitride curvature2.After understanding the molecular-level interaction between HP35 protein molecules and boron nitride nanotubes of different curvatures,The density functional tight-binding(DFTB)method was used to calculate the adsorption energy between the amino acids contained in protein species and the boron nitride nanomaterials,This work compared the adsorption energy between different amino acids and boron nitride nanomaterials,and gave a more microscopic analysis of the interaction between boron nitride nanotubes,nanosheets and proteins and gave a better understanding of the action law of different types of amino acids and boron nitride nanomaterials3.The calculation results of the above DFTB method were verified by a calculation method that combines quantum mechanics and molecular mechanics(QM/MM).The data calculated by QM/MM showed the same trend as the data calculated by DFTB.For all amino acids,the Ead value would decrease as the curvature of the BN nanomaterial decreases.For different kinds of amino acids,(5 5)BNNT always has the largest Ead value,while for different kinds of amino acids,BNNS always has the smallest Ead value.In summary,through the combination and mutual verification of three calculation methods at different scales,we compared the adsorption strength between different amino acids and boron nitride nanomaterials,thereby studying the interaction mechanism of boron nitride nanotubes,nanosheets and proteins.It provided a relevant theoretical mechanism for the application of boron nitride nanomaterials in the field of biomedicine.