The Compute Simulation Study Of Several Typical Nano-sized Biomaterials For Biological Systems

Understanding the interaction mechanism between biomolecules and nano-biomaterials is of great significance for the designing and development of biomaterials and the successful usage in the clinics.Computer simulation provides an effective way to investigate the interactions at the molecular and atomic level.In this study,the interaction of three types of nano-biomaterials,doped and Sr/F-codoped HA nanoparticles using experimental and DFT methods.The Sr/F-codoped HA was more stable than the Sr-doped HA owing to its more negative formation energy and higher crystallinity.The lattice parameters a decreased and c did not significantly change compared with those of the Sr-HA with gradually increasing F-concentration for a constant Sr concentration.These results indicated that the F-ions can be doped into HA successfully and stabilized the Sr-doped HA crystals.The codoped HA showed excellent antibacterial activities against Streptococcus mutans.There were no significant differences between the antibacterial activities of the codoped and F-doped HA nanoparticles.The Sr-doped HA showed excellent biocompatibility,and doping the Sr-doped HA with F-ions did not cause cytotoxicity.Sr ions enhanced the osteogenetic abilities of the HA nanoparticles.Incorporating the appropriate amount of Sr into the HA produced the optimal osteogenetic abilities for the codoped HA.The results will hopefully provide useful guidance for designing optimal codoped HA nanoparticles to satisfy the demand for diverse biomedical applications.(3)Integrating proteins with CS can not only improve the biocompatibility of CS,but also realize the sustained release of proteins.The deacelation degree(DD)and pH condition are considered as the most important two factors that affect the interaction between CS and proteins.In this study,the effects of chitosan with different deacetylation degrees and pH condition on bone morphogenetic protein-2(BMP-2)and human serum albumin(HSA)adsorptions were evaluated using the MD method.The results showed that the interaction is the strongest between proteins and 75%deacelation degree CS surfaces.In addition,the interactions of HSA with various DD CS surfaces are stronger than that of BMP-2 with various deacelation degree CS surfaces.Furthermore,decreasing pH value favors the interaction between proteins and CS surfaces.The result is hopeful to better understand the interaction mechanism of the CS-protein system and provide theoretical guidance for the application of chitosan with different deacetylation and different pH condition.(4)Graphene has strong hydrophobicity and low reactivity.In the experimental study,doping atoms or introducing functional groups into graphene were utilized to improve its physicochemical properties.Note that the interaction mechanism between biomolecules and atom-doped graphene was difficult to explain by traditional experimental methods.In this study,graphene was doped by Fe,Cr,Al,Mn and Ti atom.The interaction between doped graphene surfaces and serine(SER)was studied by the DFT method.The results indicated that anionic and neutral SER with the pristine graphene surface showed weak non-covalent interactions due to the formation of-COOH…?,-COO…? and-OH…? interactions.On metal doped graphene,covalent interactions to the surface dominate,due to the formation of strong "metal-O" and "O-metal-O" interactions.Furthermore,doped Fe,Cr,Mn,Al or Ti atom enhances the ability of graphene to attract both types of SER.At the same time,the interaction strength of anionic SER on various graphene surfaces is stronger than those of neutral SER.These results are expected to provide useful insights for the rational design and development of graphene-based materials related to proteins and peptides.(5)Graphene-based biomaterials commonly used dopants to improve its reactivity.However,an external electric field(E-field)is an effective way to adjust the physical properties of graphene.Dopamine is an aromatic chemical compound containing two phenolic hydroxyl groups and one amino group,and has excellent adhesion ability owing to the phenolic hydroxyl and amino groups.To the author's knowledge,the interactions between biomolecules and metal atom-doped graphene have not been reported under external E-fields.This study systematically investigated the interactions of dopamine(DA)with pristine as well as B-,N-,Ca-,and Fe-doped graphene surfaces using the DFT method.The results suggest that dopants can adjust the interaction between dopamine and graphene.Compared with pristine graphene,B-and N-doped graphene have little effect on the adsorption of dopamine because of the weak non-covalent interactions between them.Interactions of DA on Ca and Fe-doped graphene surfaces were far stronger than on the previous three kinds of graphene surfaces due to the formation of metal-O and O-metal-O covalent interactions.Moreover,DA...