Study On The Interactions Between Several Functional Nanomaterials And Biological Macromolecules And Their Mechanisms

Nanomaterials have been developed for imaging,drug delivery,diagnosis,and clinical treatment due to their superior physicochemical properties.However,the functions and effects of nanomedicine still cannot meet the needs of clinical applications.This is mainly because the current research on the biological effects of nanomaterials is limited to the in vivo or in vitro research from a single perspective,and it is often ignored that nanomaterials and biological.The physical-chemical interactions that occur between nanomaterials and biological macromolecules are often ignored,and comprehensive analysis and interpretation are required from the perspective of thermodynamics and kinetics.The combination of nanomaterials and biological macromolecules inevitably affects the original biological characteristics of nanomaterials,causing various cellular and biological reactions.These reactions are considered to be the main factors determining the targeting efficiency and biological applications of nanomedicines.At present,there is insufficient understanding of nanomaterials in biology,especially about nanomaterials and biological macromolecules(such as Human serum albumin,which is one of the most abundant proteins in the human body,and nucleic acid,which is the basic unit of genetic material).There is still a lack of research on the interactions and mechanisms between them,so it is urgent to explore the interactions between nanomaterials and biological macromolecules and their mechanisms using thermodynamic and kinetic methods.In this paper,the interaction and mechanism of four nanomaterials with different functions,namely Black phosphorus quantum dots,GO,Graphene quantum dots and Carbon dots,with three biological macromolecules,Human serum albumin,Trypsin and Calf thymus DNA,were investigated from the molecular level.This thesis is divided into five chapters:Chapter 1: Overview of the properties and biological effects of nanomaterials with different functions,Black phosphorus quantum dots,Graphene oxide,Graphene quantum dots,and fluorescent Carbon dots.Structure and function of various biological macromolecules(Human serum albumin,Trypsin and Calf thymus DNA).Chapter 2: The binding interactions between black phosphorus quantum dots(Black phosphorus quantum dots,BPQDs)and human serum albumin(Human serum albumin,HSA)were systematically characterized to further explain the conformational changes of HSA affected by BPQDs.Fluorescence and molecular docking results show that the intrinsic fluorescence of HSA is mainly quenched statically by BPQDs through Van der Waal interaction,and BPQDs arefirmly bound to HSA site I to form a ground state complex with a molar ratio of 1:1.The results of circular dichroism spectrum showed that the secondary structure of HSA and BPQDs had changed significantly,and the α-helix structure of HSA changed to β-sheet structure.After HSA is combined with BPQDs,its melting temperature and molar enthalpy change decrease,indicating that BPQDs promote the thermal denaturation process of HSA and reduce the thermal stability of HSA.These results explored the exact binding mechanism of BPQDs and HSA and the conformational changes of HSA after binding and interaction with BPQDs,providing valuable information for the potential toxicity risks of black phosphorus quantum dots on human health.Chapter 3: Exploring the conformational changes and enzymatic activity of trypsin after binding to graphene oxide,it is proved that graphene oxide effectively binds to trypsin through van der Waal interaction,hydrophobic interaction,hydrogen bonds and electrostatic force,and quenching endogenous fluorescence of Trypsin.Moreover,graphene oxide can significantly change the secondary and tertiary structure of trypsin.The calculation of Michaelis constants proved that graphene oxide was combined with allosteric sites on trypsin in a non-competitive manner.Cell digestion experiments,and gels Electrophoresis experiments proved that graphene oxide can effectively inhibit enzyme activity and protect human serum albumin and Hela cells from trypsin digestion.These results explore the exact binding mechanism of graphene oxide and trypsin,and provide more important information for the biological risks that graphene oxide may pose to humans.Chapter 4: A new method for the synthesis of chiral graphene quantum dots(L-GQDs,D-GQDs)by a one-step hydrothermal method is proposed.The synthesized graphene quantum dots have two highly symmetrical chiral signals,located at 230 nm and 305 nm,respectively.Combining chirality,stability,and biocompatibility,the mechanism of interaction between chiral graphene quantum dots and ct DNA proves that there is a large chirality difference between chiral graphene quantum dots and ct DNA.Due to the effect of steric hindrance,D-GQDs are easier to bind with right-handed B-type helical ct DNA than L-GQDs.The results of confocal microscopy imaging and MTT analysis show that the chiral graphene quantum dots can be successfully internalized in cells and have good biocompatibility.Cell morphology observations showed that chiral graphene quantum dots had no significant effect on cell morphology.These conclusions have explored the mode of interaction between chiral graphene quantum dots and DNA,linking chemistry and life sciences,and providing valuable information for the development of chiral nanomaterials in many scientific fields such as chemistry,biology,and medicine.information.Chapter 5: The role of three different carbon dots and calf thymus DNA was explored.Combined with multispectral method,melting temperature method and viscosity method,thebinding ability and combination of three different carbon dots and ct DNA were investigated.The results prove that the difference in doping elements is the reason for the difference in the three kinds of carbon dots and the groove binding interaction of ct DNA.The doping of the element can weaken the binding ability between the carbon dot and ct DNA,but increasing the charge carried on the surface of the carbon dots can enhance the binding between the carbon dot and the ct DNA.These results reveal the molecular mechanisms of three different types of carbon dots and the groove-binding interaction of ct DNA,which provides a theoretical reference for designing targeted carbon dots in the biomedical field in the future.