Spectrum Study On Interactions Between Biomolecule And Functionalize Multi-Walled Carbon Nanotubes

This research mainly focused on the interactions between surface functionalized multiwalled carbon nanotubes and proteins by studing influence factors of the complex formation using various spectroscopies.Then a carbon nanotube combinatorial library was screened with reduced protein binding and inhibited enzyme activity.It consists of the following two parts:In the first part,using steady-state fluorescence,time-resolved fluorescence and circular dichroism(CD)spectroscopies the interactions between proteins and functionalized multiwalled carbon nanotubes(f-MWNTs)were analyzed.Besides the pristine MWNTs,we chose functionalized MWNTs(carboxyl,tyrosine and isobutyl amine),and five proteins including BSA,hemoglobin and so on for their interaction study. Adding f-MWNTs into protein solution induced quenching of the protein intrinsic fluorescence,and lead to a conformational change of proteins.Through comparison and analysis of surface chemistry of f-MWNTs,we make the following conclusions:1.Using the Stern-Volmer plots to analyse the fluorescence quenching proteins and the results showed that f-MWNTs quenching effect on protein fluorescence belongs to the static quenching mechanism, therefore,there is the formation of binary complexes.2.Electrostatic interaction plays a dominant role in protein binding on f-MWNTs.The charge density changing of f-MWNTs under the surface functionalization,thus causes the differences of the binding effect.3.Larger proteins showed stronger binding with f-MWNTs,because there are more amino acid residues on a larger surface that might support a stronger binding.4.f-MWNTs with larger diameter showed stronger protein bindings. Larger surface with more functional groups made the binding easier. Moreover,smoother curvature can induce larger protein conformational changes while the protein adapts to the "unfamiliar" surface curvature in one dimensional nanoparticles.For the second part,by sreening the f-MWNTs library on the affinity of protein binding;it was found that acylator AC005 produced much less protein binding.Then,by screening the f-MWNTs library on the inhibition of enzyme activity we found that amide AM002 inhibited enzyme activity most.As a whole,this paper studies the bioeffect of f-MWNTs on a molecular level,and proves that protein/f-MWNTs binding is selectively.Protein is important in vital movement and its conformational structure determines it vital function.Therefore,by modulating the size,shape,surface charges,or surface chemistry of MWNTs,the protein-binding capability and their in-vivo toxicity can be regulated,biocompatibility be improved,and potential application in nanomedicine be optimized.