Research On The Doping Of Protein Molecules And The Regulation Of Their Electron Transport Energy Levels

Currently,the research and development of bioelectronic devices based on protein molecules have attracted widespread attention and have become a research hotspot in the field of bioelectronic technology.Miniaturization of electronic devices to nanoscale dimensions is essential for the future of the electronics industry,as it offers the benefits of reduced power consumption and improved device performance for speed and functionality.Using protein molecules as electronic components could provide a solution to the physical limitations of nanoscale electronic development because they are nm-scale and capable of undergoing effective ETp(Electron Transport)processes.Moreover,proteins also exhibit other useful properties,such as optical characteristic,that is essential for the fabrication of combined optical-electronic devices.Proteins have been studied for use in the design of many types of bioelectronic devices.One of the main factors of the performance of protein molecule-based electronic devices is their ETp abilities,which largely depend on their band gaps.Therefore,it is necessary and desirable to tune the ETp band gaps of the proteins to a suitable value for enhancing the performance of protein-related electronic devices and expanding their application fields.The band gap can be tuned in a certain range by altering the parameters regulating the ETp ability,such as change the conformational structure and/or the core composition of the proteins.However,the observed ETp features and the obtained band gaps of the denatured proteins cannot reflect the intrinsic characteristics of the proteins in their native states by changing the conformational structure.Although the core reconstitution method can retain the native conformations of the protein,it is not straightforward experimentally and requires complicated and tedious procedures.In this thesis,the BSA(Bovine Serum Albumin,without redox center)was choosen as the research model,also presented a facile method to tune the ETp band gaps of BSA by doping it with foreign molecules(Vb12,TPY,Conjugated molecules).And studied the conformational changes,ETp characteristic,and ETp band gaps of doped BSA.The main conclusions of this thesis are as follows:1.This thesis reports a facile and novel method to research the formation,ETp characteristics and ETp band gaps of BSA,which have been considered to be promising electronic components for minimizing electronic devices to nanoscales via doping with Vb12 molecule.The theoretical(molecular docking simulation)and experimental(Fluorescence spectra and UV–Vis absorption)results show that the Vb12 molecule can easily be doped into BSA and binds at its subdomain IIA,causing negligible change to the BSA conformational structures by the CD spectra.The Vb12–BSA was then immobilized on a Si substrate.The measured I?V response indicates that doping with Vb12 can significantly enhance the ETp ability of BSA and its ETp performance is improved by about 1.26 orders of magnitude compared with that before doping,the d I/d V–V spectrum results show that the band gap of BSA was reduced from 1.48 e V to 0.98 e V by doping with Vb12.2.This thesis reports a simple approach to study the influence of BSA doping with TPY molecule on its conformation,ETp characteristics and ETp band gaps.The doping was first confirmed by both the molecular docking,fluorescence spectra and UV–Vis spectra,which demonstrated the formation of the TPY–BSA complex with the TPY positioned at subdomain IIA of BSA.The CD spectra showed that the original conformation structures of BSA has hardly changed via doping with TPY molecule.The TPY–BSA complex was then immobilized on an Au substrate surface with the same orientation via the –SH group of the Cys34 on the protein surface.The I–V results show that doping TPY can improve the ETp ability of BSA with about 1.48 ordrs.The d I/d V–V spectrum results show that TPY doping can make the BSA band gap was reduced from 1.48 e V to 0.97 e V.3.This thesis reports the influence of BSA doping with conjugated molecules on its conformation,ETp characteristics and band gap.The doping was first confirmed by both the theoretical simulation and experimental characterization,which demonstrated the formation of the complex with the conjugated molecules all positioned inside a hydrophobic cavity at subdomain IIA,causing negligible change to the BSA conformational structures.Density functional theory(DFT)calculates the band gaps of the P1,P2,P3,AP,BP,HP were 3.42 e V,1.93 e V,2.66 e V,2.34 e V,2.55 e V,2.51 e V respectively.All the complex was then immobilized on an Au substrate surface with the same orientation via the –SH group of the Cys34 on the protein surface,The I–V results show that doping conjugated molecules can improve the ETp ability of BSA about 1.16–1.42 orders compared with that before doping.The d I/d V–V spectrum results show that conjugated molecules of P1,P2,P3,AP,BP,HP doping can make the BSA band gaps were reduced from 1.50 e V to 1.25 e V,0.74 e V,1.16 e V,0.83 e V,1.02 e V,0.90 e V,also the smaller the band gap of the conjugated molecule itself,the more the band gap of its complex decreases,and the better the ETp characteristics,thus achieve the purpose of modulating the protein ETp band gap.The results presented in this work may provide a general approach to regulate protein ETp band gaps with wide variability by preselecting the doping molecule.The protein bound with the foreign molecule may further serve as a suitable material for configuring nanoscale solid-state bioelectronic devices.