Adjustment And Control Of The Structure Of Alkanethiol Thiols SAMS On Gold Surface And Immobilization Of Protein

The immobilization of biological macromolecules is one of the key technologies of biosensors preparation, which is the research focus in the field of high-tech. The technology of self-assembled monolayers (SAM) has been widely used in the immobilization of biological macromolecules, which provides an effective way for the investigation of biosensors. However, the carboxyl or amino groups on the surface of SAM which are used to immobilize protein molecules for further adversely affect the immobilization process by the reason of the trends to form hydrogen bonds between the surface molecules. In this paper the self-assembled monolayers (SAMs) and protein films prepared by different conditions and matters were characterised by Polarization-modulation Fourier transform infrared reflection-absorption spectroscopy (PM-FT-IRRAS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). We have found the method to prevent the formation of hydrogen bonds in (MPA) SAMs and (MUA) SAMs. We also manage to optimize the protein fixed conditions and advanced the best assembled condition of (L-Cys). The major contents in this thesis are described as follows:1. The control of the hydrogen bonding between mercaptopropionic acid molecules and its impact of protein immobilized.MPA was assembled onto gold substrate. Applied EDC and NHS to activate the modifed surface, then immobilized Bovine serum albumin(BSA) on the MPA SAMs/Au.Investigating the hydrogen bondings on the influence of immolilizing protein and how to prevent the hydrogen bondings between mercaptopropionic acid molecules.As shown in the result, MPA solution can be used to prevent hydrogen bonding forming when pH was3.0. The hydrogen bonding could also be prevented by increasing the distance between moleculars. When Ctp:C4-MPA=3:1, hydrogen bonding could be prevent effectively.2. The preparation of three different mixed thiols.We have prepared three different mixed thiols SAMs MUA/MUOH, MUA/Mercapto-hexanol (MHOH), MUA/Mercapto-heptane (MHT) onto gold substrate by using total absorption method and the fractional step method in self-assembly process. As shown in the result, the fractional step method is more conducive to prevent the hydrogen bonds between the MUA molecules than the total absorption method. We utilize fractional step to form MS SAMs (MUA and MUOH) and the best condition is that the optimal concentration ratio of1:3. The optimal concentration ratio of CMUA:CMHOH is1:6, the assembled condition is the same with MHT. The best assembly time of MUOH, MHOH, MHT are20min.3. Study on the optimizing conditions of the assembly of L-cysteine (L-Cys) and the polarization angle of the IRThe carboxylated surfaces were constructed with L-Cys assembling onto gold substrate by useing different buffer solution to change the self-assembly conditions and PM-FT-IRRAS was used to characterize the SAMs. L-Cys SAMs was prepared in the optimal pH conditions, and polarization angle was changed during the process of characterization. It shows that SAMs form the best structure when pH is5.0and the best characterizated results was given when the polarization angle was80°.