Revealing the structure of bioinspired polydopamine (PDA) surfaces

• Applicant: Dr.-Ing. Guoguang Sun
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282219439

The project works on the in-situ analysis of the polymerization process to clarify the structure of the polydopamine films on Au, silicon and SiO2 surfaces as well as to inspect the adsorption mechanism of biomolecules onto the PDA-terminated surfaces. The polymerization process will be studied dependent on different electrochemical and autoxidation growth parameters, e. g., potential, pH value of the solution, concentration of the monomer and temperature. The growth and the structural properties of the polydopamine films will be studied in-situ by means of a multi-method approach combining optical spectroscopies [IR-spectroscopic ellipsometry (IRSE), Reflection Anisotropy Spectroscopy (RAS)], electrochemical methods and quartz crystal microbalance (QCM) measurements. The in-situ characterization will be complemented by ex-situ studies using Raman spectroscopy, UV-Vis ellipsometry, atomic force spectroscopy (AFM), IR synchrotron mapping ellipsometry, IR micoroscope, contact angle measurements and X-ray photoelectron spectroscopy (XPS). The structural and chemical properties of the prepared surfaces are of high relevance for possible add- and absorption of biomolecules and possible biosensor applications. It is planned to clarify the structure of the PDA synthesized by electrochemical deposition or autoxidation as well as the molecular structure after coupling the specific biomolecules. In detail, the project will focus on: 1) the clarification of the molecular structure of PDA under different polymerization conditions and comparison with the results from theoretical results; 2) elucidation of the structure of PDA after coupling specific peptide by using Michael addition (with thiol groups)/Schiff base (with amine groups) reactions; 3) understanding of the interactions (or adsorption, coupling) between the PDA film and the biomolecules. Finally, the achieved biomolecules-functionalized surface will be applied for identification of the specific antibody. During the whole process, the chemical binding and structural changes in the polymer-biomolecule system are studied by means of the above mentioned in-situ and ex-situ methods.

• DFG Programme: Research Grants