Synthesıs And Characterızatıon Of Bıomımetıc Nanofılms

Thesis Type: Post Graduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2018




Polydopamine P(DOPA) is a biocompatible, dark brown-black, organic solvent synthesized by the oxidative polymerization of dopamine (DOPA). It is a synthetic analog of naturally occurring melanin (eumelanin). Dopamine is a biomolecular that is processed as a neurotransmitter in the brain and is responsible for human motivation and movement. The dopamine biomolecule possesses catechol and amine groups mimicking the chemical composition of the adhesive proteins of the mussels containing high amounts of catechol and amine functional groups. Under alkaline conditions, the catechol functional group of dopamine oxidizes to the benzoquinone, which self-polymerizes to form thin films on the surface of the material. Within the scope of the thesis study, polydopamine nanofilms were synthesized under alkaline conditions with oxidative spontaneous polymerisation of dopamine (1, 2, 3, 4, 12 and 24 hours). Later, the synthesized P(DOPA) was covered with n-type Si(100) surfaces to characterize the nanofilms. Different P(DOPA) nanofilm coated silica surfaces were prepared for 1, 2, 3, 4, 12 and 24 hours. Chemical structures of the nanofilms were analyzed by combined total reflection-fourier alternating infrared spectroscopy (ATR-FT-IR) and X-ray photoelectron spectroscopy (XPS). The surface morphology of P(DOPA) nanofilms was examined by Scanning Electron Microscopy (SEM) and the thickness of the nanofilms was determined by using Spectroscopic Ellipsometer. FT-IR results show that dopamine (DOPA), self-polymerizing in alkaline environment in the presence of oxygen to form polydopamine nanofilms. The XPS results showed that, with change of the formation time of P(DOPA) coating increased without changing of the chemical structure of the Si surfaces. The surface morfology characterization results showed that, layers were formed on the surface by the changing formation time of P(DOPA). It was determined from the results of the ellipsometry, that the thickness of the polydopamine nanofilm changed proportional with time.