Investigation of specific biological interactions using surface plasmon resonance spectroscopy on anodic aluminum oxide thin films

Surface Plasmon Resonance (SPR) spectroscopy is used as outstanding optical biodetection tool by the reason of its unlabeled, real-time and noninvasive properties in biology, biochemistry and medical sciences areas. Questions such as kinetics, the specificity, affinity of an interaction, and concentrations of selected molecules in a sample of interest can be answered by SPR. Anodic aluminum oxide (AAO) thin films use in the field of drug release, biosensors and biomedical increased in addition to gas sensors, solar cells areas, due to its high porosity, controllable pore diameter and thickness, increased surface area-volume ratio, thermal and chemical stability, biocompatibility. AAO thin films, which are used in nanoscale material production using lithography, masking and molds, are also frequently used in SPR spectroscopy in the field of optical biosensors. In addition to the surface plasmon, different modes are obtained by acting as an optical waveguide of AAO thin films when added to the SPR system. In literature, it has been observed that free standing AAO films produced by two-step anodization and obtained by voltage reduction method are directly produced and are not used in surface plasmon resonance spectroscopy. In this thesis, the modes expected to be obtained according to the thickness and porosity values of AAO thin films produced under laboratory conditions were determined with the Winspall 3.02 simulation program. Then, thickness optimization studies of AAO thin films, which were freed with two-stage anodization, were carried out. Chemical etching methods have been tried at different times by using H3PO4 and NaOH solutions in different concentrations. Different methods such as coating with polycarbonate and taped from the edges of the films to the glass surface have been tried to protect a surface during abrasion. In addition, chemical etching processes were carried out at the oil-acid interface. Since the homogeneous film thickness could not be obtained by etching methods, the second anodization time was reduced and the films were thinned. Four different anodization times have been tried and the free standing 1.5 micrometer thick AAO thin films have been produced. The pore structure and thicknesses are characterized by scanning electron microscopy (SEM). The effective dielectric constants of AAO thin films whose porosity values were determined by SEM images, were calculated with the Maxwell-Garnett formula. Kretschmann configuration was used in SPR spectroscopy. Thickness and dielectric constant analyzes were made with the data of spectroscopy obtained by combining high refractive index glasses that are gold coated with sputtering method and AAO thin films using Winspall program. The thicknesses that are obtained from anaysis are similar with the result os SEM.