Metabolit Tayinine Yönelik Biyoesinlenmiş Nanomalzemelerin Geliştirilmesi ve Uygulamaları

Abstract

The thesis consists of three main sections: i) synthesis of fluorescent molecular imprinted melatonin nanoparticles; ii) synthesis of functional nanofilms for designing bioinspired sensor surfaces; iii) DNA inspired gatekeeper for developing switchable electrodes. Smart polymerisable terbium(III) complex-based fluorescent molecular imprinted nanoparticles were synthesized for the quantitative determination of potential metabolic biomarkers. Melatonin was chosen as a model metabolite to demonstrate the MIP nanoparticle sensor. We exploited lanthanide ion complexes in our biosensing platforms due to their deeper penetration ability, negligible auto-fluorescence, lack of photo bleaching and photo blinking, and their sharp absorption and emission lines, long lifetime and extreme photo stability. Given the high affinity of lanthanide ions towards carboxylic acid groups, we used two amino acid-based functional monomers, N-methacryloyl-L-aspartic acid (MA-Asp) and N-methacryloyl-L-tryptophan (MA-Trp), to coordinate terbium(III) ions and melatonin, respectively. The fluorescent MIP nanoparticles were synthesized using miniemulsion polymerization technique after forming complexes between terbium(III):MA-Asp and melatonin:MATrp molecules. The fluorescent MIP nanoparticles have been used for melatonin adsorption from aqueous solutions. The integration of biological molecules or their active sites into a synthetic polymeric backbone is one possible way to achieve biomimicking of the recognition features typical of biological molecules, such as amino acids, peptides and nucleic acids. Amino acid residues are the origin of the functional properties and highly selective substrate-binding ability of many extended biological structures. In the second part of this study, a polymerizable derivative of an amino acid (L-histidine) was synthesized N-methacryloyl-L-histidine (MAH). Then, MAH was polymerized in the presence of polyvinyl alcohol (PVA) as a sacrificial polymer, to create a macroporous functional polymer on a gold surface. For control purposes, non-porous and non-functional polymers (with and without MAH and PVA) were also synthesized. Scanning electron (SEM) and atomic force (AFM) microscopies were used to characterize the surface morphology of the polymeric films on the gold surface. We systematically investigated the electrochemical behaviour of the polymeric films using differential pulse voltammetry (DPV), to demonstrate the significant affinity of the polymeric film for Cu(II) ions. And, the applicability of proposed strategy to form Cu(II) ion-mediated supramolecular self-assembly on a quartz crystal microbalance (QCM) electrode surface in real time was showed. While DNA has the central role as carrier of genetic information and translation of the genetic code into proteins, it is also an inherently biopolymeric material consists of repeating units called as nucleotides. Besides its biological functions, DNA can be used in the construction of various functional materials via mimicking self-assembling of complementary DNA strands through non-covalent hydrogen bonds for the fields such as bioanalysis, DNA computing, DNA nanotechnology and nanomedicine due to its physical and chemical properties. Herein, inspired from DNA to synthesize polymerizable derivative of some bases (adenine, thymine and guanine) through a set of reactions with benzotriazole methacrylate (MA-Bt). By this way, new monomers methacryloyladenine (MA-Ade), methacryloylthymine (MA-Thy) and methacryloylguanine (MA-Gua) were obtained. Then, these monomers were polymerized with acrylamide to produce linear polymeric backbone carrying nucleotide functionalities. After that, each linear polymers (poly-Ade, poly-Gua, and poly-Thy) were complexed on the glassy carbon electrodes in presence of graphene which was included to enhance conductivity to develop switchable electrodes in respect to change in ambient temperature. The effects of temperature and scan rate were evaluated while some spectrometric and impedimetric measurements were conducted for characterization purpose. Finally, spectrophotometry (temperature-controlled release study by using tryptophan) was performed to show the switchability of the interpolymeric system in respect to temperature.