LDI-MS Analizleri için Etkin ve Seçici Yeni Hedef Yüzeylerin Geliştirilmesi

Abstract

Mass spectrometry (MS) is a very important technique that allows components in the sample to be analysed. When the sample is ionized to form positive or negative charged atoms or molecules, their mass/charge ratio can be determined. Prior to analysis of samples with unspecified or under-defined structures by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), enrichment studies have been the most important and sensitive process for the sample preparation step of mass spectrometry. In this thesis, it was aimed to develop a sample platform which will facilitate the MALDI-MS analyses by enriching the analyte molecule. Ciprofloxacin (CPX) imprinted polymeric nanoparticles (MIP) were prepared with the miniemulsion polymerization method and used as the enrichment material. The synthesized polymeric nanoparticles were characterized by Scanning Electron Microscopy (SEM) and their sizes were found to be about 160 nm. In addition, these nanoparticles were characterized with Fourier Transform Infrared Spectroscopy (FTIR) to understand their chemical structures. Film surfaces were prepared using Poll-L-Lactic Acid (PLLA) based electrospinning method and solvent removal method and served as sample platforms in MALDI-MS applications. Analytical molecules used in this thesis study were analysed on several specimen-holding platforms developed in MALDI-MS applications. The surface properties of the sample holder showed that the presence of 2,5-dihydroxybenzoic acid (DHB) and the MIPs enriched the analyte molecule. When CPX is analysed on PLLA films, the S/N value was calculated as 1289.6. When the same film surface was modified with MIPs, this value was increased to 3926.1. When ciprofloxacin was analysed on the surface of PLLA film with the DHB matrix in the structure, the S/N value was found to be 2847. Therefore, conclusion was made that it is possible to increase the mass intensity value 2 times by using DHB in the PLLA film structure. Moreover, it is possible to increase the relative mass intensity of ciprofloxacin more than 3 times by using MIP on PLLA film surface. This result showed us that the relative massive value of analytes is higher than the conventional matrix applications when MIPs were employed. The development of the PLLA based nanofiber and film sample platforms were used in the mass spectrometry analyses for the first time within the scope of the thesis work will shed light on many studies to be made in this area in the future.