| Summary: | 碩士 === 朝陽科技大學 === 應用化學系碩士班 === 94 === Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is used widely in various fields because it has the characteristics of speed, ease of use, high sensitivity, and wide detectable mass range. However the MALDI technique suffered from suppression effect for samples containing excessive amounts of salts or surfactants. The suppression effects can be avoided if target species are isolated from complicated matrix solutions in advance. Hence, we describe a strategy that uses iron oxide nanoparticles to capture charged species from a sample solution. Sodium oleate treated IONPs were employed as affinity probes to selectively concentrate trace amount of peptides and proteins from sample solutions through electrostatic interactions. Because peptides and proteins have unique isoelectric points (pI), by varying the values of pH of the sample solution, specific target proteins or peptides can be concentrated selectively on the surface of the sodium oleate treated IONPs. The IONP@oleate particle then could be easily isolated from the sample solution by employing a magnetic field. After isolation, the target species attached on the surfaces of the IONP@oleate particles were characterized by MALDI-TOF MS after a simple washing. We demonstrate that IONP@oleate particles having negatively charged surfaces are suitable probes for selectively trapping positively charged proteins from aqueous solutions. In addition, we have employed IONP@oleate probe to capture the peptide residues from the enzymatic digest products of cytochrome C.
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