Development of nitinol fiber chemically coated with zwitterionic polymeric ionic liquids for determination of beta-amyloids in plasma samples from patients with Alzheimer's disease by direct coupling fiber-in-tube SPME and MS/MS
Alzheimer's disease (AD) has been considered one of the main neurodegenerative diseases affecting about 5% of people over than 65 years old. Common symptoms of AD include declining in cognitive and memory skills. Considering the pathophysiology, AD has been characterized by the accumulation of ²-amyloid proteins and TAU microtubulin in senile plaques and neurofibrillary structures. The diagnosis of AD has been conducted based on the criteria established by international institutes (NINCDS and ADRDA), which are based on clinical tests of symptoms presented by the patient, family members report, cognitive tests and neurological evaluation. Therefore, the biomarkers, endogenous molecules which may be related to neurological disorders, is of utmost importance to improve the AD diagnosis. ²-amyloid peptides (A²40 and A²42) have been studied as potential biomarkers of AD. Recently, analytical techniques such as mass spectrometry coupled with liquid chromatography (HPLC-MS) and off-line solid phase extraction (SPE) have been applied for quantitative determinations of ²-amyloid peptides in biological fluids. The solid phase microextraction technique using stationary phase coated into capillaries (in-tube SPME) allows sample preparation step hyphenated with the chromatographic system, resulting in the automation of analysis and improving the analytical accuracy and precision of the method. In order to increase extraction efficiency, Jinno and colleagues propose the fiber-in-tube SPME, a variant of the in-tube SPME technique. Normally, the capillaries used in fiber-in-tube SPME are polyetheretherketone (PEEK) tubing packed with selective stationary phase coated onto fused silica SPME fibers. The longitudinal arrangement of these fibers within the capillary generates microchannels that favor both the mass transfer (convection process) process of the sample to a stationary phase and the low pressure of the analytical system and reduces the internal dead volume of the capillary. The innovation of polymeric ionic liquids as new stationary phases is due to their high chemical and physical and selective sorption capabilities that can be tuned by changes in the chemical structure of the monomers. Zwiterionic polymeric ionic liquids is a subcategory of polymeric ionic liquids, that contains positive (cation) and negative (anion) charges located in the structure of the same molecule. For this reason, zwiterionic polymeric ionic liquids exhibit greater stability in the presence of organic solvents and solutions with different ionic strength. In the first part of this project, innovative nitinol fibers (last generation SPME fibers) coated with zwiterionic polymeric ionic liquids will be synthesized in collaboration with Prof. Dr. Jared L Anderson (Ames, USA). In the laboratory of Dr. Maria Eugenia Queiroz Nassur - FFCLRP / USP (Ribeirão Preto, Brazil), PEEK tubes will be packed with these fibers for direct coupling of fiber-in-tube SPME to the mass spectrometry (fiber-in-tube SPME-MS/MS) equipped with an ESI micro source. After optimization of all variables selected in the fiber-in-tube SPME-MS/MS method, it will be validated to determine the ²-amyloid peptides in plasma sample of AD patients and the control group (healthy patients). The correlations between ²-amyloid plasma concentration and patients' clinical symptoms will be done in collaboration with Prof. Dr. Vitor Tumas at Ribeirão Preto Medical School of University of São Paulo (Ribeirão Preto, Brazil). The Fiber-in-tube-SPME-nanoHPLC-ESI-MS scale will also be evaluated in the Chemistry Institute of University of Sao Paulo (São Carlos, Brazil).
News published in Agência FAPESP Newsletter about the scholarship: