Aplicações bionalíticas do imageamento químico por técnicas de ionização ambiente de espectrometria de massas: DESI e LAESI
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2020-03-20
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Universidade Federal de Goiás
Resumo
Recent advances in mass spectrometry allowed the study of samples with little
or no sample preparation. Among these techniques, Desorption Electrospray
(DESI) and Laser Electrospray Ionization (LAESI) has gained popularity for
their ability to generate chemical images and the use of a laser to study
samples under ambient conditions respectively. New DESI users may face
several operational problems due to the lack of a literature describing a
detailed protocol on how to work with this technique. Although there is a rich
literature on DESI, scientific articles always present a brief description of how
the experiments were carried out. Thus, the objective of chapter 1 was to
present a simple protocol on how to perform imaging experiments by DESIMS. This chapter describes how to optimize the spot, geometric parameters
and how to perform an image acquisition. The main application of the DESI
imaging technique is in the medical-clinical area. Numerous researchers have
investigated the chemical signatures of tumors and cancers for biomarkers
that can not only assist on their identification, but also in the development of
new treatments for patients. However, there are several clinical areas that
have not been much explored by this technology, such as diseases caused by
restricted blood flow to the brain. Models of blood flow reduction are often
used in mice to simulate stroke that affects humans. Thus, chapter 2 presents
the results obtained from the DESI-MS evaluation of the brain of animals after
1, 3 and 7 days after ischemia induction. 2D chemical images were generated
for the most abundant ions and PSL-DA statistical analysis was used to verify
the most relevant molecular species for this model. Chapter 3 presents the
use of LAESI-MS technology in the study of cyanobacteria that commonly
produce toxins. The chosen species are known to cause damage to aquatic
bodies due to their extensive proliferation in a short period of time. The
metabolic profile of each species was investigated, and statistic tools were
used to observe the degree of separation between the cyanobacteria species
studied. In addition, ion mobility data were used in order to increase
molecular coverage and confidence in the identification of species of interest.
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VASCONCELOS, G. A. Aplicações bionalíticas do imageamento químico por técnicas de ionização ambiente de espectrometria de massas: DESI e LAESI. 2020. 116 f. Tese (Doutorado em Química) - Universidade Federal de Goiás, Goiânia, 2020.