Eletroforese em microssistemas: desenvolvimento instrumental, microfabricação e análise de nitrosotióis
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2019-09-27
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Universidade Federal de Goiás
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Microchip electrophoresis (ME) has become an important tool in analytical and bioanalytical
chemistry applications. Miniaturization of analytical devices include several advantages and the
development of new systems and methods are needed. This thesis presents some instrumental
advances in ME, including separation of carbohydrates that was possible minimizing the
electrolysis phenomena, the manufacture of ME in glass using a photo-curable resin, and a
procedure for integrated analysis of s-nitrosotióis. The separation of fructose, galactose, lactose,
glucose and sucrose in commercial microchips using an apparatus, built to minimize electrolysis, is
presented. The apparatus consists of additional reservoirs, which are connected to the reservoirs of
the microchip through a saline bridge. The separations were performed using an electrolyte
composed by NaOH (75 mmol/L) and Na 3 PO 4 (15 mmol/L) and monitored by capacitively coupled
contactless conductivity detection (C 4 D). Efficiencies ranging from 45000 to 70000 plates/m were
achieved. The system offered good linearity from 1 to 10 mmol/L and LOD between 150 and 740
μmol/L. The manufacture of microchips using glass and NOA (Norland Optical Adhesive), a
photo-curable resin, for application in electrophoresis was proposed. Simplicity in the
manufacturing process allows research centers still under development to produce their glass
microsystems simply and quickly. Studies to evaluate morphology, magnitude and stability of
electroosmotic flow and solvent compatibility were performed. S-nitrosothiols (RSNO) are very
important biomolecules that play crucial roles in many physiological and physiopathological
processes, acting as NO donors. One, two or more RSNO can then be combined to design a drug
and therefore, the quantification of each is important to establish an acceptable quality control
process. This study reports on an original and integrated microdevice allowing for the successive
electrokinetic separation of low molecular weight RSNOs, their decomposition under metal
catalysis, and their quantitation by amperometric detection of the produced nitrite in the end-
channel arrangement, leading to their quantitation in a single run. Different operating and running
parameters were optimized to achieve the best analytical data, allowing for an LOD equal to 20
μM. The simultaneous separation of S-nitrosoglutathione and S-nitrosocysteine was successfully
obtained within 75 s. The proposed methodology using SU-8/Pyrex microfluidic devices opens
new possibilities to investigate future drug candidates for NO-donors.
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DUARTE JUNIOR, Gerson F. Eletroforese em microssistemas: desenvolvimento instrumental, microfabricação e análise de nitrosotióis. 2019. 104 f. Tese (Doutorado em Química) - Universidade Federal de Goiás, Goiânia, 2019.