ABDELNUR, P. V.

COLTRO, W. K. T.

FREITAS, S. V. de

HENRY, C. S.

NETO, J. C. R

SOUZA, F. R. de

VASCONCELOS, G. A.

VAZ, B. G.

English

Repository Open Access to Scientific Information from Embrapa

 UNCOVERING THE FORMATION OF COLOR GRADIENTS ON MICROFLUIDIC PAPER-BASED ANALYTICAL DEVICES BY MASS SPECTROMETRY IMAGING  Soraia V. de Freitas (PG)a*, Fabrício R. de Souza (PG)a, Jorge C. R. Neto (PG)a,b,  Géssica A. Vasconcelos (PG)a, Patrícia V. Abdelnur (PQ)a,b, Boniek G. Vaz (PQ)a, Charles S. Henry (PQ)c and Wendell K. T. Coltro (PQ)a,d  aUniversidade Federal de Goiás, Instituto de Química, 74690-900, Goiânia/GO, Brazil.  bEmbrapa Agroenergia, Empresa Brasileira de Pesquisa Agropecuária, 70770-901, Brasília/DF, Brazil. cColorado State University, 80523, Fort Collins/CO, USA. dInstituto Nacional de Ciência e Tecnologia de Bioanalítica, 13084-971, Campinas/SP, Brazil. *e-mail: soraiavasfreitas@gmail.com  Colorimetric detection has been widely used with microfluidic paper-based devices ( PADs) for different types of studies.1,2 Even colorimetric detection is an attractive detection tool, the formation of color gradients significantly impacts assay sensitivity and reproducibility with . This study describes the use of mass spectrometry imaging with matrix-assisted laser desorption/ionization (MALDI) and desorption electrospray ionization (DESI) to understand the color gradient generation . The glucose enzymatic assay using potassium iodide (KI) as a chromogenic agent was selected to investigate the color gradient generated across a detection spot. Colorimetric measurements revealed that the relative standard deviation for the recorded pixel intensities ranged between 34 and 40%, compromising the analytical reliability. Then, mass spectrometry imaging using MALDI and DESI was applied to understand the non-uniform color distribution on the detection zone. MALDI experiments were first explored to monitor the spatial distribution of the glucose oxidase and horseradish peroxidase mixture, before and after lateral flow assay with and without KI. MALDI(+)-TOF data revealed uniform enzyme distribution on the detection spots. On the other hand, after the complete assay DESI(-) measurements revealed a heterogeneous shape indicating the presence of iodide at the zone edge. Furthermore, DESI(-) showed the presence of triiodide ions (I3-), generated from the interaction between molecular iodine and the iodide spotted on the detection zones. The I3- is transported by lateral flow towards the zone edge, generating the color gradient. Mass spectrometry imaging has been used for the first time to prove that color gradient forms as result of the mobility small molecules and not the s surface. 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 3000102030405060708090100Relative Abundance126.9m/z(A) (C)(B)1000(D) Figure 1. DESI imaging showing the spatial distribution of I- ((m/z 126,90389) in the detection zone containing (A) KI before lateral flow assay, (B) KI and (C) KI plus GOx/HRP after lateral flow for glucose detection. Graph (D) shows the MS spectrum for the mass range monitored in the paper surface   1 Morbioli, G. G.; Mazzu-Nascimento, T.; Stockton, A. M.; Carrilho, E. Technical Aspects and Challenges of Colorimetric Detection with Microfluidic Paper- - A Review. Anal. Chim. Acta 2017, 970, 1 22. 2 Li, X.; Ballerini, D. R.; Shen, W. A Perspective on Paper-Based Microfluidics: Current Status and Future Trends. Biomicrofluidics 2012, 6 (1). [CAPES, CNPq, FAPEG and INCTBio] 491

Uncovering the formation of color gradients on microfluidic paper-based analytical devices by mass spectrometry imaging.

http://www.alice.cnptia.embrapa.br/bitstream/doc/1100383/1/ENQA2018ResumoUncovering2018.pdf

Uncovering the formation of color gradients on microfluidic paper-based analytical devices by mass spectrometry imaging.

Abstract

Similar works

Full text

Available Versions

Repository Open Access to Scientific Information from Embrapa