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Navegando IQ - Artigos publicados em periódicos por Autor "Abdelnur, Patrícia Verardi"
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Item 3D printing of microfluidic devices for paper-assisted direct spray ionization mass spectrometry(2016) Duarte, Lucas da Costa; Carvalho, Thays Colletes de; Lobo Júnior, Eulício de Oliveira; Abdelnur, Patrícia Verardi; Vaz, Boniek Gontijo; Coltro, Wendell Karlos TomazelliThis study describes the use of a 3D printer to fabricate microfluidic devices for direct spray ionization mass spectrometry (DS-MS) assisted by paper tips. The layout of the proposed devices was designed in a three-dimensional model through a computer-aided design system and printed by a fused deposition modeling method using a thermoplastic filament composed of acrylonitrile butadiene styrene deposited layer by layer. The smallest channel width was 400 μm to ensure 3D printing uniformity without any obstruction. For DS-MS studies, microfluidic channels consisted of a single channel connected to a sample reservoir (3 mm diameter). The printed channel was 3 cm long, 500 μm wide and 500 μm deep. Paper tips (0.5 cm long × ca. 0.5 mm wide) were manually cut and inserted into the extremity of the printed channel to facilitate the spray formation. The spray was promoted by the application of 4 kV at the sample reservoir containing 0.1% formic acid prepared in methanol. This organic medium selected for MS experiments has demonstrated great compatibility with the polymeric material employed to create microfluidic chips. 3D printed devices were kept at a distance of 3 mm from the MS entrance. Using glucose solution as the model, the formed spray by the proposed microfluidic device was extremely stable in comparison to traditional paper spray ionization devices for at least 10 min. The analytical feasibility of printed devices for DS-MS was successfully demonstrated by qualitative analysis of ballpoint pen inks, caffeine, xylose and lysozyme. The 3D printer has allowed the fabrication of printed devices at a very low cost ($0.05) within 20 min. Furthermore, 3D printed devices have exhibited significant repeatability and reproducibility, making their reuse possible. Based on the performance of the proposed devices, we believe they can be used in a broad range of bioanalytical applications.Item Differentiation of toxic and non-toxic leaves of Jatropha curcas L. genotypes by leaf spray mass spectrometry(2017) Silva, Igor Pereira da; Carvalho, Thays Colletes de; Romão, Wanderson; Filgueiras, Paulo Roberto; Laviola, Bruno Galvêas; Rodrigues, Clenilson Martins; Abdelnur, Patrícia Verardi; Vaz, Boniek GontijoJatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A high protein pie is produced as a byproduct of the biodiesel production, which could be used as animal feed. However, the pie has toxic compounds, as phorbol esters and other toxins, which prevents the use as animal feed. For this reason, Embrapa (Brazilian Agricultural Research Corporation) has been working in genetic breeding to develop non-toxic J. curcas genotypes. To evaluate this process, a simple and fast analytical technique was employed to obtain responses in a short time. Leaf spray (LS) is a recent ambient ionization mass spectrometry technique in which the sample itself serves as support and ion source. Here, toxic and non-toxic J. curcas leaves were differentiated by LS using a linear ion trap mass spectrometer and partial least squares discriminant analysis (PLS-DA) model chemometrics. It was possible to differentiate toxic and non-toxic leaves and to identify the m/z values that contribute to discrimination between the groups.Item Metabolomics analysis of oil palm (Elaeis guineensis) leaf: evaluation of sample preparation steps using UHPLC–MS/MS(2016) Vargas, Luiz Henrique Galli; Rodrigues Neto, Jorge Candido; Ribeiro, José Antônio de Aquino; Silva, Maria Esther Ricci da; Souza Junior, Manoel Teixeira; Rodrigues, Clenilson Martins; Oliveira, Anselmo Elcana de; Abdelnur, Patrícia VerardiIntroduction Metabolomics analysis of oil palm leaves is a promising strategy to prospect new added-value compounds of this underutilized oil industry by-product. Although previous studies had reported some metabolites identified in this matrix, they had been focused on few compounds using conventional analytical techniques. Objectives This study aimed to develop a new high throughput method based on metabolomics able to detect a wide range of metabolites classes in Elaeis guineensis leaves. Furthermore, we investigate the effects caused by harvesting/sample preparation steps for the metabolites identification. Method Metabolites analyses were performed by ultra-high liquid chromatography—mass spectrometry (UHPLC–MS) using both ionization modes, ESI(+)–MS and ESI(−)–MS. ANOVA simultaneous component analysis (ASCA) of the resulting complex multivariate dataset was applied to evaluate metabolic alterations. Identification of major metabolites was performed by high resolution mass spectrometry and MS/MS experiments. Result A high throughput method based on UHPLC–MS was successfully developed to E. guineensis leaves, detecting from polar to non-polar acid and basic metabolites. According to ASCA, oil palm leaves metabolic fingerprintings have shown influence of transportation/storage and extraction solvent used chosen. In fact, the most significant effect is due to the solvent composition. A total of thirteen metabolites were assigned based on HRMS and MS/MS experiments. However, only seven metabolites identified were previously reported, which represents a potential field to discover new metabolites. Conclusion Sample preparation steps should be carefully performed in metabolomics studies, because metabolites will be extracted and identified based on transport and solvent of extraction conditions. In this study, we established a reliable analytical protocol, from sample preparation to data analyses, to prospect new metabolites in oil palm leaves. This protocol could be further applied to similar oil-bearing crops.Item Molecularly imprinted polymer-coated probe electrospray ionization mass spectrometry determines phorbol esters and deoxyphorbol metabolites in jatropha curcas leaves(2019) Silva, Lidya Cardozo da; Carvalho, Thays Colletes de; Silva, Igor Pereira da; Marana, Júlio César; Laviola, Bruno Galvêas; Abdelnur, Patrícia Verardi; Vaz, Boniek GontijoIn this study, a molecularly imprinted polymer-coated probe electrospray ionization mass spectrometry (MIPCPESI-MS) method was developed for detection of phorbol esters (PEs) and deoxyphorbol metabolites in Jatropha curcas leaves. Such an approach was established by sticking on a metallic needle a molecularly imprinted polymer to particularly design a MIP-coated probe for selective sampling and ionization of PEs and deoxyphorbol metabolites. By a subsequent application of a high voltage and methanol, as spray solvent, ESI was generated for direct and rapid analysis under ambient and open-air conditions. MIP-coated probe exhibited a high sampling capacity of the PEs and its metabolites in methanolic extracts of J. curcas leaves compared with the non-imprinted polymer (NIP)-coated probe. MIPCPESI-MS allowed the detection of phorbol 12,13-diacetate (PDA) from J. curcas leaves with minimal sample preparation, and with detection limit and quantification reaching 0.28 μg/mL and 0.92 μg/mL, respectively. Also, good linearity was obtained with R2 > 0.99 and precision and accuracy values between 4.06–13.49% and − 1.60 to − 15.26%, respectively. The current method was successfully applied to screening methanolic extracts of six different J. curcas leaf genotypes (three toxic and three non-toxic). PDA and three PE deoxyphorbol metabolites were identified only from toxic genotypes, in which PDA was determined with concentration ranging from 222.19 ± 23.55 to 528.23 ± 19.72 μg/g. All these findings support that the MIPCPESI-MS method developed here has a high potential for the analysis of PEs in plant extracts enabling differentiation of toxic and non-toxic genotypes earlier in the leaves.Item A new insert sample approach to paper spray mass spectrometry: a paper substrate with paraffin barriers(2016) Carvalho, Thays Colletes de; Garcia, Paulo de Tarso; Campanha, Raquel Bombarda; Abdelnur, Patrícia Verardi; Coltro, Wendell Karlos Tomazelli; Romão, Wanderson; Vaz, Boniek GontijoThe analytical performance for paper spray (PS) using a new insert sample approach based on paper with paraffin barriers (PS-PB) is presented. The paraffin barrier is made using a simple, fast and cheap method based on the stamping of paraffin onto a paper surface. Typical operation conditions of paper spray such as the solvent volume applied on the paper surface, and the paper substrate type are evaluated. A paper substrate with paraffin barriers shows better performance on analysis of a range of typical analytes when compared to the conventional PS-MS using normal paper (PS-NP) and PS-MS using paper with two rounded corners (PS-RC). PS-PB was applied to detect sugars and their inhibitors in sugarcane bagasse liquors from a second generation ethanol process. Moreover, the PS-PB proved to be excellent, showing results for the quantification of glucose in hydrolysis liquors with excellent linearity (R2 = 0.99), limits of detection (2.77 mmol L−1) and quantification (9.27 mmol L−1). The results are better than for PS-NP and PS-RC. The PS-PB was also excellent in performance when compared with the HPLC-UV method for glucose quantification on hydrolysis of liquor samples.Item Uncovering the formation of color gradients for glucose colorimetric assays on microfluidic paper-based analytical devices by mass spectrometry imaging(2018) Freitas, Soraia Vasconcelos de; Souza, Fabricio Ribeiro de; Vasconcelos, Géssica Adriana; Abdelnur, Patrícia Verardi; Vaz, Boniek Gontijo; Henry, Charles S.; Coltro, Wendell Karlos TomazelliThis 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 commonly seen in microfluidic paper-based analytical devices (μPADs). The formation of color gradients significantly impacts assay sensitivity and reproducibility with μPADs but the mechanism for formation is poorly understood. 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. While a variety of hypotheses have been generated to explain this phenomenon, few studies have attempted to elucidate the mechanisms associated with its formation. Mass spectrometry imaging using MALDI and DESI was applied to understand the nonuniform 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 and triiodide ions at the zone edge. The reaction product (I3–) is transported by lateral flow toward 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 enzyme distribution on μPAD surface.