Abstract
The concentrations of nitrite and thiocyanate in saliva can be used as the biomarkers of the progression of periodontitis disease and environmental tobacco smoke exposure, respectively. Therefore, it is particularly necessary to detect these two indicators in saliva. Herein, the three-dimensional single-layered paper-based microfluidic analytical devices (3D sl-μPADs) were, for the first time, fabricated by the spraying technique for the colorimetric detection of nitrite and thiocyanate at the same time. The conditions for 3D sl-μPADs fabrication were optimized in order to well control the penetration depth of the lacquer in a paper substrate. Then, the developed 3D sl-μPADs were utilized to simultaneously detect nitrite and thiocyanate and the limits of detection are 0.0096 and 0.074 mM, respectively. What is more, the μPADs exhibited good specificity, good repeatability, and acceptable recoveries in artificial saliva. Therefore, the developed 3D sl-μPADs show a great potential to determine nitrite and thiocyanate for the assessment of the human health.
Highlights
Nitrite (NO2 − ) widely exists in the environment, food, industry, and physiological systems, which is recognized as a hazardous species [1,2]
Spraying technique is effective at penetrating the lacquer vertically through the cellulose pore spaces and thereby forming a hydrophobic barrier [33]
Spraying effective at penetrating lacquer vertically through the cellulose thereby forming a hydrophobic barrier controlled lacquer deposition devicesspaces were and left at 24 h and the food dye with redLimited color
Summary
Nitrite (NO2 − ) widely exists in the environment, food, industry, and physiological systems, which is recognized as a hazardous species [1,2]. Developed the cost-effective μPADs to determine thiocyanate in saliva with low detection limit of. Li et al prepared three-dimensional microfluidic channels by a wax printer in a piece of filter paper [28] These studies have made a significant breakthrough in 3D sl-μPADs fabrication. The developed 2D μPADs provided a simple and cost-effective platform for bioassays [34] These studies have had great breakthroughs in applying the spraying technique to the manufacture of 2D μPADs, there are only a few studies to report the spraying method for fabricating 3D μPADs. Phillips group used the wax-printing technique to make patterned paper and used the glue-spraying method for layers alignment [35]. There is still a great challenge to apply the spraying method to construct 3D channels in a single piece of filter paper. The results show satisfactory sensitivity, good specificity, good repeatability, and acceptable recoveries in artificial saliva toward nitrite and thiocyanate detection
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