A paper-based device for the colorimetric determination of ammonia and carbon dioxide using thiomalic acid and maltol fu
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ORIGINAL PAPER
A paper-based device for the colorimetric determination of ammonia and carbon dioxide using thiomalic acid and maltol functionalized silver nanoparticles: application to the enzymatic determination of urea in saliva and blood Azarmidokht Sheini 1 Received: 6 June 2020 / Accepted: 4 September 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract A colorimetric assay was developed which has the capability of determining urea in biological samples. It is an origami paperbased sensor consisting of silver nanoparticles that were synthesized by using two different capping agents: thiomalic acid and maltol. The function of the assay relied on hydrolysis of urea to ammonia and carbon dioxide in the presence of urease. The products interacted with nanoparticles which caused aggregation. Interestingly, thiomalic acid capped with silver nanoparticles were selective to ammonia, and the other nanoparticles synthesized by maltol responded to carbon dioxide. These interactions turned the color of nanoparticles from yellow to brown and red, respectively. The resulting colorations were captured by a floatable scanner. A routine image analysis software was utilized to provide the response of the assays. The method was applied to individually determine ammonia, carbon dioxide, and urea. The linear range was 0.06 mg.dL−1-170.0 mg.dL−1 for ammonia, 0.08 mg.dL−1-220.0 mg.dL−1 for carbon dioxide, and 0.5 mg.dL−1-200.0 mg.dL−1 for urea. The respective limits of detection were 0.03 mg.dL−1, 0.06 mg.dL−1, and 0.18 mg.dL−1. No interferences were found in the detremination of urea. The method demonstrates a reliable performance for determination of urea in both saliva and blood samples. Keywords Microfluidic device . Nanoparticles . Optical sensor . Point of care . Renal failure
Introduction Urea is the most common biomarker used for evaluating renal failure [1]. While the normal concentration of urea in healthy people is 10–40 mg.dL −1 , it increases to more than 50 mg.dL−1 in patients [2]. Usually, the amount of urea concentration is determined in blood samples based on blood urea nitrogen (BUN) diagnostic test [3], which is regarded as an invasive, painful method. To avoid both invasion and pain, it is better to use a non-invasive process which besides being
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04553-8) contains supplementary material, which is available to authorized users. * Azarmidokht Sheini [email protected]; [email protected] 1
Department of Mechanical Engineering, Shohadaye Hoveizeh University of Technology, Susangerd 78986, Iran
harmless and lacking sampling limitations represents reasonable results. Saliva is the most available biological fluid containing various types of biomarkers [4, 5]. Saliva sampling can be a good alternative to blood tests owing to the fact that it is simple, less costly, and safe [5]. Also, salivary urea determination has gained the attention of researchers over the recent years [6]. Rega
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