Disposable Microfluidic Paper-Based Device for On-Site Quantification of Urinary Creatinine

Abstract

In this work, a new microfluidic paper-based analytical device (µPAD) was developed for on-hand creatinine quantification in urine samples. When compared to conventional methods, this innovative paper device is more accessible and portable, it provides low-cost analysis (cost of consumables of 40 cents), and it is applicable to non-invasive biological fluids. Furthermore, the paper-based approach is used within an environmentally friendly assembly with no need for wax printing and small amounts of reagents resulting in low waste production and easy disposal by incineration. Its assembly method includes cutting paper discs arranged into several reading units within a plastic pouch, enabling effective creatinine quantification with accuracy based on a vertical flow approach. The method is based on the colourimetric reaction between creatinine and alkaline picric acid, where the solution colour changes from yellow to orange/red. Under optimal conditions, the developed method allowed creatinine quantification in the dynamic range of 2.20–35.0 mg/dL, with a limit of detection (LOD) of 0.66 mg/dL and a limit of quantification (LOQ) of 2.20 mg/dL. The colour intensity developed was processed in ImageJ software, based on digital image scanning, performed in 20 min (up to 4 h) after the sample insertion. The device is stable for up to one week when stored in a vacuum at 4 °C. The method was validated by comparing the results with a batch-wise procedure, where there were no statistically significant differences between both methods.

Microfluidic Paper-Based Device Incorporated with Silica Nanoparticles for Iodide Quantification in Marine Source Dietary Supplements

“…This work aimed to devise a µPAD for quantifying iodide in different sample types based on the reaction between TMB and hydrogen peroxide, coupled with an environmentally friendly assembly technique. In our laboratory, we have developed a new assembly method, without the use of wax printing, by stacking paper discs that have the reagent either on the top or bottom layer [24,26]. The chosen reaction between 3,3 ′ ,5,5 ′tetramethylbenzidine (TMB) and hydrogen peroxide has been detailed in the work of Lin et al [27].…”