A paper-based analytical device coupled with electrochemical detection for the determination of dexamethasone and prednisolone in adulterated traditional medicines

A Simple, Low Cost, Sensitive, and Portable Electrochemical Immunochromatography Sensing Device to Measure Estrone-3-Sulfate

“…The blank value was 97.5 ± 14.1 nA, and the LOD (blank + 3σ) was 570.5 ng/mL. The results demonstrated LODs that were one to two orders of magnitude lower than those reported in other studies that analyzed small molecule steroids, namely dexamethasone and prednisolone, by electrochemical analysis of paper analysis chips [ 15 ]. Conversely, although the electrochemical signal showed a decreasing change over the entire range, the LOD was poorer than that of ELISA due to the high variability of the signal, with a variance of 9–16% at each concentration.…”

“…We measured the small molecule steroid E 1 S by competitive immunoassay using our previously developed electrochemical immunochromatography platform. Electrochemical immunochromatography demonstrated an LOD of 570.5 ng/mL, which was one to two orders of magnitude better than that of other studies that analyzed small molecule steroids, namely dexamethasone and prednisolone, by electrochemical analysis of paper analysis chips [ 15 ]. In addition, the electrochemical method was shown to be superior to the colorimetric method in immunochromatography.…”

“…For example, it was reported that dopamine, which is one of the steroids, was electrochemically measured within the detection range of 10 nM to 1 µM [ 14 ]. In contrast, dexamethasone and prednisolone that could not be measured electrochemically were measured by competitive immunoassay and they demonstrated reduced sensitivity with their limit of detection (LOD) at 3.59 µg/mL and 11.98 µg/mL, respectively [ 15 ]. In another study, creatinine, which is one of the small molecule compounds, was electrochemically measured in the range from 18.75 µg/mL to 150 µg/mL by measuring the levels of hydrogen peroxidase produced by the enzymatic reaction of creatinine with three enzymes—namely creatininase, creatinase, and sarcosine oxidase [ 12 ].…”

Paper-Based Screen-Printed Electrodes: A New Generation of Low-Cost Electroanalytical Platforms

“…As mentioned before, besides being a flat substrate, paper can have other utilities such as storage of reagents or sample [84,85], support for (biological) reactions [42,[86][87][88][89], or platform for taking [67,90] or treating the sample (e.g., preconcentration [81,91] or separation [79,92,93]). Taking this into account, paper-based electroanalytical devices integrating SPEs can be designed in different formats: (i) combining paper with a SPE card fabricated on ceramic or polymeric materials [79,[84][85][86][87][88][89]91,92,[94][95][96][97][98][99][100][101][102]; (ii) combining one electrode of the electrochemical cell (e.g., WE) made on paper with other electrodes (e.g., RE and CE) of a SPE card printed on a conventional material [42,[103][104][105]; and (iii) printing the SPE directly on paper [5,[106][107][108]. In the last case, 2D devices are the most basic but, by stacking and/or folding the paper along the vertical axis, devices with 3D formats (multilayer and origami) can be easily constructed.…”

“…A wax-dipping technique was used to design microfluidic patterns that consisted of two separation zones and one more for detection, where the enzyme glucose oxidase was immobilized ( Figure 6A). Paper can be employed for separating analytes before their detection as in the microfluidic platform developed by Primpray et al [92]. This device used Whatman SG81 paper, which is an ion exchange paper that combines cellulose with large pore silica gel, for the separation of dexamethasone or prednisolone steroids ( Figure 6B).…”