A novel ratiometric design of microfluidic paper-based analytical device for the simultaneous detection of Cu2+ and Fe3+ in drinking water using a fluorescent MOF@tetracycline nanocomposite.

The regular and on-site monitoring of ions in drinking water is essential for safeguarding public health, ensuring high water quality, and preserving the ecological balance of aquatic ecosystems. Thus, developing a portable analytical device for the rapid, cost-effective, and visual on-site detection of multiple environmental pollutants is notably significant. In the present work, a novel ratiometric microfluidic paper-based analytical device (µPAD) was designed and developed for the simultaneous detection of Fe3+ and Cu2+ ions in water samples taking advantages from built-in masking zone. The µPAD was functionalized with a greenish-yellow fluorescent Zn-based metal-organic framework@tetracycline (FMOF-5@TC) nanocomposite, and the ratiometric design was based on the change in emission color from greenish yellow (FMOF-5@TC) to blue (FMOF-5). The µPAD consisted of one sample zone linked to two detection zones via two channels: the first channel was for the detection of both ions, while the second was intended for detecting only Cu2+ ions and comprised a built-in masking zone to remove Fe3+ ions prior to reaching the detection zone. The corresponding color changes were recorded with the aid of a smartphone and RGB calculations. The linear ranges were 0.1-80 µM for Cu2+ and 0.2-160 µM for Fe3+, with limits of detection of 0.027 and 0.019 µM, respectively. The simple µPAD design enabled the simultaneous detection of Cu2+ and Fe3+ ions in drinking water samples with excellent accuracy and precision, with spike recoveries of 81.28-96.36% and 83.01-102.33% for Cu2+ and Fe3+, respectively.

Dual-spot ratiometric microfluidic paper-based analytical device for accuracy and precision improvement.

Instrumental and environmental fluctuations are common sources of error in smartphone-based optical detection, significantly affecting the accuracy of analytical measurements. In this regard, spotting the sample and reference simultaneously and in close proximity compensates for the fluctuations. This "dual-spot" design is similar to the double-beam technique used in spectrophotometry, which reduces fluctuations in the results. The underlying hypothesis is that any instrumental and/or environmental factors influencing the color intensity in the detection zones will similarly impact the color intensity in the control zone under the same conditions. To test our design, a ratiometric microfluidic paper-based analytical device (µPAD), functionalized with a mixture of green-emissive carbon dots (CDs) and red-emissive ethidium bromide, was developed for the selective detection of ascorbic acid (AA). The green emission of the CDs is quenched by both AA and Fe3+; NaF was thus loaded onto the 3D connector as a masking agent to remove the interference effect of the Fe3+ ions. The color variations were monitored under a UV lamp, using a smartphone to capture the images, and the RGB intensities were processed using the Color Grab application. The proposed double-spot method greatly enhanced the analytical precision and accuracy of the device. A linear working range from 0 to 125 µM was obtained, and the limit of detection was 2.71 µM. The µPAD was successfully used for the detection of AA in human serum, with recoveries from 87.27 to 98.52 %.

Comparing effects of beetroot juice and Mediterranean diet on liver enzymes and sonographic appearance in patients with non-alcoholic fatty liver disease: a randomized control trials.

Background: In both developed and developing countries, non-alcoholic fatty liver disease (NAFLD) has lately risen to the top of the list of chronic liver illnesses. Although there is no permanent cure, early management, diagnosis, and treatment might lessen its effects. The purpose of conducting the current study is to compare the effects of beetroot juice and the Mediterranean diet on the lipid profile, level of liver enzymes, and liver sonography in patients with NAFLD. Methods: In this randomized controlled trial, 180 people with a mean age of (45.19 ± 14.94) years participated. Participants ranged in age from 19 to 73. The mean weight before intervention was (82.46 ± 5.97) kg, while the mean weight after intervention was roughly (77.88 ± 6.26) kg. The trial lasted for 12 weeks. The participants were split into four groups: control, a Mediterranean diet with beet juice (BJ + MeD), Mediterranean diet alone (MeD), and beetroot juice (BJ). The Mediterranean diet included fruits, vegetables, fish, poultry, and other lean meats (without skin), sources of omega-3 fatty acids, nuts, and legumes. Beetroot juice had 250 mg of beetroot. Data analysis was done using SPSS software (version 26.0). p < 0.05 is the statistical significance level. Results: Following the intervention, Serum Bilirubin, alkaline phosphatase (ALP), alanine transaminase (ALT), serum cholesterol (CHOL), triglyceride (TG), and low-density lipoprotein (LDL) levels were significantly decreased in the BJ + MeD, BJ, and MeD groups (p = 0.001). Also, high-density lipoprotein (HDL) significantly increased in the BJ + MeD, BJ, and MeD groups (p = 0.001), while decreasing in the Control group (p = 0.001). Conclusion: The research findings indicate a significant reduction in hepatic steatosis among the groups receiving beetroot juice (BJ) and beetroot juice combined with the Mediterranean diet (BJ + MeD). This suggests that beetroot juice holds potential as an effective treatment for non-alcoholic fatty liver disease (NAFLD) in adults. Furthermore, the combination of beetroot juice with the Mediterranean diet showed enhanced efficacy in addressing NAFLD.Clinical trial registration: ClinicalTrials.gov, identifier NCT05909631.

Accuracy improvement via novel ratiometry design in distance-based microfluidic paper based analytical device: instrument-free point of care testing.

Developing accurate, precise, instrument-free, and point-of-need microfluidic paper-based devices is highly significant in clinical diagnosis and biomedical analysis. In the present work, a ratiometric distance-based microfluidic paper-based analytical device (R-DB-µPAD), along with a three-dimensional (3D) multifunctional connector (spacer), was designed to improve the accuracy and detection resolution analyses. Specifically, the novel R-DB-µPAD was used for the accurate and precise detection of ascorbic acid (AA) as a model analyte. In this design, two channels were fabricated as detection zones, with a 3D spacer located between the sampling and detection zones to improve the detection resolution by preventing the reagents mixing from overspreading between these zones. Two probes for AA were used: Fe3+ and 1,10-phenanthroline were deposited in the first channel, and oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) was added to the second channel. Accuracy improvement of this ratiometry-based design was achieved by enhancing the linearity range and reducing the volume dependency of the output signal. Moreover, the 3D connector improved the detection resolution by eliminating the systematic errors. Under the optimal conditions, the ratio of the distances of the color bands in the two channels was used to construct an analytical calibration curve in the range from 0.05 to 1.2 mM, with a limit of detection of 16 µM. The proposed R-DB-µPAD combined with the connector was successfully used for the detection of AA in orange juice and vitamin C tablets with satisfactory accuracy and precision. This work opens the door for multiplex analysis of various analytes in different matrices.

Paper-based optical nanosensors - A review.

Paper-based analytical devices (PADs) have shown great promise for point-of-care testing and on-site detection of analytes with chemical, biochemical, and environmental importance owing to their low cost, convenience, scalability, portability, and biocompatibility. The World Health Organization stated that sensors should meet the ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverable). Paper-based optical sensors meet most of these criteria, making them in high demand and applicable in remote areas. Optical PADs outputs are obtained by different means, such as dyes, nanostructures, redox agents, and pH indicators. The outstanding physical and chemical characteristics of nanostructures, their intense signals, and tunable optical properties make them ideal for many sensing platforms, including paper-based ones. This review focuses primarily on paper-based nanosensors using various nanostructures to fabricate and produce optical signals for visualization. We describe the fundamentals and state of the art of PADs and comprehensively explain the following topics: paper types as the substrate of PADs, PAD fabrication approaches, nanostructure stabilization on PADs, signal acquisition, data handling, interpretation of results, sensing mechanisms, and application areas. We also discuss future trends and strategies to enable PADs to reach their full potential and increase their commercialization opportunities.

Enhancing of detection resolution via designing of a multi-functional 3D connector between sampling and detection zones in distance-based microfluidic paper-based analytical device: multi-channel design for multiplex analysis.

One of the problems in the distance-based microfluidic paper-based analytical device (DB-µPAD) that limits the detection resolution is the mixing of reagents from the detection to the sampling zone or vice versa due to spreading by capillary action. In the present paper, to overcome mixing of the reagents in the zones, a multi-functional connector using a three-dimensional (3D) design has been developed externally to connect the two zones. Using such a novel design, it is acertained that there is no any mixing due to the dispersion of the reagents in the two zones. Interestingly, the simple 3D connector has other functions, such as its potential to be used as a masking zone and/or reaction zone whenever is needed. Based on this proposed 3D connector-based DB-µPAD, three parallel microchannels were built as detection zones with one sampling zone for multiplex analysis for the detection of Fe2+, Ni2+, and hardness of water. In the Ni2+ channel, the connector piece worked as both masking part and connection part. In the Fe2+ line, the connector served as the connector and reducing pad (Fe3+ to Fe2+ ions). While in the third channel, the connector has connection function only. Satisfactory limit of detection (LoD), accuracy, and precision were obtained using this design. The LODs obtained with the proposed design were 1.13, 0.62, and 1.87 mg.L-1 for total hardness, Fe2+, and Ni2+, respectively.