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Lab-on-paper, or microfluidic paper-based analytical devices (μPADs), use paper as a substrate material, and are patterned with a system of microchannels, reaction zones and sensing elements to perform analysis and detection. The sample transfer in such devices is performed by capillary action. As a result, external driving forces are not required, and hence the size and cost of the device are significantly reduced. Lab-on-paper devices have thus attracted significant attention for point-of-care medical diagnostic purposes in recent years, particularly in less-developed regions of the world lacking medical resources and infrastructures. This review discusses the major advances in lab-on-paper technology for blood analysis and diagnosis in the past five years. The review focuses particularly on the many clinical applications of lab-on-paper devices, including diabetes diagnosis, acute myocardial infarction (AMI) detection, kidney function diagnosis, liver function diagnosis, cholesterol and triglyceride (TG) analysis, sickle-cell disease (SCD) and phenylketonuria (PKU) analysis, virus analysis, C-reactive protein (CRP) analysis, blood ion analysis, cancer factor analysis, and drug analysis. The review commences by introducing the basic transmission principles, fabrication methods, structural characteristics, detection techniques, and sample pretreatment process of modern lab-on-paper devices. A comprehensive review of the most recent applications of lab-on-paper devices to the diagnosis of common human diseases using blood samples is then presented. The review concludes with a brief summary of the main challenges and opportunities facing the lab-on-paper technology field in the coming years.

Sodium benzoate (NaB) is a versatile food preservative that has also found some applications in the treatment of medical disorders. However, till date, its possible widespread effects on the body are not well studied. We examined the likely effect of diet-added NaB on weight/food intake, haematological parameters, neurobehaviour, antioxidant status, lipid profile and anti-inflammatory/apoptotic markers in mice. Animals were assigned randomly into 4 groups of 10 mice each. Groups included normal control (fed rodent chow) and three groups fed NaB at 125 (0.0125%), 250 (0.025% and 500 (0.05%) mg/kg of feed added to diet, respectively, for eight weeks. Body weight and food intake were assessed. At the end of the experimental period animals were euthanized, blood was then taken for the assessment of haematological, biochemical and inflammatory/apoptotic markers. At the lowest concentration, NaB diet increased body weight and food intake. Decrease in haematological cell counts and total antioxidant capacity were observed, whereas serum malondialdehyde levels and superoxide dismutase activity were increased across the three concentrations. Serum tumour necrosis factor-alpha and interleukin-10 decreased, whereas caspase-3 levels showed no significant difference. Lipid profile and biochemical indices of kidney and liver function were also affected by NaB diet. In conclusion, our findings suggest that NaB may be harmful if regulations regarding its limit of consumption are mistakenly or deliberately ignored. Therefore, it is advisable that regulations on quantities to be added to food be enforced.

Toxicities linked with Benzo (a) pyrene B[a]P exposure, particularly in liver and kidney have been reported in both animals and humans. Taurine (2-aminoethane sulfonic acid) is an intracellular β-amino acid reported to elicit hepatorenal protective functions. However, the modulatory effect of taurine on hepatorenal toxicity associated with exposure to B[a]P has not been reported. This study evaluated the effects of taurine on the hepatorenal toxicities induced in cohorts of rats exposed to B[a]P. Experimental rats were treated as follows: B[a]P (10 mg/kg); co-treated cohorts –B[a]P (10 mg/kg) plus taurine (100 or 200 mg/kg) for 4 successive weeks. Results show that co-dosing with taurine significantly (P

In this paper, we propose a generalized concept of microfluidic polydimethylsiloxane (PDMS) on paper (POP) devices, which combines well the merits of paper chips and PDMS chips. First, we optimized the conditions for accurate PDMS spatial patterning on paper, based on screen printing and a high temperature enabled superfast curing technique, which enables PDMS patterning to an accuracy of tens of microns in less than ten seconds. This, in turn, makes it available for seamless, reversible and reliable integration of the resulting paper layer with other PDMS channel structures. The integrated POP devices allow for both porous paper and smooth channels to be spatially defined on the devices, greatly extending the flexibility for designers to be able to construct powerful functional structures. To demonstrate the versatility of this design, a prototype POP device for the colorimetric analysis of liver function markers, serum protein, alkaline phosphatase (ALP) and aspartate aminotransferase (AST), was constructed. On this POP device, quantitative sample loading, mixing and multiplex analysis have all been realized.

In developed nations, monitoring for drug-induced liver injury through serial measurements of serum transaminases [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] in at-risk individuals is the standard of care. Despite the need, monitoring for drug-related hepatotoxicity in resource-limited settings is often limited by expense and logistics, even for patients at highest risk. This article describes the development and clinical testing of a paper-based, multiplexed microfluidic assay designed for rapid, semiquantitative measurement of AST and ALT in a fingerstick specimen. Using 223 clinical specimens obtained by venipuncture and 10 fingerstick specimens from healthy volunteers, we have shown that our assay can, in 15 min, provide visual measurements of AST and ALT in whole blood or serum, which allow the user to place those values into one of three readout "bins" [3× upper limit of normal (ULN), 3 to 5× ULN, and5× ULN, corresponding to tuberculosis/HIV treatment guidelines] with90% accuracy. These data suggest that the ultimate point-of-care fingerstick device will have high impact on patient care in low-resource settings.

This paper describes a paper-based microfluidic device that measures two enzymatic markers of liver function (alkaline phosphatase, ALP, and aspartate aminotransferase, AST) and total serum protein. A device consists of four components: (i) a top plastic sheet, (ii) a filter membrane, (iii) a patterned paper chip containing the reagents necessary for analysis, and (iv) a bottom plastic sheet. The device performs both the sample preparation (separating blood plasma from erythrocytes) and the assays; it also enables both qualitative and quantitative analysis of data. The data obtained from the paper-microfluidic devices show standard deviations in calibration runs and “spiked” standards that are acceptable for routine clinical use. This device illustrates a type of test useable for a range of assays in resource-poor settings.