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This study presents a portable, low-cost, point-of-care (POC) system for the simultaneous detection of blood glucose and hematocrit. The system consists of a disposable origami microfluidic paper-based analytical device (μPAD) for plasma separation, filtration, and reaction functions and a 3D-printed cassette for hematocrit and blood glucose detection using a smartphone. The origami μPAD is patterned using a cost-effective label printing technique instead of the conventional wax printing method. The 3D-printed cassette incorporates an array of LED lights, which mitigates the effects of intensity variations in the ambient light and hence improves the accuracy of the blood glucose and hematocrit concentration measurements. The hematocrit concentration is determined quantitatively by measuring the distance of plasma wicking along the upper layer of the origami μPAD, which is pretreated with sodium chloride and Tween 20 to induce dehydration and aggregation of the red blood cells. The filtered plasma also penetrates to the lower layer of the origami μPAD, where it reacts with embedded colorimetric assay reagents to produce a yellowish-brown complex. A color image of the reaction complex is captured using a smartphone inserted into the 3D-printed cassette. The image is analyzed using self-written RGB software to quantify the blood glucose concentration. The calibration results indicate that the proposed detection platform provides an accurate assessment of the blood glucose level over the range of 45-630 mg/dL (R 2 = 0.9958). The practical feasibility of the proposed platform is demonstrated by measuring the blood glucose and hematocrit concentrations in 13 human whole blood samples. Taking the measurements obtained from commercial glucose and hematocrit meters as a benchmark, the proposed system has a differential of no more than 6.4% for blood glucose detection and 9.1% for hematocrit detection. Overall, the results confirm that the proposed μPAD is a promising solution for cost-effective and reliable POC health monitoring.

In low-resource settings, dermatologists may not have the preferred tools needed to evaluate a patient or perform a procedure. Commonplace affordable supplies can be substituted when needed. We describe the use of a blood glucose testing lancet and a paper clip for milia extraction.

Herein we report a quantitative, multiplex assay for disease markers in plasma based on an integrated setup of a portable scanner and a disposable paper-based analytical device (PAD). The quantitative analysis relies on the digital colorimetric reading of the three-layer PAD with 30 assay sites for performing respective chromogenic reactions for plasma uric acid, glucose, and triglyceride, which are considered as important risk factors for cardiovascular diseases. A portable scanner with WiFi transmission capability was used to produce high-quality color images of the PADs and wirelessly transfer them to a smartphone or other mobile devices for data processing. The concentrations of biomarkers in both standard solutions and plasma samples can be directly obtained using a custom-designed smartphone app that is also capable of constructing calibration curves. The detection limits of uric acid, glucose, and triglyceride were determined to be 0.50 mg/dL, 0.84 mmol/L, and 14 mg/dL, respectively, which are below the normal limits and adequate for clinical validation. Owing to the distinct advantages-simple, portable, and cost-effective-this mobile assay protocol can be used for point-of-care (POC) settings or resource-limited situations, and potentially for the diagnosis and prevention of infectious diseases.

β-cyclodextrin-functionalized porous Pd@Au nanostructures (β-CD-Pd@Au) with intrinsic and enhanced peroxidase-like activity were successfully synthesized by a two-step method. The synthesized β-CD-Pd@Au can efficiently catalyze the oxidation of various substrates, such as 3,3',5,5'-tetramethylbenzidine (TMB), mixture of 4-amino antipyrine (4-AAP) and 3,5-dichloro-2-hydroxy acid sodium (DHBS) (4-AAP/DHBS), and mixture of 4-AAP and N-Ethyl-N-(3-sulfopropyl)-3-methyl-aniline sodium salt (TOPS) (4-AAP/TOPS), by H 2 O 2 to generate visual blue, purple, and pink color, respectively. The UV-vis absorbance peak of the three β-CD-Pd@Au catalyzed the chromogenic reaction system located at 650 nm, 510 nm, and 550 nm, respectively. The β-CD-Pd@Au-catalyzed TMB-H 2 O 2 chromogenic reaction exhibited higher absorbance intensity, catalytic efficiency, and color stability in comparison to 4-AAP/DHBS-H 2 O 2 and 4-AAP/TOPS-H 2 O 2 chromogenic reactions. The catalytic activity of β-CD-Pd@Au was enhanced about 4-fold compared to that of Pd@Au in terms of K cat for H 2 O 2 . Using TMB as chromogenic substrate, a colorimetric assay was fabricated for the determination of H 2 O 2 with a detection limit of 2.78 μM (absorbance at 650 nm). The colorimetric determination of glucose with a detection limit of 9.28 μM was further achieved by coupling with glucose oxidase enzymatic reaction, indicating the versatility of the β-CD-Pd@Au-based detection strategy. A paper-based detection method coupled with smartphone for fast visual and instrument-free detection of glucose was further developed. Finally, the developed colorimetric assay and paper-based detection method were successfully applied to the determination of glucose in human serum sample. Graphical abstract.

Functional laser scribing carbon paper (LSCP) decorated with highly uniform Ni nanoparticles were constructed through a facile electroless plating. The nanocomposites were characterized by high resolution scanning electron microscope, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry. The results showed high electron transferring kinetics of this sensor, which can be ascribed to their excellent properties such as rich pore channels, excellent structural durability, and large surface area. These properties facilitated mass transfer and electron conductions. Notably, a systematical response surface methodology simulating-modeling-predicting-optimizing design was employed to simulate, model and optimize processing parameters to gain the optimal conductivity of 8.52 × 10 6  S m -1 . The obtained sensor owned high electrochemical activity and wide linear responses (0.80 μM-2.50 mM and 4.50 mM-15.20 mM), low detection limit of 20 nM (S/N = 3) to the glucose detection. The glucose determination in human serum and perspiration samples are also successful. Therefore, LSCP/NN provides an excellent sensing platform towards flexible biosensors in monitoring physical conditions., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Enhancing the sensitivity of colorimetric detection in paper-devices is a quintessential step in achieving frugal diagnosis. Here, we demonstrate an effective way of improving the detection sensitivity of paper-based devices, as mediated by electro-kinetic mechanisms. By directly employing blood plasma, we investigate the electro-kinetic clustering of glucose, a neutral molecule in paper devices. Under the influence of uniform electric field, dispersed glucose gets accumulated in the paper strips. Due to the combination of EOF and electrophoretic migration, we achieve twofold increase in the colour intensity for both normal and diabetic samples. This approach is robust and possesses better sensitivity than conventional colorimetric assays and can be easily extended to other body fluid based diagnosis. These results may turn out to be of profound importance in improving the quality of pathological diagnosis in low-cost paper-based point-of-care devices deployed in resource-limited settings., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite the recent developments on the construction of point-of-care testing (POCT) devices, it is still a big challenge to build portable POCT tools for simple, sensitive, selective, and quantitative determination of disease-related biomarkers. With this in mind, we developed a simple and user-friendly POCT tool for onsite analysis of DNA adenine methyltransferase (Dam) activity by using DNA tetrahedra-based hydrogel to trap glucose-producing enzymes for target recognition and signal transduction. The enzyme-encapsulated DNA hydrogel and the substrate of enzyme were separately modified on papers and then combined onto a commercial glucose test strip for the sensitive evaluation of Dam activity via using a personal glucose meter (PGM) for quantitative signal readout. Taking advantage of the great amount of enzyme entrapped in DNA hydrogel and the high signal amplification ability of enzyme, this POCT tool is capable of highly sensitive and selective determination of Dam activity with a direct detection limit down to 0.001 U/mL, which is superior to that of most previously reported biosensors. Furthermore, this device can also be applied to screen inhibitor and analyze Dam activity in spiked serum samples, indicating the great potential for clinical practice and diagnostic applications. Additionally, all the reactions for Dam assay are performed on paper, which is simple and deliverable to end-users for medical diagnostics at home or in-field.

Biofuel cells (BFCs) based on anodic oxidation and cathodic oxygen reduction represent an attractive alternative to self-powered devices. A glucose/oxygen BFC is described for monitoring glucose. It is making use of a piece of paper carrying a glucose oxidase (GOx) based bioanode, and a bilirubin oxidase (BilOx) based biocathode. The performance of the BFC is affected by the generation of H 2 O 2 , a byproduct of enzymatic glucose oxidation. Therefore, the removal of H 2 O 2 is a crucial step in terms of BFC performance and stability. In addition, direct, unambiguous visual read-out is an ideal way to provide quantitative information. The colorimetric readout system described here is based on the consumption of undesired H 2 O 2 and to convert the extent of energy generation into recognizable variations in color. As the H 2 O 2 travels along the hydrophilic channel by capillary action, the formation of red gold nanoparticles from AuCl 4 leads to the appearance of a red bar that provides distance-based information that can be read visually. The multiply readable information (maximum power density of BFC or visible distance) provides further choices for quantification. It also enhances reliability. The self-powered system based on the BFC exhibits excellent performance. Glucose can be determined by this method in the 1 to 50 mM concentration range. Graphical abstract Schematic presentation of a paper-supported biofuel cell equipped with a visual distance readout to display the level of energy generation in biofuel cells, and its application in sensing of glucose.- leads to the appearance of a red bar that provides distance-based information that can be read visually. The multiply readable information (maximum power density of BFC or visible distance) provides further choices for quantification. It also enhances reliability. The self-powered system based on the BFC exhibits excellent performance. Glucose can be determined by this method in the 1 to 50 mM concentration range. Graphical abstract Schematic presentation of a paper-supported biofuel cell equipped with a visual distance readout to display the level of energy generation in biofuel cells, and its application in sensing of glucose.

A novel 3D paper-based microfluidic screen-printed electrode (SPE) composed of two layers was constructed by photolithography and screen-printing technology. Aldehyde functionalized hydrophilic zone of the counter and reference electrodes layer was prepared for glucose oxidase immobilization. Highly conductive prussian blue deposited reduced graphene oxide-tetraethylene pentamine (rGO-TEPA/PB) modified paper working electrode layer can be used as an electrochemical sensitive membrane for quantitative detection of hydrogen peroxide (H 2 O 2 ), which was the enzyme-catalyzed reaction product. Therefore, this 3D paper-based microfluidic electrochemical biosensor can be used for quantitative detection of glucose. Under optimum conditions, the proposed biosensor can be used for quantitative determination of glucose over a wide linear range of 0.1 mM-25 mM with detection limit of 25 μM. Finally, the 3D paper-based microfluidic electrochemical biosensor was applied to determine glucose in human sweat and blood, and the obtained results were in good consistency with values measured by Roche's blood glucose meter. In addition, the proposed 3D paper-based electrochemical device showed good repeatability, stability, and anti-interference, which would be of great potential to monitor glucose in complex biological fluids., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Diabetes mellitus is one of the most common chronic diseases worldwide. Generally, the levels of fasting or postprandial blood glucose and other biomarkers, such as glycated albumin, glycated hemoglobin, and 1,5-anhydroglucitol, are used to diagnose or monitor diabetes progression. In the present study, we developed a sensor to simultaneously detect the glucose levels and glycation ratios of human serum albumin using a lateral flow assay. Based on the specific enzymatic reactions and immunoassays, a spiked glucose solution, total human serum albumin, and glycated albumin were measured simultaneously. To test the performance of the developed sensor, clinical serum samples from healthy subjects and patients with diabetes were analyzed. The glucose level and glycation ratios of the clinical samples were determined with reasonable correlation. The R -squared values of glucose level and glycation ratio measurements were 0.932 and 0.930, respectively. The average detection recoveries of the sensor were 85.80% for glucose and 98.32% for the glycation ratio. The glucose level and glycation ratio in our results were crosschecked with reference diagnostic values of diabetes. Based on the outcomes of the present study, we propose that this novel platform can be utilized for the simultaneous detection of glucose and glycation ratios to diagnose and monitor diabetes mellitus.

Portable devices featured with fast analysis and affordable methodologies for clinical diagnostics have stimulated the rapid development of point-of-care (POC) technologies, potentially lowering the mortality rate. Herein, we demonstrated a portable, robust, and user-friendly intelligent metal-organic frameworks (MOFs) paper device, called smartphone-assisted biomimetic MOFs nanoreactor colorimetric paper (SBMCP), for on-demand POC detection of endogenous biomolecules. The concept of this paper platform was analogous to the intracellular cascades signal transduction, wherein the single/multiple enzymes components trapped within a ZIF-8 exoskeleton allowed the sensitive and selective recognition of target analyte via the accessible micropores network of ZIF-8, and then transferred the recognition event to a visual color signal based on the cascade reaction. Meanwhile, the ZIF-8 exoskeleton also endowed the enzymes with significantly elevated stability. As a result, this robust and portable SBMCP sensor enabled the on-site analysis of different important disease-related biomolecules through modulating the enzyme cascades, combining with a custom-designed smartphone application for signal readout. In the SBMCP assay, no sophisticated instruments or professional skill of the user was required, only 5 μL sample volume was needed, and the whole analysis process could be achieved within a portable MOFs paper and pervasive smartphone, endowing this new assay with the merits of low-cost, time-saving and easy-to-use. We demonstrated this SBMCP sensor was capable of real-time colorimetric detection of glucose and uric acid in diabetes and gout events. It is believed that this portable biosensor platform proposed herein potentially represents promising alternatives for POC diagnosis, especially applicable in developing world and resource-limited settings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Nowadays, environmentally friendly synthesis pathways for preserving the environment and minimizing waste are strongly required. Herein, we propose filter paper as a convenient scaffold for chemical reactions. To demonstrate this novel approach, Prussian Blue Nanoparticles (PBNPs) were synthesized on filter paper by utilizing few μL of its precursors without external inputs, i.e. pH, voltage, reducing agents, and without producing waste as well. The functional paper, named "Paper Blue", is successfully applied in the sensing field, exploiting the reduction of hydrogen peroxide at low applied potential. The eco-designed "Paper Blue" was combined with wax- and screen-printing to manufacture a reagentless electrochemical point-of-care device for diabetes self-monitoring, by using glucose oxidase as the biological recognition element. Blood glucose was linearly detected for a wide concentration range up to 25 mM (450 mg/dL), demonstrating its suitability for management of diabetes and glucose-related diseases. The Paper Blue-based biosensor demonstrated a correlation coefficient of 0.987 with commercial glucose strips (Bayer Contour XT). The achieved results demonstrated the effectiveness of this approach, which is also extendible to other (bio)systems to be applied in catalysis, remediation, and diagnostics., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We introduce for the first time a paper-based analytical device (PAD) for the non-enzymatic detection of glucose by modifying a screen-printed carbon electrode with cobalt phthalocyanine, graphene and an ionic liquid (CoPc/G/IL/SPCE). The modifying composite was characterized by UV-visible spectroscopy, energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The disposable devices show excellent conductivity and fast electron transfer kinetics. The results demonstrated that the modified electrode on PADs had excellent electrocatalytic activity towards the oxidation of glucose with NaOH as supporting electrolyte (0.1M). The oxidation potential of glucose was negatively shifted to 0.64V vs. the screen-printed carbon pseudo-reference electrode. The paper-based sensor comprised a wide linear concentration range for glucose, from 0.01 to 1.3mM and 1.3-5.0mM for low and high concentration of glucose assay, respectively, with a detection limit of 0.67µM (S/N = 3). Additionally, the PADs were applied to quantify glucose in honey, white wine and human serum. The disposable, efficient, sensitive and low-cost non-enzymatic PAD has great potential for the development of point-of-care testing (POCT) devices that can be applied in healthcare monitoring., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this work, a multilayer-modified paper-based colorimetric sensing platform with improved color uniformity and intensity was developed for the sensitive and selective determination of uric acid and glucose with smartphone as signal readout. In detail, chitosan, different kinds of chromogenic reagents, and horseradish peroxidase (HRP) combined with a specific oxidase, e.g., uricase or glucose oxidase (GOD), were immoblized onto the paper substrate to form a multilayer-modified test paper. Hydrogen peroxide produced by the oxidases (uricase or GOD) reacts with the substrates (uric acid or glucose), and could oxidize the co-immoblized chromogenic reagents to form colored products with HRP as catalyst. A simple strategy by placing the test paper on top of a light-emitting diode lamp was adopted to efficiently prevent influence from the external light. The color images were recorded by the smartphone camera, and then the gray values of the color images were calculated for quantitative analysis. The developed method provided a wide linear response from 0.01 to 1.0 mM for uric acid detection and from 0.02 to 4.0 mM for glucose detection, with a limit of detection (LOD) as low as 0.003 and 0.014 mM, respectively, which was much lower than for previously reported paper-based colorimetric assays. The proposed assays were successfully applied to uric acid and glucose detection in real serum samples. Furthermore, the enhanced analytical performance of the proposed method allowed the non-invasive detection of glucose levels in tear samples, which holds great potential for point-of-care analysis. Graphical abstract ᅟ.

In this work, a versatile point-of-care assay platform based on a microfluidic paper-based analytic device (μPAD) was developed for the simultaneous detection of multiple targets. The μPAD with a central zone and six test zones is fabricated by a simple and inexpensive wax printing method. A flower-like hybrid nanocomplex synthesized with specific dual enzymes and Cu3(PO4)2 inorganic nanocrystals is spotted in the test zones on the μPAD, followed by the introduction of assay targets. Using dual-enzyme inorganic hybrid nanoflowers in the μPAD as nanobiocatalysts, which preserve the activity and enhance the stability of the enzymes, based on the H2O2-mediated catalytic oxidizing chromogenic reaction produced by glucose/uric acid, the developed multiplex paper-based nanobiocatalytic system is demonstrated to enable simultaneous and sensitive detection of glucose and uric acid with a detection limit of 60 and 25 μM, respectively. More importantly, it has been successfully used for detecting glucose and uric acid levels in human whole blood samples. The developed multiplex paper-based nanobiocatalytic system features very easy fabrication and operation, low cost, and high sensitivity and has promising prospects for a clinical multianalyte point-of-care test.

A variety of routine methods are available for the detection of silver (I) (Ag + ) ions, but most of them rely on expensive, sophisticated and desktop instruments. Herein, a low-cost, instrument-free and portable Ag + biosensor was described by initially designing a new class of 3D origami microfluidic paper-based analytical devices (μPADs) into each of which one piece of reagent-loaded nanoporous membrane was integrated. It combines analyte-triggered self-growing of silver nanoparticles to block the membrane's pores in situ for rapid yet efficient signal amplification with a handheld personal glucose meter for a portable and sensitive quantitative readout based on the biocatalytic reactions between the glucose oxidase and glucose. Its utility is well demonstrated with the specific detection of the analyte with a limit of detection as low as ∼58.1 pM (3σ), which makes this new biosensing method one of the most sensitive Ag + assays in comparison with many other typical methods recently reported. Moreover, the satisfactory recovery of analyzing several types of real water examples, i.e., tap water, drinking water, pond water and soil water, additionally validates its feasibility for practical applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, a double-layered three-dimensional (3D) microfluidic paper-based analytical device (μPAD) with high resolution temporally resolved chemiluminescence (CL) emissions were designed for multiplexed CL analysis. The temporally resolved CL emissions were obtained by virtue of the 3D branched microfluidic channel design, which create time delays for luminol transported from one detection zone to another. The peak intensity and peak shape of the temporally resolved CL emissions were quite stable and base-line separated with resolution as high as 21.2-24.4. Then, the fabricated μPAD was applied to multiplexed determination of glucose, lactate, cholesterol, and choline as model analytes. The sample was added to four detection zone modified with CL catalyst cobalt ion and different oxidase by virtue of chitosan. When luminol flowed to μPAD, four temporally resolved CL peaks were successively generated from the cobalt ion catalyzed CL reactions between luminol and generated H 2 O 2 from the specific enzymatic reactions between the oxidase and the analytes. The generated four CL emission peaks in the CL kinetic curve increased in proportion to the concentrations of glucose, lactate, cholesterol, and choline, respectively. Finally, four linear calibration curves were obtained for the detection of glucose (0.01-1.0 mmol/L), lactate (0.02-5.0 mmol/L), cholesterol (0.01-0.4 mmol/L), and choline (0.001-1.0 mmol/L). The detection limits were as low as 8 μmol/L, 15 μmol/L, 6 μmol/L, and 0.07 μmol/L for glucose, lactate, choline, and cholesterol detection, respectively. The present work provides a new strategy for the fabrication of simple and sensitive 3D μPAD with high resolution temporally resolved CL emissions for multiplexed CL analysis, which holds great application potential for point-of-care diagnosis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

There is an urgent need to develop low cost electrochemical sensors wherein the sensor can be disposed after recording data, thereby eliminating the issue of inaccuracy arising from repeated sensing measurements, which plagues most conventional electrochemical sensors. This work is the first demonstration of a NiSe 2 based disposable, one time use electrochemical glucose sensor in bio-mimicking real samples wherein NiSe 2 was hydrothermally grown NiSe 2 on a biodegradable cellulose paper. Both physicochemical (x-ray diffraction, x-ray photoelectron spectroscopy, field emission scanning electron microscope) and electrochemical (impedance spectroscopy and cyclic voltammetry (CV)) characterization techniques confirmed the growth and presence of NiSe 2 on a cellulose paper. Electrochemical techniques like CV and amperometric (i-t) were utilized for the selective and sensitive oxidation of glucose. The results suggests that the proposed NiSe 2 sensor is effective in a linear range of 0.1-1 mM with fast response time (3.9 s), low detection limit (24.8 ± 0.1 μM) and high sensitivity (0.25 A M -1 cm -2 ) at a potential applied (E app  = 0.55 V versus Ag∣AgCl). Prior to the real sample analyses i.e. glucose detection in human urine, the fabricated NiSe 2 sensor was tested for selectivity towards glucose in co-existing interferences (dopamine, ascorbic acid, uric acid, urea, sodium chloride, fructose, lactose and cysteine). Finally, glucose in artificial blood serum and urine samples was demonstrated with the fabricated NiSe 2 sensor and the results are comparable to the conventional laboratory methods. The present methodology presents a novel possibility towards the design of next generation, affordable point-of-care devices for a broad range of clinical diagnostics.

Microfluidic paper-based analytical devices (μPADs) have a significant potential in developing portable and disposable point-of-care testing (POCT). Herein, a facile, rapid, cost-effective and environment friendly strategy for μPADs fabrication is proposed. Specifically, the substrate paper was hydrophobized by coating with trimethoxysilane (TOS), and then the selected area was hydrophilized by treating with surfactant. The whole fabrication process was implemented within 7 min, with no need for complex pre-treatment, high-temperature and special equipment. As a proof-of-concept application, the as-prepared μPAD was applied to determination of the glucose content in human serum samples. The results agreed well with those obtained by a glucometer. We believe that the μPADs fabrication method proposed here could provide a facile, rapid and low-cost reference for other related studies., (Copyright © 2017 Elsevier Inc. All rights reserved.)

In this report, we present a paper membrane-based surface-enhanced Raman scattering (SERS) platform for the determination of blood glucose level using a nitrocellulose membrane as substrate paper, and the microfluidic channel was simply constructed by wax-printing method. The rod-shaped gold nanorod particles were modified with 4-mercaptophenylboronic acid (4-MBA) and 1-decanethiol (1-DT) molecules and used as embedded SERS probe for paper-based microfluidics. The SERS measurement area was simply constructed by dropping gold nanoparticles on nitrocellulose membrane, and the blood sample was dropped on the membrane hydrophilic channel. While the blood cells and proteins were held on nitrocellulose membrane, glucose molecules were moved through the channel toward the SERS measurement area. Scanning electron microscopy (SEM) was used to confirm the effective separation of blood matrix, and total analysis is completed in 5 min. In SERS measurements, the intensity of the band at 1070 cm(-1) which is attributed to B-OH vibration decreased depending on the rise in glucose concentration in the blood sample. The glucose concentration was found to be 5.43 ± 0.51 mM in the reference blood sample by using a calibration equation, and the certified value for glucose was 6.17 ± 0.11 mM. The recovery of the glucose in the reference blood sample was about 88 %. According to these results, the developed paper-based microfluidic SERS platform has been found to be suitable for use for the detection of glucose in blood samples without any pretreatment procedure. We believe that paper-based microfluidic systems may provide a wide field of usage for paper-based applications.

The development of real-time innocuous blood diagnosis has been a long-standing goal in healthcare; an improved, miniature, all-in-one point-of-care testing (POCT) system with low cost and simplified operation is highly desired. Here, we present a one-touch-activated blood multidiagnostic system (OBMS) involving the synergistic integration of a hollow microneedle and paper-based sensor, providing a number of unique characteristics for simplifying the design of microsystems and enhancing user performance. In this OBMS, all functions of blood collection, serum separation, and detection were sequentially automated in one single device that only required one-touch activation by finger-power without additional operations. For the first time, we successfully demonstrated the operation of this system in vivo in glucose and cholesterol diagnosis, showing a great possibility for human clinical application and commercialization. Additionally, this novel system offers a new approach for the use of microneedles and paper sensors as promising intelligent elements in future real-time healthcare monitoring devices.

Fluorescent test papers are promising for the wide applications in the assays of diagnosis, environments and foods, but unlike classical dye-absorption-based pH test paper, they are usually limited in the qualitative yes/no type of detection by fluorescent brightness, and the colorimetry-based quantification remains a challenging task. Here, we report a single dual-emissive nanofluorophore probe to achieve the consecutive color variations from blue to red for the quantification of blood glucose on its as-prepared test papers. Red quantum dots were embedded into silica nanoparticles as a stable internal standard emission, and blue carbon dots (CDs) were further covalently linked onto the surface of silica, in which the ratiometric fluorescence intensity of blue to red is controlled at 5:1. While the oxidation of glucose induced the formation of Fe(3+) ions, the blue emission of CDs was thus quenched by the electron transfer from CDs to Fe(3+), displaying a serial of consecutive color variations from blue to red with the dosage of glucose. The high-quality test papers printed by the probe ink exhibited a dosage-sensitive allochromatic capability with the clear differentiations of ~5, 7, 9, 11mM glucose in human serum (normal: 3-8mM). The blood glucose determined by the test paper was almost in accordance with that measured by a standard glucometer. The method reported here opens a window to the wide applications of fluorescent test paper in biological assays., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A novel low-cost, compact and sensitive paper-based platform for the accurate monitoring of glucose in biological fluids is presented. Paper-based working and reference electrodes are combined to build a whole potentiometric cell, which also fits a sampling module for simple and fast determination of glucose in a single drop of blood. The working electrode is built using a platinized filter paper coated with a Nafion membrane that entraps the enzyme glucose oxidase; the reference electrode is made by casting a polyvinylbutyral-based membrane onto a conductive paper. The system works by detecting the hydrogen peroxide generated as a result of the enzymatic reaction. Selectivity is achieved due to the permselective behaviour of Nafion, while a significant enhancement of the sensitivity is reached by exploiting the Donnan-coupled formal potential. Under optimum conditions, a sensitivity of -95.9 ± 4.8 mV per decade in the 0.3-3 mM range is obtained. Validation of the measurements has been performed against standard methods in human serum and blood. Final integration with a wireless reader allows for truly in situ measurements with a less than 2 minute procedure including a two-point calibration, washing and measurement. This low-cost analytical device opens up new prospects for rapid diagnostic results in non-laboratory settings.

In this work, a convenient, fast, low cost, small sample volume and in situ detection of glucose in human whole blood has been developed by using a disposable screen-printed carbon electrode (SPCE) coupled with a paper disk. To perform the assay, the SPCE was modified with graphene/polyaniline/Au nanoparticles/glucose oxidase (Gr/PANI/AuNPs/GOD) biocomposite and then covered by a paper disk impregnated with the sample. After introducing PBS on the paper disk, the electrochemical measurement was carried out. The assay was based on measuring the current decrease of flavin adenine dinucleotide (FAD) in GOD provoked by the enzyme-substrate reaction using differential pulse voltammetry (DPV). The analytical performance was comparable to conventional methods, and covered the full range of clinically relevant concentrations of glucose in whole blood. This new paper-based electrochemical glucose sensor shows promise in applying point-of-care (POC) device in whole blood tests, and particularly being appropriate for use in the developing world and in resource-limited settings., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The increasing demands for portable, wearable, and implantable sensing devices have stimulated growing interest in innovative electrode materials. In this work, we have demonstrated that printing a conductive ink formulated by blending three-dimensional (3D) porous graphene-carbon nanotube (CNT) assembly with ionic liquid (IL) on two-dimensional (2D) graphene paper (GP), leads to a freestanding GP supported graphene-CNT-IL nanocomposite (graphene-CNT-IL/GP). The incorporation of highly conductive CNTs into graphene assembly effectively increases its surface area and improves its electrical and mechanical properties. The graphene-CNT-IL/GP, as freestanding and flexible substrates, allows for efficient loading of PtAu alloy nanoparticles by means of ultrasonic-electrochemical deposition. Owing to the synergistic effect of PtAu alloy nanoparticles, 3D porous graphene-CNT scaffold, IL binder and 2D flexible GP substrate, the resultant lightweight nanohybrid paper electrode exhibits excellent sensing performances in nonenzymatic electrochemical detection of glucose in terms of sensitivity, selectivity, reproducibility and mechanical properties., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This paper describes a new approach for the massive production of electrochemical paper-based analytical devices (ePADs). These devices are fully fabricated by screen-printing technology and consist of a lineal microfluidic channel delimited by hydrophobic walls (patterned with diluted ultraviolet screen-printing ink in chromatographic paper grade 4) and a three-electrode system (printed with carbon and/or Ag/AgCl conductive inks). The printing process was characterised and optimized for pattern each layer with only one squeeze sweep. These ePADs were used as transducers to develop a glucose biosensor. Ionic strength/pH buffering salts, electrochemical mediator (ferricyanide) and enzyme (glucose dehydrogenase FAD-dependent) were separately stored along the microfluidic channel in order to be successively dissolved and mixed after the sample dropping at the entrance. The analyses required only 10 µl and the biosensors showed good reproducibility (RSD = 6.2%, n = 10) and sensitivity (0.426 C/M cm 2 ), wide linear range (0.5-50 mM; r 2 = 0.999) and low limit of detection (0.33 mM). Furthermore, the new biosensor was applied for glucose determination in five commercial soft-drinks without any sample treatment before the analysis. These samples were also analysed with a commercial enzymatic-kit assay. The results indicated that both methods provide accurate results., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Hydrogen peroxide (H 2 O 2 ), an important reactive oxygen species (ROS), is related to the oxidative stress in organisms, and plays important roles in a variety of cellular activities as well. So it is of crucial importance to develop sensitive and accurate sensing strategies to detect H 2 O 2 in biological systems. Herein, by taking advantage of the unique emission characteristics of aggregation induced emission (AIE) fluorogens, we proposed a non-enzymatic fluorescence platform for facile and sensitive detection of H 2 O 2 , both in solution state using fluorescence spectrometer and on paper-based sensor via visual inspection. Through the reaction between L-cysteine and H 2 O 2 , the fluorescence of TPE-M-L, an AIE fluorogen formed between maleimide-functionalized tetraphenylethene (TPE-M) and L-cysteine, is quenched, and highly sensitive non-enzymatic H 2 O 2 assay is readily carried out. The limit of detection (LOD) of 10nM in solution state and 2.5μM on paper-based sensor were obtained for H 2 O 2 detection, which were superior or comparable to those previously reported in literature. Moreover, by integrating glucose oxidase with the AIE fluorogen of TPE-M-L, highly sensitive and selective glucose detection was also conveniently achieved both in solution state and on paper-based sensor by the as-proposed strategy, with the LODs of 50nM in solution state and 10μM via visual observation, much better than those obtained by other fluorescence methods. The as-proposed sensing strategy was also successfully applied to assay glucose in human serum samples. Therefore, the paper-based fluorescence sensor exhibits the advantages of simple fabrication, high sensitivity and portability, and has great potential to be applied in on-site assay of H 2 O 2 and glucose in real samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The monitoring of blood glucose is a key aspect of diabetes care in limiting the negative effects of hyperglycaemia to both the microvasculature and macrovasculature. Self-monitoring of blood glucose (SMBG) gives an indication of blood glucose at a specific point in time and is recommended to be carried out four times daily. However, due to the inconvenience and associated pain of blood withdrawal, SMBG is often carried out less frequently than recommended or not at all. Extraction and subsequent determination of glucose in interstitial fluid (ISF) using microneedles (MNs) is an emerging area of research due to their minimally invasive nature and lack of associated pain. In this manuscript, a novel method for the fabrication of a hollow microneedle device is reported. The microneedle produced had a sharp bevelled edge and was 400 µm in length. Additionally, a paper backplate embedded with a colorimetric system for the rapid visual determination of glucose in simulated ISF was developed and paired with the hollow MN. This device rapidly extracted simulated ISF within five seconds and its ability to produce a glucose concentration dependent colour change within 30 s was demonstrated. Using this approach, it was possible to discriminate between glucose concentrations in normal glycaemia (4-7 mM) and hyperglycaemia (>7 mM) ranges using the naked eye. While further development is required, the results herein highlight the potential of this device to be used as a blood-free minimally invasive approach to glucose monitoring., (Copyright © 2018. Published by Elsevier B.V.)

Electrochemical paper-based analytical devices (ePADs) with integrated plasma isolation for determination of glucose from whole blood samples have been developed. A dumbbell shaped ePAD containing two blood separation zones (VF2 membranes) with a middle detection zone was fabricated using the wax dipping method. The dumbbell shaped device was designed to separate plasma while generating homogeneous flow to the middle detection zone of the ePAD. The proposed ePADs work with whole blood samples with 24-60% hematocrit without dilution, and the plasma was completely separated within 4 min. Glucose in isolated plasma separated was detected using glucose oxidase immobilized on the middle of the paper device. The hydrogen peroxide generated from the reaction between glucose and the enzyme pass through to a Prussian blue modified screen printed electrode (PB-SPEs). The currents measured using chronoamperometry at the optimal detection potential for H2O2 (-0.1 V versus Ag/AgCl reference electrode) were proportional to glucose concentrations in the whole blood. The linear range for glucose assay was in the range 0-33.1 mM (r(2)=0.987). The coefficients of variation (CVs) of currents were 6.5%, 9.0% and 8.0% when assay whole blood sample containing glucose concentration at 3.4, 6.3, and 15.6mM, respectively. Because each sample displayed intra-individual variation of electrochemical signal, glucose assay in whole blood samples were measured using the standard addition method. Results demonstrate that the ePAD glucose assay was not significantly different from the spectrophotometric method (p=0.376, paired sample t-test, n=10)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

We present a method for the determination of blood glucose using dried filter paper blood spots. To validate this method, we compared our results using filter paper and simultaneously collected venous blood. We demonstrated that there is a linear relationship between the filter paper glucose levels and those determined in whole blood (r = 0.98). There was no significant difference between the results of the two methods (p > 0.05). This method is a cheap alternative which may improve the control of diabetes mellitus, and may also be very useful in the diagnosis of postprandial hypoglycemia and other special situations.

Background: Stress-induced hyperglycemia is a common feature of intensive care unit (ICU) patients. Besides mean blood glucose (BG) level, glucose variability and hypoglycemia have been highlighted as independent predictors of ICU and hospital mortality. Recent ICU recommendations suggest using insulin infusion protocols that can minimize glucose variability and hypoglycemic risk. Our aim was to assess the efficacy, safety, and acceptance by nurses of a paper-based simple dynamic insulin protocol compared with those by nurses of a paper-based static protocol., Methods: This is a 1 year stepped-wedge study that compared a static sliding scale protocol (SP - static protocol) with a validated dynamic paper-based intravenous insulin infusion protocol (DP - dynamic protocol) in medical ICU patients of a single university hospital. Patients with stress-induced hyperglycemia >9.9 mmol/L and ≥48 h intravenous insulin infusion were included in this trial., Results: One hundred thirty-one patients were included and received continuous intravenous insulin infusion managed with SP (n = 65) or DP (n = 66). Glucose variability was significantly higher in the SP group than in the DP group (mean average glucose excursion index: 0.90 [0.00-1.91] mmol/L vs. 0.00 [0.00-0.90] mmol/L, respectively; P = 0.001). The percentage of time spent in the target range (7.7-9.9 mmol/L) was lower in the SP group than in the DP group (42.5% [28.8%-54.2%] vs. 47.5% [36.6%-57.1%]; P = 0.037). Low BG (<4.4 mmol/L) and hypoglycemia (<3.3 mmol/L) were more frequent in the SP group than in the DP group. According to a satisfaction survey, this protocol was well accepted by nurses., Conclusions: Our simple and feasible paper-based, dynamic insulin infusion protocol reduced glycemic variability and hypoglycemic risk in a medical ICU.

We report here the use of multiple indicators for a single analyte for paper-based microfluidic devices (microPAD) in an effort to improve the ability to visually discriminate between analyte concentrations. In existing microPADs, a single dye system is used for the measurement of a single analyte. In our approach, devices are designed to simultaneously quantify analytes using multiple indicators for each analyte improving the accuracy of the assay. The use of multiple indicators for a single analyte allows for different indicator colors to be generated at different analyte concentration ranges as well as increasing the ability to better visually discriminate colors. The principle of our devices is based on the oxidation of indicators by hydrogen peroxide produced by oxidase enzymes specific for each analyte. Each indicator reacts at different peroxide concentrations and therefore analyte concentrations, giving an extended range of operation. To demonstrate the utility of our approach, the mixture of 4-aminoantipyrine and 3,5-dichloro-2-hydroxy-benzenesulfonic acid, o-dianisidine dihydrochloride, potassium iodide, acid black, and acid yellow were chosen as the indicators for simultaneous semi-quantitative measurement of glucose, lactate, and uric acid on a microPAD. Our approach was successfully applied to quantify glucose (0.5-20 mM), lactate (1-25 mM), and uric acid (0.1-7 mM) in clinically relevant ranges. The determination of glucose, lactate, and uric acid in control serum and urine samples was also performed to demonstrate the applicability of this device for biological sample analysis. Finally results for the multi-indicator and single indicator system were compared using untrained readers to demonstrate the improvements in accuracy achieved with the new system., (2010 Elsevier B.V. All rights reserved.)

Photoacoustic (PA) effect has been widely applied in many fields, e.g., physics, chemistry and biomedicine. Herein, a miniaturized PA device is developed by integrating laser source, photo chopper, PA cell, microphone, and laptop for point-of-care testing in bioassay. With glucose assay as model, a piece of paper strip preloading chitosan, starch-potassium iodide (KI) and glucose oxidase (GOD) as lab-on-paper is employed for loading sample prior to PA detection. In the presence of glucose, the product generated on the paper strip would give rise to a strong PA signal in the PA cell under the irradiation of frequency-modulated laser at 520 nm via laptop readout. With a sample volume of 20 μL, a detection limit of 0.03 mM is obtained for glucose assay, along with a linear range of 0.08-1 mM. The accuracy and practicability of the present PA device is well demonstrated by detecting glucose in whole blood. Differing from the conventional PA instrument, the present PA device is really small in bulk with competitive sensitivity and excellent stability, offering a promising tool for point-of-care testing in bioassay., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A ternary hierarchical hybrid Ni@Co x S y /poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (Ni@Co x S y /PEDOT-rGO) is rationally designed and in situ facilely synthesized as electrocatalyst to construct a binder-free sensing platform for non-enzymatic glucose monitoring through traditional electrodeposition procedure. The as-prepared Ni@Co x S y /PEDOT-rGO presents unique hierarchical structure and multiple valence states as well as strong and robust adhesion between Ni@Co x S y /PEDOT-rGO and GCE. Profiting from the aforementioned merits, the sensing platform constructed under optimal conditions achieved a wide detection range (0.2 μM ~ 2.0 mM) with high sensitivity (1546.32 μA cm -2  mM -1 ), a rapid response time (5 s), an ultralow detection limit (0.094 μM), superior anti-interference performance, excellent reproducibility and considerable stability. Furthermore, the sensor demonstrates an acceptable accuracy and appreciable recoveries ranging from 90.0 to 102.0% with less than 3.98% RSD in human blood serum samples, indicating the prospect of the sensor for the real samples analysis. It will provide a strategy to rationally design and fabricate ternary hierarchical hybrid as nanozyme for glucose assay., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: There is variability in the extent of outcome achievement between computerized insulin infusion programs (CIIPs) and paper-based protocols (PBPs). This reported variability may be improved by intensive CIIP training prior to implementation. The objective was to evaluate the impact of a CIIP following intensive nurse training versus a PBP in a critical care setting., Methods: A retrospective cohort study was performed on patients admitted to a mixed intensive care unit comparing glucose control between the CIIP following intensive training and a PBP. Consecutive patients on each protocol were assessed to obtain glucose concentrations and outcomes. The primary measure was the percentage of blood glucose values within target range (90-130 mg/dL). Patient glucose values were pooled and assessed using the χ(2) test for independence., Results: In total, 61 patients with 5,495 glucose tests were included in the PBP group, and 51 patients with 5,645 glucose tests in the CIIP group. A greater percentage of glucose tests was within target range in the CIIP group (68.4% vs. 36.5%, P<0.001). In the CIIP group, time-to-target (median [interquartile range] 5 [3-8] h vs. 7 [4-20] h, P=0.02) and severe hypoglycemic events were reduced (26 vs. 6, P<0.0001)., Conclusions: The nurse-driven CIIP led to a higher percentage of glucose values within target range, faster achievement of target glucose values, and a reduction in the number of severe hypoglycemic events. This improved outcome achievement compared with previous reports may be associated with intensive user training.

We report the first use of redox nanoparticles of cerium oxide as colorimetric probes in bioanalysis. The method is based on changes in the physicochemical properties of ceria nanoparticles, used here as chromogenic indicators, in response to the analyte. We show that these particles can be fully integrated in a paper-based bioassay. To construct the sensor, ceria nanoparticles and glucose oxidase were coimmobilized onto filter paper using a silanization procedure. In the presence of glucose, the enzymatically generated hydrogen peroxide induces a visual color change of the ceria nanoparticles immobilized onto the bioactive sensing paper, from white-yellowish to dark orange, in a concentration-dependent manner. A detection limit of 0.5 mM glucose with a linear range up to 100 mM and a reproducibility of 4.3% for n = 11 ceria paper strips were obtained. The assay is fully reversible and can be reused for at least 10 consecutive measurement cycles, without significant loss of activity. Another unique feature is that it does not require external reagents, as all the sensing components are fixed onto the paper platform. The bioassay can be stored for at least 79 days at room temperature while maintaining the same analytical performance. An example of analytical application was demonstrated for the detection of glucose in human serum. The results demonstrate the potential of this type of nanoparticles as novel components in the development of robust colorimetric bioassays.

Background: Paper-based continuous intravenous insulin protocols for tight glycaemic control (TGC) are typically complex, error-prone, time-consuming and burdensome. Little is known about the errors that occur as a result of misinterpretation and whether computerised protocols reduce errors., Objective: To compare the errors resulting from protocol misinterpretation, time required to manage insulin infusions and nursing satisfaction between a computerised insulin protocol and a paper-based protocol., Methods: In a crossover study, 62 ICU nurses completed 10 TGC simulated scenarios for the computerised and paper protocols. Scenarios evaluated three phases of insulin management: initiation, titration and transition. Scenarios response errors, time to completion and user satisfaction were examined., Results: A total of 620 responses were recorded using both protocols. The computerised protocols were associated with higher user satisfaction, as well as: fewer errors in the titration (13 vs. 113 errors, p=.0001) and transition phases (9 vs. 23 errors, p=.001), fewer dosing errors, although not statistically significant (p=.096), in the initiation phase, and less time to complete in the titration phase (6 vs. 9.5 min, p=.0001)., Conclusions: In a simulated environment, a computerised protocol for TGC resulted in significant insulin dosing error reduction, saved time and improved nurse satisfaction., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Introduction: Blood glucose control can be time-consuming and difficult to achieve. We hypothesized that a computerized system to obtain glucose control would enable faster "time to target" and produce less variability in blood glucose levels., Methods: Patients who underwent cardiac surgery at a community hospital between January and December 2007 (n = 1131) with glucose control obtained under a paper protocol were compared with similar patients operated on between January and December 2008 (n = 769) whose glucose control was obtained with a computer-driven protocol., Results: Glucose control was achieved in both groups. The computer group had less variability in glucose levels than the paper group. The mean time to target for the computer group was 3.5 (+/-1.3) hours. The time to target for the paper group was quite skewed; therefore, the median time to target was 6 hours., Conclusions: The computer-driven protocol achieved excellent glycemic control.

The effect of stem bark powder from paper mulberry (PMSB) on serum glucose, insulin, fructosamine, and lipid concentrations, as well as enzyme activities that serve as liver injury markers, was investigated in genetically diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats. Both nondiabetic Long-Evans Tokushima Otsuka (LETO) rats and diabetic OLETF rats (30 weeks old) were fed a semisynthetic diet with or without 50 g/kg PMSB for 8 weeks and then compared. The OLETF control rats showed a high amount of daily water intake in comparison to those in the LETO group. The concentrations of glucose, fructosamine, total lipid, triglyceride, total cholesterol, and high-density lipoprotein-cholesterol and the activities of aspartate aminotransferase and alanine aminotransferase (ALT) in serum were higher in the OLETF control rats than those in the LETO control rats. However, PMSB ingestion decreased the serum levels of glucose, fructosamine, triglyceride, and total cholesterol and the activity of ALT in the OLETF rats, but not in the LETO rats. The concentration of serum insulin was also significantly increased by PMSB consumption in the OLETF rats compared to the OLETF control rats. These results suggest that PMSB might have an antihyperglycemic effect in the OLETF rat and that the increased blood insulin level would be an important regulatory factor for improving hyperglycemia in the current animal model.

In this work, we present a facile preparation of a paper-based glucose assay for rapid, sensitive, and quantitative measurement of glucose in blood plasma and urine. Two copper phosphorescent complexes [Cu(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)(2,6-dimethylphenylisocyanide)2][B(C6H3(CF3)2)4] (Cu1) and [Cu(2,9-dimethyl-1,10-phenanthroline)(2,6-dimethylphenylisocyanide)2][B(C6H3(CF3)2)4] (Cu2) and a new silver congener [Ag(P3)CNAg(P3)][B(C6H3(CF3)2)4] (Ag3) (P3 = PPh2C6H4-PPh-C6H4PPh2 [bis(o-diphenylphosphinophenyl)phenylphosphine]) have been synthesized and their oxygen sensing abilities were investigated. The dimetallic phosphine-based Ag3 complex, having a high oxygen sensing ability, was employed as an efficient signal transducer in enzymatic reactions to recognize blood plasma glucose and urine glucose, which provided a wide linear response for a concentration range between 1.0 and 35 mM and a rapid response, with a limit of detection (LOD) of 0.09 mM for glucose. In practical application, this Ag3 paper-based device offers great analytical reliability and accuracy upon monitoring glucose concentrations in blood plasma.

A method for glucose determination in blood sampled by the patients outside hospital, is described and evaluated. Glucose in capillary blood spotted on filter paper (Schleicher& Schüll No. 2992), dried and stored at room conditions, is stable for at least 7 days. 6.5 mm discs, containing 10.3 microliter capillary blood are punched out from the spots and eluted in percloric acid. The glucose concentration in the eluate is determined by the glucose dehydrogenase method. Using duplicates, CV within assay is 3.6% between assay 4.2%. Mean recovery is 98.3%, SD 9.6%. Correlation to ordinary whole blood glucose dehydrogenase method is good, r = 0.984 (n = 244). The influence of blood spot variation, punching procedure, paper humidity and haematocrit has been examined. Results are compared to those of others, and advantages of the method are discussed.

We evaluated the effect of sampling of capillary blood on filter paper on the later analysis for glucose. We found the method simple and reliable. Determination at the central laboratory of glucose in blood collected onto filter paper and comparison of the results with those obtained with test strips read in reflectometers at outpatient units is easy. Collecting duplicate samples on filter paper facilitates quality control by avoiding the complications that arise from using quality-control solutions that are not directly comparable with fresh blood, and it avoids the disturbances of test strip chemistry attributable to the glycolysis inhibitors added to blood samples intended for quality control.