Point-of-care (POC) diagnostic devices are integral in the health care system and particularly for the diagnosis and monitoring of diseases. POC testing has a variety of advantages including the ...ability to provide rapid and accurate results, ease of use, low cost, and little need for specialized equipment. One of the goals of POC testing is the development of a chip-based, miniaturized, portable, and self-containing system that allows for the assay of different analytes in complex samples. To achieve these goals, many researchers have focused on paper-based and printed electrode technologies as the material for fabricating POC diagnostic systems. These technologies are affordable, sensitive, user-friendly, rapid, and scalable for manufacturing. Moreover, the combination such devices with nanomaterials provide a path for the development of highly sensitive and selective biosensors for future generation POC tools.
This review article discusses present technologies in on-site or at home POC diagnostic assays implemented in paper-based microfluidic and screen printing devices over the past decade as well as in the near future. In addition, recent advances in the application of nanomaterials such as gold nanoparticles, carbon nanotubes (CNTs), magnetic nanoparticles, and graphene in POC devices will be reviewed. The factors that limit POC testing to become real world products and future directions are also identified.
•The present technologies in on-site or at home POC diagnostics assays are discussed.•In this review article, we focus on strip-based microfluidic and screen printing POC devices.•The recent advances in the application of nanomaterials in POC devices are reviewed.•The factors which limit POC testing to become real world products and future directions are also identified.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We report the colorimetric detection of dopamine (DA) on microfluidic paper-based analytical devices (μPADs) using an oxidation-reduction method. Here, dopamine reacts with ferric chloride forming ...reduced Fe2+ that subsequently reacts with phenanthroline to form the red tris(1,10-phenanthroline)iron(II) complex. The devices were fabricated by wax printing and changes in color intensity were recorded using a common cell phone. Subsequent analysis using Photoshop software, yielded a limit of detection (LOD) for DA of 0.37 μmol/L with a linear range of 0.527–4.75 μmol/L and relative standard deviation of 0.11% (inter-day) and 0.15% (intra-day) for n = 15 paper chips. The effects of detection conditions have been investigated and are discussed. Cow serum samples and human blood serum and plasma samples were detected. The work, herein, demonstrates the potential of this method as a low cost and rapid colorimetric technique to detect DA in real samples.
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•A colorimetric detection of dopamine (DA) on microfluidic paper-based analytical devices (μPADs) was developed.•The changes in color intensity were recorded using a common cell phone and analysis using Photoshop software.•The method provide an inexpensive and selective determination of DA with low LOD. It does not need other assistances.•The relative standard deviation (RSD) of inter-day (n =15) and intra-day (n =15) is no more than 0.2%.•Cow serum samples and human serum and plasma samples were detected.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, a microfluidic thread‐based analytical device (μTAD) to assess the activity of acetylcholinesterase (AChE) via colorimetric analylsis is described. Fabrication of the device consists ...of two platforms, both with a nylon thread trifurcated into three channels terminating at open analysis sites at the end of the thread. 5,5’‐Dithiobis‐(2‐nitrobenzoic acid) (DTNB) was spotted and dried on the analysis sites. Acetylthiocholine iodide (ATC) (or cysteine, Cys) is transported through an inlet channel of the nylon thread by capillary action due to the hydrophilic nature of nylon. AChE is transported through the other inlet channel and mixes with the ATC (or Cys) as they travel up to the analysis sites. As the solution reaches the analysis sites, an intense yellow color change occurs indicating the reaction of the thiol with DTNB to produce the yellow anion TNB2−. The sites are then dried, scanned, yielding a linear range of inverse yellow mean intensity versus substrate concentration. An IC50 value (1.74 nM) with a known inhibitor, neostigmine bromide (NB), is obtained on the device. The multiplex design enables triplicate data collection in a device that is easy to use. μTADs have great potential to be employed in a myriad of tests including point‐of‐care diagnostic devices for resource‐challenged settings.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Neurotransmitters play key roles in cell‐to‐cell communication. These chemical messengers are involved in many functional processes, including growth, reproduction, memory, and behavior. In this ...communication, we describe a novel microfluidic paper‐based analytical device (μPAD) to detect acetylcholinesterase (AChE) activity and inhibitor screening through a colorimetric analysis. The μPAD is easily fabricated via a wax printing process whereby wax is deposited onto the surface of chromatographic paper, and heated to create a hydrophobic barrier. Separate solutions of 5,5′‐dithiobis‐(2‐nitrobenzoic acid) (DTNB) and samples containing AChE and acetylthiocholine iodide (ATC) (or cysteine, Cys), respectively, are directly spotted onto the μPAD. DTNB and AChE/ATC (or Cys) flow towards each other where a reaction occurs to form the yellow colored 2‐nitro‐5‐thiobenzoic acid anion (TNB2−). The device is dried, scanned, and analyzed yielding a linear range of average inverse yellow intensities versus substrate concentration. An IC50 value (0.045 nM) with a known inhibitor, neostigmine bromide (NB), is obtained on the device. μPADs are low cost and easy to fabricate and have great potential to quantify neurotransmitter activity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This paper describes the design and development of miniaturized microfluidic paper-based analytical devices (μPADs) for biological assays and enzyme storage instruments. Here, a glucose assay ...utilizing glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) is used as the model system. The efficacy of the miniaturized devices is further examined by assessing the activity of acetylcholinesterase (AChE). Two types of μPADs were developed: one, “strip” chips of detection zones of area 0.5, 0.1 cm2 and, two, “grid” chips of detection zone 0.05 cm2. The devices are easily fabricated via a wax printing process whereby lines of wax are deposited onto chromatographic paper and heated to create rows of hydrophobic barriers. The “strip” chips were subjected to three different temperature environments (–20, 0, and 20°C) over 30 days and glucose assays conducted at intermittent times yielding a correlation between corrected average inverse yellow intensity, days, and glucose concentration. Calculated and experimentally derived color intensity values for 1, 4, and 9 mM glucose concentrations after a 7-day storage study showed a good correlation (0.89 – 15.76% error). Both types of μPADs are effective platforms as potential point-of-care (POC) diagnostic devices and display minimal enzyme denaturation. μPADs of this size show promise as alternative devices for resource-limited regions and especially those areas where materials and instrumentation are not always available.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We describe the use of a chemometrics-based computational platform to optimize a glucose assay on a microfluidic paper-based analytical device (μPAD). Glucose is colorimetrically detected in the ...presence of glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI). Using a Y-shaped paper microfluidic chip, the concentration of glucose, volume of reagents, and the length and width of the microfluidic channel were examined. The responses of the microfluidic chips were analyzed at the halfway point of the channel length. Variables affecting the response were screened by using a 2
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factorial design, and among them, volume and concentration of the glucose were optimized by applying a rotatable central composite design (CCD). The optimum and experimental responses are 151.58 and 149.80, respectively, with an absolute error of 1.2%.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•A miniaturized, portable, lightweight and flexible alkaline aluminum/silver oxide (Al/AgO) paper battery is presented.•The metallic battery is implemented on painted paper supported ...electrodes with a paper membrane separator.•The cathode and anode of the battery consist of a painted silver epoxy ink and aluminum based composite, respectively.•The battery is activated with water yielding a maximum capacity of 0.5 mAh when 1.6 mA cm−2 is applied to the system.
This work presents the development and optimization of a very low cost, miniaturized and lightweight aluminum/silver oxide (Al/AgO) primary battery. The system is implemented on painted paper supported electrodes and it is activated using a small amount of water. The anode contains an improved composite based on aluminum powder. The cathode is made using an electrical conductive silver epoxy ink. The device displays a paper-based core comprising the electrodes and the paper matrix separator, modified with a highly concentrated dry potassium hydroxide salt, inside a flexible laminated plastic structure that provides sturdiness to the system making it safe and portable for the user. The battery turns on by applying 80 μl of water and as a result the system produces a maximum capacity of 0.5 mAh when 1.6 mA cm−2 are applied. The generated electrical power of two batteries in series is then used to power a LED during approximately one hour. Although there is room for improvement, these results allow envisaging the battery as a real commercial portable power source and allow planning potential uses of this energy to power microelectronics demanding low power consumption, such as sensors or wearable electronics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A novel microfluidic thread/paper‐based analytical device (μTPAD) to detect glucose through a colorimetric assay is described. The μTPAD was fabricated from nylon thread trifurcated into three ...channels terminating at analysis sites comprised of circular zones of chromatography paper, which have previously been spotted with glucose of different concentrations. A solution of glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) is transported via capillary action to the analysis sites where a yellow‐brown color is observed indicating oxidation of iodide to iodine. The device was then dried, scanned, and analyzed yielding a correlation between yellow intensity and glucose concentrations. Both a flat platform constructed mainly of tape, and a cone platform constructed from tape and polyvinyl chloride, are described. Studies to quantitate glucose in artificial urine showed good correlation using the μTPAD.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
There is a paucity of evidence regarding the role of food timing on cardiometabolic health and weight loss in adults.
To determine whether late eating is cross-sectionally associated with obesity and ...cardiometabolic risk factors at baseline; and whether late eating is associated with weight loss rate and success following a weight loss intervention protocol. Also, to identify obesogenic behaviors and weight loss barriers associated with late eating.
Participants were recruited from a weight-loss program in Spain. Upon recruitment, the midpoint of meal intake was determined by calculating the midway point between breakfast and dinner times, and dietary composition was determined from diet recall. Population median for the midpoint of meal intake was used to stratify participants into early (before 14:54) and late (after 14:54) eaters. Cardiometabolic and satiety hormonal profiles were determined from fasting blood samples collected prior to intervention. Weekly weight loss and barriers were evaluated during the ∼19-wk program. Linear and logistic regression models were used to assess differences between late and early eaters in cardiometabolic traits, satiety hormones, obesogenic behaviors, and weight loss, adjusted for age, sex, clinic site, year of recruitment, and baseline BMI.
A total of 3362 adults mean (SD): age: 41 (14) y; 79.2% women, BMI: 31.05 (5.58) kg/m2 were enrolled. At baseline, no differences were observed in energy intake or physical activity levels between early and late eaters (P >0.05). Late eaters had higher BMI, higher concentrations of triglycerides, and lower insulin sensitivity compared with early eaters (all P <0.05) prior to intervention. In addition, late eaters had higher concentrations of the satiety hormone leptin in the morning (P = 0.001). On average, late eaters had an average 80 g lower weekly rate of weight loss early, 585 (667) g/wk; late, 505 (467) g/wk; P = 0.008, higher odds of having weight-loss barriers OR (95% CI): 1.22 (1.03, 1.46); P = 0.025, and lower odds of motivation for weight loss 0.81 (0.66, 0.99); P = 0.044 compared with early eaters.
Our results suggest that late eating is associated with cardiometabolic risk factors and reduced efficacy of a weight-loss intervention. Insights into the characteristics and behaviors related to late eating may be useful in the development of future interventions aimed at advancing the timing of food intake.
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CMK, GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper describes the development of two microfluidic paper-based analytical devices (μPADs), one well-based and the other based on a lateral flow assay (LFA) configuration, to detect glucose via ...a colorimetric assay using the solid metal-organic framework (MOF) Zr-PCN-222(Fe), to encapsulate glucose oxidase (GOx). The well-based platform consisted of laminate sheets and multiple layers of wax-printed chromatography paper. Solutions of KI and glucose placed into the well flowed through the device and reacted with the GOx@MOF species sandwiched between the paper layers realizing a yellow-brown color. The LFA platform consisted of chromatography paper between parafilm and polyvinyl acetate (PVA) layers. GOx@MOFs spotted on the paper subjected to solutions of KI and glucose yielded a brown color. The devices were then dried, scanned, and analyzed yielding a correlation between average inverse yellow intensity and glucose concentrations. The development of these devices employing MOFs as biomimetic catalysts should further expand the applications of microfluidic technologies for sensors a variety of analytes.
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•Paper-based microfluidic devices employing a metal-organic framework detect glucose.•Metal-organic frameworks are effective encapsulating species for enzymes.•Sensors constructed from paper are easy to fabricate and are low-cost.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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