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This quantitative study examined self-efficacy as a factor in teachers’ technology use and integration efforts in urban K-12 classroom settings of 327 Catholic school teachers in Southern California. This study employed an online survey that utilized the Technology Integration Confidence Scale (TICS) version 3, an instrument developed by the first author which is aligned to the ISTE (2017) Standards for Educators, and found that, on average, participating teachers had a fair level of confidence (i.e., they are fairly but not highly confident) in both using and integrating technology (M = 3.2, SD = .73). Accordingly, the study established participating teachers’ level of confidence in using and applying technology through sustained continuous professional development intervention as a key implication that influenced teachers’ self-efficacy in leveraging technology for professional practice.

A simple, low cost, and lightweight three-dimensional (3D) primary alkaline Zn/Fe3O4 origami-battery fabricated from Whatman 1 paper was developed. The battery was created using printed wax to define the hydrophobic and hydrophilic barriers and active electrocatalytic materials for fabricating the electrodes. The boat-shaped 3D-battery consisted of two screen-printed Zn/Fe3O4 batteries connected in series that were activated with a small volume of aqueous KOH solution. The metallic electrodes were first characterized outside the folded battery using electrochemical techniques. Subsequently, the electrodes and separator were assembled together in a triangle-shaped battery resembling the main structure of the boat-shaped 3D-device and this triangle-shaped battery was further optimized. The addition of water triggered the activation of the 3D battery delivering a maximum current and power of 7 mA and 3 mW, respectively. The 3D-Zn/Fe3O4-battery displayed an OCP of 2.2 V and a maximum current and power of 22 mA and 7.5 mW, respectively, in the presence of 6 M KOH electrolyte. These results demonstrate the potential of 3D origami-based structures and Zn/Fe3O4 batteries as an alternative low cost energy source to power portable devices.

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.

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.

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.

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.

A reusable and simple to fabricate electrochemical sensor for the detection of glucose and acetylthiocholine using thread-based electrodes and nylon thread is described. The fabrication of the device consisted of two steps. First, three nylon-based electrodes (reference, working, and counter) were painted with one layer of conductive inks (silver and carbon ink, or silver/silver chloride ink). The electrodes were taped onto parafilm, and a piece of white nylon thread was wrapped around each electrode connecting the three electrodes. For the glucose system, a PBS solution containing glucose oxidase (GOx) (10 mg/mL), and potassium ferricyanide (K3 [Fe(CN)6 ]) (10 mg/mL) as mediator, was dried onto the thread, and increasing concentrations of glucose (0-15 mM) was added to the thread and measured by cyclic voltammetry (CV). The current output from the glucose oxidation was proportional to the concentration of glucose. For the second system, a solution of acetylcholinesterase (AChE) (0.08 U/mL) in PBS was added to the nylon thread, and increasing concentrations of acetylthiocholine (ATC) (0-9.84 mg/mL) was added and measured by CV. The current output from the oxidation of thiocholine (produced by AChE reacting with ATC) was proportional to the concentrations of ATC added to the thread. From both systems, a graph of current output versus substrate concentration was produced and fitted with a linear regression line that gave R2 values of 0.985 (GOX /glucose) and 0.995 (AChE/ATC).

This paper describes the fabrication of and data collection from two microfluidic devices: a microfluidic thread/paper based analytical device (μTPAD) and 3D microfluidic paper-based analytical device (μPAD). Flowing solutions of glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI), through each device, on contact with glucose, generated a calibration curve for each platform. The resultant yellow-brown color from the reaction indicates oxidation of iodide to iodine. The devices were dried, scanned, and analyzed yielding a correlation between yellow intensity and glucose concentration. A similar procedure, using an unknown concentration of glucose in artificial urine, is conducted and compared to the calibration curve to obtain the unknown value. Studies to quantify glucose in artificial urine showed good correlation between the theoretical and actual concentrations, as percent differences were ≤13.0%. An ANN was trained on the four-channel CMYK color data from 54 μTPAD and 160 μPAD analysis sites and Pearson correlation coefficients of R = 0.96491 and 0.9739, respectively, were obtained. The ANN was able to correctly classify 94.4% (51 of 54 samples) and 91.2% (146 of 160 samples) of the μTPAD and μPAD analysis sites, respectively. The development of this technology combined with ANN should further facilitate the use of these platforms for colorimetric analysis of other analytes.

Microfluidics has served as a technology for the design and development of a myriad of devices owing to their reduced reagent consumption rate and short sampling-to-result time. Chemotaxis is the movement of materials, particularly biological species, in response to the influence of chemical stimulation. Herein, we describe, for the first time, chemotactic behavior on a microfluidic paper-based analytical device (μPAD) to afford a distribution of products not obtainable under other (non-μPAD) experimental conditions using as a model enzyme-substrate system glucose oxidase (GOx) and glucose. μPADs are easily fabricated by patterning hydrophobic materials in hydrophilic paper. They are low cost, compatible with biological samples, and have shown promise as platforms for various applications and in resource-limited settings.

This paper describes enzyme-linked immunosorbent assays (ELISAs) utilizing microfluidic thread/paper-based analytical devices (μTPAD), microfluidic fabric-based analytical devices (μFAD), and microfluidic thread-based analytical devices (μTAD). Here, the quantitative detection of biotinylated goat anti-mouse IgG (system one) and rabbit IgG (system two) antibodies via colorimetric analysis is detailed. In both systems, antibody is spotted on the detection site and subjected to a series of washes, addition of streptavidin-alkaline phosphatase (Strep-ALP) (system 1) or alkaline phosphatase (ALP)-conjugated secondary antibody (system 2), and colorimetric substrate. The devices are scanned and analyzed yielding a correlation between inverse yellow (or purple) intensity. For system one, a linear range of detection at low concentrations of streptavidin-alkaline phosphatase (Strep-ALP) was observed befire the enzyme reached a Vmax . At higher concentrations of Strep-ALP, saturation is achieved for both the μTPAD and μFAD devices. For system two, the IC50 values obtained for the non-trifurcated and trifurcated μTADs were determined to be 180.2 fmol/zone and 133.8 fmol/zone, respectively. The IC50 value was demonstrated to be 1034 fmol/zone and 208.6 fmol/zone for the μTPADs and μFADs, respectively. For all devices the lowest concentration of Strep-ALP or rabbit IgG used in the assay was 3.75 × 10-4 mg/mL and 0.7 fmol/zone, respectively. The development of this technology should further facilitate the use of these platforms for ELISA to detect and quantitate antibodies.

Fabric-based microfluidic fuel cells (MFCs) serve as a novel, cost-efficient alternative to traditional FCs and batteries, since fluids naturally travel across fabric via capillary action, eliminating the need for an external pump and lowering production and operation costs. Building on previous research with Y-shaped paper-based MFCs, fabric-based MFCs mitigate fragility and durability issues caused by long periods of fuel immersion. In this study, we describe a microfluidic fabric-based direct formate fuel cell, with 5 M potassium formate and 30% hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using a two-strip, stacked design, the optimized parameters include the type of encasement, the barrier, and the fabric type. Surface contact of the fabric and laminate sheet expedited flow and respective chemical reactions. The maximum current (22.83 mA/cm2 ) and power (4.40 mW/cm2 ) densities achieved with a 65% cotton/35% polyester blend material are a respective 8.7% and 32% higher than previous studies with Y-shaped paper-based MFCs. In series configuration, the MFCs generate sufficient energy to power a handheld calculator, a thermometer, and a spectrum of light-emitting diodes.

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 24 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%.

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.

This paper describes the development and application of microfluidic cord-based analytical devices (&micro, CADs) in two enzyme-linked immunosorbent assays (ELISAs) and glucose assay. In this study, biotinylated goat anti-mouse immunoglobulin (IgG) antibody, rabbit IgG antibody, and glucose are quantitatively detected. In the ELISA systems, the antibody is spotted on the cord at the detection site and a series of washes, followed by streptavidin-alkaline phosphatase (Strep-ALP) or alkaline phosphatase (ALP)-conjugated secondary antibody and colorimetric substrate, completing the experiment. The devices are subsequently scanned and analyzed yielding a correlation between inverse yellow or inverse blue intensity and antibody concentration. For the first ELISA, a linear range of detection was observed at lower concentrations (2.50 &times, 10&minus, 4&ndash, 1.75 &times, 3 mg/mL) of Strep-ALP with saturation of the enzyme achieved at higher concentrations (&gt, 2.50 &times, 4). For the second ELISA, the L50 was demonstrated to be 167.6 fmol/zone. The glucose assay consisted of spotting increasing concentrations of glucose on the analysis sites and transporting, via capillary action, a solution containing glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) to the detection sites realizing a yellow-brown color indicating oxidation of iodide to iodine. The device was then dried, scanned, and analyzed to show the correlation between yellow inverse intensity and glucose. Glucose in artificial urine showed good correlation using the devices.

This paper describes the use of aluminum and zinc as anodic materials for a battery employing nickel (II) oxide (NiO) as cathode. Comparison of both materials resulted in the development of a compact, cost effective, and easy to use primary NiO/Al battery employing an alkaline electrolyte. The system features electrodes composed of powder forms of the active materials on modified paper substrates that are contained in a simple multilayer design utilizing thin laminated plastic materials to provide structure and flexibility to the battery as well as a paper separator. Various concentrations of potassium hydroxide (KOH) electrolyte were examined and maximum performance was observed at 6 M KOH. A maximum current density and power density of 1.94 mA/cm2 and 1 mW/cm2 , respectively was achieved. This user-friendly device was able to produce a maximum capacity of 2.33 mAh/g when 2 mA/g was applied. This work demonstrates the viability of a paper-based battery featuring powder electrodes as a possible power source for microelectronic devices.

Paper microfluidics is used to produce single layer galvanic and hybrid cells to produce energy that could power paper-based analytical sensors. When two aqueous streams are absorbed onto paper to establish co-laminar flow, the streams stay in contact with each other with limited mixing. The interface at which mixing occurs acts as a charge-transfer region, eliminating the need for a salt bridge. We designed a Cu Zn galvanic cell that powers an LED when two are placed in series. We also used more powerful redox couples (formate and silver, formate and permanganate) to produce higher power density (18 and 3.1 mW mg−1 Pd). These power densities are greater than previously reported paper microfluidic fuel cells using formate or methanol. The single layer design is much more simplified than previous reports of multi-layer galvanic cells on paper.

Paper-based microfluidic fuel cells (MFCs) are a potential replacement for traditional FCs and batteries due to their low cost, portability, and simplicity to operate. In MFCs, separate solutions of fuel and oxidant migrate through paper due to capillary action and laminar flow and, upon contact with each other and catalyst, produce electricity. In the present work, we describe an improved microfluidic paper-based direct formate FC (DFFC) employing formate and hydrogen peroxide as the anode fuel and cathode oxidant, respectively. The dimensions of the lateral column, current collectors, and cathode were optimized. A maximum power density of 2.53 mW/cm(2) was achieved with a DFFC of surface area 3.0 cm(2) , steel mesh as current collector, 5% carbon to paint mass ratio for cathode electrode and, 30% hydrogen peroxide. The longevity of the MFC's detailed herein is greater than eight hours with continuous flow of streams. In a series configuration, the MFCs generate sufficient energy to power light-emitting diodes and a handheld calculator.

In this paper we describe the fabrication of novel 3D microfluidic paper-based analytical devices (3D-μPADs) and a 3D microfluidic thread/paper-based analytical device (3D-μTPAD) to detect glucose and BSA through colorimetric assays. The 3D-μPAD and 3D-μTPAD consisted of three (wax, heat pressed wax-printed paper, single-sided tape) and four (hole-punched single-sided tape, blank chromatography circles, heat-pressed wax-printed paper, hole-punched single-sided tape containing trifurcated thread) layers, respectively. The saturation curves for each assay were generated for all platforms. For the glucose assay, a solution of glucose oxidase (GOx), horseradish peroxidase, and potassium iodide was flowed through each platform and, upon contact with glucose, generated a yellow-brown color indicative of the oxidation of iodide to iodine. For the protein assay, BSA was flowed through each device and, upon contact with citrate buffer and tetrabromophenol blue, resulted in a color change from yellow to blue. The devices were dried, scanned, and analyzed yielding a correlation between either yellow intensity and glucose concentration or cyan intensity and BSA concentration. A similar glucose assay, using unknown concentrations of glucose in artificial urine, was conducted and, when compared to the saturation curve, showed good correlation between the theoretical and actual concentrations (percent differences

In this paper, an alkaline nickel oxide hydroxide/zinc (NiOOH/Zn) battery featuring a cellulose matrix separator between electrodes is presented. The metallic electrodes and the paper separator are inserted in a layer-by-layer assembly that provides mechanical stability to the system resulting in a lightweight and easy-to-use device. The battery was optimized for the amount of NiOOH-ink used at the cathode (11.1 mg/cm2 ) and thickness of the paper membrane separating the electrodes (360 μm). The battery was able to function using a small volume (75 μL) of 1.5 M potassium hydroxide (KOH) producing a maximum voltage, current density, and power density of 1.35 ± 0.05 V, 10.62 ± 0.57 mA/cm², and 0.56 ± 0.01 mW/cm², respectively. The system displayed a maximum current of 23.9 mA and a maximum power of 1.26 mW. Moreover, four batteries connected in series were able to power a small flameless candle for approximately 22 min. This work has potential in fulfilling the demands for short-term and lightweight power supplies.

An electrochemical sensor for the detection of glucose using thread-based electrodes and fabric is described. This device is relatively simple to fabricate and can be used for multiple readings after washing with ethanol. The fabrication of the chip consisted of two steps. First, three thread-based electrodes (reference, working, and counter) were fabricated by painting pieces of nylon thread with either layered silver ink and carbon ink or silver/silver chloride ink. The threads were then woven into a fabric chip with a beeswax barrier molded around the edges in order to prevent leaks from the tested solutions. A thread-based working electrode consisting of one layer of silver underneath two layers of carbon was selected to fabricate the final sensor system. Using the chip, a PBS solution containing glucose oxidase (GOx) (10 mg/mL), potassium ferricyanide (K3 [Fe(CN)6 ]) (10 mg/mL) as mediator, and different concentrations of glucose (0-25 mM), was measured by cyclic voltammetry (CV). It was found that the current output from the oxidation of glucose was proportional to the glucose concentrations. This thread-based electrode system is a viable sensor platform for detecting glucose in the physiological range.

We describe the first direct formate fuel cell on a paper microfluidic platform. In traditional membrane-less microfluidic fuel cells (MFCs), external pumping consumes power produced by the fuel cell in order to maintain co-laminar flow of the anode stream and oxidant stream to prevent mixing. However, in paper microfluidics, capillary action drives flow while minimizing stream mixing. In this work, we demonstrate a paper MFC that uses formate and hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using these materials we achieve a maximum power density of nearly 2.5 mW/mg Pd. In a series configuration, our MFC achieves an open circuit voltage just over 1 V, and in a parallel configuration, short circuit of 20 mA absolute current. We also demonstrate that the MFC does not require continuous flow of fuel and oxidant to produce power. We found that we can pre-saturate the materials on the paper, stop the electrolyte flow, and still produce approximately 0.5 V for 15 min. This type of paper MFC has potential applications in point-of-care diagnostic devices and other electrochemical sensors.

A novel microfluidic paper-based analytical device (μPAD) utilizing a nitrocellulose (NC) membrane to detect IgG antibodies through a colorimetric analysis is described. The μPAD was constructed using layered polyethylene terephthalate (PET) and pressure-sensitive adhesives (PSA). The biotin labeled Goat Anti-Mouse IgG antibody was spotted and dried on the NC channel prior to subjecting it to a series of wash solutions (Tris-tween), increasing concentrations of alkaline phosphatase conjugated to streptavidin (Strep-ALP), and para-nitrophenyl phosphate (p-NPP) realizing a vibrant yellow color. The reaction proceeds for 10 min before applying the p-NPP stop solution. The device was then dried, scanned, and analyzed yielding a linear range of inverse yellow color intensities versus Strep-ALP concentrations. The development of this simple μPAD should further facilitate the use of NC in colorimetric assays to detect and quantitate antibodies.

Osteocalcin (bone gamma-carboxyglutamate protein; BGLAP) is a highly conserved molecule associated with mineralization of bone matrix. It regulates the dynamics of new bone formation and bone resorption. The synthesis of osteocalcin by osteoblasts is regulated by the active form of vitamin D. In this paper, we report the use of two fluorescent-based assays, one bead-based and a second involving an amino-silane surface pre-treatment, to obtain binding constants of 3.53×10 6 M −1 and 3.19×10 6 M −1 , respectively, for the binding of BGLAP to fluorescently labeled monoclonal-anti BGLAP-clone 2D5. These simple microfluidic techniques demonstrate the feasibility of developing microsphere-based and surface electrostatically-attached binding assays to study peptide–antibody interactions. Both techniques utilize sub-microliter volumes of material an important consideration when studying bone turnover markers (BTMs) like BGLAP.

Enzyme-linked immunosorbent assay (ELISA) is an immunological assay commonly used to measure antibodies, antigens, proteins, and glycoproteins in biological samples. While the procedure is routine and straightforward, there are a number of variables (reagent selection, volume measurement, temperature, and time) that if not carefully considered, can affect the test outcome. Herein, we describe the development of microfluidic thread/paper-based analytical devices (µTPAD), microfluidic fabric-based analytical devices (µFAD), and microfluidic thread-based analytical devices (µTAD) as new platforms for ELISA. The quantitative detection of biotinylated goat anti-mouse IgG (system one) and rabbit IgG (system two) antibodies via colorimetric analysis is detailed. We explain the design and fabrication of the devices and the step-by-step protocol for the ELISA. A comparison between the techniques is described and the results obtained from them elucidated.

We describe the use of a computational neural network platform to optimize the fluorescence upon binding 5-carboxyfluorescein-d-Ala-d-Ala-d-Ala (5-FAM(DA)3 ) (1) to the antibiotic teicoplanin covalently attached to a glass slide. A three-level response surface experimental design was used as the first stage of investigation. Subsequently, three defined experimental parameters were examined by the neural network approach: (i) the concentration of teicoplanin used to derivatize a glass platform on the microfluidic device, (ii) the time required for the immobilization of teicoplanin on the platform, and (iii) the length of time 1 is allowed to equilibrate with teicoplanin in the microfluidic channel. Optimal neural structure provided a best fit model, both for the training set (r(2) = 0.961) and test set (r(2) = 0.934) data. Model simulated results were experimentally validated with excellent agreement (% difference) between experimental and predicted fluorescence shown, thus demonstrating efficiency of the neural network approach.

Surface plasmon resonance (SPR) spectroscopy is utilized to study in real-time and, by label-free means, the reversible and quasi-irreversible adsorption of small ionic or neutral molecules, pharmaceuticals, and proteins on poly(dimethylsiloxane) (PDMS) surfaces. The SPR sensor is covered with 0.2% (w/v) PDMS in octane. During the timescale of a typical lab-on-a-chip analysis or an electrophoretic separation, it was found that small neutral components containing a hydrophobic part do not adsorb or absorb onto PDMS, while larger, water-soluble polymer-like materials like proteins generally irreversibly adsorb to PDMS. The technique can be used to monitor the kinetics of adsorption and desorption of the molecules. For the non-specific adsorption of teicoplanin to PDMS, a Langmuir-like adsorption isotherm was obtained (Kd = 32 ± 2 μmol L−1).

This paper demonstrates the use of surface plasmon resonance to study adsorption (either reversible or irreversible) of detergents on PDMS surfaces in real time. The surface plasmon resonance measurements can directly provide information about the adsorption/desorption processes of detergents on the surface revealing the durability of the adsorbed layer and the anticipated degree of the EOF. Hydroxypropyl methylcellulose very strongly adsorbs onto PDMS and can be considered both a semipermanent layer and stable semipermanent coating. Adsorbed SDS or CTAB layers were stable for several minutes upon rinsing the surface with solution not containing the detergent. It was shown that SDS coated onto PDMS in microchips has the potential to afford similar separations in PDMS as found in conventional fused silica capillaries.

Vet Med Today: Timely Topics in Nutrition 1453 C is becoming increasingly common in both human and veterinary medicine. In the United States, it has been reported that cancer accounts for approximately 1 in 4 human deaths. One in 2 men and 1 in 3 women will develop cancer during their lifetime. Similarly, cancer is the leading cause of death in dogs > 2 years old, and in some breeds, such as Golden Retrievers, the rate of death attributable to cancer is > 50%. Diet can alter cancer risk in humans and laboratory animals, and many investigators are exploring nutritional strategies to prevent cancer as well as aid in the treatment of cancer. A pet owner will often pursue dietary strategies that are believed to have the potential to benefit a pet with cancer. Anecdotally, dietary strategies often proposed for pets with cancer include low-carbohydrate diets, grain-free diets, raw-food diets, dietary supplementation with omega-3 fatty acids, and forgoing commercial pet foods in favor of preparing food at home for a pet. Clients who opt to prepare food for their dogs with cancer do so for various reasons. Some pet owners believe that a commercial diet contributed to the development of the cancer, despite a general lack of evidence to support this belief. Others believe that avoiding preservatives and ingredients perceived to be undesirable (eg, grains) will improve their pet’s prognosis. Still others want a way to be a direct part of their pet’s treatment or are concerned because their pet’s appetite is decreased and a home-prepared diet is perceived by the owner to be more palatable. Regardless of the reason for the decision to prepare their pet’s food at home, once this decision is made, many pet owners seek advice on the preparation of meals from veterinarians, websites, books, newsgroups, and other sources. Most commercial over-the-counter diets are complete and balanced (ie, they meet the minimum amounts established by the AAFCO for all nutrients for the appropriate life stage). Manufacturers must verify that Assessment of commercial diets and recipes for home-prepared diets recommended for dogs with cancer

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.

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.

This paper describes the use of a genetically tuned neural network platform to optimize the fluorescence realized upon binding 5-carboxyfluorescein-D-Ala-D-Ala-D-Ala (5-FAM-(D-Ala)(3) ) (1) to the antibiotic teicoplanin from Actinoplanes teichomyceticus electrostatically attached to a microfluidic channel originally modified with 3-aminopropyltriethoxysilane. Here, three parameters: (i) the length of time teicoplanin was in the microchannel; (ii) the length of time 1 was in the microchannel, thereby, in equilibrium with teicoplanin, and; (iii) the amount of time buffer was flushed through the microchannel to wash out any unbound 1 remaining in the channel, are examined at a constant concentration of 1, with neural network methodology applied to optimize fluorescence. Optimal neural structure provided a best fit model, both for the training set (r(2) = 0.985) and testing set (r(2) = 0.967) data. Simulated results were experimentally validated demonstrating efficiency of the neural network approach and proved superior to the use of multiple linear regression and neural networks using standard back propagation.

Background: The aim was to develop a simple route to coupling microchip CE (MCE) to surface plasmon resonance (SPR). MCE is a microfluidic technology that utilizes microfabrication techniques to connect interacting fluid reservoirs. Its advantages include rapid analysis (typically seconds), easy integration of multiple analytical steps and parallel operation. SPR detects changes in refractive index within a short distance from the surface of a thin metal film as variations in light intensity reflected from the back of the film and, thus, does not require labeling. There is a great demand for developing hyphenated techniques like MCE–SPR that are fast, sensitive and inexpensive to analyze biological materials. Materials & Methods: The separation channel and flow cell exist as overlapping regions constructed during the microchip production and buffer solution was delivered mechanically. Such a design has successfully isolated the electrical field inherent in the MCE from the SPR detector. Consequently, the potential interference to the SPR signal (or modulation of the density of surface plasmons at the gold chip) is circumvented. Results: The limits of detection for bovine serum albumin and sodium fluorescein were determined to be 7.5 µM and 3.1 mM, respectively. Conclusion: The technique described, herein, has been successfully applied in the separation of two species. The method offers the advantages of a near zero connection dead volume, electrical shielding from the separation voltage and minimization of the mass transfer effect.

The ability to accurately inject small volumes of sample into microfluidic channels is of great importance in electrophoretic separations. While electrokinetic injection of nanoliter scale volumes is commonly utilized in microchip capillary electrophoresis (MCE), mobility and matrix bias makes quantitation difficult. Herein, we describe a new injection method based on the simple patterning of the crossing of channels that does not require sophisticated instrumentation. The sample volume injected into the separation channel is dependent on the ratio of the widths of the crossing channels. This injection method is capable of introducing, into a separation channel, multiple plugs of sample on a large scale. This injection technique is tested for zone electrophoresis in native and surface modified poly(dimethylsiloxane) (PDMS) chips.

We describe a paper microfluidic-based enzyme catalyzed double microreactor assay using fluorescent detection. Here, solutions of lactate dehydrogenase (LDH) and diaphorase (DI) were directly spotted onto the microfluidic paper-based analytical device (μPAD). Samples containing lactic acid, resazurin, and nicotinamide adenine dinucleotide oxidized form (NAD(+) ), potassium chloride (KCl), and BSA, in MES buffer were separately spotted onto the μPAD and MES buffer flowed through the device. A cascade reaction occurs upon the sample spot overlapping with LDH to form pyruvate and nicotinamide adenine dinucleotide reduced form (NADH). Subsequently, NADH is used in the conversion of resazurin to fluorescent resorufin by DI. The μPAD avoids the need of surface functionalization or enzyme immobilization steps. These microreactor devices are low cost and easy to fabricate and effect reaction based solely on buffer capillary action.

This study sought to examine high school students’ self-reported drinking behaviors following the introduction of flavored malt beverages, also known as alcopops, to the US market. We hypothesized that adolescents’ reported drinking behaviors would be significantly altered following the introduction of alcopops in the US. A cross-sectional time series Youth Risk Behavior Survey data set was created from publicly available data collected by the Centers for Disease Control and Prevention (N = 60,426) and used to conduct secondary data analysis, using an interrupted time series quasi-experimental design. Segmented regression analyses estimated how much the introduction of alcopops in the US affected drinking behaviors, whether the effects were immediate and/or delayed, and whether there may have been other factors than the intervention that could explain the effects. Respondents aged ≥18 years had statistically significant increases in three drinking behaviors after alcopops were introduced. Binge drinking i...

This paper describes the design, development and application of microfluidic "thin chips" fabricated from PDMS. Thin chips consist of multiple layers of PDMS chemically bonded onto each other. Unlike thicker PDMS chips that suffer from lack of sensitivity due to PDMS absorption in the VIS and UV range, the thinness of these chips allows for the detection of chromophoric species within the microchannel via an external fiber optics detection system. C18-modified reversed-phase silica particles are packed into the microchannel using a temporary taper created by a magnetic valve and separations using both pressure- and electrochromatographic-driven methods are detailed.