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This study introduces the development of a photothermal-based microfluidic paper analytical device (PT-µPAD) integrated with near-field communication (NFC) technology and smartphone readout for enzyme-free glucose quantification in human samples. With the properties of gold nanoparticles (AuNPs) both as a nanozyme and as a photothermal substrate, there is no need for costly reagents like enzymes or a readout instrumentation for the selective and sensitive detection of glucose. In PT-µPADs, AuNPs are etched by hydrogen peroxide (H2O2) generated from glucose catalysis. Photothermal detection from the plasmonic heating of these AuNPs when illuminated by a 533nm LED light source is achieved by inserting the PT-µPAD sensor into a portable NFC platform suitable for smartphone readout. Temperature variation is directly proportional to the glucose concentration. After optimization, we acquired a linear range between 5.0 and 20.0 µmol L−1 (R2 = 0.9967) and a limit of detection (LOD) of 25.0 nmol L−1 for glucose. Additionally, while our sensor does not utilize any enzyme, it is remarkably selective to glucose with no effects from interferences. Recovery studies in various human control samples indicated a range of 99.73–102.66% with the highest RSD of 3.53%, making it highly accurate and precise. Moreover, our method is more sensitive than other methods relying on conventional µPADs for glucose sensing. By integrating the potential benefits of microfluidics, nanomaterials as nanozymes, and NFC technology for wireless readout, our sensor demonstrates great promise as an accessible, affordable, and shelf-stable device for glucose quantification. Moreover, this concept can be extended to detect other molecules of interest as a point-of-care (POC) diagnostics device. [ABSTRACT FROM AUTHOR]

This article introduces distance-based paper analytical devices (dPADs) integrated with molecularly imprinted polymers (MIPs) and carbon dots (CDs) for simultaneous quantification of cytokine biomarkers, namely C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-a), and interleukin-6 (IL-6) in human biological samples for diagnosis of cytokine syndrome. Using fluorescent CDs and MIP technology, the dPAD exhibits high selectivity and sensitivity. Detection is based on fluorescence quenching of CDs achieved through the interaction of the target analytes with the MIP layer on the paper substrate. Quantitative analysis is easily accomplished by measuring the distance length of quenched fluorescence with a traditional ruler and naked eye readout enabling rapid diagnosis of cytokine syndrome and the underlying infection. Our sensor demonstrated linear ranges of 2.50-24.0 pg mL-1 (R2 = 0.9974), 0.25-3.20 pg mL-1 (R2 = 0.9985), and 1.50-16.0 pg mL-1 (R2 = 0.9966) with detection limits (LODs) of 2.50, 0.25, and 1.50 pg mL-1 for CRP, TNF-a, and IL-6, respectively. This sensor also demonstrated remarkable selectivity compared to a sensor employing a non-imprinted polymer (NIP), and precision with the highest relative standard deviation (RSD) of 5.14%. The sensor is more accessible compared to prior methods relying on expensive reagents and instruments and complex fabrication methods. Furthermore, the assay provided notable accuracy for monitoring these biomarkers in various human samples with recovery percentages ranging between 99.22% and 103.58%. By integrating microfluidic systems, nanosensing, and MIPs technology, our developed dPADs hold significant potential as a cost-effective and user-friendly analytical method for point-of-care diagnostics (POC) of cytokine-related disorders. This concept can be further extended to developing diagnostic devices for other biomarkers. [ABSTRACT FROM AUTHOR]

We present a microfluidic optoelectronic sensor for saliva diagnostics with a potential application for non-invasive early diagnosis of stomach cancer. Stomach cancer is the second most common cause of cancer-related deaths in the world. The primary identified cause is infection by a gram-negative bacterium Helicobacter pylori . These bacteria secrete the enzyme urease that converts urea into carbon dioxide (CO 2 ) and ammonia (NH 3 ), leading to their elevated levels in breath and body fluids. The proposed optoelectronic sensor will detect clinically relevant levels of CO 2 and NH 3 in saliva that can potentially be used for early diagnosis of stomach cancer. The sensor is composed of the embedded in a microfluidic device array of microwells filled with ion-exchange polymer microbeads doped with various organic dyes. The optical response of this unique highly diverse sensor is monitored over a broad spectrum, which provides a platform for cross-reactive sensitivity and allows detection of CO 2 and NH 3 in saliva at ppm levels. [ABSTRACT FROM AUTHOR]

Technologies capable of noninvasively sampling different locations in the gut upstream of the colon enable new insights into the role of organ‐specific microbiota in human health. Herein, an ingestible, biocompatible, battery‐less, 3D‐printed microengineered pill with an integrated osmotic sampler and microfluidic channels for in vivo sampling of the gut lumen and its microbiome upstream of the colon is discussed. The pill's sampling performance is characterized using realistic in vitro models and validated in vivo in pigs and primates. Herein, the results show that the bacterial populations recovered from the pill's microfluidic channels closely resemble the bacterial population demographics of the microenvironment to which the pill is exposed. Herein, it is believed that such lab‐on‐a‐pill devices revolutionize the understanding of the spatial diversity of the gut microbiome and its response to medical conditions and treatments. [ABSTRACT FROM AUTHOR]

We demonstrate dissolved ammonia (NH3) sensing in complex mixtures using an optoelectronic sensor comprising a composite sensing material based on a metalloporphyrin zinc tetraphenylporphyrin (ZnTPP) and spectroscopic detection. The metalloporphyrin dye is incorporated within ion-exchange polymeric microbeads arranged in a microfluidic array. Spectroscopic analysis at multiple wavelengths allows sensitive detection in complex backgrounds. The sensor shows preferential sensitivity to ppm levels of concentrations of NH3 dissolved in water, as well as in human saliva, making it relevant for medical diagnostic applications (e.g. detection of stomach bacterial infections). The microfluidic platform and a miniaturized optical arrangement provide a potential for the development of a portable low-power sensor for detection of dissolved ammonia for a variety of applications. [ABSTRACT FROM AUTHOR]

Abstract: We present a microfluidic optoelectronic cross-reactive sensor based on a novel composite material for selective detection of dissolved CO2. A microfluidic device contains an array of micro-wells filled with ion-exchange polymeric microbeads doped by halochromic dyes paired to quaternary ammonium cations. The sensor configuration allows incorporation of virtually any combination of halochromic ion-pairs, providing a route for cross reactive sensing. A versatile optical arrangement based on a white LED and a miniature portable USB spectrometer allows recording optical spectra, which are easily translated into electronic readouts. Rather than monitoring response at a particular absorption or emission wavelength of the dye, data acquisition is performed over a broad continuous spectrum. This results in a rich multidimensional readout useful for ultrasensitive detection. The sensor provides distinctive responses to different concentrations of dissolved CO2, with no cross sensitivity to other sources of acidity. Our findings could lead to the development of a cost-effective, lightweight, and low-power sensor for detection of dissolved CO2 for a variety of applications. [Copyright &y& Elsevier]

Abstract: We present a portable lab-on-chip device for high-throughput trapping and lysis of single cells with in-situ impedance monitoring in an all-electronic approach. The lab-on-chip device consists of microwell arrays between transparent conducting electrodes within a microfluidic channel to deliver and extract cells using alternating current (AC) dielectrophoresis. Cells are lysed with high efficiency using direct current (DC) electric fields between the electrodes. Results are presented for trapping and lysis of human red blood cells. Impedance spectroscopy is used to estimate the percentage of filled wells with cells and to monitor lysis. The results show impedance between electrodes decreases with increase in the percentage of filled wells with cells and drops to a minimum after lysis. Impedance monitoring provides a reasonably accurate measurement of cell trapping and lysis. Utilizing an all-electronic approach eliminates the need for bulky optical components and cameras for monitoring. [Copyright &y& Elsevier]