scholarly journals A New Paper-Based Microfluidic Device for Improved Detection of Nitrate in Water

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 102
Author(s):  
Amer Charbaji ◽  
Hojat Heidari-Bafroui ◽  
Constantine Anagnostopoulos ◽  
Mohammad Faghri
Keyword(s):  
Microfluidic Device ◽  
Limit Of Detection ◽  
Fibrous Composite ◽  
Sample Volume ◽  
Optimized Design ◽  
Detection Zone ◽  
Fibrous Composite Material ◽  
Recent Developments ◽  
Immobilized Reagent ◽  
Control Technologies

In this paper, we report a simple and inexpensive paper-based microfluidic device for detecting nitrate in water. This device incorporates two recent developments in paper-based technology suitable for nitrate detection and has an optimized microfluidic design. The first technical advancement employed is an innovative fibrous composite material made up of cotton fibers and zinc microparticles that can be incorporated in paper-based devices and results in better nitrate reduction. The second is a detection zone with an immobilized reagent that allows the passage of a larger sample volume. Different acids were tested—citric and phosphoric acids gave better results than hydrochloric acid since this acid evaporates completely without leaving any residue behind on paper. Different microfluidic designs that utilize various fluid control technologies were investigated and a design with a folding detection zone was chosen and optimized to improve the uniformity of the signal produced. The optimized design allowed the device to achieve a limit of detection and quantification of 0.53 ppm and 1.18 ppm, respectively, for nitrate in water. This accounted for more than a 40% improvement on what has been previously realized for the detection of nitrate in water using paper-based technology.

scholarly journals Fully integrated rapid microfluidic device translated from conventional 96-well ELISA kit

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Jalal Uddin ◽  
Nabil H. Bhuiyan ◽  
Joon S. Shim
Keyword(s):  
Microfluidic Device ◽  
Troponin I ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Sample Volume ◽  
Elisa Test ◽  
Enzyme Linked Immunosorbent Assay ◽  
Fully Integrated ◽  
Assay Time ◽  
On Chip

AbstractIn this work, a fully integrated active microfluidic device transforming a conventional 96-well kit into point-of-care testing (POCT) device was implemented to improve the performance of traditional enzyme-linked immunosorbent assay (ELISA). ELISA test by the conventional method often requires the collection of 96 samples for its operation as well as longer incubation time from hours to overnight, whereas our proposed device conducts ELISA immediately individualizing a 96-well for individual patients. To do that, a programmable and disposable on-chip pump and valve were integrated on the device for precise control and actuation of microfluidic reagents, which regulated a reaction time and reagent volume to support the optimized protocols of ELISA. Due to the on-chip pump and valve, ELISA could be executed with reduced consumption of reagents and shortening the assay time, which are crucial for conventional ELISA using 96-well microplate. To demonstrate highly sensitive detection and easy-to-use operation, this unconventional device was successfully applied for the quantification of cardiac troponin I (cTnI) of 4.88 pg/mL using a minimum sample volume of 30 µL with a shorter assay time of 15 min for each ELISA step. The limit of detection (LOD) thus obtained was significantly improved than the conventional 96-well platform.

scholarly journals Validation of a Novel Diagnostic Approach Combining the VersaTREK™ System for Recovery and Real-Time PCR for the Identification of Mycobacterium chimaera in Water Samples

2021 ◽  
Vol 9 (5) ◽  
pp. 1031
Author(s):  
Roberto Zoccola ◽  
Alessia Di Blasio ◽  
Tiziana Bossotto ◽  
Angela Pontei ◽  
Maria Angelillo ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Limit Of Detection ◽  
Detection System ◽  
Bacterial Load ◽  
Microbial Control ◽  
Hospital Setting ◽  
Sample Volume ◽  
Analytical Sensitivity ◽  
Initial Water

Mycobacterium chimaera is an emerging pathogen associated with endocarditis and vasculitis following cardiac surgery. Although it can take up to 6–8 weeks to culture on selective solid media, culture-based detection remains the gold standard for diagnosis, so more rapid methods are urgently needed. For the present study, we processed environmental M. chimaera infected simulates at volumes defined in international guidelines. Each preparation underwent real-time PCR; inoculates were placed in a VersaTREK™ automated microbial detection system and onto selective Middlebrook 7H11 agar plates. The validation tests showed that real-time PCR detected DNA up to a concentration of 10 ng/µL. A comparison of the isolation tests showed that the PCR method detected DNA in a dilution of ×102 CFU/mL in the bacterial suspensions, whereas the limit of detection in the VersaTREK™ was <10 CFU/mL. Within less than 3 days, the VersaTREK™ detected an initial bacterial load of 100 CFU. The detection limit did not seem to be influenced by NaOH decontamination or the initial water sample volume; analytical sensitivity was 1.5 × 102 CFU/mL; positivity was determined in under 15 days. VersaTREK™ can expedite mycobacterial growth in a culture. When combined with PCR, it can increase the overall recovery of mycobacteria in environmental samples, making it potentially applicable for microbial control in the hospital setting and also in environments with low levels of contamination by viable mycobacteria.

scholarly journals Direct and rapid measurement of hydrogen peroxide in human blood using a microfluidic device

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Gaikwad ◽  
P. R. Thangaraj ◽  
A. K. Sen
Keyword(s):  
Hydrogen Peroxide ◽  
Microfluidic Device ◽  
Human Blood ◽  
Blood Cells ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Time Interval ◽  
Fluorescence Measurement ◽  
Rapid Measurement ◽  
Automated Method

AbstractThe levels of hydrogen peroxide ($${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 ) in human blood is of great relevance as it has emerged as an important signalling molecule in a variety of disease states. Fast and reliable measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 levels in the blood, however, continues to remain a challenge. Herein we report an automated method employing a microfluidic device for direct and rapid measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in human blood based on laser-induced fluorescence measurement. Our study delineates the critical factors that affect measurement accuracy—we found blood cells and soluble proteins significantly alter the native $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 levels in the time interval between sample withdrawal and detection. We show that separation of blood cells and subsequent dilution of the plasma with a buffer at a ratio of 1:6 inhibits the above effect, leading to reliable measurements. We demonstrate rapid measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in plasma in the concentration range of 0–49 µM, offering a limit of detection of 0.05 µM, a sensitivity of 0.60 µM−1, and detection time of 15 min; the device is amenable to the real-time measurement of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in the patient’s blood. Using the linear correlation obtained with known quantities of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 , the endogenous $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 concentration in the blood of healthy individuals is found to be in the range of 0.8–6 µM. The availability of this device at the point of care will have relevance in understanding the role of $${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$ H 2 O 2 in health and disease.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

scholarly journals MODEL OF DEFORMATION OF FIBROUS MATERIALS OF MULTIDIRECTIONAL REINFORCEMENT WITH NONORIENTED FIBERS

2021 ◽  
Vol 1 (37) ◽  
pp. 119-129
Author(s):  
E. Shikula
Keyword(s):  
Strain State ◽  
Fibrous Composite ◽  
Theory Of Elasticity ◽  
Fibrous Materials ◽  
Thermoelastic Properties ◽  
Fibrous Composite Material ◽  
Conditional Moments ◽  
Second Stage ◽  
Two Stages ◽  
Nonlinear Theory Of Elasticity

A model of deformation of multidirectional reinforcement fibrous materials with differently oriented fibers is proposed. The solution to the problem is built in two stages. At the first stage, the known properties of fibers and binder are used to determine the effective thermoelastic properties and stress-strain state of the subsystem with fibers oriented in a certain way relative to the main coordinate system. It is based on stochastic differential equations of the physically nonlinear theory of elasticity using the method of conditional moments. At the second stage, using a given distribution function based on the Voigt scheme, a model of deformation of the entire system is constructed from the calculated properties of the subsystems. Strain curves are obtained for simple loading, and the deformation of materials at uniform orientation of fibers is investigated. It was found that a fibrous composite material with differently oriented fibers in a macrovolume is isotropic, and its effective thermoelastic constants substantially depend on the volumetric content of fibers.

In Vivo Dynamics of the Latent Reservoir for HIV-1: New Insights and Implications for Cure

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Janet D. Siliciano ◽  
Robert F. Siliciano
Keyword(s):  
Limit Of Detection ◽  
Latent Reservoir ◽  
Annual Review ◽  
Publication Date ◽  
Viral Rebound ◽  
Major Barrier ◽  
Persons Living With Hiv ◽  
Recent Developments ◽  
Hiv 1

Although antiretroviral therapy (ART) can reduce viremia to below the limit of detection and allow persons living with HIV-1 (PLWH) to lead relatively normal lives, viremia rebounds when treatment is interrupted. Rebound reflects viral persistence in a stable latent reservoir in resting CD4+ T cells. This reservoir is now recognized as the major barrier to cure and is the focus of intense international research efforts. Strategies to cure HIV-1 infection include interventions to eliminate this reservoir, to prevent viral rebound from the reservoir, or to enhance immune responses such that viral replication is effectively controlled. Here we consider recent developments in understanding the composition of the reservoir and how it can be measured in clinical studies. We also discuss exciting new insights into the in vivo dynamics of the reservoir and the reasons for its remarkable stability. Finally we discuss recent discoveries on the complex processes that govern viral rebound. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Portable Real-Time Detection of Pb(II) Using a CMOS MEMS-Based Nanomechanical Sensing Array Modified with PEDOT:PSS

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2454
Author(s):  
Yi-Kuang Yen ◽  
Chao-Yu Lai
Keyword(s):  
Limit Of Detection ◽  
Quality Measurement ◽  
Complementary Metal Oxide Semiconductor ◽  
Cost Effective ◽  
Sample Volume ◽  
Small Sample ◽  
Oxide Semiconductor ◽  
Resistance Change ◽  
Site Water ◽  
Cmos Mems

Detecting the concentration of Pb2+ ions is important for monitoring the quality of water due to it can become a health threat as being in certain level. In this study, we report a nanomechanical Pb2+ sensor by employing the complementary metal-oxide-semiconductor microelectromechanical system (CMOS MEMS)-based piezoresistive microcantilevers coated with PEDOT:PSS sensing layers. Upon reaction with Pb2+, the PEDOT:PSS layer was oxidized which induced the surface stress change resulted in a subsequent bending of the microcantilever with the signal response of relative resistance change. This sensing platform has the advantages of being mass-produced, miniaturized, and portable. The sensor exhibited its sensitivity to Pb2+ concentrations in a linear range of 0.01–1000 ppm, and the limit of detection was 5 ppb. Moreover, the sensor showed the specificity to Pb2+, required a small sample volume and was easy to operate. Therefore, the proposed analytical method described here may be a sensitive, cost-effective and portable sensing tool for on-site water quality measurement and pollution detection.

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