Analysis of Magnetic Microbead Capture With and Without Bacteria in a Microfluidic Device Under Different Flow Scenarios

2018 ◽  
Vol 12 (4) ◽  
Author(s):  
Samuel A. Miller ◽  
William R. Heineman ◽  
Alison A. Weiss ◽  
Rupak K. Banerjee
Keyword(s):  
Microfluidic Device ◽  
Calibration Curve ◽  
Point Of Care ◽  
Percentage Increase ◽  
Constant Flow ◽  
Microfluidic Platforms ◽  
Fluorescent Intensity ◽  
Efficient Detection ◽  
Specific Antigens ◽  
Magnetophoretic Separation

Efficient detection of pathogens is essential for the development of a reliable point-of-care diagnostic device. Magnetophoretic separation, a technique used in microfluidic platforms, utilizes magnetic microbeads (mMBs) coated with specific antigens to bind and remove targeted biomolecules using an external magnetic field. In order to assure reliability and accuracy in the device, the efficient capture of these mMBs is extremely important. The aim of this study was to analyze the effect of an electroosmotic flow (EOF) switching device on the capture efficiency (CE) of mMBs in a microfluidic device and demonstrate viability of bacteria capture. This analysis was performed at microbead concentrations of 2 × 106 beads/mL and 4 × 106 beads/mL, EOF voltages of 650 V and 750 V, and under constant flow and switching flow protocols. Images were taken using an inverted fluorescent microscope and the pixel count was analyzed to determine to fluorescent intensity. A capture zone was used to distinguish which beads were captured versus uncaptured. Under the steady-state flow protocol, CE was determined to range from 31% to 42%, while the switching flow protocol exhibited a CE of 71–85%. The relative percentage increase due to the utilization of the switching protocol was determined to be around two times the CE, with p < 0.05 for all cases. Initial testing using bacteria-bead complexes was also performed in which these complexes were captured under the constant flow protocol to create a calibration curve based on fluorescent pixel count. The calibration curve was linear on a log-log plot, with R2-value of 0.96. The significant increase in CE highlights the effectiveness of flow switching for magnetophoretic separation in microfluidic devices and prove its viability in bacterial analysis.

scholarly journals Electroosmotic flow driven microfluidic device for bacteria isolation using magnetic microbeads

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Samuel Miller ◽  
Alison A. Weiss ◽  
William R. Heineman ◽  
Rupak K. Banerjee
Keyword(s):  
Microfluidic Device ◽  
Electroosmotic Flow ◽  
Point Of Care ◽  
Food Poisoning ◽  
Fluorescent Intensity ◽  
Magnetic Microbeads ◽  
E Coli ◽  
Detection Assay ◽  
Flow Capture ◽  
Improved Performance

Abstract The presence of bacterial pathogens in water can lead to severe complications such as infection and food poisoning. This research proposes a point-of-care electroosmotic flow driven microfluidic device for rapid isolation and detection of E. coli in buffered solution (phosphate buffered saline solution). Fluorescent E. coli bound to magnetic microbeads were driven through the microfluidic device using both constant forward flow and periodic flow switching at concentrations ranging from 2 × 105 to 4 × 107 bacteria/mL. A calibration curve of fluorescent intensity as a function of bacteria concentration was created using both constant and switching flow, showing an increase in captured fluorescent pixel count as concentration increases. In addition, the use of the flow switching resulted in a significant increase in the capture efficiency of E. coli, with capture efficiencies up to 83% ± 8% as compared to the constant flow capture efficiencies (up to 39% ± 11%), with a sample size of 3 µL. These results demonstrate the improved performance associated with the use of the electroosmotic flow switching system in a point-of-care bacterial detection assay.

scholarly journals A Compact, Syringe-Assisted, Vacuum-Driven Micropumping Device

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 543 ◽  
Author(s):  
Anyang Wang ◽  
Domin Koh ◽  
Philip Schneider ◽  
Evan Breloff ◽  
Kwang W. Oh
Keyword(s):  
Microfluidic Device ◽  
Point Of Care ◽  
Microfluidic Devices ◽  
Microfluidic Channels ◽  
Constant Flow ◽  
Proof Of Concept ◽  
Point Of Care Testing ◽  
Microfluidic Mixing ◽  
Pumping System ◽  
Dead End

In this paper, a simple syringe‑assisted pumping method is introduced. The proposed fluidic micropumping system can be used instead of a conventional pumping system which tends to be large, bulky, and expensive. The micropump was designed separately from the microfluidic channels and directly bonded to the outlet of the microfluidic device. The pump components were composed of a dead‑end channel which was surrounded by a microchamber. A syringe was then connected to the pump structure by a short tube, and the syringe plunger was manually pulled out to generate low pressure inside the microchamber. Once the sample was loaded in the inlet, air inside the channel diffused into the microchamber through the PDMS (polydimethylsiloxane) wall, acting as a dragging force and pulling the sample toward the outlet. A constant flow with a rate that ranged from 0.8 nl · s − 1 to 7.5 nl · s − 1 was achieved as a function of the geometry of the pump, i.e., the PDMS wall thickness and the diffusion area. As a proof-of-concept, microfluidic mixing was demonstrated without backflow. This method enables pumping for point-of-care testing (POCT) with greater flexibility in hand-held PDMS microfluidic devices.

Magnetic Digital Microfluidics for Point-of-Care Testing: Where Are We Now?

2020 ◽  
Vol 27 ◽  
Author(s):  
Yi Zhang
Keyword(s):  
System Integration ◽  
Diagnostic Tests ◽  
Point Of Care ◽  
Digital Microfluidics ◽  
Controlled Environment ◽  
Point Of Care Testing ◽  
Microfluidic Platforms ◽  
Interface System ◽  
Technical Issues ◽  
Sample System

: Point-of-care (POC) testing decentralizes the diagnostic tests to the sites near the patient. Many POC tests rely microfluidic platforms for sample-to-answer analysis. Compared to other microfluidic systems, magnetic digital microfluidics demonstrate compelling advantages for POC diagnostics. In this review, we have examined the capability of magnetic digital microfluidics-based POC diagnostic platforms. More importantly, we have categorized POC settings into three classes based on “where is the point”, “who to care” and “how to test”, and evaluated the suitability of magnetic digital microfluidics in various POC settings. Furthermore, we have addressed other technical issues associated with POC testing such as controlled environment, sample-system interface, system integration and information connectivity. We hope this review would provide a guideline for the future development of magnetic digital microfluidics-based platforms for POC testing.

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.

A Thread/Fabric-Based Band as A Flexible and Wearable Microfluidic Device for Sweat Sensing and Monitoring

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Zhiqi Zhao ◽  
Qiujin Li ◽  
Linna Chen ◽  
Yu Zhao ◽  
Jixian Gong ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Point Of Care ◽  
Monitoring Systems ◽  
Biological Analytes

Flexible biosensors for monitoring systems have emerged as a promising portable diagnostics platform due to their potential for in situ point-of-care (POC) analytic devices. Assessment of biological analytes in sweat...

scholarly journals Assessment of reliability and validity of the 5-scale grading system of the point-of-care immunoassay for tear matrix metalloproteinase-9

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Minjeong Kim ◽  
Ja Young Oh ◽  
Seon Ha Bae ◽  
Seung Hyeun Lee ◽  
Won Jun Lee ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Calibration Curve ◽  
Point Of Care ◽  
Interobserver Reliability ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Correlation Coefficients ◽  
Grading System ◽  
Intraclass Correlation Coefficients ◽  
The Difference

AbstractWe evaluated the reliability and validity of the 5-scale grading system to interpret the point-of-care immunoassay for tear matrix metalloproteinase (MMP)-9. Six observers graded red bands of photographs of the readout window in MMP-9 immunoassay kit (InflammaDry) two times with 2-week interval based on the 5-scale grading system (i.e. grade 0–4). Interobserver and intraobserver reliability were evaluated using intraclass correlation coefficients. The interobserver agreements were analyzed according to the severity of tear MMP-9 expression. To validate the system, a concentration calibration curve was made using MMP-9 solutions with reference concentrations, then the distribution of MMP-9 concentrations was analyzed according to the 5-scale grading system. Both intraobserver and interobserver reliability was excellent. The readout grades were significantly correlated with the quantified colorimetric densities. The interobserver variance of readout grades had no correlation with the severity of the measured densities. The band density continued to increase up to a maximal concentration (i.e. 5000 ng/mL) according to the calibration curve. The difference of grades reflected the change of MMP-9 concentrations sensitively, especially between grade 2 and 4. Together, our data indicate that the subjective 5-scale grading system in the point-of-care MMP-9 immunoassay is an easy and reliable method with acceptable accuracy.

scholarly journals Disposable Voltammetric Immunosensors Integrated with Microfluidic Platforms for Biomedical, Agricultural and Food Analyses: A Review

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4124 ◽  
Author(s):  
Fabiana Felix ◽  
Alexandre Baccaro ◽  
Lúcio Angnes
Keyword(s):  
Quality Management ◽  
Signal Amplification ◽  
Screen Printing ◽  
Point Of Care ◽  
Microfluidic Devices ◽  
Strong Interactions ◽  
Point Of Care Testing ◽  
Microfluidic Platforms ◽  
Broad Variety ◽  
Interesting Alternative

Disposable immunosensors are analytical devices used for the quantification of a broad variety of analytes in different areas such as clinical, environmental, agricultural and food quality management. They detect the analytes by means of the strong interactions between antibodies and antigens, which provide concentration-dependent signals. For the herein highlighted voltammetric immunosensors, the analytical measurements are due to changes in the electrical signals on the surface of the transducers. The possibility of using disposable and miniaturized immunoassays is a very interesting alternative for voltammetric analyses, mainly, when associated with screen-printing technologies (screen-printed electrodes, SPEs), and microfluidic platforms. The aim of this paper is to discuss a carefully selected literature about different examples of SPEs-based immunosensors associated with microfluidic technologies for diseases, food, agricultural and environmental analysis. Technological aspects of the development of the voltammetric immunoassays such as the signal amplification, construction of paper-based microfluidic platforms and the utilization of microfluidic devices for point-of-care testing will be presented as well.

‘Off–on’ switchable fluorescent probe for prompt and cost-efficient detection of bacteria

2019 ◽  
Vol 43 (33) ◽  
pp. 13094-13102
Author(s):  
Giorgia Giovannini ◽  
Vladimir Gubala ◽  
Andrew J. Hall
Keyword(s):  
Fluorescent Probe ◽  
Bacterial Infections ◽  
Point Of Care ◽  
Lab On A Chip ◽  
Human Samples ◽  
Efficient Detection ◽  
Prevention And Treatment ◽  
Cost Efficient

The rapid and straightforward detection of bacteria in food and human samples is becoming important, particularly in view of the development of point-of-care devices and lab-on-a-chip tools for prevention and treatment of bacterial infections.

scholarly journals Switching from Multiplex to Multimodal Colorimetric Lateral Flow Immunosensor

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6609
Author(s):  
Simone Cavalera ◽  
Fabio Di Nardo ◽  
Luca Forte ◽  
Francesca Marinoni ◽  
Matteo Chiarello ◽  
...  
Keyword(s):  
Point Of Care ◽  
Lateral Flow ◽  
Proof Of Concept ◽  
Point Of Care Testing ◽  
Human Immunoglobulins ◽  
Immunodeficiency Virus ◽  
Specific Antigens ◽  
Increasing Demand ◽  
Gold Nanomaterials ◽  
Two Parameter

Multiplex lateral flow immunoassay (LFIA) is largely used for point-of-care testing to detect different pathogens or biomarkers in a single device. The increasing demand for multitargeting diagnostics requires multi-informative single tests. In this study, we demonstrated three strategies to upgrade standard multiplex LFIA to multimodal capacity. As a proof-of-concept, we applied the strategies to the differential diagnosis of Human Immunodeficiency Virus (HIV) infection, a widespread pathogen, for which conventional multiplex LFIA testing is well-established. In the new two-parameter LFIA (x2LFIA), we exploited color encoding, in which the binding of multiple targets occurs in one reactive band and the color of the probe reveals which one is present in the sample. By combining the sequential alignment of several reactive zones along the membrane of the LFIA strip and gold nanoparticles and gold nanostars for the differential visualization, in this demonstration, the x2LFIA can furnish information on HIV serotype and stage of infection in a single device. Three immunosensors were designed. The use of bioreagents as the capturing ligand anchored onto the membrane or as the detection ligand labelled with gold nanomaterials affected the performance of the x2LFIA. Higher detectability was achieved by the format involving the HIV-specific antigens as capturing agent and labelled secondary bioligands (anti-human immunoglobulins M and protein G) as the probes.

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