Surface plasmon resonance (SPR) is a label-free, highly-sensitive, and real-time sensing technique. Conventional SPR sensors, which involve a planar thin gold film, have been widely exploited in ...biosensing; various miniaturized formats have been devised for portability purposes. Another type of SPR sensor which utilizes localized SPR (LSPR), is based on metal nanostructures with surface plasmon modes at the structural interface. The resonance condition is sensitive to the refractive index change of the local medium. The principles of these two types of SPR sensors are reviewed and their integration with microfluidic platforms is described. Further applications of microfluidic SPR sensors to point-of-care (POC) diagnostics are discussed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Existing microfluidic technologies for blood tests have several limitations, including difficulties in integrating the sample preparation steps, such as blood dilution, and precise metering of tiny ...samples (microliter) for accurate downstream analyses on a chip. Digital microfluidics (DMF) is a liquid manipulation technique that can provide precise volume control of micro or nano-liter liquid droplets. Without using sensitive but complex detection methods for tiny droplets involving fluorescence, luminescence, and electrochemistry, this article presents a DMF device with embedded paper-based sensors to detect blood lithium-ion (Li+) concentration by colorimetry. Dielectrophoresis on the DMF device between two parallel planar electrodes separates plasma droplets (from tens to hundreds of nanoliters in volume) from undiluted whole blood (a few microliters) within 4 min with an efficiency exceeding 90%. The embedded paper sensors contain a detection reagent to absorb the DMF-transported plasma droplets. These droplets change the color of the paper sensors in accordance with the Li+ concentration. Subsequently, colorimetry is used to reveal the Li+ concentration via image analysis. The proposed method meets the detection-sensitivity requirement for clinical diagnosis of bipolar disorder, making the DMF device a potential therapeutic tool for rapid whole-blood Li+ detection.
•Plasma droplets can be separated from whole blood via dielectrophoresis with DMF.•Paper sensor–embedded DMF devices can detect lithium ions via colorimetry.•Detection of lithium ions in whole blood can be completed within 4 min.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Considerable evidence points to cancer stem-like cells (CSCs) as responsible for promoting progression, metastasis, and drug resistance. Without damage to the cell biological properties, ...single-cell-derived tumor-sphere is encouraging options for CSCs identification and studies. Although several single cell-based microfluidic methods have been developed for CSCs studies, clarifying liaison between the biomechanics of cells (such as size and deformability) and stem (such as tumor-sphere formation and drug resistance) remains challenging. Herein, we present a platform of integrated microfluidics for the analysis of single-cell-derived tumor-sphere formation and drug resistance. Tumor-spheres derived from different biomechanics (size and/or deformation) single-cells could be formed efficiently using this device. To demonstrate the microfluidic-platform capability, a proof-of-concept experiment was implemented by evaluating single-cell-derived sphere formation of single glioblastoma cells with different biomechanics. Additionally, a course of chemotherapy to study these single-cell-derived spheres was determined by coculture with vincristine. The results indicate that tumor cell biomechanics is associated with single-cell-derived spheres formation; that is, smaller and/or more deformable tumor cells are more stem-like defined by the formation of single-cell-derived spheres than more prominent and/or lesser deformable tumor cells. Also, tumor-spheres derived from single small and/or more deformable tumor cell have higher drug resistance than more prominent and/or less deformable tumor cells. Our device offers a new approach for single-cell-derived sphere formation according to tumor cell different biomechanical properties. Furthermore, it offers a new method for CSC identification and downstream analysis on a single-cell level.
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IJS, KILJ, NUK, PNG, UL, UM
Handling the aqueous two‐phase systems (ATPSs) formed by liquid–liquid phase separation (LLPS) relies on the accurate construction of binodal curves and tie‐lines, which delineate the polymer ...concentrations required for phase separation and depict the properties of the resulting phases, respectively. Various techniques to determine the binodal curves and tie‐lines of ATPSs exist, but most rely on manually pipetting relatively large volumes of fluids in a slow and tedious manner. We describe a method to determine ATPS binodals and tie‐lines that overcomes these disadvantages: microscale droplet manipulation by electrowetting‐on‐dielectric (EWOD). EWOD enables automated handling of droplets in an optically transparent platform that allows for in situ droplet observation. Separated phases are clearly visible, and the volumes of each phase are readily determined. Additionally, in considering the molecular crowding present in living cells, this work examines the role of a macromolecule in prompting LLPS. These results show that EWOD‐driven droplet manipulation effectively interrogates the phase dynamics of ATPSs and macromolecular crowding in LLPS.
Not phased out: EWOD‐enabled droplet manipulation integrated with ATPSs quantifies the phase dynamics of various ATPS solutions. In situ observation of droplets in the presence of background macromolecules reveals macromolecular crowding effects on the phase dynamics and can potentially interrogate the physiological liquid–liquid phase separation prevalent in living cells.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Digital microfluidics for cell manipulation Pang, Long; Ding, Jing; Liu, Xi-Xian ...
TrAC, Trends in analytical chemistry (Regular ed.),
August 2019, 2019-08-00, Volume:
117
Journal Article
Peer reviewed
A droplet-based technique to handle liquids called digital microfluidics (DMF) has attracted attention for cell manipulation (e.g., cell culture, cell sorting and single-cell analysis). With DMF, one ...manipulates droplets, of size ranging from picolitre to microlitre, on a planar surface by means of an electric field. DMF hence becomes an appealing platform to use for eventual integration into standard biological workflows. In this paper our aim is to provide a synopsis of cutting-edge developments in DMF-based cell manipulation, and to focus particularly on cell culture, cell sorting and single-cell applications.
•Digital microfluidics (DMF) operating discrete droplets for cell culture, cell sorting and single-cell analysis.•Suspension cell, microorganism, two-dimensional (2D) adherent cell and three-dimensional (3D) cell culture on DMF devices.•Cell sorting and concentrating within DMF droplets with integrated electrical, optical and magnetic forces.•Single cell culture, stimulation, immunocytochemistry, DNA analysis, mRNA extraction and transcriptome analysis with DMF.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microbubbles (MBs) serve as a critical catalyst to amplify local cavitation in CNS capillary lumen to facilitate focused ultrasound (FUS) to transiently open the blood-brain barrier (BBB). However, ...limited understanding is available regarding the effect of different microbubbles to induce BBB opening. The aim of this study is to characterize different MBs on their effect in FUS-induced BBB opening. Three MBs, SonoVue, Definity, and USphere, were tested, with 0.4-MHz FUS exposure at 0.62-1.38 of mechanical index (MI) on rats. Evans blue, dynamic contrast-enhanced (DCE) MRI and small-animal ultrasound imaging were used as surrogates to allow molecule-penetrated quantification, BBB-opened observation, and MBs circulation/persistence. Cavitation activity was measured via the passive cavitation detection (PCD) setup to correlate with the exposure level and the histological effect. Under given and identical MB concentrations, the three MBs induced similar and equivalent BBB-opening effects and persistence. In addition, a treatment paradigm by adapting exposure time is proposed to compensate MB decay to retain the persistence of BBB-opening efficiency in multiple FUS exposures. The results potentially improve understanding of the equivalence among MBs in focused ultrasound CNS drug delivery, and provide an effective strategy for securing persistence in this treatment modality.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Engineering approaches were adopted for liver microsystems to recapitulate cell arrangements and culture microenvironments in vivo for sensitive, high-throughput and biomimetic drug screening. This ...review introduces liver microsystems in vitro for drug hepatotoxicity, drug-drug interactions, metabolic function and enzyme induction, based on cell micropatterning, hydrogel biofabrication and microfluidic perfusion. The engineered microsystems provide varied microenvironments for cell culture that feature cell coculture with non-parenchymal cells, in a heterogeneous extracellular matrix and under controllable perfusion. The engineering methods described include cell micropatterning with soft lithography and dielectrophoresis, hydrogel biofabrication with photolithography, micromolding and 3D bioprinting, and microfluidic perfusion with endothelial-like structures and gradient generators. We discuss the major challenges and trends of liver microsystems to study drug response in vitro.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Over the past few years, manipulating and analyzing methods based on single-cell level have become frequently adopted to conduct the cell heterogeneity study (e.g., differentiation of stem cells, ...tumor cell heterogeneity). Traditional single-cell analysis techniques exhibit high processing complexity and time-consuming characteristic, and require expensive equipment, considerably limiting their applications in cellular heterogeneity study. Microfluidics-based systems to conduct single-cell study have appeared to be powerful methods as fueled with the advancement of microfluidics techniques. This paper reviews microstructure-based methods for single-cell manipulation and analysis. The methods based on microvalve for single-cell manipulation are also discussed in this paper. Lastly, the challenges required to be addressed in the future are highlighted.
•Introduction of microfluidics for single-cell isolation and analysis.•Summarization and illustration of various microstructure-based technologies for single-cell manipulation and analysis.•The challenges and future perspectives of microstructure-based techniques.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Point-of-care (POC) tests capable of individual health monitoring, transmission reduction, and contact tracing are especially important in a pandemic such as the coronavirus disease 2019 (COVID-19). ...We develop a disposable POC cartridge that can be mass produced to detect the SARS-CoV-2 N gene through real-time quantitative polymerase chain reaction (qPCR) based on digital microfluidics (DMF). Several critical parameters are studied and improved, including droplet volume consistency, temperature uniformity, and fluorescence intensity linearity on the designed DMF cartridge. The qPCR results showed high accuracy and efficiency for two primer-probe sets of N1 and N2 target regions of the SARS-CoV-2 N gene on the DMF cartridge. Having multiple droplet tracks for qPCR, the presented DMF cartridge can perform multiple tests and controls at once.
Current human fertilization in vitro (IVF) bypasses the female oviduct and manually inseminates, fertilizes and cultivates embryos in a static microdrop containing appropriate chemical compounds. A ...microfluidic microchannel system for IVF is considered to provide an improved in-vivo-mimicking environment to enhance the development in a culture system for an embryo before implantation. We demonstrate a novel digitalized microfluidic device powered with electrowetting on a dielectric (EWOD) to culture an embryo in vitro in a single droplet in a microfluidic environment to mimic the environment in vivo for development of the embryo and to culture the embryos with good development and live births. Our results show that the dynamic culture powered with EWOD can manipulate a single droplet containing one mouse embryo and culture to the blastocyst stage. The rate of embryo cleavage to a hatching blastocyst with a dynamic culture is significantly greater than that with a traditional static culture (p<0.05). The EWOD chip enhances the culture of mouse embryos in a dynamic environment. To test the reproductive outcome of the embryos collected from an EWOD chip as a culture system, we transferred embryos to pseudo-pregnant female mice and produced live births. These results demonstrate that an EWOD-based microfluidic device is capable of culturing mammalian embryos in a microfluidic biological manner, presaging future clinical application.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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