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Paper has been proposed as an inexpensive and versatile carrier for microfluidics devices with abilities well beyond simple capillary action for pregnancy tests and the like. Unlike standard microfluidics devices, extracting a fluid from the paper is a challenge and a drawback to its broader use. Here, we extract fluid from narrow paper strips using surface acoustic wave (SAW) irradiation that subsequently atomizes the extracted fluid into a monodisperse aerosol for use in mass spectroscopy, medical diagnostics, and drug delivery applications. Two protein molecules, ovalbumin and bovine serum albumin (BSA), have been preserved in paper and then extracted using atomized mist through SAW excitation; protein electrophoresis shows there is less than 1% degradation of either protein molecule in this process. Finally, a solution of live yeast cells was infused into paper, which was subsequently dried for preservation then remoistened to extract the cells viaSAW atomization, yielding live cells at the completion of the process. The successful preservation and extraction of fluids, proteins and yeast cells significantly expands the usefulness of paper in microfluidics. [ABSTRACT FROM AUTHOR]

Immunoassays are frequently used for analysis of protein biomarkers. The specificity of antibodies enables parallel analysis of several target proteins, at the same time. However, the implementation of such multiplexed assays into cost-efficient and mass-producible thermoplastic microfluidic platforms remains difficult due to the lack of suitable immobilization strategies for different capture antibodies. Here, we introduce and characterize a method to functionalize the surfaces of microfluidic devices manufactured in the thermoplastic material cyclic olefin copolymer (COC) by a rapid prototyping process. A laser-induced immobilization process enables the surface patterning of anchor biomolecules at a spatial resolution of 5 μm. We employ the method for the analysis of prostate cancer associated biomarkers by competitive immunoassays in a microchannel with a total volume of 320 nL, and successfully detected the proteins PSA, CRP, CEA and IGF-1 at clinically relevant concentrations. Finally, we also demonstrate the simultaneous analysis of three markers spiked into undiluted human plasma. In conclusion, this method opens the way to transfer multiplexed immunoassays into mass-producible microfluidic platforms that are suitable for point of care applications. [ABSTRACT FROM AUTHOR]

This paper presents a rapid, ultra-low-cost approach to fabricate microfluidic devices using a polyolefin shrink film and a digital craft cutter. The shrinking process (with a 95% reduction in area) results in relatively uniform and consistent microfluidic channels with smooth surfaces, vertical sidewalls, and high aspect ratio channels with lateral resolutions well beyond the tool used to cut them. The thermal bonding of the layers results in strongly bonded devices. Complex microfluidic designs are easily designed on the fly and protein assays are also readily integrated into the device. Full device characterization including channel consistency, optical properties, and bonding strength are assessed in this technical note. [ABSTRACT FROM AUTHOR]

HPLC purification and reformulation of positron emission tomography (PET) tracers can lead to significant dilution of the final product, making it difficult to produce a sufficiently high radioactivity concentration for some applications (e.g. small animal imaging, in vitro assays, and labelling of proteins with prosthetic groups). This is especially true for molecules with lengthy or low-yield syntheses. Starting the synthesis with more radioactivity increases the final radioactivity concentration but increases hazards and complexity of handling. An alternative is to concentrate the final product by a process such as rotary evaporation prior to downstream use. Because a rotovap requires significant space within a hot cell that could be put to more productive use, we developed a compact microfluidic system for concentration of PET tracers. This system also provides advantages in terms of repeatability, interfacing and potential for automation. We present here the design and performance characterization of the system, and demonstrate the concentration of several tracers in aqueous-based HPLC mobile phases. [ABSTRACT FROM AUTHOR]

In developing tissues, proteins and signaling molecules present themselves in the form of concentration gradients, which determine the fate specification and behavior of the sensing cells. To mimic these conditions in vitro, we developed a microfluidic device designed to generate stable concentration gradients at low hydrodynamic shear and allowing long term culture of adhering cells. The gradient forms in a culture space between two parallel laminar flow streams of culture medium at two different concentrations of a given morphogen. The exact algorithm for defining the concentration gradients was established with the aid of mathematical modeling of flow and mass transport. Wnt3a regulation of β-catenin signaling was chosen as a case study. The highly conserved Wnt-activated β-catenin pathway plays major roles in embryonic development, stem cell proliferation and differentiation. Wnt3a stimulates the activity of β-catenin pathway, leading to translocation of β-catenin to the nucleus where it activates a series of target genes. We cultured A375 cells stably expressing a Wnt/β-catenin reporter driving the expression of Venus, pBARVS, inside the microfluidic device. The extent to which the β-catenin pathway was activated in response to a gradient of Wnt3a was assessed in real time using the BARVS reporter gene. On a single cell level, the β-catenin signaling was proportionate to the concentration gradient of Wnt3a; we thus propose that the modulation of Wnt3a gradients in real time can provide new insights into the dynamics of β-catenin pathway, under conditions that replicate some aspects of the actual cell-tissue milieu. Our device thus offers a highly controllable platform for exploring the effects of concentration gradients on cultured cells. [ABSTRACT FROM AUTHOR]

The article focuses on a study on the development of an integrated microfluidic array using soft lithography techniques for high-throughput surface plasmon resonance imaging (SPRi)-based detection and determination of binding affinities of antibodies against protein targets. It informs that SPRi is a label-free technique used for the quantitation of binding affinities and for concentrating a wide variety of target molecules.

The article focuses on a study on the design and operation of an ultrafast microfluidic mixer with three-dimensional (3D) flow focusing. It informs that it is necessary to study the kinetics of biochemical rections for understanding the function of biomolecules and processes in living cells including the folding of proteins and RNA.

We report herein on a self-powered, self-contained microfluidic-based chip designed to separate plasma from whole blood, and then execute an assay of a multiplexed panel of plasma biomarker proteins. The power source is based upon a chemical reaction that is catalytically triggered by the push of a button on the chip. We demonstrate assays of a dozen blood-based protein biomarkers using this automated, self-contained device. This platform can potentially permit high throughput, accurate, multiplexed blood diagnostic measurements in remote locations and by minimally trained individuals. [ABSTRACT FROM AUTHOR]

Current methods used for analyzing biomarkers involve expensive and time consuming techniques like the Sandwich ELISA which require lengthy incubation times, high reagent costs, and bulky optical equipment. We have developed a technique involving the use of a micro-channel with integrated electrodes, functionalized with receptors specific to target biomarkers. We have applied our biochip to the rapid electrical detection and quantification of target protein biomarkers using protein functionalized micro-channels. We successfully demonstrate detection of anti-hCG antibody, at a concentration of 1 ng ml−1and a dynamic range of three orders of magnitude, in less than one hour. We envision the use of this technique in a handheld device for multiplex high throughput analysis using an array of micro-channels for probing various protein biomarkers in clinically relevant samples such as human serum for cancer detection. [ABSTRACT FROM AUTHOR]