Microfluidic Bioanalytical Device and Assay Development for High-Throughput Electrophoretic Protein Analysis (original) (raw)
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Current advances and challenges in microfluidic free-flow electrophoresis—A critical review
Analytica Chimica Acta, 2017
The research field on microfluidic free-flow electrophoresis has developed vast amounts of devices, methods, applications and raised new questions, often in analogy to conventional techniques from which it derives. Most efforts have been employed on device development and a myriad of architectures and fabrication techniques have been reported using simple proof-of-principle separations. As technological aspects reach a quite mature state, researchers' new challenges include the development of protocols for the separation of complex mixtures, as required in the fields of application. The success of this effort is extremely dependent on the capability to transfer the device's fabrication to an industrial setting as well as to ensure interfacing simplicity, namely at the solutions' supply and collection, and actuation such as electric potential application and temperature control. Other advanced applications such as direct interfacing to downstream systems such as mass spectrometry, integration of sensing and feedback controls will require further development in the laboratory. In this review we provide an overview on the field, from basic concepts, through advanced developments both in the theoretical and experimental arenas, and addressing the above details. A comprehensive survey of designs, materials and applications is presented with particular highlights to most recent developments, namely the integration of electrodes, flow control and hyphenation of microfluidic free-flow electrophoresis with other techniques.
Analytical Chemistry, 2001
This article presents the first example of a microfluidic chip for heterogeneous bioassays using a locally immobilized biospecific layer and operated electrokinetically. The reaction chamber has picoliter dimensions and is integrated into a network of microchannels etched in glass. The high affinity of protein A (PA) for rabbit immunoglobulin G (rIgG) was exploited for chip testing, with PA being immobilized on microchannel walls and fluorescently labeled (Cy5) rIgG serving as sample. It was possible to operate the chip in an immunoaffinity chromatographic manner, using electrokinetically pumped solutions. Concentration of antibody from dilute solution onto the solid phase was demonstrated, with signal gains of ∼30 possible. A dose-response curve for Cy5-rIgG was obtained for concentrations down to 50 nM, for an incubation time of 200 s. The flexibility of chip layout was demonstrated for competitive immunoassay of rIgG, using both a combined sample/tracer incubation and sequential addition of these solutions. With assay times generally below 5 min for this unoptimized device, the microfluidic approach described shows great potential for many highthroughput screening applications.
Microfluidics in Bioanalytical Instrumentation
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Portable and field deployable analytical instruments are attractive in many fields, including medical diagnostics where point-of-care and on-site diagnostics systems capable of providing rapid quantitative results have the potential to improve the productivity and quality of medical care. A major limitation and impediment to the usage of portable and field deployable microfluidic chip based analytical instruments in solving real world analytical problems has been the scarcity of commercially available portable or field deployable platforms, which are fully flexible for research. The bench-top analytical instrument , the Agilent Bioanalyzer 2100 used in this research is a microfluidic chip-based platform with fluorescence detection system, available on the market since 1999. Originally, this instrument was capable of electrophoretic analysis of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA), with user-tailored application solutions including chips, reagents and pre-develope...
Why the move to microfluidics for protein analysis?
Current opinion in …, 2004
There has been a recent trend towards the miniaturization of analytical tools, but what are the advantages of microfluidic devices and when is their use appropriate? Recent advances in the field of micro-analytical systems can be classified according to instrument performance (which refers here to the desired property of the analytical tool of interest) and two important features specifically related to miniaturisation, namely reduction of the sample volume and the time-to-result. Here we discuss the contribution of these different parameters and aim to highlight the factors of choice in the development and use of microfluidic devices dedicated to protein analysis.
High performance microfluidic capillary electrophoresis devices
Biomedical Microdevices, 2007
This paper presents a novel microfluidic capillary electrophoresis (CE) device featuring a double-T-form injection system and an expansion chamber located at the inlet of the separation channel. This study addresses the principal material transport mechanisms depending on parameters such as the expansion ratio, the expansion length, the fluid flow. Its design utilizes a double-L injection technique and combines the expansion chamber to minimize the sample leakage effect and to deliver a highquality sample plug into the separation channel so that the detection performance of the device is enhanced. Experimental and numerical testing of the proposed microfluidic device that integrates an expansion chamber located at the inlet of the separation channel confirms its ability to increase the separation efficiency by improving the sample plug shape and orientation. The novel microfluidic capillary electrophoresis device presented in this paper has demonstrated a sound potential for future use in high-quality, high-throughput chemical analysis applications and throughout the micro-total-analysis systems field.
Analytical Chemistry, 2001
A six-channel microfluidic immunoassay device with a scanned fluorescence detection system is described. Six independent mixing, reaction, and separation manifolds are integrated within one microfluidic wafer, along with two optical alignment channels. The manifolds are operated simultaneously and data are acquired using a singlepoint fluorescence detector with a galvano-scanner to step between separation channels. A detection limit of 30 pM was obtained for fluorescein with the scanning detector, using a 7.1-Hz sampling rate for each of the reaction manifolds and alignment channels (57-Hz overall sampling rate). Simultaneous direct immunoassays for ovalbumin and for anti-estradiol were performed within the microfluidic device. Mixing, reaction, and separation could be performed within 60 s in all cases and within 30 s under optimized conditions. Simultaneous calibration and analysis could be performed with calibrant in several manifolds and sample in the other manifolds, allowing a complete immunoassay to be run within 30 s. Careful chip conditioning with methanol, water, and 0.1 M NaOH resulted in peak height RSD values of 3-8% (N) 5 or 6), allowing for cross-channel calibration. The limit of detection (LOD) for an anti-estradial assay obtained in any single channel was 4.3 nM. The LOD for the crosschannel calibration was 6.4 nM. Factors influencing chip and detection system design and performance are discussed in detail.
Microfab-less microfluidic capillary electrophoresis devices
Analytical Methods, 2013
Compared to conventional benchtop instruments, microfluidic devices possess advantageous characteristics including great portability potential, reduced analysis time (minutes), and relatively inexpensive production, putting them on the forefront of modern analytical chemistry. Fabrication of these devices, however, often involves polymeric materials with less-than-ideal surface properties, specific instrumentation, and cumbersome fabrication procedures. In order to overcome such drawbacks, a new hybrid platform is proposed. The platform is centered on the use of 5 interconnecting microfluidic components that serve as either the injector or reservoirs. These plastic units are interconnected using standard capillary tubing, enabling in-channel detection by a wide variety of standard techniques, including capacitively coupled contactless conductivity detection (C 4 D). Due to the minimum impact on the separation efficiency, the plastic microfluidic components used for the experiments discussed herein were fabricated using an inexpensive engraving tool and standard Plexiglas. The presented approach (named 5 2 -platform) offers a previously unseen versatility, enabling the assembly of the platform within minutes using capillary tubing that differs in length, diameter, or material. The advantages of the proposed design are demonstrated by performing the analysis of inorganic cations by capillary electrophoresis on soil samples from the Atacama Desert.