Microfluidic chip system for the selection and enrichment of cell binding aptamers

Abstract

Aptamers are promising cell targeting ligands for several applications such as for the diagnosis, therapy, and drug delivery. Especially, in the field of regenerative medicine, stem cell specific aptamers have an enormous potential. Using the combinatorial chemistry process SELEX (Systematic Evolution of Ligands by Exponential enrichment), aptamers are selected from a huge oligonucleotide library consisting of approximately 10 15 different oligonucleotides. Here, we developed a microfluidic chip system that can be used for the selection of cell specific aptamers. The major drawbacks of common cell-SELEX methods are the inefficient elimination of the unspecifically bound oligonucleotides from the cell surface and the unspecific binding/uptake of oligonucleotides by dead cells. To overcome these obstacles, a microfluidic device, which enables the simultaneous performance of dielectrophoresis and electrophoresis in the same device, was designed. Using this system, viable cells can be selectively assembled by dielectrophoresis between the electrodes and then incubated with the oligonucleotides. To reduce the rate of unspecifically bound sequences, electrophoretic fields can be applied in order to draw loosely bound oligonucleotides away from the cells. Furthermore, by increasing the flow rate in the chip during the iterative rounds of SELEX, the selection pressure can be improved and aptamers with higher affinities and specificities can be obtained. This new microfluidic device has a tremendous capability to improve the cell-SELEX procedure and to select highly specific aptamers. V C 2015 AIP Publishing LLC. [http://dx

Recent Microdevice-Based Aptamer Sensors

“…Using this strategy, they successfully identified a high-affinity aptamer that was a subset of specific interactions with distinct epitopes on malaria-parasite infected red blood cells. In order to improve efficiency and selectivity, some groups have developed techniques such as the volume dilution challenge microfluidic SELEX (VDC-MSELEX) [ 20 ], dielectrophoresis and electrophoresis SELEX [ 21 ], SELEX assisted by graphene oxide (GO) [ 22 ], surface plasmon resonance (SPR)-based SELEX methods [ 23 , 24 ]. SPR-based SELEX methods have attracted attention in recent years because selection and evaluation can be performed simultaneously without labeling the sensor.…”

Integrated Microfluidic Selex Using Free Solution Electrokinetics

“…Microfluidic affinity selection has been performed, in conjunction with off-chip amplification, against targets retained using silica capillary walls [24], microbeads [25–32] or sol-gels [33–35], or against cells in solution [36, 37], to increase selection stringency [25–29, 36, 37], create more favorable biomolecular environments [33–35], or allow simultaneous positive and negative selections [38]. Moreover, microchips have been developed in an attempt to integrate the overall SELEX process using pneumatically based flow control for isolation of aptamers against viruses [39], cells [28, 40, 41] and proteins [30–32, 42, 43].…”

Fabrication of anti-protein-fouling poly(ethylene glycol) microfluidic chip electrophoresis by sandwich photolithography

“…Since the first demonstration in 1990, 1,2 microfluidic chip electrophoresis (MCE), as a highly integrated and automated portable device, has been developed rapidly with important applications in many areas such as life science, biology, medicine, food, and environmental monitoring, [3][4][5][6][7] where entire chemical and bio-analyses in miniaturized volumes are performed with high sensitivities and efficencies. [8][9][10][11][12][13][14] Organic materials such as polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) have been used to fabricate MCE.…”