title: 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.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Tuebingen , Calwerstraße 7/1, 72076 Tuebingen, Germany.
authors.forename: Heidi
authors.initials: H
authors.lastname: Stoll
authors.affiliation: BioMEMS and Sensors Department, Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstraße 55, 72770 Reutlingen, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Kiessling
authors.affiliation: BioMEMS and Sensors Department, Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstraße 55, 72770 Reutlingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Stelzle
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Tuebingen , Calwerstraße 7/1, 72076 Tuebingen, Germany.
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Wendel
authors.affiliation: BioMEMS and Sensors Department, Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstraße 55, 72770 Reutlingen, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Schütte
authors.affiliation: BioMEMS and Sensors Department, Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstraße 55, 72770 Reutlingen, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Hagmeyer
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Tuebingen , Calwerstraße 7/1, 72076 Tuebingen, Germany.
authors.forename: Meltem
authors.initials: M
authors.lastname: Avci-Adali