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AFBI assay – Aptamer Fluorescence Binding and Internalization assay for cultured adherent cells
Journal article   Peer reviewed

AFBI assay – Aptamer Fluorescence Binding and Internalization assay for cultured adherent cells

William H Thiel and Paloma H Giangrande
Methods (San Diego, Calif.), Vol.103, pp.180-187
07/01/2016
DOI: 10.1016/j.ymeth.2016.03.005
PMCID: PMC4921262
PMID: 26972784
url
http://doi.org/10.1016/j.ymeth.2016.03.005View
Open Access

Abstract

[Display omitted] •Cell-based, rapid, scalable, high-throughput aptamer screening assay.•Utilizes fluorescently labeled aptamer, microplate reader and 96-well plates.•Quantitative measures of aptamer binding and internalization.•Minimal processing: assay is performed in a single plate with no microfuge tubes. The SELEX (Systematic Evolution of Ligands by Exponential Enrichment) process allows for the enrichment of DNA or RNA aptamers from a complex nucleic acid library that are specific for a target molecule. The SELEX process has been adapted from identifying aptamers in vitro using recombinant target protein to cell-based methodologies (Cell-SELEX), where the targets are expressed on the surface of cells. One major advantage of Cell-SELEX is that the target molecules are maintained in a native confirmation. Additionally, Cell-SELEX may be used to discover novel therapeutic biomarkers by performing selections on diseased versus healthy cells. However, a caveat to Cell-SELEX is that testing of single aptamers identified in the selection is laborious, time-consuming, and expensive. The most frequently used methods to screen for aptamer binding and internalization on cells are flow cytometry and quantitative PCR (qPCR). While flow cytometry can directly assess binding of a fluorescently-labeled aptamer to a target, it requires significant starting material and is not easily scalable. qPCR-based approaches are highly sensitive but have non-negligible experiment-to-experiment variability due to the number of sample processing steps. Herein we describe a cell-based aptamer fluorescence binding and internalization (AFBI) assay. This assay requires minimal reagents and has few experimental steps/manipulations, thereby allowing for rapid screening of many aptamers and conditions simultaneously and direct quantitation of aptamer binding and internalization.
Fluorescence Aptamer Cell-SELEX Microplate reader SELEX

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