A lambda-exonuclease SELEX method for generating aptamers to bacterial targets

Robert Gowland, Darren M. Gowers

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)peer-review


Nucleic acid aptamers are short sequences of single-stranded (ss) DNA or RNA that fold into a three-dimensional shape with useful binding properties. Traditionally, these properties have included specific recognition and binding of ions, small-molecules, proteins, and enzyme targets. Increasingly though, aptamers are being raised against complex subcellular or cellular targets. These broader-affinity aptamers can be usefully employed for detection, labeling, or therapeutic targeting of intact/living cells, whether prokaryotic or eukaryotic. Aptamers are usually developed from a random-sequence oligonucleotide library by repeated rounds of selection and amplification, a process named “systematic evolution of ligands by exponential enrichment” (SELEX). We describe here a widely applicable cell-SELEX method for raising aptamers against bacteria, using Escherichia coli strain HB101 as an example. Our cell-SELEX method uses a cycle of four stages: (1) incubation of a fluorescently labeled random-sequence ssDNA library with bacterial cells; (2) separation of cell-associated ssDNA from free ssDNA; (3) amplification of bound ssDNA by PCR, and (4) use of lambda-exonuclease to selectively regenerate ssDNA for further rounds of selection.
Original languageEnglish
Title of host publicationDNA Manipulation and Analysis
EditorsGarry Scarlett
Place of PublicationNew York
PublisherHumana Press
Number of pages17
ISBN (Electronic)9781071630044
ISBN (Print)9781071630037
Publication statusPublished - 1 Mar 2023

Publication series

NameMethods in Molecular Biology
ISSN (Print)1064-3745
ISSN (Electronic)1940-6029


  • aptamer
  • oligonucleotide library
  • lambda exonuclease
  • E. coli

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