Selective Aptamers for Detection of Estradiol and Ethynylestradiol in Natural Waters

Spurti U. Akki, Charles J. Werth, Scott K Silverman

Research output: Contribution to journalArticle

Abstract

We used in vitro selection to identify new DNA aptamers for two endocrine-disrupting compounds often found in treated and natural waters, 17β-estradiol (E2) and 17α-ethynylestradiol (EE). We used equilibrium filtration to determine aptamer sensitivity/selectivity and dimethyl sulfate (DMS) probing to explore aptamer binding sites. The new E2 aptamers are at least 74-fold more sensitive for E2 than is a previously reported DNA aptamer, with dissociation constants (Kd values) of 0.6 μM. Similarly, the EE aptamers are highly sensitive for EE, with Kd of 0.5-1.0 μM. Selectivity values indicate that the E2 aptamers bind E2 and a structural analogue, estrone (E1), equally well and are up to 74-fold selective over EE. One EE aptamer is 53-fold more selective for EE over E2 or E1, but the other binds EE, E2, and E1 with similar affinity. The new aptamers do not lose sensitivity or selectivity in natural water from a local lake, despite the presence of natural organic matter (∼4 mg/L TOC). DMS probing suggests that E2 binding occurs in relatively flexible single-stranded DNA regions, an important finding for rational redesign of aptamers and their incorporation into sensing platforms. This is the first report of aptamers with strong selectivity for E2 and E1 over EE, or with strong selectivity for EE over E2 and E1. Such selectivity is important for achieving the goal of creating practically useful DNA-based sensors that can distinguish structurally similar estrogenic compounds in natural waters.

Original languageEnglish (US)
Pages (from-to)9905-9913
Number of pages9
JournalEnvironmental Science and Technology
Volume49
Issue number16
DOIs
StatePublished - Jul 16 2015

Fingerprint

Nucleotide Aptamers
Estradiol
DNA
Water
fold
Estrone
Single-Stranded DNA
sulfate
estrogenic compound
water
Biological materials
Lakes
Estrogens
Binding Sites
Sensors
sensor
organic matter
detection
lake
dimethyl sulfate

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Selective Aptamers for Detection of Estradiol and Ethynylestradiol in Natural Waters. / Akki, Spurti U.; Werth, Charles J.; Silverman, Scott K.

In: Environmental Science and Technology, Vol. 49, No. 16, 16.07.2015, p. 9905-9913.

Research output: Contribution to journalArticle

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