Abstract
The compound 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p’-DDT) has been identified as one of the endocrine-disrupting chemicals causing adverse effects on wildlife and even humans through bioaccumulation. Its detection has become increasingly important. We have obtained candidate aptamers binding to o,p’-DDT by a systematic evolution of ligands by exponential enrichment (SELEX) protocol. Five out of seventeen candidate sequences were selected for preliminary characterization by SYBR Green I assay. One sequence with highest fluorescence response with o,p’-DDT, designated DDT_13, was chosen for further characterization. Its dissociation constant (Kd) was determined to be 412.3 ± 124.6 nM. DDT_13 exhibited low cross-binding activities on other tested small molecules. The good bioactivities of DDT_13 were demonstrated for the analysis of spiked lake water and tap water samples. This study provides a novel o,p’-DDT-specific probe for its future applications.
Highlights
Dichlorodiphenyltrichloroethane (DDT), a ubiquitous environmental organochlorine contaminant, has been associated with several disorders of the endocrine and reproductive systems in humans and wildlife [1]
The selection of aptamers binding to small molecule targets by systematic evolution of ligands by exponential enrichment (SELEX) is always a challenge
Capture-SELEX is suitable for the selection of aptamers bound to small molecule targets, because it allows using a free target solution without the loss of possible binding sites and unwanted steric restrictions [20]
Summary
Dichlorodiphenyltrichloroethane (DDT), a ubiquitous environmental organochlorine contaminant, has been associated with several disorders of the endocrine and reproductive systems in humans and wildlife [1]. It has been postulated that DDT-induced endocrine disruption is caused by the compound binding to sex hormone receptors, which interferes with normal hormone responses [4]. The results of in vitro competitive binding assays have shown that o,p’-DDT binds to the estrogen receptor (ER) in mammals, birds, and fish. O,p’-DDT has been found to be estrogenic, as measured by uterotrophic responses in mammals and vitellogenins production in fish [1,6]. O,p’-DDT has been identified as a relatively potent estrogen agonist in in vitro tests with estrogen-responsive tumor cells and in the yeast estrogen screening (YES) assay [2,7]
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