Selection of Group-Specific Phthalic Acid Esters Binding DNA Aptamers via Rationally Designed Target Immobilization and Applications for Ultrasensitive and Highly Selective Detection of Phthalic Acid Esters

Abstract

Phthalic acid esters (PAEs) are ubiquitous in the environment, and some of them are recognized as endocrine disruptors that cause concerns on ecosystem functioning and public health. Due to the diversity of PAEs in the environment, there is a vital need to detect the total concentration of PAEs in a timely and low-cost way. To fulfill this requirement, it is highly desired to obtain group-specific PAE binders that are specific to the basic PAE skeleton. In this study, for the first time we have identified the group-specific PAE-binding aptamers via rationally designed target immobilization. The two target immobilization strategies were adopted to display either the phthalic ester group or the alkyl chain, respectively, at the surface of the immobilization matrix. The former enabled the rapid enrichment of aptamers after four rounds of selection. The top 100 sequences are cytosine-rich (44.7%) and differentiate from each other by only 1-4 nucleotides at limited locations. The top two aptamers all display the nanomolar dissociation constants to both the immobilized target and the free PAEs [dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP)]. We further demonstrate the applications of the aptamers in the development of high-throughput PAE assays and DEHP electrochemical biosensors with exceptional sensitivity [limit of detection (LOD), 10 pM] and selectivity (>10-fold). PAE aptamers targeting one of the most sought for targets thus offer the promise of convenient, low-cost detection of total PAEs. Our study also provides insights on the aptamer selection and sensor development of highly hydrophobic small molecules.

Programmable and Multifunctional DNA‐Based Materials for Biomedical Applications

“…For example, phthalic acid esters (PAEs) and their ubiquitousness exist in environment, and are potential toxic for human. Thus, PAE skeleton‐binding DNA aptamers were identified to detect bis(2‐ethylhexyl)phthalate with exceptional sensitivity (limit of detection (LOD): 10 × 10 −12 m ) and selectivity (>10 5 folds) against potential interferences commonly existing in the soft drinks and environmental waters, such as glucose, ethanol, and antibiotics . The label‐free biosensing of Salmonella enterica 's serovars from the food source was carried out at single‐cell level attributing to aptamers with specific binding affinity to the membrane proteins on foodborne pathogens surface .…”

Rapid Multi-Residue Detection Methods for Pesticides and Veterinary Drugs

“…As it is impossible to select aptamers for all of the analytes, being able to generate aptamers that can recognize a group of molecules with a common structure would be significant for the detection of residues [65]. By rational design of the initial targets, group-specific aptamers can be selected with general specificity for a group of analytes [66]. Nikolaus et al [67] used kanamycin (KAN) A as a target molecule in the Capture-SELEX procedure.…”

Selection of Aptamers Specific for DEHP Based on ssDNA Library Immobilized SELEX and Development of Electrochemical Impedance Spectroscopy Aptasensor

“…However, these methods are expensive, time-consuming, and have high LOD, which inhibit their application in the field for on-spot rapid detection. Alternatively, enzyme-linked immunosorbent assay (ELISA) has a LOD of 4.2 pg/mL [11], while the LOD is 3.9 pg/mL [12] for electrochemical aptasensor, 0.5 pg/mL for quantum dot aptasensor [13], and 8 pM for surface-enhanced raman spectroscopy (SERS) aptasensor [14]. The obvious advantages of these rapid-detection techniques are that they are fast, low-cost, and exhibit high selectivity and sensitivity in monitoring trace DEHP in samples.…”