title: Optofluidics-based DNA structure-competitive aptasensor for rapid on-site detection of lead(II) in an aquatic environment.
abstract: Lead ions (Pb(2+)), ubiquitous and one of the most toxic metallic pollutants, have attracted increasing attentions because of their various neurotoxic effects. Pb(2+) has been proven to induce a conformational change in G-quadruplex (G4) aptamers to form a stabilizing G4/Pb(2+) complex. Based on this principle, an innovative optofluidics-based DNA structure-competitive aptasensor was developed for Pb(2+) detection in an actual aquatic environment. The proposed sensing system has good characteristics, such as high sensitivity and selectivity, reusability, easy operation, rapidity, robustness, portability, use of a small sample volume, and cost effectiveness. A fluorescence-labeled G4 aptamer was utilized as a molecular probe. A DNA probe, a complementary strand of G4 aptamer, was immobilized onto the sensor surface. When the mixture of Pb(2+) solution and G4 aptamer was introduced into the optofluidic cell, Pb(2+) and the DNA probe bound competitively with the G4 aptamer. A high Pb(2+) concentration reduced the binding of the aptamer and the DNA probe; thus, a low-fluorescence signal was detected. A sensitive sensing response to Pb(2+) in the range of 1.0-300.0 nM with a low detection limit of 0.22 nM was exhibited under optimal conditions. The potential interference of the environmental sample matrix was assessed with spiked samples, and the recovery of Pb(2+) ranged from 80 to 105% with a relative standard deviation value of <8.5%. These observations clearly illustrate that with the use of different DNA or aptamer probes, the sensing strategy presented can be easily extended to the rapid on-site monitoring of other trace analytes.
authors.affiliation: School of Environment and Natural Resources, Renmin University of China, Beijing, China. Electronic address: longf04@ruc.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Long
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Zhu
authors.affiliation: School of Environment and Natural Resources, Renmin University of China, Beijing, China. Electronic address: whc@ruc.edu.cn.
authors.forename: Hongchen
authors.initials: H
authors.lastname: Wang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D002413:Cations, Divalent / Q000032:analysis; D004867:Equipment Design; D054856:G-Quadruplexes; D007854:Lead / Q000032:analysis*; D057230:Limit of Detection; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D002413:Cations, Divalent; D014874:Water Pollutants, Chemical; D007854:Lead
keywords: Aptasensor; Functional DNA; G4 aptamer; Lead ions; Optofluidics