title: Reusable evanescent wave DNA biosensor for rapid, highly sensitive, and selective detection of mercury ions.
abstract: Mercury ions (Hg(2+)) are a highly toxic and ubiquitous pollutants requiring rapid and sensitive on-site detection methods in the environment and foods. Herein, we report an envanescent wave DNA-based biosensor for rapid and very sensitive Hg(2+) detection based on a direct structure-competitive detection mode. In this system, a DNA probe covalently immobilized onto a fiber optic sensor contains a short common oligonucleotide sequences that can hybidize with a fluorescently labeled complementary DNA. The DNA probe also comprises a sequence of T-T mismatch pairs that binds with Hg(2+) to form a T-Hg(2+)-T complex by folding of the DNA segments into a hairpin structure. With a structure-competitive mode, a higher concentration of Hg(2+) leads to less fluorescence-labeled cDNA bound to the sensor surface and thus to lower fluorescence signal. The total analysis time for a single sample, including the measurement and surface regeneration, was under 6 min with a Hg(2+) detection limit of 2.1 nM. The high specificity of the sensor was demonstrated by evaluating its response to a number of potentially interfering metal ions. The sensor's surface can be regenerated with a 0.5% SDS solution (pH 1.9) over 100 times with no significant deterioration of performance. This platform is potentially applicable to detect other heavy metal ions or small-molecule analytes for which DNA/aptamers can be used as specific sensing probes.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: F
authors.initials: F
authors.lastname: Long
authors.forename: C
authors.initials: C
authors.lastname: Gao
authors.forename: H C
authors.initials: HC
authors.lastname: Shi
authors.forename: M
authors.initials: M
authors.lastname: He
authors.forename: A N
authors.initials: AN
authors.lastname: Zhu
authors.forename: A M
authors.initials: AM
authors.lastname: Klibanov
authors.forename: A Z
authors.initials: AZ
authors.lastname: Gu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D015342:DNA Probes; D008628:Mercury / Q000032:analysis*; D055100:Optical Fibers; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D015342:DNA Probes; D014874:Water Pollutants, Chemical; D008628:Mercury