title: Highly sensitive and selective label-free optical detection of mercuric ions using photon upconverting nanoparticles.
abstract: We demonstrate a fluorescence-based, label-free detection scheme that reports the presence of Hg(II) ion using photon upconverting nanoparticles. A single-stranded DNA containing a number of thymine bases to be used as the Hg(2+)-capturing element is covalently attached to the photon upconverting NaYF(4):Yb(3+),Tm(3+) nanoparticles. Under the illumination of 980 nm laser, energy transfer takes place between the NaYF(4):Yb(3+),Tm(3+) nanoparticles as the donor and SYBR Green I, a DNA intercalating dye, as the acceptor. By monitoring the ratio of the acceptor emission to the donor emission, we can quantitatively detect the presence of the mercuric ions with a directly observed detection limit of 0.06 nM. The remarkably high signal-to-noise ratio of photon upconverting particles leads to very high sensitivity and specificity without the need of fluorophore labeling. The sensor also does not suffer from photobleaching.
authors.affiliation: Laboratory of Nanomaterial Science, Department of Chemistry, New Mexico Tech, Socorro, NM 87801, United States.
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D007477:Ions; D008628:Mercury / Q000032:analysis*; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry*; D010783:Photometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
chemical_list: D007477:Ions; D008628:Mercury
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