title: Highly sensitive and selective chip-based fluorescent sensor for mercuric ion: development and comparison of turn-on and turn-off systems.
abstract: Miniaturization is currently an important trend in environmental and food monitoring because it holds great promise for on-site monitoring and detection. We report here two ready-to-use chip-based fluorescent sensors, compatible with microarray technology for reagentless, one-step, fast, highly sensitive and selective detection of the mercuric ion (Hg(2+)) in the turn-on and turn-off operation modes. Both operation modes are based on the highly selective T-Hg(2+)-T coordination between two neighboring polythymine (T) strands at a high probe density and its induced displacement of the complementary polyadenine strand labeled with either fluorophore or quencher, which enables the turn-off and turn-on detection of Hg(2+), respectively. The turn-off sensor is slightly more sensitive than the turn-on sensor, and their detection limits are 3.6 and 8.6 nM, respectively, which are both lower than the U.S. Environmental Protection Agency limit of [Hg(2+)] for drinkable water (10 nM, 2 ppb). Compared to the turn-off sensor with the dynamic Hg(2+) detection range from 3.6 nM to 10 μM (R(2) = 0.99), the turn-on sensor has a broader dynamic Hg(2+) detection range, from 8.6 nM to 100 μM (R(2) = 0.996). Both sensors exhibited superior selectivity over other reported sensors using thymine-rich probes for Hg(2+) detection over other common metal ions. In addition, the practical application of the chip-based sensors was demonstrated by detecting spiked Hg(2+) in drinking water and fresh milk. The sensor has great potential for on-site practical applications due to its operational convenience, simplicity, speed, and portability.
authors.affiliation: State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.forename: Meiying
authors.initials: M
authors.lastname: Liu
authors.forename: Xinhui
authors.initials: X
authors.lastname: Lou
authors.forename: Tao
authors.initials: T
authors.lastname: Zhao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xue
authors.forename: Jianlong
authors.initials: J
authors.lastname: Zhao
authors.forename: Yuanshen
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000818:Animals; D002417:Cattle; D007477:Ions / Q000737:chemistry; D008628:Mercury / Q000032:analysis*; D046228:Microarray Analysis; D008892:Milk / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry; D011071:Poly T / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D007477:Ions; D009841:Oligonucleotides; D014867:Water; D011071:Poly T; D008628:Mercury