title: Detection of mercury(II) ions using colorimetric gold nanoparticles on paper-based analytical devices.
abstract: An on-field colorimetric sensing strategy employing gold nanoparticles (AuNPs) and a paper-based analytical platform was investigated for mercury ion (Hg(2+)) detection at water sources. By utilizing thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination chemistry, label-free detection oligonucleotide sequences were attached to unmodified gold nanoparticles to provide rapid mercury ion sensing without complicated and time-consuming thiolated or other costly labeled probe preparation processes. Not only is this strategy's sensing mechanism specific toward Hg(2+), rather than other metal ions, but also the conformational change in the detection oligonucleotide sequences introduces different degrees of AuNP aggregation that causes the color of AuNPs to exhibit a mixture variance. To eliminate the use of sophisticated equipment and minimize the power requirement for data analysis and transmission, the color variance of multiple detection results were transferred and concentrated on cellulose-based paper analytical devices, and the data were subsequently transmitted for the readout and storage of results using cloud computing via a smartphone. As a result, a detection limit of 50 nM for Hg(2+) spiked pond and river water could be achieved. Furthermore, multiple tests could be performed simultaneously with a 40 min turnaround time. These results suggest that the proposed platform possesses the capability for sensitive and high-throughput on-site mercury pollution monitoring in resource-constrained settings.
authors.affiliation: Graduate Institute of Biomedical Engineering, National Chung Hsing University , Taichung 402, Taiwan.
authors.forename: Guan-Hua
authors.initials: GH
authors.lastname: Chen
authors.forename: Wei-Yu
authors.initials: WY
authors.lastname: Chen
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Yen
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Wang
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
authors.forename: Chien-Fu
authors.initials: CF
authors.lastname: Chen
mesh_terms: D040421:Cell Phone; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D004277:DNA, Single-Stranded; D006046:Gold / Q000737:chemistry; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques; D010209:Paper; D045483:Rivers; D013941:Thymine / Q000737:chemistry; D014867:Water / Q000032:analysis / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004277:DNA, Single-Stranded; D014874:Water Pollutants, Chemical; D014867:Water; D006046:Gold; D008628:Mercury; D013941:Thymine