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Immobilization of DNA on Magnetic Microparticles for Mercury Enrichment and Detection with Flow Cytometry
Author(s) -
Huang PoJung Jimmy,
Liu Juewen
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002934
Subject(s) - mercury (programming language) , sybr green i , chemistry , fluorescence , adsorption , streptavidin , biosensor , detection limit , analytical chemistry (journal) , chromatography , biotin , biochemistry , real time polymerase chain reaction , organic chemistry , physics , gene , programming language , quantum mechanics , computer science
Mercury detection in water has attracted a lot of research interest due to its highly toxic nature and adverse environmental impact. In particular, the recent discovery of specific binding of Hg II to thymine‐rich (T‐rich) DNA resulting in T‐Hg II ‐T base pairs has led to the development of a number of sensors with different signaling mechanisms. However, the majority of such sensors were non‐immobilized. Immobilization, on the other hand, allows active mercury adsorption, signal amplification, and sensor regeneration. In this work, we immobilized a thymine‐rich DNA on a magnetic microparticle (MMP) surface through biotin–streptavidin interactions. In the presence of Hg II , the DNA changes from a random coil structure into a hairpin, upon which SYBR Green I binds to emit green fluorescence. Detection was carried out by using flow cytometry where the fluorescence intensity increased ≈9‐fold in the presence of mercury and the binding of mercury reached equilibrium in less than 2 min. The sensor showed a unique sample‐volume‐dependent fluorescence signal change where a higher fluorescence was obtained with a larger sample volume, suggesting that the particles can actively adsorb Hg II . Detection limits of 5 n M (1 ppb) and 14 n M (2.8 ppb) were achieved in pure buffer and in mercury‐spiked Lake Ontario water samples, respectively.