Ultrasensitive electrogenerated chemiluminescence biosensor for the determination of mercury ion incorporating G4 PAMAM dendrimer and Hg(II)-specific oligonucleotide.
A novel electrogenerated chemiluminescence (ECL) biosensor for highly sensitive and selective detection of mercury ion was developed on the basis of mercury-specific oligonucleotide (MSO) served as a molecular recognition element and the ruthenium(II) complex (Ru1) as an ECL emitting species. The biosensor was fabricated on a glassy carbon electrode coated with a thin layer of single wall carbon nanotubes, where the ECL probe, NH(2)-(CH(2))(6)-oligo(ethylene oxide)(6)-MSO↔Dend-Ru1, was covalently attached. The Dend-Ru1 pendant was prepared by covalent coupling Ru1 with the 4th generation polyamidoamine dendrimer (Dend), in which each dendrimer contained 35 Ru1 units so that a large amplification of ECL signal was obtained. Upon binding of Hg(2+) to thymine (T) bases of the MSO, the T-Hg-T structure was formed, and the MSO changed from its linear shape to a "hairpin" configuration. Consequently, the Dend-Ru1 approached the electrode surface resulting in the increase of anodic ECL signal in the presence of the ECL coreactant tri-n-propylamine. The reported biosensor showed a high reproducibility and possessed long-term storage stability (92.3% initial ECL recovery over 30 day's storage). An extremely low detection limit of 2.4 pM and a large dynamic range of 7.0 pM to 50 nM Hg(2+) were obtained. An apparent binding constant of 1.6 × 10(9)M(-1) between Hg(2+) and the MSO was estimated using an ECL based extended Langmuir isotherm approach involving multilayer adsorption. Determination of Hg(2+) contents in real water samples was conducted and the data were consistent with the results from cold vapor atomic fluorescence spectroscopy.
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an, 710062, PR China.
Fen
F
Ma
Yu
Y
Zhang
Honglan
H
Qi
Qiang
Q
Gao
Chengxiao
C
Zhang
Wujian
W
Miao
D015374:Biosensing Techniques / Q000379:methods*; D050091:Dendrimers / Q000737:chemistry*; D057230:Limit of Detection; D049449:Luminescence; D008163:Luminescent Measurements / Q000379:methods; D008628:Mercury / Q000032:analysis*; D009757:Nylons / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry*; D015203:Reproducibility of Results; D012428:Ruthenium / Q000737:chemistry
D050091:Dendrimers; D009757:Nylons; D009841:Oligonucleotides; C520550:PAMAM-G4; D012428:Ruthenium; D008628:Mercury