Objective: To develop a nanobiosensor for rapid colorimetric detecting Mercury (II) Ions (Hg(2+)) in water by mercury-specific oligonucleotides (MSOs) probe and gold nanoparticles.
Methods: The nanobiosensor was assembled by adsorbing the optimized MSOs on the surface of gold nanoparticles. A direct colorimetric probe of Hg(2+) which relied on the T-T mismatches in DNA duplexes was used to selectively and strongly capture Hg(2+). Hg(2+) induces the aggregation of gold nanoparticles with appropriate amount of salts, resulting the color change (red to blue).
Results: The diameter and concentration of the gold nanoparticle preparation were 15 nm and 2.97 nmol/L, respectively. Truncated MSOs (9 bp) showed the similar Hg(2+)-binding activity. The optimum concentration of the NaNO3 solution was 0.5 mol/L. The nanobiosensor could detect Hg(2+)in a range of 10 ∼ 1000 µmol/L within few minutes and the specificity was 100%.
Conclusion: A new nanobiosensor is developed successfully for rapid colorimetric detecting Hg(2+) in water, avoiding either MSOs labeling or gold nanoparticles modification. This technique is simple, convenient and rapid detecting method with high sensitivity and specificity.