OBJECTIVETo develop a nanobiosensor for rapid colorimetric detecting Mercury (II) Ions (Hg(2+)) in water by mercury-specific oligonucleotides (MSOs) probe and gold nanoparticles.

METHODSThe 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).

RESULTSThe 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%.

CONCLUSIONA 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.

Biosensing Techniques ; methods ; Ions ; analysis ; Mercury ; analysis ; Metal Nanoparticles ; Water ; analysis

BACKGROUND: Airborne particulate pollution is more critical in the developing world than in the developed countries in which industrialization and urbanization are rapidly increased. Yangon, a second capital of Myanmar, is a highly congested and densely populated city. Yet, there is limited study which assesses particulate matter (PM) in Yangon currently. Few previous local studies were performed to assess particulate air pollution but most results were concerned PM alone using fixed monitoring. Therefore, the present study aimed to assess distribution of PM in different townships of Yangon, Myanmar. This is the first study to quantify the regional distribution of PM in Yangon City. METHODS: The concentration of PM was measured using Pocket PM Sensor (Yaguchi Electric Co., Ltd., Miyagi, Japan) three times (7:00 h, 13:00 h, 19:00 h) for 15 min per day for 5 days from January 25 to 29 in seven townships. Detailed information of eight tracks for PM pollution status in different areas with different conditions within Kamayut Township were also collected. RESULTS: The results showed that in all townships, the highest PM concentrations in the morning followed by the evening and the lowest concentrations in the afternoon were observed. Among the seven townships, Hlaingtharyar Township had the highest concentrations (164 ± 52 μg/m) in the morning and (100 ± 35 μg/m) in the evening. Data from eight tracks in Kamayut Township also indicated that PM concentrations varied between different areas and conditions of the same township at the same time. CONCLUSION Myanmar is one of the few countries that still have to establish national air quality standards. The results obtained from this study are useful for the better understanding of the nature of air pollution linked to PM. Moreover, the sensor which was used in this study can provide real-time exposure, and this could give more accurate exposure data of the population especially those subpopulations that are highly exposed than fixed station monitoring.
Air Pollutants ; analysis ; Cities ; Environmental Monitoring ; Myanmar ; Particulate Matter ; analysis