Evanescent-wave biosensor for highly sensitive detection of mercury in aqueous solution using DNA-conjugated gold nanoparticles

• Main Author: 范淑媚
• Other Authors: Lai-Kwan Chau
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/x3ak92

碩士 === 國立中正大學 === 化學暨生物化學研究所 === 107 === Detection of mercury ion (Hg2+), a highly-toxic and ubiquitous pollutant, is in high demand in environmental analysis. In this work, we employed the Fiber Optic-Particle Plasmon Resonance (FOPPR) biosensing system for detection of Hg2+ based on evanescent wave excitation. The FO-PPR system is a biosensing platform that combines gold nanoparticles with an optical fiber in a microfluidic channel. The use of microfluidic chip can effectively save the consumption of samples, each detection requiring only about 200 μL. We can obtain the information of the measured sample by the change of the luminous flux of the optical fiber for the purpose of biochemical detection. The system has the characteristics of instant detection and can shorten the overall sensing time. The total analysis time for a single sample is about 15 minutes. This system can discriminate the presence of Hg2+ and is also quantitative. A hairpin oligonucleotide probe was immobilized on the fiber core surface through a linker layer―dextran, which is a polysaccharide. Its molecular property also allows the fiber sensing region to form a non-specific adsorption layer. In the presence of an oligonucleotide with T-T mismatch, the hairpin opens up and selectively binds with Hg2+ to form a T-Hg2+-T complex. Then the signal is enhanced in the presence of an oligonucleotide-AuNP conjugate which binds with the opened end of the hairpin probe. The sensing strategy enables rapid detection of Hg2+ with high specificity and low detection limit of 3.657 fM. The calibration plot of sensor response versus Hg2+ concentration shows a good linear relationship of R2=0.9936.