Polymerization Combined with Affinity Nanoparticle-Assisted Detection of Pathogenic Bacteria

• Main Authors: Wu Kai-Chieh, 吳開傑
• Other Authors: Chen Yu-Chie
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/18802034281600752914

碩士 === 國立交通大學 === 應用化學系所 === 97 === Polymerization has been widely applied in the development of analytical methods. Owing to the ease of synthesis, high specific surface area, and ease of modification, nanoparticles have been used as functional probes for interacting target species. Nanoparticles such as silica beads can be generated from polymerization, i.e., Stöber’s method. In this thesis, two-steps of functionalized nanoparticle-based affinity approach for the detection of pathogenic bacteria was proposed. Staphylococcus saprophyticus and Escherichia coli were used as the model bacteria. It has been known that Fc site of immunoglobulin G (IgG) is capable of interacting with pathogenic bacteria such as S. saprophyticus through the binding proteins on the cell wall. However, there is no binding interaction between the Fc site with E. coli. In this study, two types of affinity probes bound with IgG were generated: magnetic iron oxide nanoparticles generated from co-precipitation and silica nanoparticles generated from polymerization. Magnetic iron oxide nanoparticles were first used to target S. saprophyticus and E. coli followed by magnetic isolation. The aggregated NPs were then interacted with the IgG-bound silica beads (ca. 30 nm). The results show that when the magnetic isolated conjugates contain Fc binding-bacteria, i.e. S. saprophyticus, the volume of the conjugates can be enlarged by the IgG-silica nanoparticles and lead it is possible to be visible by the naked eye. However, when using E. coli as the sample, the volume of the conjugates remains similar to that of the original magnetic iron oxide nanoparticles. The results indicate that this approach can be used to detect the presence of target bacteria from aqueous and urine samples simply by using this two-step functionalized nanoparticle-based affinity approach. MALDI-MS and further polymerization by ATRP (atom transfer radical polymerization) were also employed for confirmation. The detection limits of this approach for S. saprophyticus in aqueous and urine samples (90 μL) are were as low as 104 cfu/mL and 106 cfu/mL, respectively.