Preparation of fluorescent silica nanoparticles using reverse microemulsion and the detection of Escherichia coli O157:H7

• Main Authors: Wen Chi Shih, 石文奇
• Other Authors: Ke Liang B.Chang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/66637140782023345566

碩士 === 國立臺灣海洋大學 === 食品科學系 === 95 === Abstract The first objective of this thesis is to utilize a reverse microemulsion (W/O) composed of sodium silicate, protein A, and fluorescent dyes (Rubpy) to prepare protein A-fluorescent silica nanoparticles. The other objective is to use the antibody-bioconjugated fluorescent silica nanoparticles to detect Escherichia coli O157:H7, through fluorescent immunoassay. The loading of fluorescent dyes was 83.5 % when 5.5 mg/mL sodium silicate and 1 mg/mL Rubpy were used during the synthesis of nanoparticles. SEM pictures show that the average particle diameter of fluorescent silica nanoparticles was 138± 17 nm. The protein A-fluorescent silica nanoparticles were made with 5.5 mg/mL sodium silicate, 5.5 mg/mL Rubpy, and 520 µg/mL protein A. The average diameter of protein A-fluorescent silica nanoparticles was 62± 11 nm and the loading of protein A was 60.72 %. The FTIR spectra and Zeta potential measurements suggest that protein A might be immobilized in silica network by electrostatic interaction. Before the detection of Escherichia coli O157:H7, the bacterial samples were ruptured by ultrasonication. We were able to detect 10 CFU/mL of Escherichia coli O157:H7 by using fluorescent measurement in a 96-well microplate. This nanoparticle-based bioassay allows for detecting Escherichia coli O157:H7 within 2 hours and it is easy to fabricate. It is a rapid and convenient technique for quantifying pathogenic bacteria.