Facile and Sensitive Epifluorescent Silica Nanoparticles for the Rapid Screening of EHEC

Abstract

This study was to develop antibodies conjugated fluorescent dye-doped silica nanoparticles (FDS-NPs) aiming to increase signals for the rapid detection of Escherichia coli O157:H7 with glass slide method. The FDS-NPs were produced with microemulsion/solgel techniques resulting in spherical in shape with 47 ± 6 nm in diameter. The particles showed high intensity and stable orange color Rubpy luminescent dye. The XRD spectrum showed a broad diffraction peak in the range of 18-30 ∘ (centered at 22 ∘) indicating an amorphous structure. Surface modifications for bioconjugation with affinity chromatography purified (IgGs) antibodies were successful. The properties were evident from FTIR spectra at 1631.7 cm −1. Results indicated that nanoparticles could attach onto cells of E. coli O157:H7 coated on a glass slide, and give distinctively bright color under epifluorescence microscope (400x). It was shown that FDS-NPs could detect a very low amount of cells of E. coli O157:H7 (16 CFU in 10 ml) in 60 min. The phosphate buffered saline (PBS) with ionic strength of 1.70 gave zeta potential of good particle dispersion (−40 mV). This work demonstrated that highly sensitive bioconjugated E. coli O157:H7 FDS-NPs were successfully developed with a potential to be used for the rapid detection of E. coli O157:H7 in foods.

Validation of a Rapid Visual Screening of Campylobacter jejuni in Chicken Using Antibody-Conjugated Fluorescent Dye-Doped Silica Nanoparticle Reporters

“…This finding was corresponding well with that of Gunasekaran et al [25], Tansub et al [17], and Tuitemwong et al [18] who suggested that wave numbers 3500-3220 cm −1 indicated amine group N-H stretching and 1850-1550 cm −1 for carboxyl group C=O on the FDS-NP surfaces.…”

“…The size of FDS-NPs of approximately 30-60 nm was consistent with that previously reported [14,15,17,18]. Thepwiwatjit et al [14] reported the FDS-NPs with relatively narrow size of 29-43 nm.…”

“…Our research group had developed silica and ferromagnetic nanoparticle-based detection for Vibrio cholerae in seafoods, Salmonella spp., E. coli O157:H7, and C. jejuni in poultry and products [14][15][16][17][18]. These methods showed potential applications in the routine use.…”

“…Modifications. Synthesis of FDS-NPs and surface modifications were carried out as previously described [14,15,17,18]. Briefly, mixtures of cyclohexane (75 ml), Triton X-100 (17.7 ml), and n-hexanol (18 ml) as oil, surfactant, and cosurfactant phases, respectively, were mixed with 4.8 ml aliquots of Rubpy dye solution (20 mM in deionized water).…”

Recent Trends in Rapid Environmental Monitoring of Pathogens and Toxicants: Potential of Nanoparticle‐Based Biosensor and Applications

“…Use of fluorescence nanoparticles in combination with magnetic beads capable of capturing and concentrating target specimens in the sampling process has been established to overcome the limitation of fluorescence intensity [ 9 – 12 ]. Fluorescent nanoparticles (about 10–20 μ m diameter in range) including semiconductor nanoparticles, quantum dots, metal nanoparticles, silica nanoparticles, and polymer nanoparticles have been focused for research and development.…”