Synthesis, modification, bioconjugation of silica coated fluorescent quantum dots and their application for mycotoxin detection

Abstract

To create bright and stable fluorescent biolabels for immunoassay detection of mycotoxin deoxynivalenol in food and feed, CdSe/CdS/ZnS core-shell quantum dots (QDs) were encapsulated in silica nanoparticles through a water-in-oil reverse microemulsion process. The optical properties and stability of the obtained silica coated QDs (QD@SiO2), modified with amino, carboxyl and epoxy groups and stabilized with polyethylene glycol fragments, were characterized in order to assess their bioapplicability. The developed co-condensation techniques allowed maintaining 80% of the initial fluorescent properties and yielded stable fluorescent labels that could be easily activated and bioconjugated. Further, the modified QD@SiO2 were efficiently conjugated with antibodies and applied as a novel label in a microtiter plate based immunoassay and a quantitative column-based rapid immunotest for deoxynivalenol detection with IC50 of 473 and 20 ng/ml, respectively.

Use of IHF-QD Microscopic Analysis for the Detection of Food Allergenic Components: Peanuts and Wheat Protein

“…Due to the photostability, quantum dots have a great potential for use in fluorescence microscopy. The use of QDs has been also verified in research on developing imaging methods of mouse fibroblasts, where QDs gave a high signal-to-background ratio [26], the same as in immunoanalytical analyses [23][24][25]. QD fluorescent labeling has been widely used to detect a number of food grade substances such as vanillin [39], allergens such as alpha lactalbumin [21], mycotoxins [40], or pathogens [41,42].…”

“…Conventional fluorochromes are relatively sensitive to the external environment, including normal imaging conditions [21]. In terms of the fluorescence life of conventional fluorochromes, organic semiconductor nanoparticles-quantum dots (QDs)-appear to be suitable for immunoanalytical labeling [22,23]. Quantum dots are inorganic semiconductor fluorescent nanoparticles with a size in the range of several nm, the most common arrangement being the so-called core-shell.…”

“…This is very important because they are used as a fluorescent tool for labeling of countless biologically active substances, especially in the form of so-called bioconjugates [25]. Quantum dots possess exceptional photophysical properties, such as dimensionally tuned narrow and symmetric emission, broad and strong quantum yield, and high stability to photochemical and chemical radiation, and thus occupy a new class in the group of inorganic fluorescent labeling tools [23,[25][26][27]. In addition to their optical properties, CdSe/ZnS QDs, which consist of a CdSe core and a ZnS sheath that increase the QDs' resistance to light and increase their quantum yield, are the most popular among scientists [28,29].…”

“…The use of such QDs is widespread in the life sciences, but several publications have reported the use of QDs in the food sciences, where they were mostly used to detect pathogenic bacteria, proteins, and rotaviruses. They were also used in applying polyclonal antibody-bound QDs and to intensify the signal of detecting allergens [23,[25][26][27][29][30][31][32].…”

Multicolored silica coated CdSe core/shell quantum dots

“…) were encapsulated in silica NPs through the microemulsion process 14 . First, 1 ml of hexane, 0.32 ml Brij L4 as surfactant and 50 µl H 2 O were mixed and let to stir for 30 min to form the microemulsion.…”