Galactose-functionalized magnetic iron-oxide nanoparticles for enrichment and detection of ricin toxin.

To generate a new specific recognition module for the enrichment and detection of ricin, galactose-functionalized silanized magnetic iron-oxide nanoparticles (Gal-SiMNPs) were assembled by amino-silanized MNPs (amino-SiMNPs) and a galactose linker. Amino-SiMNPs were produced by a coprecipitation method, and were coated with double layers of silica and aminosilane by hydrolysis of tetraethoxysilane and 3-aminopropyltriethoxysilane, respectively. A galactose with an amido-acid linker was synthesized by four steps of chemical modification from O-acetyl protected galactose. The diameters of Gal-SiMNPs were characterized as being 60 ± 20 nm. The average amount of galactose-loading and ricin-binding on Gal-SiMNPs was 30 ± 2 µg galactose and 29 ± 2 µg ricin toxin on the surface of 1 mg of Gal-SiMNPs, respectively. Furthermore, a rapid, simple and efficient colorimetric assay was established for the detection of ricin based on the Gal-SiMNPs, and the limits of detection (LODs) of 2 and 4 ng/mL for ricin in physiological buffer and serum were obtained, respectively.