Fabrication and dual imaging properties of quantum dot/silica core-shell particles immobilized with gold nanoparticles

The present work proposes a preparation method for core-shell nanoparticles composed of quantum dots (QDs), SiO2, large Au nanoparticles (Au-L), and small Au nanoparticles (Au-s). The QDs were silica-coated with a sol-gel method using tetraethyl orthosilicate (QD/SiO2). Au-L and Au-s were fabricated by reducing Au3+ ions with sodium citrate and tetrakis(hydroxymethyl)phosphonium chloride in water, respectively. Amino groups were introduced onto QD/SiO2 surface by using (3-aminopropyl)-triethoxysilane (QD/SiO2/NH2). Both Au-L and Au-s were immobilized on QD/SiO2/ NH2 by successively reacting Au-L and Au-s with QD/SiO2/NH2 (QD/SiO2/NH2/Au-L/Au-s). Surface modification of QD/SiO2/NH2/Au-L/Au-s was performed by using polyethylene glycol (PEG) with a thiol group (QD/SiO2/NH2/Au-L/Au-s/PEG). The QD/SiO2/NH2/Au-L/Au-s/PEG colloid solution could be clearly imaged via its fluorescence. Its computed tomography (CT) value per unit concentration of Au {M) was 1.2 x 10(4) HU/M. The QD/SiO2/NH2/Au-L/Au-S/PEGs were circulated in a mouse through blood vessels, and some of them became trapped and accumulated in the liver and spleen.