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

Abstract

This work develops a process for fabricating particles composed of a quantum dot (QD) core, a SiO2 shell, and single-nanometer-sized Au nanoparticles (AuS) immobilized on the particle surface. The QD nanoparticles were silica-coated with a sol-gel process using tetraethyl orthosilicate (QD/SiO2). A colloidal solution of the AuS was prepared by reducing Au3+ with tetrakis(hydroxymethyl)phosphonium chloride in an aqueous solution. The QD/SiO2 particles were surface-modified with thiol groups by using (3-mercaptopropyl)trimethoxysilane (QD/SiO2/SH). The AuS nanoparticles were immobilized on the QD/SiO2/SH particle surface by adding a colloidal AuS solution to a colloidal QD/SiO2/SH solution (QD/SiO2/SH/AuS). The QD/SiO2/SH/AuS particles were surface-modified with thiol-terminated polyethylene glycol (PEG) (QD/SiO2/SH/AuS/PEG). Fluorescence images and computed tomography (CT) images could be obtained for the colloidal QD/SiO2/SH/AuS/PEG particle solution. The colloidal QD/SiO2/SH/AuS/PEG particle solution had a CT value per unit concentration of Au (M) of 6.68 × 103 HU/M. The circulation of the QD/SiO2/SH/AuS/PEG particles was confirmed in a mouse after injection of a colloidal particle solution into its blood vessels, and they accumulated in the heart. A portion of the QD/SiO2/SH/AuS/PEG particles accumulated in the liver and spleen and remained there.