Facile synthesis of amino-functionalized hollow silica microspheres and their potential application for ultrasound imaging

Abstract

By using the positive charged polystyrene (PS) microsphere as template, mono-disperse amino-(–NH 2) functionalized hollow silica microspheres (HSMS-NH 2) with ∼1310 nm in diameter and uniform shells were successfully prepared with a modified sol–gel process. The amino functionalized silica were coated on the PS microspheres via ammonia catalysis, co-hydrolysis and condensation of TEOS and APTES, and then the PS templates were selectively dissolved in THF solution to form the functional hollow microspheres. The controllable thickness (35–85 nm) and amino density (2.46 × 10 −5–6.18 × 10 −5 mol/g) of the shells could be facilely tuned by changing the amount of TEOS and APTES. In vitro ultrasound images of as-prepared HSMS-NH 2 with different concentrations in the physiological saline solution were further investigated. The obvious signal enhancement indicates that as-prepared HSMS-NH 2 has a great potential application for ultrasound imaging.