Dextran-coated silica nanoparticles for calcium-sensing

Abstract

This article describes the synthesis and characterisation of fluorescent composite nanoparticles consisting of a silica core and a dextran shell. The silica core contains a rhodamine-based reference dye, which allows ratiometric measurements and the dextran shell is labelled with the Ca²⁺-sensitive dye Fluo-4. The nanoparticles have an average hydrodynamic diameter of 95 nm, good colloidal stability and show a 2.9-fold increase in fluorescence intensity upon binding to Ca²⁺ ions. The apparent dissociation constant of K′_d ≈ 520 nM is well suited for measurements in the physiological range.