Surface Modification of Magnetic Nanoparticle Clusters for Biomedical Applications

Abstract

The diagnosis and therapy of disease require information of multiple targets. In order to identify multiple biomolecule, an effective strategy for separation and multiplexing is important.1) A bio-barcoding system that incorporates quantum dots (QDs) and magnetic nanoparticles can be useful for such applications.2) Silica-shell-coated magnetic nanoparticle cluster (SMNC) were synthesized and the surface of SMNC was decorated by zwitterionic ligands, which made the SMNC colloidally stable at physiological condition and possess minimal non-specific adsorptions.3) Zwitterion tethered SMNC showed enhanced colloidal stability in high salt concentration and under broad pH range. The minimal non-specific adsorption was confirmed by non-specific adsorption level assays using fluorescein conjugated serum albumin. Also, SMNCs were loaded with QDs using amphiphilic polyethyleneimine derivatives (amPEIs). The resultant a few hundred nanometer sized SMNC-QDs-amPEIs were composed of SMNC core surrounded by hundreds of QDs. SMNC-QDs complexs showed excellent photoluminescene(PL) property and can be facilely collected in presence of an external magnetic field. These SMNC-QDs complexs and SMNC with reduced non-specific adsorption can be useful as bio- barcoding agent.