Bio-functionalization of magnetite nanoparticles using an aminophosphonic acid couplingagent: new, ultradispersed, iron-oxide folate nanoconjugates for cancer-specifictargeting

Abstract

The present study describes a systematic approach towards the design and development ofnovel, bio-functionalized, magneto-fluorescent nanoparticles for cancer-specific targeting.Biocompatible, hydrophilic, magneto-fluorescent nanoparticles with surface-pendant amine,carboxyl or aldehyde groups, to be later used for bio-conjugation, were designed using anaminophosphonic acid coupling agent. These magneto-fluorescent nanoparticles werefurther functionalized with folic acid, using diverse conjugation strategies. A series of newiron-oxide folate nanoconjugates with excellent aqueous dispersion stability and reasonablygood hydrodynamic sizes under a wide range of physiological conditions were developed.These ultradispersed nanosystems were analyzed for their physicochemical properties andcancer-cell targeting ability, facilitated by surface modification with folic acid. Thenanoparticle size, charge, surface chemistry, magnetic properties and colloidal stabilitywere extensively studied using a variety of complementary techniques. Confocalmicroscopy, performed with folate receptor positive human cervical HeLa cancercells, established that these non-cytotoxic iron-oxide folate nanoconjugates wereeffectively internalized by the target cells through receptor-mediated endocytosis.Cell-uptake behaviors of nanoparticles, studied using magnetically activated cell sorting(MACS), clearly demonstrated that cells over-expressing the human folate receptorinternalized a higher level of these nanoparticle–folate conjugates than negative controlcells.