Synthesis, characterization, and protein labeling of difunctional magnetic nanoparticles modified with thiazole orange dye

A dual functional nanoparticle was designed and synthesized by encapsulating magnetic core inside silica particles and subsequently a thiazole orange (TO) dye derivative was modified on the surface of the nanoparticles. The obtained particles were characterized by Fourier transform infrared spectroscope, Uv–Vis spectrophotometer, fluorescence spectrophotometer, transmission electron microscope, dynamic light scattering, etc. The size of preliminary magnetic particles is ca. 7 nm, but after coating a silica layer and dye, the size of particles is increased to ca. 60 nm. The hydrodynamic diameter, water dispersibility, and zeta potential were also determined. The hydrodynamic diameter of particles with silica and dye is 65.2 and 70.5 nm, respectively, with positive zeta potential (25.1, 38.5 mV). Furthermore magnetic properties of the particles were measured and the experimental results suggested that it could meet the requirement of application as magnetic resonance imaging agent. Finally to verify the availability of the particles as fluorescent labeling, protein labeling experiment was performed using bovine serum albumin (BSA) protein and the results showed that the dual functional particle has higher affinity with BSA than TO molecule itself.