Characterization and bio-binding ability study on size-controllable highly monodisperse magnetic nanoparticles

With the advances in micro-/nano-electronic technology, the development of portable lab-on-chip biodetection device by utilizing magnetic nanoparticles as bio-probes and magnetic field sensor as signal detector has attracted considerable interests in healthcare area. Magnetic probes with required sizes are crucial in quantitative magnetic bio-detection for specific bio-analytes. The objective of this study was to synthesize and characterize amphiphilic co-polymer coated magnetic iron oxide nanoparticles with tunable sizes and study their bio-binding ability. Transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analyzer (TGA), and vibrating sample magnetometer (VSM) were employed to investigate the particle dimension, hydrodynamic size, surface property, mass ratio of surface surfactants, and magnetic behavior. The investigation on their biologically binding ability with bovine serum protein was carried out on thin gold film. The results showed iron oxide nanoparticles with controllable sizes were coated by amphiphilic co-polymer successfully and could be completely transferred and well-dispersed in aqueous solutions. The final products with magnetic core sizes ranging from 6 nm to 17 nm showed superparamagnetic behavior, stable hydrodynamic sizes in aqueous suspensions, and binding ability with bio-molecules, making them promising candidates as magnetic tags for the development of bio-detection devices.