Multimodal ultra-small CoFe-WOx nanohybrids synthesized by a pilot microfluidic system

Among all the nanomaterials, ultra-small nanohybrids have gained considerable attention as drugs, contrast agents, molecular nanoprobes, and catalysts owing to their multi-functionality and size effect. However, their extension and commercialization are restricted due to low synthetic efficiency and uncontrollable structure. Herein, a pilot microfluidic system (PMS) was built to successfully synthesize the ultra-small (2.3 +/- 0.7 nm) CoFe-WOx nanohybrids (NHs) with a tiny CoFe core and a mixed metal oxides shell (CoWO4-Fe2WO6-WO3). Furthermore, the CoFe-WOx NHs displayed excellent multi-modal imaging properties, which could be observed optically via a dark-field microscope, imaged through X-ray computed tomography and magnetic resonance imaging device. For the first time, hybridization between metal cores and metal-oxide shells produced two strong absorption peaks in the long band of near infrared radiation, one at 1450 nm and the other at 1980 nm. Overall, CoFe-WOx NHs emonstrated distinct magnetic and optical properties and multimode imaging capabilities due to their microstructure and composition. These findings may prove to be effective in finding alternatives for nanoprobes that can be used for visible/infrared/MRI/CT imaging, as well as pre-drugs for photothermal/ photodynamic and magnetothermal/magneto-dynamic therapies.