Magnetic nanomotors with integrated theranostic capabilities can revolutionize biomedicine of the future. Typically, these nanomotors contain ferromagnetic materials, such that small magnetic fields can be used to maneuver and localize them in fluidic or gel-like environments. However, motors with large permanent magnetic moment tend to agglomerate, which limits the scalability of this otherwise promising technology.
In a recent study published in the journal Nanoscale, Dr. Pooyath Lekshmy Venugopalan, Dr. Shilpee Jain (BSSE), Prof. Srinivasrao Shivashankar along with Prof. Ambarish Ghosh from the Centre for Nano Science and Engineering, IISc have demonstrated how the application of a microwave-synthesized ferrite layer on these helical ferromagnetic nanomotors renders them suitable as magnetic hyperthermia agents, as demonstrated by their cytotoxic effects on cancer cells. The ferrite layer also reduces the agglomeration, allowing them to be stored in a colloidal suspension for longer than six months with undiminished performance. The two functionalities were inter-related since higher hyperthermia efficiency required a denser suspension, both of which were achieved in a single microwave-synthesized ferrite coating.
These three-micron ferrite coated nanomotors were subjected to hyperthermia run on cervical cancer cells (HeLa cells) for a period of 20 minutes which resulted in the temperature rise of about 8 oC from the physiological temperatures thereby causing cell death ((~ 43oC). A crucial advantage of the nanomotors demonstrated here is their scalable fabrication processes which would allow large scale production and storage of magnetic nanomotors, taking us a step closer to the vision of a swarm of fantastic nanovoyagers deployed in human patients.
Figure: A) Schematic of the steps of fabrication of ferrite coated magnetic nanomotors. B) Temperature as a function of time for 2 mg/ml ferrite coated (ZF-SiO2) nanomotors. C) Cell viability after exposure to AC magnetic fields for 20 minutes with ferrite-coated nanomotors at ferrite concentrations of 1 mg/ml and 2 mg/ml. D) Bright field and fluorescence images of the cells with 1 mg/ml ferrite-coated nanomotors before (I, II) and after (III) the hyperthermia run. Arrows in panel I show nanomotors on the cell surfaces.
Reference: P.L. Venugopalan, S. Jain. S.A. Shivashankar and A.Ghosh, Single coating of zinc ferrite renders magnetic nanomotors therapeutic and stable against agglomeration, Nanoscale, 10, 2327-2332, (2018).
More details on our work can be found at:
Website URL: http://www.cense.iisc.ac.in/ambarish/