Abstract
An efficient magnetic resonance imaging (MRI) contrast agent with a high R2 relaxivity value is achieved by controlling the shape of iron oxide to rod like morphology with a length of 30-70 nm and diameter of 4-12 nm. Fe3O4 nanorods of 70 nm length, encapsulated with polyethyleneimine show a very high R2 relaxivity value of 608 mM(-1) s(-1). The enhanced MRI contrast of nanorods is attributed to their higher surface area and anisotropic morphology. The higher surface area induces a stronger magnetic field perturbation over a larger volume more effectively for the outer sphere protons. The shape anisotropy contribution is understood by calculating the local magnetic field of nanorods and spherical nanoparticles under an applied magnetic field (3 Tesla). As compared to spherical geometry, the induced magnetic field of a rod is stronger and hence the stronger magnetic field over a large volume leads to a higher R2 relaxivity of nanorods.
Highlights
We found that the relaxation coefficient (R2) gradually increases from 312 to 608 mM−1 s−1 with an increase in the length of NRs; this increase is a consequence of magnetization enhancement as well as a sharp increase in the surface area due to anisotropic morphology
For further confirmation of the magnetite phase formation, the X-ray photoelectron spectroscopy (XPS) spectrum is recorded after the reduction process
A larger number of water protons experience a strong magnetic field over a large volume and rapidly de-phase, a higher R2 value is realized for NRs than for the NPs of equivalent material volume
Summary
Magnetic nanoparticles (MNPs) have been established for use in various promising biomedical applications, such as contrast agents in magnetic resonance imaging (MRI),[1,2,3,4,5,6] vectors in drug delivery[7,8,9] and mediators to convert electromagnetic energy to heat.[9,10,11] The MNP based MRI contrast agent can improve diagnosis in several pathologies.[12,13] Iron oxide NPs (Fe3O4) of several formulations such as Resovist, Combidex and Feridex have been used as T2 weighted contrast agents to accelerate the R2 relaxivity of protons.[13].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
