Magnetic nanoparticles (MNPs) have been widely used in biomedical fields, especially in gene delivery, thermomagnetic therapy, in vitro diagnosis and magnetic resonance imaging. The Nano-Biomaterial Group of NIMTE, CAS has been mainly engaged in the synthesis, modification, functionalization and biomedical application of MNPs for many years, and has successively realized the accurate imaging, treatment and treatment visualization of MNPs for tumors (PHYS Chem phys Chem 2012, 142631-2636; J mater Chem B 2015, 35172-5181; ACS Nano 2017, 1110992-11004.). Recently, the group has made new progress in magnetic regulation of MNPs by using transition metal doping as an alternative strategy.
Given that the contrast of Zn-doped Fe3O4 nanoparticles (NPs) (ZnxFe3xO4) in magnetic resonance imaging (MRI) depends on their intrinsic chemical and physical properties such as doping content or size, the ability to finely control these characteristics is very important but at the same time very challenging. The group introduce a novel doping mechanism and present how various desired MRI contrast levels can be precisely achieved by synthesizing ZnxFe3xO4 nanoparticles in a controlled and reproducible manner, exhibiting different Zn doping concentrations (ZnxFe3xO4, x = 0/0.1/0.2/0.3/0.4) and different dimensions (4/7/10 nm). Finally the group conclude that (i) Ms is the main factor affecting T2 -weighted imaging with the increase of Ms , the r2 value increases, and the contrast agent is better suited to a T2-weighted imaging effect; (ii) in the T1 -weighted imaging mode, r1 and r2 /r1 values are not the main factors affecting the achievable contrast/brightness. Relevant achievements were published in Chem. Mater. (2019, 31, 7255-7264.) and applied for invention patent 201811510968.3201910062833.3.
The above-mentioned related series of work has applied for 12 patents, and 3 has been authorized. The work was supported by the National Natural Science Foundation, the national key R&D plan "precision medicine research" project, the Zhejiang provincial key R&D plan and the Ningbo industrial major project.
Figure 1 a) Schematic illustration of the crystal structure of Fe3O4, b) effects of Zn doping concentrations towards the Ms.