High-Performance Ferrite Nanoparticles through Nonaqueous Redox Phase Tuning
详细信息 查看全文
- 作者：Ritchie Chen ; Michael G. Christiansen ; Alexandra Sourakov ; Alan Mohr ; Yuri Matsumoto ; Satoshi Okada ; Alan Jasanoff ; Polina Anikeeva
- 刊名：Nano Letters
- 出版年：2016
- 出版时间：February 10, 2016
- 年：2016
- 卷：16
- 期：2
- 页码：1345-1351
- 全文大小：546K
- ISSN：1530-6992
文摘
From magnetic resonance imaging to cancer hyperthermia and wireless control of cell signaling, ferrite nanoparticles produced by thermal decomposition methods are ubiquitous across biomedical applications. While well-established synthetic protocols allow for precise control over the size and shape of the magnetic nanoparticles, structural defects within seemingly single-crystalline materials contribute to variability in the reported magnetic properties. We found that stabilization of metastable wüstite in commonly used hydrocarbon solvents contributed to significant cation disorder, leading to nanoparticles with poor hyperthermic efficiencies and transverse relaxivities. By introducing aromatic ethers that undergo radical decomposition upon thermolysis, the electrochemical potential of the solvent environment was tuned to favor the ferrimagnetic phase. Structural and magnetic characterization identified hallmark features of nearly defect-free ferrite nanoparticles that could not be demonstrated through postsynthesis oxidation with nearly 500% increase in the specific loss powers and transverse relaxivity times compared to similarly sized nanoparticles containing defects. The improved crystallinity of the nanoparticles enabled rapid wireless control of intracellular calcium. Our work demonstrates that redox tuning during solvent thermolysis can generate potent theranostic agents through selective phase control in ferrites and can be extended to other transition metal oxides relevant to memory and electrochemical storage devices.