College of Basic Medical Sciences, Chongqing Medical University, Chongqing 400016, China.
Functional Magnetic Resonance and Molecular Imaging Key Laboratory of Henan Province, Department of Magnetic Resonance Imaging, First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou 450001, China.
J Colloid Interface Sci. 2022 Nov 15;626:364-373. doi: 10.1016/j.jcis.2022.06.118. Epub 2022 Jun 27.
Doping Mn (II) ions into iron oxide (IO) as manganese ferrite (MnIO) has been proved to be an effective strategy to improve T relaxivity of IO nanoparticle in recent years; however, the high T relaxivity of MnIO nanoparticle hampers its T contrast efficiency and remains a hurdle when developing contrast agent for early and accurate diagnosis. Herein, we engineered the interfacial structure of IO nanoparticle coated with manganese ferrite shell (IO@MnIO) with tunable thicknesses. The Mn-doped shell significantly improve the T contrast of IO nanoparticle, especially with the thickness of ∼0.8 nm. Compared to pristine IO nanoparticle, IO@MnIO nanoparticle with thickness of ∼0.8 nm exhibits nearly 2 times higher T relaxivity of 9.1 mMs at 3 T magnetic field. Moreover, exclusive engineering the interfacial structure significantly lower the T enhancing effect caused by doped Mn (II) ions, which further limits the impairing of increased T relaxivity to T contrast imaging. IO@MnIO nanoparticles with different shell thicknesses reveal comparable T relaxation rates but obvious lower T relaxivities and r/r ratios to MnIO nanoparticles with similar sizes. The desirable T contrast endows IO@MnIO nanoparticle to provide sufficient signal difference between normal and tumor tissue in vivo. This work provides a detailed instance of interfacial engineering to improve IO-based T contrast and a new guidance for designing effective high-performance T contrast agent for early cancer diagnosis.
近年来，将锰(II)离子掺杂到氧化铁（IO）中形成锰铁氧体（MnIO）已被证明是提高 IO 纳米粒子 T1弛豫率的有效策略；然而，MnIO 纳米粒子的高 T1弛豫率会阻碍其 T1对比效率，这仍然是开发用于早期和准确诊断的对比剂的一个障碍。在此，我们通过控制具有可调厚度的锰铁氧体壳包覆的 IO 纳米粒子的界面结构来实现。掺杂的 Mn 壳显著提高了 IO 纳米粒子的 T1对比效果，尤其是厚度约为 0.8nm 时。与原始 IO 纳米粒子相比，厚度约为 0.8nm 的 IO@MnIO 纳米粒子在 3T 磁场下的 T1弛豫率提高了近 2 倍，达到 9.1mMs。此外，通过对界面结构的独特工程设计，可以显著降低掺杂 Mn(II)离子引起的 T1增强效应，从而进一步限制了因 T1弛豫率增加而对 T1对比成像造成的损害。具有不同壳层厚度的 IO@MnIO 纳米粒子具有相当的 T1弛豫率，但与具有相似尺寸的 MnIO 纳米粒子相比，其 T1弛豫率和 r/r 比值明显较低。理想的 T1对比使 IO@MnIO 纳米粒子能够在体内为正常组织和肿瘤组织之间提供足够的信号差异。这项工作提供了一个详细的界面工程实例，用于提高基于 IO 的 T1 对比，并为设计用于早期癌症诊断的有效高性能 T1 对比剂提供了新的指导。
