Magnetic nanoparticles development is an intense subject in various biomedical applications. Among these applications, magnetic nanoparticles as contrast agents are of special interest for improving the diagnostic accuracy of magnetic resonance imaging (MRI). We report here the synthesis of magnetic iron carbide nanoparticles and their stabilization in aqueous media. The challenge of achieving phase transfer of hydrophobic iron carbide nanoparticles to hydrophilic media was addressed by silica shell. Silica coated iron carbide nanoparticles were fabricated with both mesoporous and dense silica shells followed by investigating the impact of such a coating on their performance as T₂‐negative contrast agents in MRI. The crystalline structure of silica coated iron carbide nanoparticles was confirmed via X‐ray diffraction (XRD) analysis. Fourier transform infrared spectroscopy (FTIR) demonstrated formation of the silica coating and transmission electron microscopy (TEM) confirmed the core@shell morphology of silica coated iron carbide nanoparticles. Mesoporous and dense silica coated iron carbide nanoparticles exhibited high transverse relaxivity values of 457 and 365 mM⁻¹s⁻¹, respectively. The enhanced MRI efficiency obtained from the silica coated iron carbide nanoparticles highlights these core@shell structures as promising negative contrast agents. Based on the results, the nature of silica coating both in porous or dense forms has a significant effect on water relaxivity which makes the iron carbide@mesoporous silica nanoparticles highly efficient T₂ contrast agents.

中文翻译：

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T2加权磁共振成像中二氧化硅涂层对碳化铁纳米颗粒对比度增强的多孔与致密效应

磁性纳米粒子的开发是各种生物医学应用中的一个热门课题。在这些应用中，磁性纳米粒子作为造影剂对于提高磁共振成像（MRI）的诊断准确性特别重要。我们在这里报告磁性碳化铁纳米粒子的合成及其在水性介质中的稳定性。二氧化硅壳解决了实现疏水性碳化铁纳米颗粒向亲水介质的相转移的挑战。用中孔和致密的二氧化硅壳制造二氧化硅涂层的碳化铁纳米颗粒，然后研究这种涂层对其T ₂性能的影响MRI中的阴性造影剂。通过X射线衍射（XRD）分析确认了二氧化硅包覆的碳化铁纳米颗粒的晶体结构。傅里叶变换红外光谱（FTIR）证明了二氧化硅涂层的形成，而透射电子显微镜（TEM）证实了二氧化硅涂层的碳化铁纳米颗粒的核壳结构。介孔且致密的二氧化硅包覆的碳化铁纳米颗粒表现出较高的横向弛豫值，分别为457和365 mM ^-1 s ^-1， 分别。从二氧化硅涂层的碳化铁纳米颗粒获得的增强的MRI效率突显了这些核壳结构作为有希望的负对比剂。基于该结果，多孔或致密形式的二氧化硅涂层的性质对水弛豫性具有显着影响，这使碳化铁@介孔二氧化硅纳米颗粒成为高效的T ₂造影剂。