Highly sensitive iron oxide nanoparticles with stable, safe and efficient surface functionalization, as potential substitutes for gadolinium-based contrast agents (GBCAs) with increasing biosafety concerns, exhibit great potential for high-performance magnetic resonance angiography (MRA). Herein, we developed ultrasmall catechol-PEG-anchored ferrite nanoparticles (PEG-UMFNPs) for highly sensitive MRA. The obtained nanoprobe has a high T₁ relaxivity value (7.2 mM⁻¹ s⁻¹) due to its ultrasmall size and Mn doping. It has a suitable hydrodynamic size of 20 nm, which prevents rapid vascular extravasation and renal clearance and prolongs its blood circulation time. In vivo MRA at 3.0 T using the nanoprobe shows that the arteries and veins of rats, even blood vessels as small as 0.32 mm, are distinctly visible, and the contrast enhancement can last for at least 1 h. In addition, due to the outstanding contrast enhancement and long circulation time, the stenosis and recanalization process of the rat’s carotid artery can be continuously monitored with a single injection of the nanoprobe. Our study indicates that PEG-UMFNPs are outstanding MR imaging nanoprobes that can be used to diagnose vascular diseases without the biosafety issues of GBCAs.

中文翻译：

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用于高灵敏度磁共振血管造影的超小儿茶酚-PEG-锚定铁氧体纳米颗粒

具有稳定、安全和高效表面功能化的高灵敏度氧化铁纳米粒子，作为生物安全性日益受到关注的钆基造影剂（GBCA）的潜在替代品，在高性能磁共振血管造影（MRA）方面表现出巨大的潜力。在此，我们开发了用于高灵敏度 MRA 的超小型儿茶酚-PEG 锚定铁氧体纳米颗粒 (PEG-UMFNP)。所获得的纳米探针由于其超小尺寸和Mn掺杂而具有高T ₁弛豫率值（7.2 mM ^-1 s ^-1 ）。它具有合适的流体动力学尺寸20 nm，可防止快速血管外渗和肾脏清除，延长其血液循环时间。使用纳米探针在3.0 T的体内MRA显示，大鼠的动脉和静脉，甚至小至0.32 mm的血管都清晰可见，并且对比度增强可持续至少1小时。此外，由于显着的对比度增强和较长的循环时间，只需单次注射纳米探针即可连续监测大鼠颈动脉的狭窄和再通过程。我们的研究表明，PEG-UMFNP 是出色的 MR 成像纳米探针，可用于诊断血管疾病，而不会出现 GBCA 的生物安全问题。