钆纳米对比剂的研制及其与小分子对比剂钆喷酸葡胺的磁共振成像性能对比

Preparation of Gadolinium Nano-Contrast Agent and Comparison of Magnetic Resonance Imaging Performance with Small Molecule Contrast Agents

目的通过简单易行的方法制备高性能钆掺杂碳纳米点(Gd-CDs),通过与临床使用的钆喷酸葡胺对比剂作对比,探讨Gd-CDs作为新型MR对比剂的可行性。方法以精氨酸和钆喷酸葡胺为原料,在200℃反应1.5 h,一步无溶剂法合成Gd-CDs。对Gd-CDs的粒径、形貌、组分和稳定性进行表征分析;通过MTS法测得不同浓度Gd-CDs对786-O肾癌细胞以及HK-2肾小管上皮细胞毒性;以Gd-CDs为实验组,钆喷酸葡胺为对照组,进行T1弛豫效率、小鼠MR成像和体内分布特性对比分析。通过检测注射后不同时间点小鼠血液的MR信号,计算对比剂的血液半衰期。通过血生化和组织病理进行毒性分析。采用单因素方差分析和两样本t检验进行数据分析。结果制得的Gd-CDs水溶性好,粒径均一,平均尺寸为5.38 nm。Gd-CDs可明显缩短T1弛豫时间,在T_(1)WI中产生阳性高信号,T1弛豫效率为6.26 mM^(-1)s^(-1),高于钆喷酸葡胺(4.49 mM^(-1)s^(-1))。在常温下放置1个月及在较宽的pH值(pH=4~10)范围内,其MR成像性能仍相对稳定。小鼠MR成像显示,相同条件下Gd-CDs较钆喷酸葡胺产生更强的对比增强(P>0.05),增强效果至少持续6 h,血液半衰期是钆喷酸葡胺的3.2倍。纳米粒子在肌肉、心、肝和脑等主要器官中几乎无积累,经泌尿系统排泄,在成像所用的浓度下对细胞及组织无明显毒性。结论通过无溶剂绿色合成方法得到Gd-CDs,性能稳定,生物相容性好,T1弛豫效率和MR成像效果优于钆喷酸葡胺,有望成为新型MR分子探针载体。

Objective Constructing of high performance gadolinium-doped carbon nanodots(Gd-CDs)by a simple method and evaluate the feasibility of Gd-CDs as a new magnetic resonance(MR)contrast agent by comparing with the clinically used Magnevist.Methods Gd-CDs were synthesized by a facile and general strategy using one-step direct solvent-free reaction by carbonization of arginine and gadolinium dideoximelate at 200℃ for 1.5 h.The particle size,morphology,surface chemical properties and stability of Gd-CDs are characterized.The cytotoxicity of Gd-CDs toward 786-O kidney cancer cells and HK-2 tubular epithelial cells was performed by the conventional MTS assay.The T_(1)relaxation efficiency,MR imaging and in vivo distribution of Gd-CDs and Magnevist were compared.The blood half-life times were calculated by measuring MR signals of blood of mice at different time post-injection.In vivo toxicity was analyzed by blood biochemistry and histopathology.One-way analysis of variance and two-sample t test were used for data analysis.Results The prepared water soluble Gd-CDs had uniform size with average size of 5.38 nm.MR imaging results showed that Gd-CDs can significantly shorten the T_(1)relaxation time and enhance the T_(1)WI image signal.The T_(1)relaxivity was found to be 6.26±0.26 mM^(-1)s^(-1),which was higher than Magnevist(4.49 mM^(-1)s^(-1)).The MR imaging performance of Gd-CDs remained relatively stable at room temperature for one month and in solutions with a wide pH value(4-10).In vivo MR imaging showed that Gd-CDs produced stronger contrast enhancement than Magnevist under the same conditions(P>0.05),and the enhancement effect lasted at least 6 hours.The blood half-life of Gd-CDs was 3.2 times that of Magnevist.There was little accumulation of nanoparticles in major organs such as muscle,heart,liver and brain.They are excreted through the urinary system and have no obvious toxicity to cells and tissues at the concentration used for imaging.Conclusions Gd-CDs obtained by a solvent-free green synthesis method exhibited stable performance,good biocompatibility,higher T_(1)relaxation efficiency and better MRI imaging effect than Magnevist,and is expected to serve as a new MR molecular probe carrier.