纳米级超声造影剂的技术进展

纳米级超声造影剂是指直径〈1000nm的超声造影剂。与微米级微泡相比,纳米造影剂粒径较小,渗透能力极强,可以通过血管内皮间隙,进行病变部位血管外显影。同时因为纳米系统具有一定的靶向能力,将纳米级造影系统与临床治疗相结合可以在肿瘤治疗方面表现出其特定的靶向治疗优势。现就纳米级超声造影剂的特征、国内外制备方法及研究前景进行总结。     

靶向超声造影的研究进展

靶向超声造影是分子影像学组成的重要部分。通过靶向微泡声学造影剂与细胞表面特异性抗体或配体结合,可以实现在体观察靶组织在组织、细胞及亚细胞水平的病理生理变化。随着对超声造影剂尤其是纳米造影剂研究的深入,靶向超声造影剂在疾病诊断及治疗中的作用越来越受到重视,本文对此作一简要综述。     

靶向超声造影剂制备的方法学研究

靶向超声造影是目前超声造影的前沿性课题，随着超声造影剂在临床的不断应用与实践，使得超声诊断学与治疗学发生了跳跃式的前进。靶向超声造影技术通过靶向作用于生物分子组成成分来突出显示病变组织的病变部位，从而提高影像诊断的准确性与敏感性，因此靶向超声造影剂成为现今研究领域的热点。然而，要想设计生产靶向超声造影剂能够按照预定的靶向至病变部位，且能流经循环系统后依然保持其特有的稳定性，故要求研究靶向超声造影剂的学者不断在基础研究与方法学上改进。现就靶向超声造影剂的方法学方面作一综述。     

靶向超声造影成像的研究进展

靶向超声造影成像是一门新兴的将超声造影技术与靶向超声微泡造影剂相结合,对体内组织器官微观病变进行分子水平探测与成像的方法.靶向超声造影是目前超声造影的前沿性课题,随着超声造影剂在临床的不断应用与实践,使得超声诊断学与治疗学发生了跳跃式的前进.     

靶向超声造影剂在制备领域中的研究进展

随着超声造影技术的飞越发展,靶向超声分子成像技术逐渐成为可能,而作为其核心的靶向超声造影剂也越来越受研究者的关注.靶向超声造影剂种类较多,且制备方法不一,本文阐述了靶向超声造影剂的分类,对其制备领域的研究现状及未来面临的挑战做一综述.     

载自杀基因的靶向超声分子探针的制备及超声显像的实验研究

目的:制备一种包裹液态氟碳，载肝癌治疗基因质粒，并具有叶酸分子靶向性的纳米级超声分子探针, 研究其基本特性及超声显像能力? 方法:通过聚乙二醇亚胺在PLGA表面连接叶酸（Fa）分子，制成靶向膜材料(PLGA-Fa)后,采用双乳化法制备载有PFP的纳米级靶向超声造影剂，将其与多聚赖氨酸孵育后，形成表面带正电荷的阳离子，利用正负电荷吸附作用，使纳米粒表面载上质粒C（PLGA-Fa-PFP-C）。 分别用加热及LIFU辐照的方式处理纳米粒，于显微镜下观察其相变情况，于超声造影模式下观察其体外显影效果。另同样用双乳法制备无叶酸的非靶向造影剂，将两者分别与肝癌细胞HepG2孵育，观察其寻靶能力。 结果: 成功制备了载有质粒、PFP的纳米级靶向超声造影剂(Fa-PLGA/PFP/C)，该纳米微粒大小均匀,形态圆整,分散性好，直径分布为200.5nm，平均电位为+37MV,当加热至50度时及用LIFU5档辐照后5分钟后，显微镜下可见较多的纳米粒相变，超声造影模式下亦可见显像;并在细胞实验中观察到该靶向造影剂有明显的靶向作用。 结论:本研究成功制备了一种载质粒及PFP的纳米级靶向超声造影剂(Fa-PLGA/PFP/C)，该纳米粒可用于超声造影显像，并具有肿瘤靶向性。     

靶向超声造影剂在心血管疾病应用中的研究进展

随着新型靶向超声造影剂的不断研制和超声造影技术的不断发展,对病变组织的超声靶向分子显影和治疗成为可能。本文阐述了靶向超声造影剂的组成、理化特性及制备方式,对其在心血管疾病诊断和治疗中的应用做一综述。     

载自杀基因靶向超声分子探针制备及其超声显像的实验研究

目的制备一种包裹液态氟碳及载肝癌治疗基因质粒,并具有叶酸分子靶向性的纳米级超声分子探针,研究其基本特性及超声显像能力。方法通过碳乙亚胺法在聚乳酸-羟基乙酸共聚物(PLGA)表面连接叶酸分子,制成靶向膜材料(FA-PLGA)后,采用双乳化法制备载有全氟戊烷(PFP)的纳米级靶向超声造影剂,将其与多聚赖氨酸孵育后,形成表面带正电荷的阳离子,利用正负电荷吸附作用,使纳米粒表面载上目标质粒S-HSV1-TK,得到S-HSV1-TK/PFP@FA-PLGA。使用低强度聚焦超声(LIFU)辐照的方式处理纳米粒,显微镜下观察其相变情况,于超声造影模式下观察其体外显影效果,流式细胞仪检测其连靶率;用PLGA代替FA-PLGA,使用相同方法制备无叶酸的非靶向造影剂,将靶向造影剂和非靶向造影剂分别与肝癌细胞HepG2孵育,观察其体外寻靶能力。结果成功制备了载有质粒及PFP的纳米级靶向超声造影剂S-HSV1-TK/PFP@FA-PLGA,该纳米粒大小均一,分散性好,平均粒径(200.50±66.34)nm,平均表面电位(37.40±7.08)mV。使用LIFU 5档辐照5 min后,显微镜下可见较多的纳米粒相变,超声造影模式下亦可见显像。流式细胞仪检测纳米粒连靶率约95%;体外细胞实验结果显示该靶向造影剂有明显的靶向作用。结论本实验成功制备了一种载质粒及PFP的纳米级靶向超声造影剂S-HSV1-TK/PFP@FA-PLGA;该纳米粒可用于超声造影显像,并具有肿瘤靶向性,为研究质粒的转染及肿瘤的治疗奠定了良好基础。     

免疫脂质体超声造影剂增强荷肝癌裸鼠肿瘤显像的实验研究

目的探讨人肝细胞癌靶向脂质体超声造影剂对荷肝癌裸鼠肿瘤的增强显像效果。方法采用人肝癌细胞株HHCC接种于裸鼠皮下,建立荷人肝癌裸鼠模型;将靶向脂质体超声造影剂或普通脂质体超声造影剂经尾静脉注入荷瘤裸鼠体内,使用二次谐波显像模式观察并记录造影过程;采用目测观察和视频灰阶分析技术,以时间-强度曲线分析来定量评价肿瘤显像的增强效果。结果造影后目测观察,靶向造影剂对肿瘤有延迟增强显像效果,靶向造影剂组肿瘤的增强显影约在8min达到峰值,峰值灰阶强度值为(39.545±10.099)dB;普通造影剂组肿瘤增强显影达峰值时间约为10s,峰值灰阶强度值为(22.438±5.108)dB,与靶向造影剂造影后灰阶强度峰值比较相差显著(P<0.01)。结论人肝细胞癌靶向脂质体超声造影剂可以增强荷人肝癌裸鼠的肿瘤超声显像效果。     

靶向超声造影剂的制备与评价

靶向超声造影剂是将造影剂连接上特异性配体,使得这些造影剂仅与靶区相结合,从而实现特异性的造影增强.近几年,由于分子生物学及分子影像技术的迅速发展,靶向超声造影剂的研发也有了较快的进步,Klibanov[1]在这个领域做了大量的研究工作,并预测靶向超声造影剂今后将成为第三代超声造影剂的主流.     

纳米级超声造影剂的研究进展

随着超声分子成像技术和生物纳米技术的迅猛发展,近年来出现了多种纳米级超声造影剂,包括纳米级脂质体造影剂、纳米级氟烷乳剂和纳米级微泡造影剂。本文就纳米级超声造影剂的研究背景、研究现状、现存的问题及发展前景做一综述。     

超声造影剂靶向治疗肿瘤的应用发展

随着超声造影技术的不断发展,超声造影剂联合靶向载药功能在肿瘤的诊断和治疗中发挥了越来越大的作用,尤其是在肿瘤治疗方面具有巨大的潜力。     

携抗HER-2抗体PLGA高分子纳米超声造影剂的制备及其体外寻靶实验

目的以高分子聚合物聚乳酸-羟基乙酸（PLGA）为成膜材料制备携抗HER-2抗体空心纳米靶向超声造影剂,并考察其体外寻靶及显像效果。方法以樟脑为致孔剂,通过改进的双乳化溶剂挥发法制备PLGA纳米超声造影剂,利用扫描电子显微镜、透射电子显微镜及激光粒度仪对其一般特性进行表征;并用碳二亚胺法将造影剂与抗HER-2抗体耦联制备携抗HER-2抗体的PLGA靶向纳米超声造影剂,用激光共聚焦扫描显微镜对其体外寻靶能力进行初步评估,考察其体外成像效果。结果 PLGA纳米超声造影剂的平均粒径为（152.00±58.08）nm,粒子呈规则球形,大小均一,分散性好。体外寻靶实验显示,携抗HER-2抗体的PLGA靶向造影剂较多牢固地聚集到乳腺癌细胞表面。体外成像实验显示,PLGA靶向纳米超声造影剂显像呈细腻均匀的点状高回声,后方回声未见明显衰减。结论本研究成功制备了携抗HER-2抗体的PLGA靶向纳米超声造影剂,其能与HER-2受体高表达的乳腺癌细胞体外特异性靶向结合,且体外显像效果较好。     

去唾液酸糖蛋白受体介导的肝靶向纳米脂质超声造影剂的制备及体外实验

目的 以肝细胞膜特异性受体去唾液酸糖蛋白受体为靶向受体,利用共价结合的原理,制备出肝靶向性液态氟碳纳米超声造影剂,观察该造影剂的一般特性、与人肝细胞L02的靶向结合及体外聚集显像效果.方法 利用还原胺法制备去唾液酸糖蛋白特异性配体半乳糖化多聚赖氨酸(Gal-PLL);利用旋转蒸发及声振法制备液态氟碳纳米脂质超声造影剂;培养人肝细胞L02,于不同时间点观察与L02细胞的靶向结合;Philips iU 22超声诊断仪L12-5探头对比观察靶向液态氟碳纳米脂质超声造影剂的体外显像效果.结果 靶向液态氟碳纳米脂质超声造影剂粒径极小,分布均匀,形态呈圆球形,且能与L02有效结合;体外乳胶囊显示:脱气水侧呈现无回声,靶向液态氟碳纳米脂质超声造影剂侧呈现高回声.结论 以去唾液酸糖蛋白受体为靶向受体,自制的携半乳糖化多聚赖氨酸的靶向液态氟碳纳米脂质超声造影剂能有效与人肝细胞LO2靶向结合,该靶向超声造影剂能在体外聚集显影.该靶向超声造影剂粒径极小,是细胞水平上肝靶向性超声分子显像的一种理想的超声分子探针.

Abstract：

Objective To prepare the liver targeting nano-liquid perfluorocarbon ultrasound contrast agent and observe its general characteristics;to observe the targeting combined effects of the human liver cells L02 and the targeted ultrasound contrast agent ;to evaluate the gathering imaging effects of the targeted ultrasound contrast agent. Methods Amine method was used to prepared asialoglycoprotein Gal specific ligand polylysine (Gal-PLL), rotary evaporator and sonicated liquid fluorocarbon were used to prepare nano lipid ultrasound contrast agent. Human liver cell L02 were cultured, the combined effects were observed according to the reacting time of the cells and the targeted nano-lipid ultrasound contrast agent. The nanolipid ultrasound contrast agent and the degassed_ water_ were loaded into cysts and their ultrasound imaging effects were observed by ultrasound diagnostic apparatus Philips iU22. Results The particle size of the liquid fluorocarbon nano-targeted lipid ultrasound contrast agent was extremely small, uniform, cylindrical and spherical. The cysts in vitro showed that the side of the targeted liquid perfluorocarbon nano-lipid ultrasound contrast agent showed high echo. Conclusions The targeted liquid perfluorocarbon nano-lipid ultrasound contrast agent can be effectively targeted to the human liver cells L02 due to carrying home-made Gal-PLL. The targeted ultrasound contrast agents can be imaging by ultrasound and be confirmed in vitro.The size of the contrast agent was small, therefore, it can be considered an ideal ultrasonic molecular probe and achieve the ultrasound molecular imaging in cell level.     

The Gandras catheter for uterine artery embolization: The procedure-driven development of a novel medical device

Microbubble contrast media are used to enhance ultrasound images. Because ultrasound is a real‐time investigation, contrast‐enhanced ultrasound offers possibilities for perfusion imaging. This review is conducted to evaluate the safety of contrast‐enhanced ultrasound and its possible role in medical imaging. The safety of diagnostic ultrasound is still an important field of research. The wanted and unwanted effects of ultrasound and microbubble contrast media as well as the effects of ultrasound on these microbubbles are described. Furthermore, some of the possible applications and indications of contrast‐enhanced ultrasound will be discussed. The shared advantages of MRI and ultrasound are the use of non‐ionizing radiation and non‐nephrotoxic contrast media. From this review it can be concluded that, for certain indications, contrast enhanced ultrasound could be a safe alternative to MRI and a valuable addition to medical imaging.     

Ultrasound imaging and contrast agents: a safe alternative to MRI?

Microbubble contrast media are used to enhance ultrasound images. Because ultrasound is a real-time investigation, contrast-enhanced ultrasound offers possibilities for perfusion imaging. This review is conducted to evaluate the safety of contrast-enhanced ultrasound and its possible role in medical imaging. The safety of diagnostic ultrasound is still an important field of research. The wanted and unwanted effects of ultrasound and microbubble contrast media as well as the effects of ultrasound on these microbubbles are described. Furthermore, some of the possible applications and indications of contrast-enhanced ultrasound will be discussed. The shared advantages of MRI and ultrasound are the use of non-ionizing radiation and non-nephrotoxic contrast media. From this review it can be concluded that, for certain indications, contrast enhanced ultrasound could be a safe alternative to MRI and a valuable addition to medical imaging.     

Toward Ultrasound Molecular Imaging With Phase-Change Contrast Agents: An In Vitro Proof of Principle

Phase-change contrast agents (PCCAs), which normally consist of nanoscale or microscale droplets of liquid perfluorocarbons in an encapsulating shell, can be triggered to undergo a phase transition to the highly echogenic gaseous state upon the input of sufficient acoustic energy. As a result of the subsequent volumetric expansion, a number of unique applications have emerged that are not possible with traditional ultrasound microbubble contrast agents. Although many studies have explored the therapeutic aspects of the PCCA platform, few have examined the potential of PCCAs for molecular imaging purposes. In this study, we demonstrate a PCCA-based platform for molecular imaging using α_vβ₃-targeted nanoscale PCCAs composed of low-boiling-point perfluorocarbons. In vitro, nanoscale PCCAs adhered to target cells, could be activated and imaged with a clinical ultrasound system and produced a six-fold increase in image contrast compared with non-targeted control PCCAs and a greater than fifty-fold increase over baseline. Data suggest that low-boiling-point nanoscale PCCAs could enable future ultrasound-based molecular imaging techniques in both the vascular and extravascular spaces.     

液态氟碳造影剂——一种极具潜力的靶向超声造影剂

靶向超声造影剂是超声分子显像的重要物质基础。本文就液态氟碳造影剂作为靶向超声造影剂的优势及其在超声分子显像领域的应用和展望作一综述。