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Chemie

在EOB-DTPA和镓（三）复杂的调查其<sup> 68</sup>嘎放射性标记模拟

Published: August 17, 2016
doi:
10.3791/54334
, , ,
1Clinic of Nuclear Medicine,University Hospital Jena, 2Friedrich Schiller University

Summary

一种用于EOB-DTPA的分离和随后的络合天然镓（III）和68镓是本文中所呈现，以及所有化合物和调查上标记效率的透彻分析，体外稳定性和辛醇 /水过程放射性标记的复杂分配系数。

Abstract

我们证明为EOB-DTPA（3,6,9-三氮杂-3,6,9-三（羧甲基）-4-（乙氧基苄基）-undecanedioic酸）从其钆（III）络合物和协议的分离方法制备其的新的非放射性的， 即天然镓（Ⅲ），以及放射性68镓络合物。通过核磁共振（NMR）谱，质谱和元素分析复杂的配位体以及作为Ga（III）进行了表征。68嘎通过标准洗脱法从68锗/ 68 Ga产生获得。实验，以评估在pH值进行3.8-4.0 EOB-DTPA的68嘎标记效率。建立的分析技术无线电TLC（薄层色谱法）和无线电HPLC（高效液相色谱法）来测定示踪剂的放射化学纯度。由于68嘎示踪剂'亲脂性正辛醇/水分布的第一个调查的存在于pH为7.4的溶液68镓物种n个系数是由萃取法在体外在生理pH下在各种媒体示踪剂的稳定性的测量进行测定。，揭示分解的不同的费率。

Introduction

Gadoxetic酸，对配体的钆（III）络合物的EOB-DTPA 1的通用名称，是在肝胆磁共振成像（MRI）。2,3-一个常用的造影剂由于其特异性摄取由肝细胞和高百分比肝胆排泄它使局灶性病变和肝脏肿瘤的本地化。2-5然而，MRI技术有一定的局限性（如造影剂毒性，患者的幽闭恐惧症或金属植入物的应用受到限制）调用的替代诊断工具。

正电子发射断层扫描（PET）是一种分子成像方法，其中，一种放射性物质（示踪）的少量施用，在其它在体内的分布由PET扫描器记录6 PET是一种动态的方法，其允许高图像的空间和时间分辨率以及结果的量化，而无需处理MRI造影剂的副作用。所获得的代谢信息的信息值可与来自其他成像方法接收解剖数据进一步增加组合，最通常通过在PET / CT扫描仪计算机断层扫描（CT）的混合成像实现的。

适用于PET示踪剂的化学结构必须包括用作正电子发射放射性同位素。正电子有一个短暂的寿命，因为它们几乎立即消灭与周围组织的原子炮弹电子。通过湮灭与运动的相反方向的两个511keV的伽玛光子发射，这是由PET扫描器记录。-7,8-为了形成示踪剂，PET的核素可以共价结合到分子，如在2-脱氧的情况下2- [18 F] fluoroglucose葡萄糖（FDG），是最广泛使用的PET示踪剂。7然而，核素也可以形成配位键合到一个或多个配体（ 如[68镓] -DOTATOC 9,10）或溶解无机盐）施加（ 例如，[18 F]氟化物钠11。总而言之，示踪剂的结构是至关重要的，因为它决定了它的生物分布，代谢和排泄行为。

合适的PET核素应该结合像便利正电子的能量和可用性，以及半衰期足够预期调查有利特征。 68镓核素已成为PET的字段的必要的力，在过去的二十年。12,13这主要是由于通过一个发电机系统其可用性，它独立地允许在现场标签从回旋加速器的附近。在一台发电机，母核素68戈被吸收在从该子体核素68镓洗脱，随后标记，以一个合适的螯合剂的一列。6,14由于68镓核素的存在是为繁琐耳鼻喉科阳离子就像钆（III）10,13，螯合EOB-DTPA 68嘎，而不是将产生复杂的具有相同的整体负电荷的gadoxetic酸。相应地，68镓示踪剂可能与适宜用于PET成像合并相似的特性肝特异性。虽然gadoxetic酸购买并施用二钠盐，在下面的上下文中，我们将称其为钆〔EOB-DTPA]和非放射性镓（Ⅲ）配合物作为镓[EOB-DTPA]，或68镓[ EOB-DTPA]为方便起见放射性标记组分的情况下。

要用作PET示踪剂，放射性金属配合物需要被广泛地在体外第一检查，在体内或离体实验评估其适用性。要确定相应的医学难题的适用性，各种示踪特征，如生物分布行为和清除轮廓，稳定性，器官特异性和细胞或Tissu酒店Ë摄取需要进行调查。由于它们的非侵入性的性质， 在体外测定常常之前在体内实验进行。人们普遍承认，DTPA及其衍生物是有限的适用性如由于这些配合螯合剂为68镓缺乏动力学惰性，导致同等快速分解的，当体内施用。14-20这主要是通过充当载脂蛋白转引起竞争对手68嘎血浆。然而，我们研究了关于在肝胆成像，其特征在于，可在数分钟内提供诊断信息后注入3,4,21-23，从而不一定需要长期示踪剂稳定性及其可能的应用这种新的示踪剂。为此目的，我们从gadoxetic酸分离EOB-DTPA和最初与天然镓（Ⅲ），它存在两个稳定同位素，69 Ga和71的混合物进行的络合</SUP>嘎。由此获得的复杂的担任非放射性标准68的Ga以下螯合。我们采用建立的方法，同时评估其是否适合确定EOB-DTPA的68 Galabeling效率，并探讨新的68嘎示踪剂的亲脂性及其在不同介质中的稳定性。

Protocol

1. EOB-DTPA和Ga的制备EOB-DTPA] 注意：使用前请先咨询的使用有机溶剂，耐酸，耐碱所有相关的材料安全数据表（MSDS）。执行所有步骤，在通风橱中，并使用个人防护用品（防护眼镜，手套，实验室外套）。 从gadoxetic酸EOB-DTPA的分离 花费3毫升0.25M的gadoxetic酸注射溶液到烧瓶中。草酸的500毫克（5.6毫摩尔）添加到搅拌的溶液中。 搅拌1小时后，通过使用减压玻璃?…

Representative Results

该配体EOB-DTPA和非放射性镓（III）络合物通过 1 H和13 C {1 1 H} NMR谱，质谱和元素分析进行分析。 表1中列出并描绘在图1-6的结果证实了物质的纯度。 68锗/ 68镓发生器洗脱，得到400-600活度68嘎的解决方案。在所需的示踪剂68镓[EOB-DTPA]形成所?…

Discussion

EOB-DTPA是通过多步骤合成33访问，但可能只是以及由含有gadoxetic酸可用的造影剂中分离。为了这个目的，中央的Gd（III）离子可以与过量草酸的沉淀。除去钆（Ⅲ）草酸盐和草酸后的配位体可以通过沉淀在冷水中，在pH 1.5分离。然而，为了增强滤液产量柱色谱可以代替或作为后续程序执行的。任一方法产生的70％的总产率的分析纯的配体（ 图1-3， 表1）。

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Offenlegungen

The authors have nothing to disclose.

Acknowledgements

The authors have no acknowledgements.

Materials

primovist Bayer – 0.25 M
gallium(III) chloride Sigma-Aldrich Co. 450898
water (deionized) – –  tap water deionizing equipment by Auma-Tec GmbH
hydrochloric acid 12 M VWR 20252.29
sodium hydroxide Polskie Odczynniki Chemiczne S.A. 810925429
oxalic acid Sigma-Aldrich Co. 75688
ethyl acetate Brenntag GmbH 10010447
silica gel Merck KGaA 1.10832.9025 Geduran Si 60 0,063-0,2 mm
TLC silica gel 60 F254 Merck KGaA 1.16834.0001
methanol VWR 20903.55
ethanol Brenntag GmbH 10018366
eiethylether VWR 23807.468 stored over KOH plates
ammonia solution (25 %) VWR 1133.1
pH electrode VWR 662-1657
stirring and heating unit Heidolph 505-20000-00
pump Ilmvac GmbH 322002
frit – custom design
NMR spectrometer Bruker Coorporation – Ultra Shield 400
mass spectrometer Thermo Fisher Scientific Inc. –
elemental analyser Hekatech GmbH Analysentechnik – EuroVector EA 3000 CHNS
deuterated water D2O euriso-top D214 99,90 % D
Name Company Catalog Number Comments
Material/Equipment required for labeling procedures
68Ge/68Ga generator ITG Isotope Technologies Garching GmbH A150
pump and dispenser system Scintomics GmbH – Variosystem
hydrochloric acid 30 % (suprapur) Merck KGaA 1.00318.1000
water (ultrapur) Merck KGaA 1.01262.1000
sodium chloride (suprapur) Merck KGaA 1.06406.0500
sodium acetate (suprapur) Merck KGaA 1.06264.0050
glacial acetic acid (suprapur) Merck KGaA 1.00066.0250
sodium citrate dihydrate VEB Laborchemie Apolda 10782 >98.5%
PS-H+ Cartridge (S) Macherey-Nagel 731867 Chromafix
apo-Transferrin Sigma-Aldrich Co. T2036
PBS  buffer (tablets) Sigma-Aldrich Co. 79382
human serum Sigma-Aldrich Co. H4522 from human male AB plasma
flasks, columns etc. custom design
pH electrode Knick Elektronische Messgeräte GmbH & Co. KG 765-Set
binary pump (HPLC) Hewlett-Packard G1312A (HP 1100)
UV Vis detector (HPLC) Hewlett-Packard G1315A (HP 1100)
radioactive detector (HPLC) EGRC Berthold
HPLC C-18-PFP column Advanced Chromatography Technologies Ltd. ACE-1110-1503/A100528
HPLC glass vials GTG Glastechnik Graefenroda GmbH 8004-HP-H/i3µ
pipette Eppendorf –
plastic vials Sarstedt AG & Co. 6542.007
plastic vials Greiner Bio-One International GmbH 717201
activimeter MED Nuklear-Medizintechnik Dresden GmbH – Isomed 2010
tweezers custom design
incubator Heraeus Instruments GmbH 51008815
vortex mixer Fisons – Whirlimixer
centrifuge Heraeus Instruments GmbH 75003360
gamma well counter MED Nuklear-Medizintechnik Dresden GmbH – Isomed 2100
water for chromatography Merck KGaA 1.15333.2500
acetonitrile for chromatography Merck KGaA 1.00030.2500
trifluoroacetic acid Sigma-Aldrich 91707
TLC radioactivity scanner raytest Isotopenmessgeräte GmbH B00003875 equipped with beta plastic detector
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Tags

Keywords: Ga(III) ComplexEOB-DTPA68Ga RadiolabelingGallium-68 Tracer ChemistryLabeling ConditionsTracer StabilityLipophilicityGadoxetic AcidOxalic AcidHydrochloric AcidSodium HydroxideGallium TrichlorideAmmoniaAmmonium ChloridePSH Plus CartridgeSilica Column Generator
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Greiser, J., Niksch, T., Weigand, W., Freesmeyer, M. Investigations on the Ga(III) Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue. J. Vis. Exp. (114), e54334, doi:10.3791/54334 (2016).
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