The financial support of the Max-Planck Society, the Turkish Ministry of National Education (PhD fellowship to S. G.), and the German Exchange Academic Service (DAAD, PhD fellowship to T. S.) are gratefully acknowledged.

1. DCA的制备<ol><li> 单体单元4 6的合成。 <ol><li> 4-（4-硝基苯基）-2-（4,7,10-三- 叔丁氧基羰基环十二烷-1,4,7,10-四氮杂-1-基）丁酸叔丁基酯（2）。 <ol><li>溶解（4,7-双- 叔丁氧基羰基- 1,4,7,10-四氮杂cyclododec -1-基）在N -乙酸叔丁基酯1（1.00克，1.94毫摩尔），N-二甲基甲（ DMF，5ml）中，加入碳酸钾（0.67克，4.86毫摩尔，2.5当量）和在室温下搅拌45分钟该混合物。 注:大环1从CYCLEN制备和叔根据先前公布的程序7 -丁基溴。 </li><li>添加叔丁基-2-溴-4-（4-硝基苯基）丁酸甲酯（0.87克，2.53毫摩尔，1.3当量）分批1小时。继续下ŧ搅拌混合物他相同的反应条件下18小时。 注: 叔丁基-2-溴-4-（4-硝基苯基）丁酸根据先前公布的程序8由4-（4-硝基苯基） -丁酸，亚硫酰氯和溴制备。 </li><li>通过球对球真空蒸馏的手段在40-60℃9除去DMF。 </li><li>将该残余物通过柱色谱法（硅胶，7％甲醇/二氯甲烷），得到产物2，为棕色无定形固体（1.09克，72％）10。 </li></ol></li><li> 4-（4-氨基苯基）-2-（4,7,10-三- 叔丁氧基羰基环十二烷-1,4,7,10-四氮杂-1-基）丁酸叔丁基酯（3）。 <ol><li>溶解硝基苯衍生物2（1.00克，1.28毫摩尔）在乙醇（10毫升）和甲醇（150微升）的7N氨溶液。活性炭上添加钯作为催化剂（钯/炭，150毫克，15重量％）至soluti上。 </li><li>摇在帕尔氢化装置中在氢气氛（2.5巴）下16小时的非均相混合物。 </li><li>通过它在乙醇中悬浮，并通过烧结的玻璃漏斗过滤该悬浮液制备硅藻土饼。倾从1.1.2.2悬浮在所制备的滤饼通过过滤除去Pd / C催化剂。 </li><li>在旋转蒸发器（水浴温度〜40℃）除去通过温和蒸馏溶剂，得到化合物3，为棕色无定形固体（0.91克，95％）。 </li></ol></li><li>的4-（4-异硫氰基）合成-2-（4,7,10-三- 叔丁氧基羰基- 1,4,7,10-四氮杂-1-基）丁酸叔丁基酯（4）。 <ol><li> （0.124毫升，1.58毫摩尔，1.3当量）加入二氯硫化碳为3的三乙胺的混合物（0.91克，1.22毫摩尔）和（0.685毫升，4.87毫摩尔，4当量）的二氯甲烷（15毫升）中。 </li><li>大力搅拌反应英里在室温下用磁力搅拌器16小时夹具。 </li><li>在旋转蒸发器（水浴温度〜40℃）除去通过温和蒸馏出溶剂，然后纯化通过柱色谱法（硅胶，5％甲醇/二氯甲烷）粗产物，得到产物4，为浅棕色无定形固体（0.51克，53％）。 </li></ol></li></ol></li><li> 树枝状DCA的合成。 <ol><li>树枝状聚合物5的合成。 <ol><li>取G4-PAMAM树枝状聚合物（667毫克，在甲醇中10％的树枝状聚合物的溶液，4.67微摩尔），蒸发通过温和蒸馏甲醇用旋转蒸发器（水浴温度〜40℃），并溶解于DMF，残余物（4毫升）中。 </li><li>添加三乙胺（0.105毫升，0.75毫摩尔，160当量），在60℃下搅拌45分钟，并添加异硫氰酸酯4（354毫克，0.45毫摩尔，1.5当量相对于树枝状聚合物的氨基表面基团）分批OVE，R 1小时。 </li><li>搅拌用磁力搅拌器将反应混合物在45℃下48小时。 </li><li>在40-60℃除去的球对球真空蒸馏装置中的溶剂。 </li><li>净化用亲脂性凝胶过滤介质和甲醇作为洗脱剂通过大小排阻层析残余物。收拾列中，不施加压力溶胀该过滤介质在甲醇中在室温下（&gt;4毫升每1g粉末的甲醇）至少3小时。通过收集1毫升分数进行重力分离。 </li><li>分析用薄层色谱（TLC）所收集的级分。开发在15％甲醇/二氯甲烷的TLC板（仅位于基线时的最极性点是从树枝状产物衍生）。蒸发在旋转蒸发器（水浴温度〜40℃）通过温和蒸馏收集到的馏分，得到产物5（270毫克，91％）。 </li></ol></li><li>树枝状聚合物的合成<strong&gt; 6。 <ol><li>溶解在甲酸（5毫升）中的受保护的树枝状螯合剂5（270毫克，4.23微摩尔），搅拌在60℃下该混合物24小时。 </li><li>蒸发在旋转蒸发（约15毫巴的压力，水浴温度〜40℃）通过蒸馏甲酸并冷冻干燥该产物，得到6-（压力〜0.2毫巴）9。 </li></ol></li><li>所述树枝状造影剂的合成（DCA） <ol><li>溶解在水中的树枝状螯合剂6（4.35微摩尔）和将pH调节至7.0与0.1M氢氧化钠。 </li><li>溶解GdCl 3·6H 2 O（113毫克，304微摩尔）的水（1毫升）中，并添加其滴加至螯合剂6的历时4小时的溶液;保持与氢氧化钠水溶液（0.05M），通过测量pH值用pH计的pH值在7.0。 </li><li>搅拌在室温吨磁力搅拌器将混合物emperature 24小时。 </li><li>乙二胺四乙酸（EDTA，158毫克，426微摩尔）的溶液中分批添加经4小时以除去过量的Gd（III），同时保持与氢氧化钠水溶液（0.05M）pH在7.0。在室温下搅拌该混合物24小时。 </li><li>执行大小排阻层析以除去大部分GdEDTA的和过量的EDTA。在使用水溶胀亲水凝胶过滤介质收拾列。混合物降低至合适的体积，并装载柱。洗脱用离子交换水列不施加压力。 </li><li>使用3 kDa的离心过滤单元30分钟，在离心力1800 XG删除GdEDTA和EDTA的残留离心机样品。重复此步骤（左右五次）直到滤液显示不存在EDTA和GdEDTA的。将样品转移到一个烧瓶中，蒸发，然后冷冻干燥该溶剂，得到灰白色产物作为最终的DCA（186毫克，71％）。 注:ESI-MS的方法检查没有EDTA和GdEDTA的。 </li><li>确认没有钆（III）的作为使用二甲酚橙测试一个自由离子。溶解在醋酸盐缓冲液（pH 5.8），滤液（0.5毫升）中。添加二甲酚橙溶液几滴和跟踪变色（黄色或紫色表明不存在或游离钆（Ⅲ）分别离子在溶液中，存在）11。 </li></ol></li></ol></li></ol> 2.树枝状产品在体外表征<ol><li> 联接到PAMAM树枝状聚合物（具有DOTA状的大环化合物的树枝状聚合物的载量）大环DOTA-单元的数目的估计 <ol><li>估计用1 H-NMR（核磁共振-核磁共振光谱）。 注意:此过程有可能在树枝状5和6，但不是在DCA。 <ol><li>记录1 H NMR谱12。 </li><li>整合芳香族区和两个单独的脂族区（1脂族树枝状聚合物和大环的质子的信号; 2。第t -Bu基的信号）为树枝状聚合物5和6或只是一个脂族区域，分别。 注意:没有单独的信号中的脂族区来自第t -Bu组树枝状6，因为它们已被水解。 </li><li>运用EQ。 1或公式。 2来估计大环单元（n），其中R =积分的比值的数量（脂族/在等式1或脂族-树枝状芳香族/脂肪- 叔卜在公式2），H DEND =质子数在树枝状聚合物， 高度 的Ar =芳族质子的数量，H t中 BU =质子在叔 -Bu组的数量，和H MAC =在一个大环的质子数。 注意:无论是公式。 1或公式。 2 FO可以使用ř树枝状5，而只有等式1可用于树枝状聚合物6。由于可交换质子（在胺，酰胺，硫脲，或羧酸盐）通常被用氘取代，他们没有在计算假定。这里，H DEND = 1128（5）或1000（6），H 氩 = 4，和H MAC = 27被使用。 <img alt="式（1）" src="/files/ftp_upload/54776/54776eq1.jpg" /> （1） <img alt="公式（2）" src="/files/ftp_upload/54776/54776eq2.jpg" /> （2） </li></ol></li><li>通过使用氮气的比率为硫从元素分析估计。 <ol><li>执行对固体样品枝（DCA在此工作）的元素分析。 </li><li>运用EQ。 3估计大环单元（n），其中R =测定％N和％S，N DEND或S DEND的比例数=数氮或树枝状聚合物中的硫原子，和N MAC或S MAC =氮或硫原子的一个大环单元的数目。 注意:因子2.29是从硫和氮的原子质量的比获得。在这项工作中，N- DEND = 250，S DEND = 2，N MAC = 5和S MAC = 1被使用。 <img alt="公式3" src="/files/ftp_upload/54776/54776eq3.jpg" /> （3） </li></ol></li><li>估计用的飞行基质辅助激光解吸/电离飞行时间（MALDI-TOF）。 <ol><li>执行MALDI-TOF MS分析13。 </li><li>计算大环单元（n）的根据式的数目。 4，其中M Z =所观察到的质量（M / Z）中，z =电荷的物种中，M DEND =树枝状部分的质量，以及M MAC =一个大环单元的质量。 没有TE:M = DEND 14,306和M MAC = 719在这项工作中使用。 <img alt="公式4" src="/files/ftp_upload/54776/54776eq4.jpg" /> （4） </li></ol></li></ol></li><li> DCA浓度（[DCA]）的测定:散装磁化率测量（BMS） <ol><li>在一个塑料瓶中管（[DCA]〜5-10毫摩尔）溶解在水（360微升）的DCA（5-10毫克）。 注:[DCA]应在5-10毫的范围，以避免叔丁醇共振的可能的重叠在样品浓度&gt; 15毫米，与水的谐振在δ= 4.7 ppm的。 </li><li>添加60微升D 2 O中的: 叔丁醇混合物（2:1体积/体积）至DCA的水溶液，并使用涡旋混合器将所得的溶液（420微升）混合。 </li><li>转移400微升样品放入一个外NMR管，并放置一同轴NMR插入管与叔丁醇:H 2 O的混合物（10:90体积/体积）到样品管中。 </li><li>记录1 H NMR谱，并测量在内部和外部的NMR管中（参考）12从叔丁醇衍生谐振信号之间的频移。 </li><li>运用EQ。 5，以确定[DCA]，其中T =绝对温度，Δχ=记录的移位，μ 有效 =有效磁的镧系元素离子为钆（III）14，和s =一个常数依赖力矩（μ 有效 = 7.94在样品的形状和其在磁场（0，1/3，和在一个球体，平行于气缸，和气缸垂直于磁场的情况下的1/6，分别地）的位置。 注:对于[DCA]得到的计算值应该被校正的原始浓度由于加入的D 2 O中的: 叔丁醇溶液（60微升）。 <img alt="公式5" src="/files/ftp_upload/54776/54776eq5.jpg" /> （5） </li></ol></li><li> 动态光散射（DLS）测量。 <ol><li>制备过滤DCA溶液（0.2微米聚四氟乙烯/ PTFE过滤，每钆0.75毫（III））在4-（2-羟乙基）-1-哌嗪乙磺酸（HEPES）缓冲液（25mM，pH7.4）中，并将其转移到一个比色皿为DLS测量。 </li><li>放置反应杯插入DLS装置和设置以下参数:30秒之前记录5次重复的15扫描（1次扫描= 12秒，折射率= 1.345，吸收= 1％），而不会在扫描之间，并与温度平衡延时。 </li><li>导出所获取的数据和通过绘制人口（％），为大小（流体动力学直径）的函数得到的粒度分布的直方图。 </li></ol></li><li> 纵向和横向弛豫的测量。 注意:使用弛豫时间分析仪15用类似的方法已经描述;使用具有的Topspin 300MHz的NMR波谱仪进行此过程软件。 <ol><li>准备一套H中DCA解决方案2 O的:D 2 O（500微升，10％D 2 O H中2 O，[DCA] = 2.0，2.5，3.0，3.5，4.0，4.5和5.0毫米，[HEPES ] = 25毫米）从DCA股票样本（见第2.2节）。 </li><li>转移450微升溶液进入核磁共振管，并将其放入仪器中。 </li><li>优化采集参数（90°激励脉冲持续时间（P1），以及辐射频率偏移（O 1）），然后执行T使用反转恢复（IR）和台车式赛尔Meiboom -吉尔和 T2实验（CPMG ）的脉冲序列。 </li><li>的T1和T2 2弛豫时间测定。 <ol><li>选择所记录的测量，过程在F2尺寸的二维频谱，并执行交互式相位校正。 </li><li>在分析/ T选择适当的切片（最大强度峰值） <sub&gt; 1 / T 2松弛窗口，整合它，以及该地区出口到放松模块。 </li><li>选择合适的拟合函数（invrec或uxnmrt2红外和CPMG实验，分别），得到的T 1或T 2弛豫时间。 </li></ol></li><li>重复步骤2.4.4.2-2.4.4.4的所有剩余[DCA]解决方案。 </li><li>计算从所获得的Ť1值的弛豫率（R 1和R 2）（R 1,2 = 1 / T 1,2）。 </li><li>情节的 R 1和R 2（秒-1），为钆（III）浓度的在毫函数。 </li><li>确定纵向和横向弛豫，R 1和R 2（毫-1秒-1），从拟合直线的斜率，由式所定义。 6，其中R I，观测值 =纵向（ⅰ= 1）或横向（ⅰ= 2）抗磁松弛率水在实验中所用的情况下顺磁物质的和[钆] =钆（III）的浓度。 <img alt="公式6" src="/files/ftp_upload/54776/54776eq6.jpg" /> （6） </li></ol></li></ol> 3. 在体外 MRI; DCA和GdDOTA的比较<ol><li> 管幻影的制备 <ol><li>为两组实验其中计算造影剂的浓度制备的DCA（4×350微升）和GdDOTA（4×350微升）以及水样（4×350微升）的水溶液:（3.1.1.1）每钆（III）或每分子（3.1.1.2）。 <ol><li>准备两个样品DCA和两个GdDOTA 样品的分别每钆0.5和1.0毫米（III）的浓度。此外，准备两个水样（如控制管）。 </li><li>准备两个DCA样品（2.5和每钆（III）或0.05 5.0毫和每个树枝状分子0.1毫摩尔），二GdDOTA样品（0.25，0.5毫摩尔）和两个水样（CONTRO升管）。 注意:适当的DCA和GdDOTA浓度应通过稀释各自的股票样本通过BMS法测定浓度制备（参见2.2节）与HEPES缓冲液（pH 7.4）。为了简化计算，假设为平均每树枝状聚合物分子的大环单元的N = 50。因此，DCA的比率:GdDOTA为1:5，计算上的每个分子基础。 </li></ol></li><li>放置在300μl的塑料瓶管中的样品，从而避免气泡的在溶液中的存在。 注:在塑料小瓶管的尺寸取决于所使用的射频线圈的类型和大小（在此，与卷线圈给出一个例子）。 </li><li>插入样品的注射器（60 ml，此）的内部，用1mM GdDOTA填充 溶液，并将其放置在扫描仪。 注:样品置于GdDOTA的水溶液，以避免易感性的影响（在磁场的Field变化对发生的不同磁化率的物质之间的接口附近）trength。 </li></ol></li><li> 参数优化和成像。 <ol><li>使用解剖扫描（航向/ Tripilot）与样品的注射器放置在磁体的等角点。 </li><li>按红绿灯（调整扫描）来执行调整为垫补整个卷，中心频率（O 1），接收器增益（RG），并且所述发射增益（TX0和TX1）的（磁场均匀的调整）。 </li><li>用于T 1 -加权（T 1W）成像，选择快速低角度拍摄（FLASH）法。 </li><li>选择在扫描仪使用扫描定位器垂直放置（注射器水平）样本冠状切片。 </li><li>运用EQ。 7对比度-噪声（CNR）采集的优化参数16，其中α=翻转角，TE =回波时间TR =重复时间，T 1，A，T 1，B =第t样品A的1倍（T 1，A）和样品B（T 1，B）该CNR应该最大化（同样是有效的ŧ2次:T 2，A和T 2，B）。 注:t 1和T 2弛豫时间应设置为从纵向和横向弛豫（第2.4节）的测量获得的值，而TE，TR，α应距离CNR优化计算而获得。 <img alt="公式7" src="/files/ftp_upload/54776/54776eq7.jpg" /> （7） </li><li>取得使用在前面的步骤（3.2.5）中获得的参数的图像。 </li><li>计算信噪比（SNR）。 <ol><li>加载收购牛逼 1瓦特图像（扫描）转换成图像显示及处理窗口，单击定义感兴趣区域 （ROI） 的区域 。 </li><li>选择一个圆形的投资回报率，并在样品位置和背景绘制。接着，点击显示以获得的平均信号振幅（S 信号 ）和背景（S 噪声 ）的标准偏差。 </li><li>重复步骤3.2.7.2对于DCA，GdDOTA和水样。 </li><li>用计算公式SNR:SNR = S 信号 / S 的噪音 。 </li></ol></li><li>经过稍微修改程序，用快速采集弛豫增强（RARE）方法执行T2加权（T 2W）成像。对于CNR采集参数的优化，运用EQ。 8。 <img alt="式（8）" src="/files/ftp_upload/54776/54776eq8.jpg" /> （8） </li></ol></li></ol>

<ol>
	<li>Merbach, A. E., Helm, L., T&#243;th, &. #. 2. 0. 1. ;. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The chemistry of contrast agents in medical magnetic resonance imaging. 2nd ed. , (2013).</li><li>Geraldes, C. F. G. C., Laurent, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classification+and+basic+properties+of+contrast+agents+for+magnetic+resonance+imaging.">Classification and basic properties of contrast agents for magnetic resonance imaging.</a> Contrast Media Mol. Imaging. 4 (1), 1-23 (2009).</li><li>Caravan, P., Ellison, J. J., McMurry, T. J., Lauffer, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gadolinium(III)+chelates+as+MRI+contrast+agents:+Structure,+dynamics,+and+applications.">Gadolinium(III) chelates as MRI contrast agents: Structure, dynamics, and applications.</a> Chem. Rev. 99 (9), 2293-2352 (1999).</li><li>Villaraza, A. J. L., Bumb, A., Brechbiel, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macromolecules,+Dendrimers,+and+Nanomaterials+in+Magnetic+Resonance+Imaging:+The+Interplay+between+Size,+Function,+and+Pharmacokinetics.">Macromolecules, Dendrimers, and Nanomaterials in Magnetic Resonance Imaging: The Interplay between Size, Function, and Pharmacokinetics.</a> Chem. Rev. 110 (5), 2921-2959 (2010).</li><li>Langereis, S., Dirksen, A., Hackeng, T. M., van Genderen, M. H. P., Meijer, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendrimers+and+magnetic+resonance+imaging.">Dendrimers and magnetic resonance imaging.</a> New J. Chem. 31 (7), 1152-1160 (2007).</li><li>G&#252;nd&#252;z, S., Power, A., Maier, M. E., Logothetis, N. K., Angelovski, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Characterization+of+a+Biotinylated+Multivalent+Targeted+Contrast+Agent.">Synthesis and Characterization of a Biotinylated Multivalent Targeted Contrast Agent.</a> ChemPlusChem. 80 (3), 612-622 (2015).</li><li>Pope, S. J. A., Kenwright, A. M., Heath, S. L., Faulkner, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+luminescence+properties+of+a+kinetically+stable+dinuclear+ytterbium+complex+with+differentiated+binding+sites.">Synthesis and luminescence properties of a kinetically stable dinuclear ytterbium complex with differentiated binding sites.</a> Chem. Commun. (13), 1550-1551 (2003).</li><li>Vibhute, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+characterization+of+pH-sensitive,+biotinylated+MRI+contrast+agents+and+their+conjugates+with+avidin.">Synthesis and characterization of pH-sensitive, biotinylated MRI contrast agents and their conjugates with avidin.</a> Org. Biomol. Chem. 11 (8), 1294-1305 (2013).</li><li>Vogel, A. I., Furniss, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Vogel's textbook of practical organic chemistry. 5th ed. , (1989).</li><li>Lundanes, E., Reubsaet, L., Greibrokk, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Chromatography : basic principles, sample preparations and related methods. , (2013).</li><li>Barge, A., Cravotto, G., Gianolio, E., Fedeli, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+determine+free+Gd+and+free+ligand+in+solution+of+Gd+chelates.+A+technical+note.">How to determine free Gd and free ligand in solution of Gd chelates. A technical note.</a> Contrast Media Mol. Imaging. 1 (5), 184-188 (2006).</li><li>Keeler, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Understanding NMR spectroscopy. 2nd ed. , (2010).</li><li>Hillenkamp, F., Peter-Katalini&#263;, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> MALDI MS : a practical guide to instrumentation, methods and applications. , (2007).</li><li>Peters, J. A., Huskens, J., Raber, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lanthanide+induced+shifts+and+relaxation+rate+enhancements.">Lanthanide induced shifts and relaxation rate enhancements.</a> Prog. Nucl. Magn. Reson. Spectrosc. 28, 283-350 (1996).</li><li>Averill, D. J., Garcia, J., Siriwardena-Mahanama, B. N., Vithanarachchi, S. M., Allen, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation,+Purification,+and+Characterization+of+Lanthanide+Complexes+for+Use+as+Contrast+Agents+for+Magnetic+Resonance+Imaging.">Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging.</a> J. Vis. Exp. (53), e2844 (2011).</li><li>Hagberg, G. E., Scheffler, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+r1+and+r2+relaxivity+of+gadolinium-based+contrast+agents+on+the+T1-weighted+MR+signal+at+increasing+magnetic+field+strengths.">Effect of r1 and r2 relaxivity of gadolinium-based contrast agents on the T1-weighted MR signal at increasing magnetic field strengths.</a> Contrast Media Mol. Imaging. 8 (6), 456-465 (2013).</li><li>Boswell, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis,+characterization,+and+biological+evaluation+of+integrin+alpha(v)beta(3)-targeted+PAMAM+dendrimers.">Synthesis, characterization, and biological evaluation of integrin alpha(v)beta(3)-targeted PAMAM dendrimers.</a> Mol. Pharmaceut. 5 (4), 527-539 (2008).</li><li>Sherry, A. D., Caravan, P., Lenkinski, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primer+on+Gadolinium+Chemistry.">Primer on Gadolinium Chemistry.</a> J. Magn. Reson. Imaging. 30 (6), 1240-1248 (2009).</li><li>Caki&#263;, N., G&#252;nd&#252;z, S., Rengarasu, R., Angelovski, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+strategies+for+preparation+of+cyclen-based+MRI+contrast+agents.">Synthetic strategies for preparation of cyclen-based MRI contrast agents.</a> Tetrahedron Lett. 56 (6), 759-765 (2015).</li><li>Polasek, M., Hermann, P., Peters, J. A., Geraldes, C. F. G. C., Lukes, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PAMAM+Dendrimers+Conjugated+with+an+Uncharged+Gadolinium(III)+Chelate+with+a+Fast+Water+Exchange:+The+Influence+of+Chelate+Charge+on+Rotational+Dynamics.">PAMAM Dendrimers Conjugated with an Uncharged Gadolinium(III) Chelate with a Fast Water Exchange: The Influence of Chelate Charge on Rotational Dynamics.</a> Bioconjugate Chem. 20 (11), 2142-2153 (2009).</li><li>Ali, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+relaxometric+studies+of+a+dendrimer-based+pH-responsive+MRI+contrast+agent.">Synthesis and relaxometric studies of a dendrimer-based pH-responsive MRI contrast agent.</a> Chem. Eur. J. 14 (24), 7250-7258 (2008).</li><li>Jackson, C. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+dendrimer+molecules+by+transmission+electron+microscopy+(TEM):+Staining+methods+and+Cryo-TEM+of+vitrified+solutions.">Visualization of dendrimer molecules by transmission electron microscopy (TEM): Staining methods and Cryo-TEM of vitrified solutions.</a> Macromolecules. 31 (18), 6259-6265 (1998).</li><li>Jain, K., Kesharwani, P., Gupta, U., Jain, N. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendrimer+toxicity:+Let's+meet+the+challenge.">Dendrimer toxicity: Let's meet the challenge.</a> Int. J. Pharm. 394 (1-2), 122-142 (2010).</li><li>Rudovsky, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PAMAM+dendrimeric+conjugates+with+a+Gd-DOTA+phosphinate+derivative+and+their+adducts+with+polyaminoacids:+The+interplay+of+global+motion,+internal+rotation,+and+fast+water+exchange.">PAMAM dendrimeric conjugates with a Gd-DOTA phosphinate derivative and their adducts with polyaminoacids: The interplay of global motion, internal rotation, and fast water exchange.</a> Bioconjugate Chem. 17 (4), 975-987 (2006).</li><li>Xu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+improved+syntheses+of+dendrimer-based+magnetic+resonance+imaging+contrast+agents:+New+bifunctional+diethylenetriaminepentaacetic+acid+ligands+and+nonaqueous+conjugation+chemistry.">Toward improved syntheses of dendrimer-based magnetic resonance imaging contrast agents: New bifunctional diethylenetriaminepentaacetic acid ligands and nonaqueous conjugation chemistry.</a> J. Med. Chem. 50 (14), 3185-3193 (2007).</li><li>Nwe, K., Bryant, L. H., Brechbiel, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(amidoamine)+Dendrimer+Based+MRI+Contrast+Agents+Exhibiting+Enhanced+Relaxivities+Derived+via+Metal+Preligation+Techniques.">Poly(amidoamine) Dendrimer Based MRI Contrast Agents Exhibiting Enhanced Relaxivities Derived via Metal Preligation Techniques.</a> Bioconjugate Chem. 21 (6), 1014-1017 (2010).</li><li>Livramento, J. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=First+in+vivo+MRI+assessment+of+a+self-assembled+metallostar+compound+endowed+with+a+remarkable+high+field+relaxivity.">First in vivo MRI assessment of a self-assembled metallostar compound endowed with a remarkable high field relaxivity.</a> Contrast Media Mol. Imaging. 1 (1), 30-39 (2006).</li><li>Norek, M., Kampert, E., Zeitler, U., Peters, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+of+the+Size+of+Dy2O3+Nanoparticles+for+Optimal+Performance+as+an+MRI+Contrast+Agent.">Tuning of the Size of Dy2O3 Nanoparticles for Optimal Performance as an MRI Contrast Agent.</a> J. Am. Chem. Soc. 130 (15), 5335-5340 (2008).</li></ol>

The authors have nothing to disclose.

所述树枝状MRI造影剂的制备需要的单体单元的适当选择（ 即，螯合剂为钆（III））。它们减少这种顺磁性离子的毒性，迄今为止，各种各样的无环的和大环螯合剂用于此目的1-3。在这些中，大环DOTA型螯合剂具有最高热力学稳定性和动力学惰性的，因此，是惰性MRI造影剂1,18的制剂最优选的选择。此外，它们易发生各种合成转化，这导致双官能螯合剂，能够链接到各种功能分...

磁共振成像（MRI）是广泛用于生物医学研究和临床诊断的有力和非电离成像技术，由于其非侵入性和优良特性的软组织的对比。最常用的MRI方法利用从水的质子获得的信号的基础上，在水信号的密度差异的组织中提供高清晰度的图像和详细的信息。的信号强度和在MRI实验的特异性可以使用造影剂（CA）的进一步提高。这些都是影响的纵向（T 1）和横向分别1,2-顺磁性或超顺磁性物质（T 2）弛豫时间。 用聚氨基聚羧酸配体的镧系元素离子钆配合物是最常用的Ť1的CA。钆（III）缩短的T 1松弛因此水的质子的时间，增加的MRI实验3中的信号对比度。然而，钆离子是有毒的;它的大小近似于钙（Ⅱ），它严重影响钙辅助细胞信号传导。因此，无环和大环螯合物被用来抵消这种毒性。各种多齿配体迄今已开发的，导致具有高的热力学稳定性和动力学惰性1钆（Ⅲ）配合物。那些基于所述12元azamacrocycle CYCLEN，特别是其四衍生物DOTA（1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸）是此CA类的最研究和应用的复合物。 尽管如此，GdDOTA型CA是低分子量的系统，其中显示某些缺点，例如低对比度效率和快速的肾排泄。大分子和多价的CA可能是一个很好的解决了这些问题，4。由于CA biodistribu化主要是由它们的大小决定的，大分子的CA显示组织中更长的保留时间。同样重要的是，在单体的MR 探测器 （ 如 GdDOTA复合），基本上改善所获取的MR信号和测量质量的增加的局部浓度这些试剂的结果的多价。 树枝状聚合物之间的编写多价的CA用于MRI 4,5最好支架。这些具有良好定义的尺寸的高度支化的大分子易于在其表面上的不同的偶合反应。在这项工作中，我们报道的制备，纯化和树枝状的CA用于MRI由第4代（G4）聚（酰氨基胺），耦合到GdDOTA状螯合物（DCA）（PAMAM）树枝状聚合物的表征。我们描述了反应性的DOTA衍生物的合成及其与PAMAM树枝状耦合。在与钆（III），标准的理化性质络合procedu再DCA的进行。最后，进行核磁共振实验证明DCA的以产生具有比从低分子量的CA获得的那些较强的对比度的MR图像的能力。

<table><tbody><tr><td>Cyclen</td><td>CheMatech</td><td>C002</td><td></td></tr><tr><td>&lt;em&gt;tert&lt;/em&gt;-Butyl bromoacetate&amp;nbsp;</td><td>Alfa Aesar</td><td>A14917</td><td></td></tr><tr><td>&lt;em&gt;N,N&lt;/em&gt;-Dimethylformamide</td><td>Fluka</td><td>40248</td><td></td></tr><tr><td>Potassium carbonate</td><td>Sigma-Aldrich</td><td>209619</td><td></td></tr><tr><td>4-(4-Nitrophenyl)butryic acid</td><td>Aldrich</td><td>335339</td><td></td></tr><tr><td>Thionyl chloride&amp;nbsp;</td><td>Acros Organics</td><td>382662500</td><td>Note: Corrosive substance; toxic if inhaled</td></tr><tr><td>Bromine</td><td>Acros Organics</td><td>402841000</td><td>Note: causes severe skin burns, fatal if inhaled&amp;nbsp;</td></tr><tr><td>Diethyl ether</td><td>any source</td><td></td><td></td></tr><tr><td>Sodium sulphate</td><td>Acros Organics</td><td>196640010</td><td></td></tr><tr><td>Chloroform&amp;nbsp;</td><td>VWR Chemicals</td><td>22711.29</td><td></td></tr><tr><td>&lt;em&gt;tert&lt;/em&gt;-Butyl 2,2,2-trichloroacetimidate</td><td>Aldrich</td><td>364789</td><td>Note: flammable substance; irritrant to skin and eyes</td></tr><tr><td>Boron trifluoride etherate</td><td>Acros Organics</td><td>174560250</td><td>48% BF&lt;sub&gt;3&lt;/sub&gt;. Note: Flammable substance; causes skin burns, fatal if inhaled</td></tr><tr><td>Sodium bicarbonate</td><td>Acros Organics</td><td>424270010</td><td></td></tr><tr><td>Ethyl-acetate</td><td>any source</td><td></td><td>For column chromatography</td></tr><tr><td>&lt;em&gt;n&lt;/em&gt;-Hexane</td><td>any source</td><td></td><td>For column chromatography</td></tr><tr><td>Bulb-to-bulb (Kugelrohr) distillation apparatus</td><td>B&amp;uuml;chi</td><td></td><td>Model type: Glass oven B-585</td></tr><tr><td>Silicagel</td><td>Carl Roth GmbH</td><td>P090.2</td><td></td></tr><tr><td>Methanol</td><td>any source</td><td></td><td>For column chromatography</td></tr><tr><td>Dichloromethane&amp;nbsp;</td><td>any source</td><td></td><td>For column chromatography</td></tr><tr><td>Ethanol</td><td>VWR Chemicals</td><td>20821.296</td><td></td></tr><tr><td>Ammonia</td><td>Acros Organics</td><td>428381000</td><td>7 N Solution in Methanol</td></tr><tr><td>Palladium</td><td>Aldrich</td><td>643181</td><td>15% wet</td></tr><tr><td>Hydrogenation apparatus PARR</td><td>PARR Instrument Company</td><td></td><td></td></tr><tr><td>Celite 503</td><td>Aldrich</td><td>22151</td><td></td></tr><tr><td>Sintered glass funnel</td><td>any source</td><td></td><td></td></tr><tr><td>Thiophosgen</td><td>Aldrich</td><td>115150</td><td>Note: irritrant to skin; toxic if inhaled</td></tr><tr><td>Triethylamine</td><td>Alfa Aesar</td><td>A12646</td><td></td></tr><tr><td>Dichloromethane&amp;nbsp;</td><td>Acros Organics</td><td>348460010</td><td>Extra dry&amp;nbsp;</td></tr><tr><td>Magnetic stirrer</td><td>any source</td><td></td><td></td></tr><tr><td>PAMAM G4 Dendrimer</td><td>Andrews ChemService</td><td>AuCS - 297</td><td>10% wt. solution in MeOH</td></tr><tr><td>Lipophylic Sephadex LH-20</td><td>Sigma</td><td>LH20100</td><td></td></tr><tr><td>Thin-layer chromatography plates</td><td>Merck Millipore</td><td>1.05554.0001</td><td></td></tr><tr><td>Formic acid</td><td>VWR Chemicals</td><td>20318.297</td><td></td></tr><tr><td>Lophylizer&amp;nbsp;</td><td>any source</td><td></td><td></td></tr><tr><td>Gadollinium(III) chloride hexahydrate</td><td>Aldrich</td><td>G7532</td><td></td></tr><tr><td>Sodium hydroxide</td><td>Acros Organics</td><td>134070010</td><td></td></tr><tr><td>pH meter</td><td>any source</td><td></td><td></td></tr><tr><td>Ethylenediaminetetraacetic acid disodium salt dihydrate</td><td>Aldrich</td><td>E5134</td><td></td></tr><tr><td>Mass spectrometer (ESI)</td><td>Agilent</td><td></td><td>Ion trap SL 1100&amp;nbsp;</td></tr><tr><td>Acetate buffer</td><td>any source</td><td></td><td>pH 5.8</td></tr><tr><td>Xylenol orange</td><td>Aldrich</td><td>52097</td><td>20 &amp;mu;M in acetate buffer</td></tr><tr><td>Hydrophylic Sephadex G-15</td><td>GE Healthcare</td><td>17-0020-01</td><td></td></tr><tr><td>Amicon Ultra-15 Centrifugal Filter Unit</td><td>Merck Millipore</td><td>UFC900324</td><td>Ultracel-3 membrane (MWCO 3000)</td></tr><tr><td>Centrifuge</td><td>any source</td><td></td><td></td></tr><tr><td>NMR spectrometer&amp;nbsp;</td><td>Bruker</td><td></td><td>Avance III 300 MHz</td></tr><tr><td>Topspin</td><td>Bruker</td><td></td><td>Version 2.1</td></tr><tr><td>Combustion analysis instrument</td><td>EuroVector SpA</td><td></td><td>EuroEA 3000 Elemental Analyser&amp;nbsp;</td></tr><tr><td>MALDI-ToF MS instrument</td><td>Applied Biosystems</td><td></td><td>Voyager-STR</td></tr><tr><td>Deuteriumoxid</td><td>Carl Roth GmbH</td><td>6672.3</td><td></td></tr><tr><td>&lt;em&gt;tert&lt;/em&gt;-Butyl alcohol</td><td>Carl Roth GmbH</td><td>AE16.1</td><td></td></tr><tr><td>Vortex mixer</td><td>any source</td><td></td><td></td></tr><tr><td>Norell NMR tubes</td><td>Deutero GmbH</td><td>507-HP-7</td><td></td></tr><tr><td>NMR coaxial tube</td><td>Deutero GmbH</td><td>coaxialb-5-7</td><td></td></tr><tr><td>DLS instrument</td><td>Malvern</td><td></td><td>Zetasizer Nano ZS</td></tr><tr><td>0.20 &amp;mu;m PTFE filter&amp;nbsp;</td><td>Carl Roth GmbH</td><td>KC94.1</td><td></td></tr><tr><td>HEPES</td><td>Fisher BioReagents</td><td>BP310</td><td></td></tr><tr><td>Plastic tube vials</td><td>any source</td><td></td><td></td></tr><tr><td>Dotarem</td><td>Guerbet</td><td></td><td>NDC 67684-2000-1</td></tr><tr><td>MRI scanner</td><td>Bruker</td><td></td><td>BioSpec 70/30 USR magnet (7 T). Note: potential hazards related to high magnetic fields</td></tr><tr><td>RF coil</td><td>Bruker</td><td></td><td>Dual frequency volume coil (RF RES 300 1H/19F 075/040 LIN/LIN TR)</td></tr><tr><td>Paravision (software)</td><td>Bruker</td><td></td><td>Version 5.1</td></tr></tbody></table>

preparation and in vitro characterization of dendrimer-based contrast agents for magnetic resonance imaging

钆（III）与无环或大环螯合物的顺磁性配合物是用于磁共振成像（MRI）中最常用的造影剂（CA）的。他们的目的是提高在组织的水质子的弛豫率，从而增加了MR图像对比度和磁共振测量的特异性。当前临床批准的造影剂是正在迅速从体内清除的低分子量分子。作为顺磁性螯合剂的载体的使用树枝状聚合物可以在更高效的MRI造影剂的未来发展中发挥重要作用。具体地，增加在一个较高的信号对比度顺磁物质的结果的局部浓度。此外，此CA提供由于其高分子量和尺寸较长的组织的保留时间。这里，我们证明了基于聚（酰氨基胺）大分子MRI造影剂（PAMAM）与monomacro树枝状聚合物的制备便利过程环状DOTA型螯合剂（DOTA - 1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸）。螯合单元通过利用朝向PAMAM树枝状聚合物的胺基表面基团的异硫氰酸酯（NCS）基团的反应性，以形成硫脲桥追加。树枝状产物纯化并通过核磁共振谱，质谱和元素分析法分析。最后，高清晰度的MR图像记录和从制备树枝状和市售单体剂获得的信号反差进行比较。

DCA的制备包括两个阶段:1）的单体的DOTA型螯合剂的合成（ 图1）和2）与G4 PAMAM树枝状聚合物和树枝状钆（III）络合物的后续制备螯合剂的耦合（ 图2） 。在第一阶段，制备含有四个羧酸的基于CYCLEN-DOTA型螯合剂和适合于进一步合成修饰的正交基。从1（DO3A- 叔丁基酯）7开始制备，这是烷基化叔丁基2-溴...

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Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

本协议描述携带CYCLEN基于大环螯合物协调顺钆离子树枝状磁共振成像（MRI）造影剂的制备和表征。在一系列的体外 MRI实验中，相对于可商购的单体类似物时此代理产生的放大的磁共振信号。

制备及<em&gt;体外</em&gt;磁共振成像基于树状大分子造影剂的表征

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

preparation-vitro-characterization-dendrimer-based-contrast-agents

Universidad San Sebastian

Research

JoVE Journal

Chemistry

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

9.8K 次观看.  Max Planck Institute for Biological Cybernetics. 本协议描述携带CYCLEN基于大环螯合物协调顺钆离子树枝状磁共振成像（MRI）造影剂的制备和表征。在一系列的体外 MRI实验中，相对于可商购的单体类似物时此代理产生的放大的磁共振信号。 

视频: Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

控制的大小，形状和稳定性超分子聚合物在水

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

科研

工程学

Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring 

Nanomedications can be carried by blood borne monocyte-macrophages into the reticuloendothelial system (RES; spleen, liver, lymph nodes) and to end organs. The latter include the lung, RES, and brain and are operative during human immunodeficiency virus type one (HIV-1) infection. Macrophage entry into tissues is notable in areas of active HIV-1 replication and sites of inflammation. In order to assess the potential of macrophages as nanocarriers, superparamagnetic iron-oxide and/or drug laden particles coated with surfactants were parenterally injected into HIV-1 encephalitic mice. This was done to quantitatively assess particle and drug biodistribution. Magnetic resonance imaging (MRI) test results were validated by histological coregistration and enhanced image processing. End organ disease as typified by altered brain histology were assessed by MRI. The demonstration of robust migration of nanoformulations into areas of focal encephalitis provides '"proof of concept" for the use of advanced bioimaging techniques to monitor macrophage migration. Importantly, histopathological aberrations in brain correlate with bioimaging parameters making the general utility of MRI in studies of cell distribution in disease feasible. We posit that using such methods can provide a real time index of disease burden and therapeutic efficacy with translational potential to humans.

Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring

Bioimaging methods used to assess cell biodistribution of nanoparticles are applicable for therapeutic and diagnostic monitoring of nanoformulated compounds. The methods described herein are sensitive and specific when assessed by histological coregistration. The methodologies provide a translational pathway from rodent to human applications.

注册生物成像，纳米材料可用于诊断和治疗监测

Nanomedications can be carried by blood borne monocyte-macrophages into the reticuloendothelial system (RES; spleen, liver, lymph nodes) and to end ...

生物工程

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

Fluorescence sensors are powerful tools in life science. Here we describe a methodology to synthesize and use dendrimer-based fluorescent sensors to measure pH in living cells and in vivo. The dendritic scaffold enhances the properties of conjugated fluorescent dyes leading to improved sensing properties.

合成，细胞和交货<em&gt;在体内</em&gt;的树状为基础的pH值传感器应用

The development of  fluorescent indicators represented a revolution for life sciences. Genetically  encoded and synthetic fluorophores with sensing ...

化学

In vitro Labeling of Human Embryonic Stem Cells for Magnetic Resonance Imaging

Human embryonic stem cells (hESC) have demonstrated the ability to restore the injured myocardium. Magnetic resonance imaging (MRI) has emerged as one of the predominant imaging modalities to assess the restoration of the injured myocardium. Furthermore, ex-vivo labeling agents, such as iron-oxide nanoparticles, have been employed to track and localize the transplanted stem cells. However, this method does not monitor a fundamental cellular biology property regarding the viability of transplanted cells. It has been known that manganese chloride (MnCl2) enters the cells via voltage-gated calcium (Ca2+) channels when the cells are biologically active, and accumulates intracellularly to generate T1 shortening effect. Therefore, we suggest that manganese-guided MRI can be useful to monitor cell viability after the transplantation of hESC into the myocardium.
In this video, we will show how to label hESC with MnCl2 and how those cells can be clearly seen by using MRI in vitro. At the same time, biological activity of Ca2+-channels will be modulated utilizing both Ca2+-channel agonist and antagonist to evaluate concomitant signal changes.

In this video, we are showing how to label human embryonic stem cells (hESC) with manganese chloride (MnCl2) which can enter cells via voltage-gated calcium channels when the cells are biologically active. Additionally, we show the use of MnCl2 as cellular MRI contrast agent to determine the in vitro viability of hESC.

在人类胚胎干细胞体外培养的标签用于磁共振成像

Human embryonic stem cells (hESC) have demonstrated the ability to restore the injured myocardium. Magnetic resonance imaging (MRI) has emerged as one of ...

生物学

Monitoring Dendritic Cell Migration using 19F / 1H Magnetic Resonance Imaging

Continuous advancements in noninvasive imaging modalities such as magnetic resonance imaging (MRI) have greatly improved our ability to study physiological or pathological processes in living organisms. MRI is also proving to be a valuable tool for capturing transplanted cells in vivo. Initial cell labeling strategies for MRI made use of contrast agents that influence the MR relaxation times (T1, T2, T2*) and lead to an enhancement (T1) or depletion (T2*) of signal where labeled cells are present. T2* enhancement agents such as ultrasmall iron oxide agents (USPIO) have been employed to study cell migration and some have also been approved by the FDA for clinical application. A drawback of T2* agents is the difficulty to distinguish the signal extinction created by the labeled cells from other artifacts such as blood clots, micro bleeds or air bubbles. In this article, we describe an emerging technique for tracking cells in vivo that is based on labeling the cells with fluorine (19F)-rich particles. These particles are prepared by emulsifying perfluorocarbon (PFC) compounds and then used to label cells, which subsequently can be imaged by 19F MRI. Important advantages of PFCs for cell tracking in vivo include (i) the absence of carbon-bound 19F in vivo, which then yields background-free images and complete cell selectivityand(ii) the possibility to quantify the cell signal by 19F MR spectroscopy.

Monitoring Dendritic Cell Migration using 19F / 1H Magnetic Resonance Imaging

Tracking of cells using MRI has gained remarkable attention in the past years. This protocol describes the labeling of dendritic cells with fluorine (19F)-rich particles, the in vivo application of these cells, and monitoring the extent of their migration to the draining lymph node with 19F/1H MRI and 19F MRS.

监测树突状细胞迁移<sup&gt; 19</sup&gt; F /<sup&gt; 1</sup&gt; H磁共振成像

Continuous  advancements in noninvasive imaging modalities such as magnetic resonance  imaging (MRI) have greatly improved our ability to study ...

免疫与感染

MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent

Tumor extracellular matrix has abundance of cancer related proteins that can be used as biomarkers for cancer molecular imaging. In this work, we demonstrated effective MR cancer molecular imaging with a small molecular peptide targeted Gd-DOTA monoamide complex as a targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma. We performed the experiment of evaluating the effectiveness of the agent for non-invasive detection of prostate tumor with MRI in a mouse orthotopic PC-3 prostate cancer model. The targeted contrast agent was effective to produce significant tumor contrast enhancement at a low dose of 0.03 mmol Gd/kg. The peptide targeted MRI contrast agent is promising for MR molecular imaging of prostate tumor.

To demonstrate MR cancer molecular imaging with a small peptide targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma in a mouse prostate cancer model.

前列腺癌与小分子肽CLT1靶向造影剂的磁共振分子成像

Tumor extracellular  matrix has abundance of cancer related proteins that can be used as biomarkers  for cancer molecular imaging. In this work,  we ...

医学

Biofunctionalized Prussian Blue Nanoparticles for Multimodal Molecular Imaging Applications

Multimodal, molecular imaging allows the visualization of biological processes at cellular, subcellular, and molecular-level resolutions using multiple, complementary imaging techniques. These imaging agents facilitate the real-time assessment of pathways and mechanisms in vivo, which enhance both diagnostic and therapeutic efficacy. This article presents the protocol for the synthesis of biofunctionalized Prussian blue nanoparticles (PB NPs) - a novel class of agents for use in multimodal, molecular imaging applications. The imaging modalities incorporated in the nanoparticles, fluorescence imaging and magnetic resonance imaging (MRI), have complementary features. The PB NPs possess a core-shell design where gadolinium and manganese ions incorporated within the interstitial spaces of the PB lattice generate MRI contrast, both in T1 and T2-weighted sequences. The PB NPs are coated with fluorescent avidin using electrostatic self-assembly, which enables fluorescence imaging. The avidin-coated nanoparticles are modified with biotinylated ligands that confer molecular targeting capabilities to the nanoparticles. The stability and toxicity of the nanoparticles are measured, as well as their MRI relaxivities. The multimodal, molecular imaging capabilities of these biofunctionalized PB NPs are then demonstrated by using them for fluorescence imaging and molecular MRI in vitro.

This protocol describes the synthesis of biofunctionalized Prussian blue nanoparticles and their use as multimodal, molecular imaging agents. The nanoparticles have a core-shell design where gadolinium or manganese ions within the nanoparticle core generate MRI contrast. The biofunctional shell contains fluorophores for fluorescence imaging and targeting ligands for molecular targeting.

Biofunctionalized普鲁士蓝纳米粒子多式联运分子成像应用

Multimodal, molecular imaging allows the visualization of biological processes at cellular, subcellular, and molecular-level resolutions using multiple, ...

In vivo 19F MRI for Cell Tracking

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.

In vivo 19F MRI for Cell Tracking

We describe a general protocol for in vivo cell tracking using MRI in a mouse model with ex vivo labeled cells. A typical protocol for cell labeling, image acquisition processing and quantification is included.

在体内 19女性 MRI对细胞跟踪

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. ...

<meta charset="utf8"></head><body>氧化铁纳米颗粒用于小鼠胶质母细胞瘤的图像引导治疗递送

Nanoparticle Delivery of an Oligonucleotide Payload in a Glioblastoma Multiforme Animal Model

Glioblastoma multiforme (GBM) is the most common and aggressive form of primary brain malignancy for which there is no cure. The blood-brain barrier is a significant hurdle in the delivery of therapies to GBM. Reported here is an image-guided, iron oxide-based therapeutic delivery nano platform capable of bypassing this physiological barrier by virtue of size and accumulating in the tumor region, delivering its payload. This 25 nm nano platform consists of crosslinked dextran-coated iron oxide nanoparticles labeled with Cy5.5 fluorescent dye and containing antisense oligonucleotide as a payload. The magnetic iron oxide core enables tracking of the nanoparticles through in vivo magnetic resonance imaging, while Cy5.5 dye allows tracking by optical imaging. This report details the monitoring of the accumulation of this nanoparticle platform (termed MN-anti-miR10b) in orthotopically implanted glioblastoma tumors following intravenous injection. In addition, it provides insight into the in vivo delivery of RNA oligonucleotides, a problem that has hampered the translation of RNA therapeutics into the clinic.

<meta charset="utf8"></head><body>作者聚焦:使用氧化铁纳米颗粒治疗胶质母细胞瘤的创新癌症疗法

The blood-brain barrier is a significant hurdle in the delivery of therapies for glioblastoma, a disease for which there is no cure. Here, we report an in vivo image-guided iron oxide therapeutic nano platform that can bypass this physiological barrier by virtue of size and accumulate in the tumor.

多形性胶质母细胞瘤动物模型中寡核苷酸有效载荷的纳米颗粒递送

Glioblastoma multiforme (GBM) is the most common and aggressive form of primary brain malignancy for which there is no cure. The blood-brain barrier is a ...

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控制的大小，形状和稳定性超分子聚合物在水

注册生物成像，纳米材料可用于诊断和治疗监测

合成，细胞和交货

在人类胚胎干细胞体外培养的标签用于磁共振成像

监测树突状细胞迁移

前列腺癌与小分子肽CLT1靶向造影剂的磁共振分子成像

Biofunctionalized普鲁士蓝纳米粒子多式联运分子成像应用

在体内 ^19女性 MRI对细胞跟踪

多形性胶质母细胞瘤动物模型中寡核苷酸有效载荷的纳米颗粒递送

多形性胶质母细胞瘤动物模型中寡核苷酸有效载荷的纳米颗粒递送