钆类造影剂用于肿瘤靶向性成像

核磁共振成像(MRI)是肿瘤诊断的重要手段,特别是各种造影剂的使用加速了临床应用范围.目前临床MRI检查所用各类造影剂如Gd-DTPA-BMA、Gd-DOTA等均为小分子造影剂,存在组织特异性低、体内停留时间短等缺点.构建具有组织特异性的新一代高效、低毒MRI造影剂成为材料界、医学界的研究热点之一.本文在综合最新文献的...     

pH响应的磁共振成像造影剂的研究进展

pH响应的磁共振成像(MRI)造影剂不仅能够对病变部位进行特异性增强成像,提高MRI检测疾病的灵敏度,而且可通过检测病变组织中的pH变化,为疾病的诊断提供依据。本文综述了pH响应的MRI造影剂的研究进展,介绍了其pH响应机理、种类与结构及应用,并对它的发展前景做了展望。     

自组装多肽探针在磁共振成像中的应用

磁共振成像(MRI)是一种强大的非侵入式生物医学诊断技术. 临床上, MRI需要借助造影剂来提高成像质量, 从而提高诊断的准确性. 由于具有优越的信号放大能力和生物相容性, 自组装多肽探针可负载特定的MRI分子, 通过酶促自组装过程实现肿瘤靶向和特异性富集, 增强肿瘤病灶区MRI信号, 从而进一步提高MRI的准确性和灵敏度. 本综述总结了近年来多肽自组装探针在不同MRI模式( ¹H MRI, ¹⁹F MRI和双自旋核MRI)下的最新进展, 并展望了这类新型探针在MRI领域的应用前景.     

医疗诊断新技术--磁共振成像术

本文介绍了2003年诺贝尔生理医学奖项的内容-磁共振成像技术。简述了核磁共振(NMR)和磁共振成像(MRI)的基本原理,介绍了目前MRI造影剂的研究进展。     

成像核弛豫速率和化学位移与其分子量大小和钆喷酸浓度的相关性

在测试磁共振成像(MRI)用造影剂钆喷酸葡胺(Magnevist)溶液的纵向弛豫速率和化学位移实验中, 观察到溶液中被观测核的弛豫速率加快和化学位移变化与其分子大小和造影剂浓度呈密切的相关性: 对于小分子成像核(水), 弛豫速率和化学位移都与造影剂浓度变化呈很好的线性关系; 而对于大分子成像核(PEG-2000和PEG-6000), 其化学位移和弛豫速率与造影剂浓度变化则呈非线性关系.     

激活型有机光声造影剂的应用

光声(PA)成像作为一种结合了光学和声学成像优势的新型成像方式,具有深层组织穿透和高空间分辨率等优点,在重大疾病的早期影像诊断方面有着巨大的应用前景。然而传统的PA造影剂依然存在信噪比低、选择性及特异性差等不足,容易产生假阳性诊断结果。激活型PA造影剂可以有效的降低背景噪声,并提升成像的灵敏度和特异性,是目前PA造影剂设计与构筑的主要趋势。本综述首先简单介绍了PA成像的原理,然后结合近几年在金属离子、酶、活性氮和活性氧等相关方面的生物成像应用,梳理了可激活探针在不同微环境中的响应方式。最后,对激活型探针在PA成像中的应用进行了总结和展望。     

19F磁共振成像造影剂研究进展

19F磁共振成像(19F magnetic relaxation imaging, 19F MRI)技术因其无内源性背景噪声而被广泛应用于生物医学研究领域。磁共振成像技术被提出后,19F MRI造影剂的研究主要集中于全氟化碳类有机物,这类有机物具有高的19F载量、合适的弛豫时间、高的影像信噪比,同时可以通过修饰功能性的基团实现多模式造影。近年来,19F MRI造影剂由全氟化碳等有机物逐渐向无机物延伸,出现了无机氟化物纳米粒子造影剂。本文主要介绍了19F MRI造影剂的种类、研究现状和应用前景。     

T1-T2双模式磁共振造影剂的设计及应用

核磁共振成像作为一种无侵入的早期诊断方式早已在临床上得到了非常广泛的应用,其成像方式分为弛豫加权和扩散加权,其中弛豫加权又分为T₁加权成像和T₂加权成像。为了增强MR图像对比度,可通过引入造影剂,根据其增强类型可以分为阳性的T₁造影剂和阴性的T₂造影剂。虽然两种造影剂各有其优点,但是也存在着一些不足,因此一种全新的T₁-T₂双模态造影剂应运而生。T₁-T₂双模态造影剂的优势就在于可以利用同一台仪器,实现MRI成像在时间和空间上的精确匹配。本文系统地总结了T₁-T₂双模态造影剂的设计思路和其化学合成方法,并对其生物医学应用作了介绍。     

纳米级造影剂在肿瘤影像学诊疗中的基础应用进展

肿瘤的早期诊断对其生存率及预后有极大的意义,医学成像造影剂的应用可极大地提高肿瘤的早期诊断水平。通过新兴纳米技术开发无毒、成像能力更强、循环时间更长的纳米级造影剂是目前研究的热点。本文综述了纳米级造影剂在MRI、CT、US、PET和SPECT等生物医学成像技术中,对于肿瘤诊疗的基础应用,并列举了部分研究实例。纳米级造影剂具有广阔的临床应用前景,未来的研究重点将会是开发集诊断、治疗于一体的多功能的纳米平台。     

温度和pH敏感高分子含钆核磁共振成像造影剂的合成及性能

以N-异丙基丙烯酰胺为温度敏感单体,以甲基丙烯酸为p H敏感单体,与三丙烯酸菲洛啉钆进行无皂乳液聚合,一步合成了具有温度和pH敏感的高分子含钆核磁共振成像(MRI)造影剂(TPRPP).动态光散射测试结果表明,TPRPP的粒径随温度或p H值的变化而发生较大的改变.体外MRI测试结果表明,TPRPP的横向弛豫时间(T_1)的加权弛豫率约为11.3 L/(mmol·s),为临床造影剂Magnevist~的2.6倍.体内MRI结果表明,TPRPP在肝和脾中具有明显的正增强效果.研究结果表明,TPRPP是一种优异的多功能MRI造影剂,具有极大的临床研究价值.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.