乏氧光学影像探针的设计与应用

氧气在生命活动中具有重要意义, 为需氧生物提供了重要的能量来源, 氧气供应不足会导致组织乏氧. 乏氧往往与炎症、 慢性伤口及肿瘤等多种疾病密切相关, 而组织氧浓度是评估机体健康的重要依据. 光学成像在空间分辨率、 灵敏性和成本方面的巨大优势使其成为炎症、 癌症、 脑部疾病和手术导航的重要影像诊断工具. 本文介绍了数种乏氧响应的光学探针的合成策略, 并展示了不同的乏氧光学探针在肿瘤检测、 炎症监测、 伤口氧含量监测、 治疗响应监测和食品包装检测等方面的应用, 最后探讨了乏氧光学成像的应用前景.     

偶氮苯衍生物探针在乏氧细胞成像中的应用

细胞不受控制的生长增殖和异常的血管系统导致肿瘤部位氧气供应不足,氧气浓度低于正常组织.细胞乏氧是大多数实体瘤的共同特征,可用作恶性组织和癌症进展的指标.准确的乏氧检测和成像对癌症患者的诊断和临床治疗至关重要.荧光成像具有高灵敏度、无创、实时等优点,常被用于癌症检查.偶氮基团由于其对荧光基团的荧光猝灭作用和还原断裂荧光恢...     

缺氧响应荧光探针的成像及治疗应用

由于肿瘤内部细胞远离血管, 其氧气消耗量远远超出血液供应量, 因此容易导致肿瘤缺氧. 肿瘤缺氧会引发肿瘤扩散加速、 诱导某些基因过表达及产生药物抗药性等问题. 基于此, 发展性能优异的缺氧响应荧光探针对肿瘤的诊断和治疗具有重要意义. 本文对缺氧响应荧光探针在成像及治疗方面的应用进展进行了综合评述, 介绍了硝基、 偶氮键和醌3种常用的缺氧响应基团, 并探讨了它们在缺氧微环境下的识别机理; 介绍了缺氧响应荧光探针的构建及其在生物成像方面的最新研究成果; 总结了缺氧响应荧光探针在基因治疗、 光动力学治疗、 化学治疗及协同治疗方面的研究进展; 展望了缺氧响应荧光探针在临床诊断和治疗方面的应用前景.     

高选择性过氧化亚硝酰荧光探针的合成及性能研究

过氧化亚硝酰(ONOO^-)是生物体系中重要活性氧之一,对其高效检测一直备受关注。本研究以4-二乙基氨基水杨醛和6-甲氧基-1-萘满酮为原料,经一步有机反应,合成了一种带氧鎓正离子的荧光探针PFP,用于检测ONOO^-。通过紫外-可见吸收光谱和荧光发射光谱系统考察了探针PFP对ONOO^-的光学响应。结果表明,此探针具有选择性好、灵敏度高(检出限为15.5 nmol/L)、响应快速(数秒内)、Stokes位移较大(42 nm)、水溶性好等优点。细胞毒性实验表明,探针PFP具有良好的生物相容性,探针浓度为20μmol/L时,细胞存活率>95%。激光扫描共聚焦显微成像结果表明,此探针可用于活细胞中外源性和内源性ONOO^-的荧光成像研究。     

可激活的NIR-Ⅱ探针用于肿瘤成像

波长位于1000~1700 nm之间的近红外窗口,通常被称为第二近红外(NIR-Ⅱ)窗口,在生物成像方面(荧光成像、光声成像等),该窗口展现出强大的吸引力。相比在可见光(400~700 nm)区域和第一近红外(NIR-Ⅰ,700~900 nm)窗口的传统成像,NIR-Ⅱ生物成像提供了分辨率高和穿透深度深等优点。但是,目前大多数“always-on”探针,并不能实现更高的信噪比。肿瘤微环境响应型智能药物的成像只在肿瘤中触发,可以克服这一局限性。因此,应充分结合肿瘤微环境和NIR-Ⅱ智能响应探针,充分发挥两者的优势,提高肿瘤的精准诊断。本文从不同的病理参数综述了可激活的NIR-Ⅱ荧光探针在生物成像中的最新研究进展,并对这一新兴的领域所面临的机遇和挑战提出看法。     

调控供电子策略简易制备近红外二区有机小分子光学诊疗试剂

有机小分子凭借着明确的化学结构、出色的生物相容性、优异的可重复性等诸多优势被广泛应用于光学诊疗领域. 然而, 目前报道的有机小分子存在合成步骤复杂、成像波长位于近红外一区(NIR-I)、光热转换效率及单线态氧产率低等缺陷, 严重限制了其诊疗效果. 基于此, 本工作以吡咯并吡咯二酮作为缺电子单元、分别以苯、苯胺、邻苯二胺作为供电子单元, 通过一步偶联反应简易制备得到三种有机小分子DPP-0、DPP-2、DPP-4, 进一步利用纳米沉淀法制备得到对应的水溶性纳米粒子DPP-0 NPs、DPP-2 NPs和DPP-4 NPs. 研究发现, 随着氨基数量的增加, 纳米粒子吸收/发射均发生了红移, 其中DPP-4 NPs具有良好的NIR-I吸收能力且其最大荧光发射达到了近红外二区(NIR-II)区域, 表明可以通过改变供电子单元策略实现光学性能的调控. 在单一激光照射下, DPP-4 NPs可以同时产生NIR-II荧光信号、过高热及单线态氧, 其光热转换效率和单线态氧产率分别高达40.2%及34.3%, 可成功应用于肿瘤深层次NIR-II荧光成像诊断及高效光热/光动力联合治疗.     

超小金纳米簇用于荧光及CT双模态成像的研究

基于金纳米簇强烈的量子限制效应（strong quantum confinement effect,SQCE）,采用一步合成法,制备了同时具有高效近红外荧光与CT双模态成像能力的超小金纳米簇.实验表明,通过优化合成比例以及合成条件,所合成的超小金纳米簇具有很大的斯托克斯（Stokes）位移、较高的荧光强度和X射线吸收效率.除此之外,该超小金纳米簇具有良好的单分散性、稳定性和生物相容性.4T1肿瘤细胞荧光成像实验结果表明,该纳米粒子可被肿瘤细胞快速、高效地摄取.     

手术导航用荧光探针

荧光成像技术因具有操作简便、分辨率高、安全性好且可实时成像等优势,在术中导航中具有广阔的应用前景.虽然目前还没有靶向荧光探针在临床上得到批准,但已经有相当一部分荧光探针进入了临床试验阶段.最早进入临床试验的是一些偶联肿瘤靶向配体的荧光染料,例如近红外菁染料(IRDye800CW)标记的肿瘤特异抗体,叶酸标记的异硫氰酸荧...     

一种新型咔唑类菁染料黏度荧光探针

合成了一种带有醛基的咔唑类菁染料KQ, 其自身的荧光量子产率较低, 对极性的敏感性小, 且荧光信号不受核酸等生物分子的干扰. KQ对环境黏度有很好的荧光响应, 相对荧光强度随着环境黏度的增大而增强, 并且在1×10^-3~1.3216 Pa·s黏度范围内, 染料的荧光强度与溶液的黏度呈良好的线性关系. 活细胞荧光成像实验结果表明, 染料KQ具有良好的细胞膜通透性, 并可对细胞内不同位置的黏度检测成像.     

利用聚合物自组装实现绿色荧光蛋白生色团的荧光增强

根据绿色荧光蛋白的发光原理,采用聚乙二醇与聚甲基丙烯酸甲酯的两亲性两嵌段聚合物通过自组装包覆生色团的方式,模拟了绿色荧光蛋白发光,考察了组装行为对光学性能的影响,并将其用于细胞成像.通过核磁共振、高分辨质谱、傅里叶变换红外光谱、凝胶渗透色谱、紫外-可见吸收光谱及荧光光谱等表征了生色团分子和聚合物的结构及性能.生色团紫外最大吸收在371 nm,荧光最大发射峰在428 nm.聚合物和生色团进行组装后,其紫外吸收消失,而最大荧光发射峰强度大大增强,且发生了约70 nm的红移,这是因为组装使得生色团的自由旋转受到了限制,且生色团共平面性增加.动态光散射(DLS)和透射电镜(TEM)证明了纳米粒子的结构和尺寸.由于尺寸适合且具有较好的荧光性能,纳米粒子成功应用于细胞成像.这种绿色荧光蛋白生色团的简单自组装方式在生物成像领域具有良好应用前景.     

“Turn-On” Activatable AIE Dots for Tumor Hypoxia Imaging

A hypoxia-responsive fluorescence probe of amphiphilic PEGylated azobenzene caged tetraphenylethene (TPE) for tumor cell imaging is reported; it possesses excellent solubility in aqueous medium due to the easy formation of micelles by self-assembly. The fluorescence resonance energy transfer (FRET) process ensures that the fluorescence of the azobenene caged AIE fluorogen is quenched efficiently. When cultured with tumor cells, the azo-bond is reduced under hypoxia conditions and the fluorescence of AIE fluorogen recovers dramatically. Besides using UV light, NIR light can also be used as the excited light resource to generate the fluorescence due to the two-photon fluorescence imaging process.     

A New Tetraphenylethylene‐Derived Fluorescent Probe for Nitroreductase Detection and Hypoxic‐Tumor‐Cell Imaging

The fluorescence detection of nitroreductase (NTR) and evaluation of the hypoxia status of tumor cells are vital, not only for clinical diagnoses and therapy, but also for biomedical research. Herein, we report the synthesis and application of a new fluorometric “turn‐on” probe for the detection of NTR ( TPE?NO₂ ) that takes advantage of the aggregation‐induced emission of tetraphenylethylene. TPE?NO₂ can detect NTR at concentrations as low as 5 ng mL^?1 in aqueous solution. The detection mechanism relied on the aggregation and deaggregation of tetraphenylethylene molecules. Moreover, this fluorescent probe can be used to monitor the hypoxia status of tumor cells through the detection of endogenous NTR.     

A Lysosome‐Compatible Near‐Infrared Fluorescent Probe for Targeted Monitoring of Nitric Oxide

The requirement for nitric oxide (NO) of lysosomes has motivated the development of a sophisticated fluorescent probe to monitor the distribution of this important biomolecule at the subcellular level in living cells. A near‐infrared (NIR) fluorescent Si‐rhodamine (SiRB)‐NO probe was designed based on the NO‐induced ring‐opening process of Si‐rhodamine. The probe exhibits fast chromogenic and fluorogenic responses, and high sensitivity and selectivity toward trace amounts of NO. Significantly, the spirolactam in Si‐rhodamine exhibits very good tolerance to H⁺, which in turn brings extremely low background fluorescence not only in the physiological environment but also under acidic conditions. The stability of the highly fluorescent product in acidic solution provides persistent fluorescence emission for long‐term imaging experiments. To achieve targeted imaging with improved spatial resolution and sensitivity, an efficient lysosome‐targeting moiety was conjugated to a SiRB‐NO probe, affording a tailored lysosome‐targeting NIR fluorescent Lyso‐SiRB‐NO probe. Inheriting the key advantages of its parent SiRB‐NO probe, Lyso‐SiRB‐NO is a functional probe that is suited for monitoring lysosomal NO with excellent lysosome compatibility. Imaging experiments demonstrated the monitoring of both exogenous and endogenous NO in real time by using the Lyso‐SiRB‐NO probe.     

罗丹明6G衍生物基偏酸性“关开型”pH荧光探针

以罗丹明6G和水合肼为原料,先制备罗丹明6G酰肼,接着在乙醇中滴加少量冰醋酸做催化剂后与2,5-二甲氧基苯甲醛反应,合成了一种新型的pH荧光分子探针(RGSBD),进行了结构表征及荧光性能研究。结果表明,原本在氢离子浓度较低,即体系pH较高时(pH≥4.0),探针RGSBD内酰胺螺环闭环导致不显示荧光并且无色,然而在氢离子浓度较大即体系pH较低时(pH<4.0)时,其内酰胺螺环闭环产生了明显的颜色变化,发出强烈的荧光。pH 1.9时,探针的荧光强度达到最大,最大荧光峰发生显著的红移。进一步研究表明,探针RGSBD的荧光峰强度差值与pH在1.9~3.2范围内呈良好的线性关系,探针RGSBD识别H^+的选择性高,稳定性与可逆性强,可发展用作生物体内pH荧光传感材料。     

Exclusive Detection of Sub‐Nanomolar Levels of Palladium(II) in Water: An Excellent Probe for Multiple Applications

A new colorimetric probe has been developed for the detection and estimation of Pd^II at sub‐nanomolar concentrations. The probe consisted of rhodamine (signaling unit), which was linked with a bis‐picolyl moiety (binding site) through a phenyl ring. Pd^II induced opening of the spirolactam ring of the probe with the generation of a prominent pink color. The excellent selectivity of the probe towards Pd^II over Pd⁰ or Rh^II ensured its potential utility for the detection of residual palladium contamination in pharmaceutical drugs and in Pd‐catalyzed reactions. The probe showed a “turn‐on” (bright yellow) fluorescence upon the addition of Pd^II, which made it suitable for the detection of Pd contaminants in mammalian cells.     

Synthesis, crystal structure and living cell imaging of a Cu(2+)-specific molecular probe

We report the development of a rhodamine chromene-based fluorescence probe to monitor the intracellular Cu(2+) level in living cells. The new fluorescent probe exhibits a fluorescence response towards Cu(2+) under physiological conditions with high sensitivity and selectivity, and facilitates the naked-eye detection of Cu(2+). The fluorescence intensity was significantly increased by about 40-fold with 10 equiv. of added Cu(2+).     

Imaging brain tumor by dendrimer-based optical/paramagnetic nanoprobe across the blood-brain barrier

A multimodal optical/paramagnetic nanoprobe, Den-Angio, was developed and demonstrated a capability to circumvent the blood brain barrier (BBB) and visualize brain tumors with high sensitivity in vivo. Den-Angio holds promise to pre-operatively localize brain tumors and make image-guided tumor resection possible during surgery.     

Tumor-homing peptide-based NIR-II probes for targeted spontaneous breast tumor imaging

Fluorescence imaging in the second near-infrared window(NIR-Ⅱ,1000-1700 nm) is a promising modality for real-time imaging of cancer and image-guided surgery with superior in vivo optical properties.So far,very few NIR-Ⅱ fluorophores have been reported for in vivo biomedical imaging of chemically-induced spontaneous breast carcinoma.Herein,a NIR-Ⅱ fluorescent probe CH1055-F3 with the nucleolin-targeted tumor-homing peptide F3 was demonstrated to prefe rentially accumulate in 4 T1 tumors.More importantly,CH1055-F3 exhibited specific NIR-Ⅱ signals with high spatial and temporal resolution,strong tumor uptake,and remarkable NIR-Ⅱ image-guided surgery in dimethylbenzanthracene(DMBA)-induced spontaneous breast tumor rats.This report presents the first tumor-homing peptide-based NIR-Ⅱ probe to diagnose transplantable and spontaneous breast tumors by the active targeting.     

A novel fluorescent probe derived from isophorone and its application in imaging in vivo hypoxia

Herein, an isophorone-derived fluorescent probe, ARP, was developed to realize the imaging of in vivo hypoxia under the catalysis of the typical enzyme AzoR. Under the excitation at 456 nm, the detecting system with ARP could exhibit a red emission signal at 638 nm. ARP indicated advantages including high sensitivity (LOD = 0.37 Eq), high selectivity, anti-interference ability and wide pH adaption (3.0–12.0). Moreover, ARP could image the aggravation of the hypoxia in both the incubating oxygen percentage scale and the time scale in living cells. The AzoR-activated mechanism was convinced by the experimental result of adding inhibitors and illustrated by the molecular docking simulation. ARP could co-locate with the commercial dyes in the endoplasmic reticulum (ER), lysosomes, and mitochondria, which meant that ARP might be sensitive to the occurrence of the oxidation-reduction process or the passage through the intracellular membranes. Further, ARP achieved the imaging of hypoxia in both mice tumor model as well as tying model. ARP could distinguish the tumor site or the tied-up position according to the hypoxia extent. Therefore, this work raised a new trial for the imaging of the hypoxia, and might be helpful in future designs of more pragmatic fluorescent implements.     

Azo‐Based Fluorogenic Probes for Biosensing and Bioimaging: Recent Advances and Upcoming Challenges

T he use of nonfluorescent azo dyes as dark quenchers in activatable optical bioprobes based on the Förster resonance energy transfer (FRET) mechanism and designed to target a wide range of enzymes has been established for over two decades. The key value of the azo moiety (−N=N−) to act as an efficient “ON–OFF” switch of fluorescence once introduced within the core structure of conventional organic‐based fluorophores (mainly fluorescent aniline derivatives) has recently been exploited in the development of alternative reaction‐based small‐molecule probes based on the “profluorescence” concept. These unprecedented “azobenzene‐caged” fluorophores are valuable tools for the detection of a wide range of reactive (bio)analytes. This review highlights the most recent and relevant advances made in the design and biosensing/bioimaging applications of azo‐based fluorogenic probes. Emphasis is also placed on relevant achievements in the synthesis of bioconjugatable/biocompatible azo dyes used as starting building blocks in the rational and rapid construction of these fluorescent chemodosimeters. Finally, a brief glimpse of possible future biomedical applications (theranostics) of these “smart” azobenzene‐based molecular systems is presented.