基于硅杂蒽类染料的荧光探针及其应用

近年来,荧光成像技术为人们研究活体细胞及组织内的化学生物学过程提供了有效的研究工具,可以无损、实时、原位地以高时空分辨率实现对目标物进行生物荧光成像与分析。荧光成像技术在生物学、环境监测、临床诊断和药物发现等诸多研究领域发挥着越来越重要的作用。生物荧光成像技术的最新进展对发展新型小分子荧光染料及探针提出了更高的要求。激发和发射波长位于近红外光区（600~900 nm）的荧光染料及探针由于具有光毒性低、生物分子自发荧光干扰小、光散射低、组织穿透能力强等优点,非常适合用于生物荧光成像领域。通过将罗丹明分子中O桥原子用Si代替,得到了一类新型的探针分子--硅杂蒽类荧光探针。这类染料分子在保留了氧杂蒽荧光染料优越的光学性质的同时,光谱发生明显红移,满足了近红外荧光检测的要求,具有良好的生物相容性。本文综述了近年来基于硅杂蒽及其衍生物荧光探针的合成及在金属离子、pH值、小分子、生物酶等检测方面的研究进展,并且简要阐述了基于硅杂蒽类探针分子的识别检测机理以及其在生物成像等方面的应用。     

单分子定位超分辨显微成像有机荧光探针的研究进展

在生物医学领域,对纳米尺寸级别的微小生物目标进行精确定位研究具有非常重要的意义,而光学显微成像技术为此提供了强有力的工具。 光学显微成像技术受到光学衍射极限的限制,难以分辨尺寸在衍射极限(<200 nm)以下的生物结构,无法直接获取微小生物结构信息,阻碍了生物医学的进一步发展。 近年来,随着纳米分辨显微成像技术的出现,新型荧光探针的开发、成像系统与设备的不断发展及成像算法不断完善地深入结合,促进了光学衍射极限以下尺寸微观目标的研究。 基于单分子定位的超分辨荧光显微成像(SMLM)包括光激活定位成像(PALM)与随机光学重构超分辨成像(STORM),将有机荧光探针与超分辨光学显微成像技术紧密结合在一起,荧光探针的光物理性质直接决定着超分辨成像结果的好坏。 因此,设计不同性能的荧光探针可以实现超精细结构的不同超分辨成像,为研究其生物学功能提供了有力的工具。 本文着重围绕基于SMLM的原理、有机荧光探针的设计要求、用于SMLM的荧光探针种类及其生物应用等方面进行总结综述,指出了单分子定位成像上存在的不足,并对其发展方向进行了展望,希望为对超分辨成像研究感兴趣或初涉该领域的研究者提供成像理论与探针设计方面的帮助。     

近红外二区荧光探针在生物成像领域的研究进展

荧光技术具有操作简便、分辨率高且可实现实时成像等特点,已被广泛应用于生物医学检测和成像领域,其中,近红外二区荧光染料(NIR-Ⅱ,10001700 nm)由于其发射波长较长,光散射和组织自发荧光干扰较少,在生物组织成像中具有更高的时空分辨率和更深的成像深度。 本文主要介绍了基于近红外二区荧光探针的设计原理及其在生物成像领域的研究现状,并对其发展作了进一步展望。     

多光谱光声层析成像及其在生物医学中的应用

多光谱光声层析成像(MSOT)技术是一种将多光谱成像与光声层析成像(PACT)技术相结合的新技术,该技术利用不同生物组织的光谱吸收特性,用多组不同波长的短脉冲激光照射组织以产生组织特异性的光声信号,从而更好地进行光声成像和组分识别。MSOT兼具光学成像的高灵敏度、高分辨率优势和超声成像可对数厘米深组织成像的长处,同时又能弥补光学成像深度有限和超声成像对比度差的短处,能够实现深层组织的高分辨率、高对比度、高穿透深度的实时无损伤成像。迄今为止,MSOT已应用于肿瘤内光吸收粒子的检测、血管结构和血液氧合作用的评价、生物荧光蛋白的成像以及乳腺癌患者检测的初步研究。随着光声成像系统的不断改进,MSOT与生物标记物(如荧光试剂、金纳米颗粒等)结合对体内分子进行成像,在生物医学中得到了广泛的应用。本文简要综述了MOST的成像原理、实验装置及其性能特点,着重总结了其在生物医学领域的最新应用进展,尤其是在新生血管成像、肿瘤的早期诊断及肿瘤的原位成像方面。     

聚集诱导发光高分子在光学诊疗应用中的研究进展

高分子因其优异的光学特性、良好的生物相容性和分子结构易于调控等优势,在光学诊疗领域表现出巨大应用潜力.然而,传统荧光分子的聚集导致荧光淬灭现象限制了其生物应用.聚集诱导发光(AIE)分子因其聚集态高效发光的优势而备受关注.本文从AIE高分子的构建出发,重点介绍了D-A型共轭聚合物的构建策略、构-效关系以及相对于小分子的性能和应用优势,并从生物成像、肿瘤诊疗和抗菌三个方面总结了AIE高分子在光学诊疗领域的最新研究进展.生物成像方面主要总结了NIR-Ⅱ区AIE高分子在深部组织高分辨率荧光成像中的应用;肿瘤诊疗方面主要介绍了AIE高分子在光动力治疗、光热治疗及联合治疗中的应用;以及介绍了AIE高分子在细菌感染光动力治疗中的应用.最后对AIE高分子在光学诊疗领域的未来发展前景进行了展望.     

量子点在生物体系中的光学应用

量子点（QDs）与传统染料分子相比,具有量子产率高、光学漂白低、稳定性强、尺寸可调等独特的光学特性.通过与荧光、电化学发光、荧光共振能量转移、循环伏安、差分脉冲伏安以及方波伏安等光电化学技术的联用,使得量子点在DNA、蛋白质、酶等生物分子,细胞以及活体成像中的应用越来越广.本综述简单介绍了量子点的特性及制备方法,重点讨论了其在生物体系中光学检测DNA、蛋白质及酶等生物分子,细胞分析以及活体成像中的应用,并展望了其在未来生命分析中的研究趋势与前景.     

基于聚集诱导发光荧光探针的细胞成像研究进展

荧光探针是化学传感技术领域在20世纪末的一项重大发现,具有合成简单、灵敏度高、选择性好、响应时间短、可视化高等优点。 将具有聚集诱导发光现象(AIE)特征的荧光基团与具有生物相容性的高分子结合起来,使得荧光材料具有毒性低、光稳定性好、生物相容性好等特点。 在分子、离子检测和细胞成像技术中得到广泛的研究和应用。 本文综述了细胞质成像、细胞膜成像、线粒体成像、溶酶体成像、脂滴成像、细胞核成像、细胞核和线粒体双靶向性成像的荧光探针,并对其应用前景做了展望。     

嘧啶基双光子荧光染料的设计合成与生物成像

生理条件下光学性质稳定的双光子荧光染料在生物成像领域具有广阔的应用前景。我们使用2,4-二甲基-6-羟基嘧啶与4-(N,N-二甲氨基)苯甲醛进行缩合反应,设计合成了具有双光子荧光性质的化合物2-[(1E)-2-[4-(二甲氨基)苯基]乙烯基]-6-甲基-4(3H)-嘧啶(NHP)。通过质谱(MS)、核磁共振波谱(NMR)、紫外可见吸收光谱和荧光发射光谱等技术手段表征了其结构,研究了其光物理性质,以及外部环境改变对其发射光谱的影响。结果表明,化合物NHP的最佳吸收峰位于400 nm,最佳发射峰位于540 nm左右,且荧光发射不受金属离子、氨基酸和pH等环境因素的影响。生物实验结果表明,化合物NHP细胞毒性较小,且具有很好的活细胞和果蝇脑组织成像效果,是一种较为理想的双光子荧光生物成像染料。     

近红外荧光染料的结构、性质及生物荧光成像应用

近红外荧光生物成像技术由于具有深的组织穿透性、低背景荧光干扰、最小生物样本光损伤等特点引起人们越来越多的关注。开发高荧光效率、低毒性的近红外荧光染料是近红外荧光成像技术发展的关键所在。本文综述了五类主要的有机近红外荧光染料(菁类、BODIPY类、罗丹明类、方酸类、卟啉类)的研究进展,重点分析其结构与光学性质等构效关系,为近红外荧光染料的设计和制备提供指导。另外,总结了有机近红外荧光材料功能化修饰的主要方法以改善生物相容性、靶向性能等,最后对近红外荧光染料存在的主要问题以及未来的热点方向进行了分析和展望。     

稀土纳米材料在高分辨活体成像及诊疗中的应用

荧光成像具有时空分辨率高、 反馈快、 非侵入和无电离辐射等优点, 是一种重要的生物成像技术. 与传统用于荧光成像的可见光和近红外一区(NIR-I, 600~950 nm)相比, 近红外二区(NIR-Ⅱ, 1000~1700 nm)窗口具有低生物组织散射系数和低生物自发荧光, 采用NIR-Ⅱ光进行活体荧光成像能有效提高成像的分辨率、 信噪比和穿透深度. 稀土纳米颗粒(RENPs)具有大斯托克斯位移、 高化学稳定性、 可调的荧光寿命以及较窄的发射带, 是一种重要的荧光成像探针. 近年来, 一系列具有优异的NIR-Ⅱ发光性能的稀土纳米材料被用于高分辨活体荧光成像. 本文综合评述了近年来RENPs用于高分辨活体成像及诊疗中的研究进展, 概述了RENPs的掺杂调控、 基质晶格选择和复合敏化等NIR-Ⅱ发光增强策略, 介绍了其在多种生物医学场景中的靶向聚集、 荧光传感和疾病治疗等功能, 并总结了其在多路成像、 多模态成像和疾病诊疗中的应用. 最后, 简要分析了RENPs在未来生物医学应用中面临的挑战和发展的方向.     

光学相干层析技术在法庭科学中的新应用

光学影像技术是法庭科学物证检验分析的重要技术手段，具有无损、原位、快速等优势。近年来，随着光学影像技术的不断发展，一些新技术、新方法不断被引入法庭科学领域并付诸应用。光学相干层析技术（简称OCT技术）是一种光学断层成像技术，具有无损、高分辨、快速、断层成像的特点，特别是其可以无损地得到材料或生物组织内部的结构信息，突破了传统二维成像只能进行物质表面分析的局限，因此可成为一种很有前景的新型法庭科学光学影像技术。本文首先介绍了自主搭建的一套三维OCT成像系统，并着重介绍了基于该系统应用于法庭科学油漆物证检验、胶带指纹显现和毛囊特征分析等方面的研究。结果表明，OCT技术非常适合用于法庭科学物证检验分析，作为其他检验的先导技术手段，获取样品内部信息，提取新型光学特征参数。由于其采用光纤化技术，还有望实现便携化、小型化，在现场勘查中开展相关应用。     

Quantitative analysis in medicine using photoacoustic tomography

Photoacoustic imaging, or photoacoustic tomography, is a 2D or 3D optical imaging method based on localized optical absorption of pulsed laser radiation. By a spatially resolved detection of the following thermoelastic expansion, the local distribution of the absorption can be determined. The technique has been proven to have significant potential for the imaging of human and animal organs and single blood vessels, combining high contrast with good spatial resolution. The contrast is based on the specific optical absorption of certain components in the visible and near-infrared spectral range, for most applications of blood. Generally, the images represent the local distribution of blood in a qualitative or semiquantitative way. Although photoacoustic imaging is capable of revealing absolute and spatially resolved concentrations of endogenous (such as oxyhemoglobin and deoxyhemoglobin) or artificial (such as tumor markers) chromophores, only a very limited number of publications have dealt with this demanding task. In this report, the problems involved and possible solutions are reviewed and summarized.     

Combined optoacoustic/ultrasound system for tomographic absorption measurements: possibilities and limitations

In this paper, we present the OPUS (optoacoustic plus ultrasound) system, which is a combination of a wavelength-tunable pulsed optical parametrical oscillator (OPO) laser with a commercial ultrasound (US) scanner. Optoacoustic (OA) or, synonymously, photoacoustic (PA) imaging is a spectroscopic technique to measure optical absorption in semitransparent solids and liquids. The measured signal is an acoustical pressure wave, which represents the absorption of pulsed optical radiation. By temporally and spatially resolved detection of the pressure wave on the sample surface, a 2D or even 3D image of the distribution of the optical absorption in the sample can be generated. In recent years, OA tomography has found increasing application in medical imaging. Most of these applications are based on qualitative OA imaging. The reported system is intended primarily for breast cancer detection, in which the optoacoustic imaging modality offers additional information to the ultrasound image. Consequently, the system is developed in a way that the OA imaging mode can be installed without major changes to the US instrument. The capabilities of the OPUS system for the quantitative analysis of absorber concentrations in tissue models are exploited.     

Functional tumor imaging based on inorganic nanomaterials

Inorganic nanomaterials have attracted substantial research interest due to their unique intrinsic physicochemical properties.We highlighted recent advances in the applications of inorganic nanoparticles regarding their imaging efficacy, focusing on tumor-imaging nanomaterials such as metal-based and carbon-based nanomaterials and quantum dots. Inorganic nanoparticles gain excellent in vivo tumor-imaging functions based on their specific characteristics of strong near-infrared optical absorption and/or X-ray attenuation capability. The specific response signals from these novel nanomaterials can be captured using a series of imaging techniques, i.e., optical coherence tomography(OCT), X-ray computed tomography(CT) imaging, two-photon luminescence(TPL), photoacoustic tomography(PAT), magnetic resonance imaging(MRI), surface-enhanced Raman scattering(SERS) and positron emission tomography(PET). In this review, we summarized the rapid development of inorganic nanomaterial applications using these analysis techniques and discussed the related safety issues of these materials.     

Recent advances in organic-dye-based photoacoustic probes for biosensing and bioimaging

Photoacoustic imaging(PAI) is a non-destructive biomedical imaging technology with broad application prospects. PAI combines the advantages of optical imaging and ultrasound imaging with high selectivity and deep penetration to overcome the high scattering limitation of light in tissues. This emerging technology also achieves high-resolution and high-contrast imaging of deep tissue in vivo. Recently, photoacoustic(PA) probes based on organic dyes have emerged prominently in biosensing and bioimaging due to their excellent optical properties and structural adaptability. This paper gives an outline of the basic PAI principles and focuses on the application of organic-dye-based PA probes for molecular detection and in vivo imaging. The advantages of PAI technology and the drawbacks of current PA probes are then summarized. Finally, the prospects for application are evaluated considering the potential challenges in the biomedical fields.     

Synthesis of 11C, 18F, 15O, and 13N radiolabels for positron emission tomography

Positron emission tomography (PET) is a powerful and rapidly developing area of molecular imaging that is used to study and visualize human physiology by the detection of positron-emitting radiopharmaceuticals. Information about metabolism, receptor/enzyme function, and biochemical mechanisms in living tissue can be obtained directly from PET experiments. Unlike magnetic resonance imaging (MRI) or computerized tomography (CT), which mainly provide detailed anatomical images, PET can measure chemical changes that occur before macroscopic anatomical signs of a disease are observed. PET is emerging as a revolutionary method for measuring body function and tailoring disease treatment in living subjects. The development of synthetic strategies for the synthesis of new positron-emitting molecules is, however, not trivial. This Review highlights key aspects of the synthesis of PET radiotracers with the short-lived positron-emitting radionuclides (11)C, (18)F, (15)O, and (13)N, with emphasis on the most recent strategies.     

Activatable Molecular Probes for Second Near‐Infrared Fluorescence,Chemiluminescence, and Photoacoustic Imaging

Optical imaging plays a crucial role in biomedicine. However, due to strong light scattering and autofluorescence in biological tissue between 650–900 nm, conventional optical imaging often has a poor signal‐to‐background ratio and shallow penetration depth, which limits its ability in deep‐tissue in vivo imaging. Second near‐infrared fluorescence, chemiluminescence, and photoacoustic imaging modalities mitigate these issues by their respective advantages of minimized light scattering, eliminated external excitation, and ultrasound detection. To enable disease detection, activatable molecular probes (AMPs) with the ability to change their second near‐infrared fluorescence, chemiluminescence, or photoacoustic signals in response to a biomarker have been developed. This Minireview summarizes the molecular design strategies, sensing mechanisms, and imaging applications of AMPs. The potential challenges and perspectives of AMPs in deep‐tissue imaging are also discussed.     

Molecular Targeting of Epidermal Growth Factor Receptor (EGFR) and Vascular Endothelial Growth Factor Receptor (VEGFR)

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) are two extensively studied membrane-bound receptor tyrosine kinase proteins that are frequently overexpressed in many cancers. As a result, these receptor families constitute attractive targets for imaging and therapeutic applications in the detection and treatment of cancer. This review explores the dynamic structure and structure-function relationships of these two growth factor receptors and their significance as it relates to theranostics of cancer, followed by some of the common inhibition modalities frequently employed to target EGFR and VEGFR, such as tyrosine kinase inhibitors (TKIs), antibodies, nanobodies, and peptides. A summary of the recent advances in molecular imaging techniques, including positron emission tomography (PET), single-photon emission computerized tomography (SPECT), computed tomography (CT), magnetic resonance imaging (MRI), and optical imaging (OI), and in particular, near-IR fluorescence imaging using tetrapyrrolic-based fluorophores, concludes this review.     

Optical imaging in tissue with X-ray excited luminescent sensors

We report a high-spatial resolution imaging technique to measure optical absorption and detect chemical and physical changes on surfaces embedded in thick tissue. Developing sensors to measure chemical concentrations on implanted surfaces through tissue is an important challenge for analytical chemistry and biomedical imaging. Tissue scattering dramatically reduces the resolution of optical imaging. In contrast, X-rays provide high spatial resolution imaging through tissue but do not measure chemical concentrations. We describe a hybrid technique which uses a scanning X-ray beam to irradiate Gd(2)O(2)S scintillators and detect the resulting visible luminescence through the tissue. The amount of light collected is modulated by optical absorption in close proximity to the luminescence source. By scanning the X-ray beam, and measuring total amount of light collected, one can measure the local absorption near scintillators at a resolution limited by the width of luminescence source (i.e. the width of the X-ray excitation beam). For proof of principle, a rectangular 1.7 mm scanning X-ray beam was used to excite a single layer of 8 μm Gd(2)O(2)S particles, and detect the absorption of 5 nm thick silver island film through 10 mm of pork. Lifetime and spectroscopic measurements, as well changing the refractive index of the surroundings indicate that the silver reduces the optical signal through attenuated total internal reflection. The technique was used to image the dissolution of regions of the silver island film which were exposed to 1 mM of H(2)O(2) through 1 cm of pork tissue.     

Optical imaging: bacteria,viruses, and mammalian cells encoding light-emitting proteins reveal the locations of primary tumors and metastases in animals

Early detection of tumors and their metastases is crucial for the prognosis of cancer treatment. Traditionally, tumor detection is achieved by various methods, including magnetic resonance imaging and computerized tomography. With the recent cloning, cellular expression, and real-time imaging of light-emitting proteins, such as Renilla luciferase (Ruc), bacterial luciferase (Lux), firefly luciferase (Luc), green fluorescent protein (GFP), or Ruc-GFP fusion protein, significant efforts have been focused on using these marker proteins for tumor detection. It has also been demonstrated that certain bacteria, viruses, and mammalian cells (BVMC), when administered systemically, are able to gain entry and replicate selectively in tumors. In addition, many tissue/tumor specific promoters have been cloned which allow transgene expression specifically in tumor tissues. Therefore, when light-emitting protein encoded BVMC are injected systemically into rodents, tumor-specific marker gene expression is achieved and is detected in real time based on light emission. Consequently, the locations of primary tumors and previously unknown metastases in animals are revealed in vivo. In the future it will likely be feasible to use engineered light-emitting BVMC as probes for tumor detection and as gene-delivery vehicles in vivo for cancer therapy.