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。     

近红外二区有机小分子荧光探针

荧光成像凭借灵敏度高、特异性强等诸多优势在重大疾病的诊疗领域发挥着重要作用.然而传统的近红外一区（NIR-I,700~900 nm）荧光成像存在组织穿透性差等问题,限制了其临床应用.近红外二区（NIR-II,1000~1700 nm）荧光成像可以极大地减弱生物组织对光的吸收、散射和自发荧光,从而显著提升成像深度及成像效果.在众多NIR-II荧光探针中,有机小分子由于具有毒性低、代谢快等优点正成为该领域的研究热点.作者以近年来NIR-II有机小分子荧光探针的发展为主体,概括了提升探针荧光量子产率的策略,分别就可激活型、多模态成像型和诊疗一体化型NIR-II荧光探针进行分类讨论,系统介绍了近年来该领域内的研究成果,并针对NIR-II荧光探针未来的发展进行了展望.     

近红外荧光探针检测金属离子、小分子和生物大分子

荧光探针技术是近年来发展迅速的一种荧光分析方法,具有灵敏度高、选择性好、操作简便和响应迅速等特点,受到环境及生命科学领域的青睐。随着荧光探针技术的发展,近红外一区荧光探针由于具有发射波长长(600~900 nm)、对细胞损伤小、组织穿透性强和自发荧光背景低等优点,被广泛应用于细胞、组织等复杂生物体系中生物分子的检测、示踪及成像。本文评述了近年来(2016~2020年)近红外荧光探针对金属离子(Hg²⁺、Cu²⁺、Zn²⁺、Al³⁺、Fe³⁺)、生物小分子(Cys、N₂H₄、H₂S、H₂O₂)与生物大分子(亮氨酸氨基肽酶、β-半乳糖苷酶)等重要生物分子的检测及成像的研究进展,讨论了该类探针在细胞及活体的分析应用,并对近红外荧光探针的前景进行了展望。     

近红外二区活体荧光成像在肿瘤诊疗中的应用

由于具备组织穿透深度深和时空分辨率高等优势, 近年来近红外二区(Near-infrared-Ⅱ, NIR-Ⅱ, 1000~1700 nm)荧光成像技术得到了快速发展, 其在肿瘤临床诊断和治疗的潜力更是引发了广泛关注. 本文首先阐释了NIR-Ⅱ窗口荧光成像的原理及其优势, 随后根据结构分类归纳总结了现有荧光团的特征, 重点介绍了荧光探针在性能优化上的进展以及在肿瘤早期检测、 术中导航和光疗中的应用, 最后讨论了现有NIR-Ⅱ 荧光探针的局限以及临床转化面临的挑战, 并对未来的发展方向进行了展望.     

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.     

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.     

pH响应型近红外菁类荧光探针的合成及细胞成像

癌症的早期诊治是提高癌症患者治愈率的关键。但传统的"always on"型显影剂存在自身背景干扰且易造成"假阳性"等问题。本文利用肿瘤细胞具有弱酸性这一特性,设计合成了p H激活型不对称菁类荧光探针,并选用氨基葡萄糖作为修饰基团以增强探针母体的水溶性并赋予其肿瘤靶向性。该探针具有p H调控的"off-on"可逆的近红外荧光特性,以及与肿瘤弱酸性微环境相吻合的p H响应范围。此外,探针的浓度高达1.0×10~(-5)mol/L时仍未表现出明显的细胞毒性。该探针在细胞水平实现了肿瘤细胞弱酸性微环境的特异性成像。     

用于肿瘤成像的半乳糖/酞菁近红外荧光探针

本文首次报道半乳糖酞菁近红外荧光探针在肿瘤成像方面的应用。以酞菁为荧光发射基团,其在近红外区域有较高的量子产量和光学稳定性,可以解决探针的近红外光学特性;通过半乳糖对酞菁的修饰能够改善探针的溶解性和生物相容性,而且利用半乳糖的肿瘤靶向功能可以提高探针肿瘤主动靶向成像效果。结果表明它对恶性肿瘤具有高特异性结合和高灵敏度的分子探针体系,提高近红外光学分子成像效果。     

近红外荧光BSA-CdSeTe探针的制备及在生物学中的应用

本文用半胱氨酸作表面修饰剂,水相合成水溶性的近红外量子点CdSeTe,并偶联标记BSA,形成近红外BSA-CdSeTe探针。对CdSeTe QDs和BSA-CdSeTe探针进行荧光光谱分析,探讨了pH值、CdSeTe用量和反应时间这三个因素对近红外BSA-CdSeTe探针荧光强度的影响,对近红外BSA-CdSeTe探针进行了体外细胞成像实验和细胞毒性实验。结果表明,制得的CdSeTe粒径约5 nm,BSA-CdSeTe粒径约19 nm。当λex≈470 nm时,二者的λem均在750 nm左右。在pH=8、1m L CdSeTe和反应120 min时体系的荧光强度最大。当BSACdSeTe探针浓度在4~200μg·mL~(-1)范围之间,L929细胞的存活率均在85%之上。该探针在近红外荧光显微镜中可视,与L929细胞共孵育后可实现实时成像。因此,近红外荧光探针BSA-CdSeTe是一种可以进行实时细胞成像且生物相容性良好的纳米探针。     

基于共轭聚合物的纳米粒子用于肿瘤的近红外二区荧光成像及光热治疗

为提高生物组织荧光成像质量以及对肿瘤的高效光热治疗,设计合成了一种新型的窄带隙共轭聚合物(BDT-TTQ),并通过纳米沉积的方式将聚合物制备成水溶性纳米粒子(BDT-TTQ NPs).该共轭聚合物纳米粒子在1000~1200 nm近红外二区范围具有较好的吸收,在1064 nm的激发光下能实现1200~1400 nm的近红外二区荧光成像. BDT-TTQ NPs纳米粒子粒径分布较窄,形貌呈规则的球形且分散均匀,具有好的生物相容性.该纳米粒子既可以在体外实现较高的近红外二区荧光成像穿透深度,又可以实现对小鼠活体血管的高清晰度的近红外二区荧光成像.此外,BDT-TTQ NPs纳米粒子在1064 nm激光下展现出优异的光热转换效率,具有较高的光毒性,对体外的肿瘤细胞以及小鼠的异质瘤具有高的光热杀伤能力.     

Discovery of naphthalimide conjugates as fluorescent probes for α_1-adrenoceptors

α_1-Adrenoceptors(α_1-ARs), including at least three subtypes, α_(1A), α_(1B) and α_(1D), which play essential roles in G protein-coupled receptors(GPCRs), can convey multiple pivotal extracellular signals in varied tissues and organs. In this research, a series of napthalimide-based small-molecule fluorescent probes(1a–1f) for α_1-ARs, including two parts, a pharmacophore(quinazoline and phenylpiperazine) for α_1-AR recognition and a fluorophore(naphthalimide) for visualization, were designed and synthesized successfully. These compounds display excellent fluorescence property and high affinity to receptors,which were used successfully for in vitro visualization of α_1-adrenoceptors.     

Development of Radiogallium-Labeled Peptides for Platelet-Derived Growth Factor Receptor β (PDGFRβ) Imaging: Influence of Different Linkers

The purpose of this study is to develop peptide-based platelet-derived growth factor receptor β (PDGFRβ) imaging probes and examine the effects of several linkers, namely un-natural amino acids (D-alanine and β-alanine) and ethylene-glycol (EG), on the properties of Ga-DOTA-(linker)-IPLPPPRRPFFK peptides. Seven radiotracers, ⁶⁷Ga-DOTA-(linker)-IPLPPPRRPFFK peptides, were designed, synthesized, and evaluated. The stability and cell uptake in PDGFRβ positive peptide cells were evaluated in vitro. The biodistribution of [⁶⁷Ga]Ga-DOTA-EG₂-IPLPPPRRPFFK ([⁶⁷Ga]27) and [⁶⁷Ga]Ga-DOTA-EG₄-IPLPPPRRPFFK ([⁶⁷Ga]28), which were selected based on in vitro stability in murine plasma and cell uptake rates, were determined in BxPC3-luc-bearing nu/nu mice. Seven ⁶⁷Ga-labeled peptides were successfully synthesized with high radiochemical yields (>85%) and purities (>99%). All evaluated radiotracers were stable in PBS (pH 7.4) at 37 °C. However, only [⁶⁷Ga]27 and [⁶⁷Ga]28 remained more than 75% after incubation in murine plasma at 37 °C for 1 h. [⁶⁷Ga]27 exhibited the highest BxPC3-luc cell uptake among the prepared radiolabeled peptides. As regards the results of the biodistribution experiments, the tumor-to-blood ratios of [⁶⁷Ga]27 and [⁶⁷Ga]28 at 1 h post-injection were 2.61 ± 0.75 and 2.05 ± 0.77, respectively. Co-injection of [⁶⁷Ga]27 and an excess amount of IPLPPPRRPFFK peptide as a blocking agent can significantly decrease this ratio. However, tumor accumulation was not considered sufficient. Therefore, further probe modification is required to assess tumor accumulation for in vivo imaging.     

具有肿瘤荧光成像性能的核壳纳米过氧化氢酶模拟物

运用微波法在硅核壳荧光材料的表面修饰了2-(二吡啶甲胺基)丙酸的锰配合物,获得具有荧光性能的锰-硅核壳纳米结构复合物,运用IR,UV,TEM等方法表征了纳米复合物的结构。H2O2岐化实验显示锰-硅核壳纳米复合物具有较好的过氧化氢酶模拟特性,是一种新的纳米过氧化氢酶模拟物。体外细胞荧光成像研究表明2-(二吡啶甲胺基)丙酸修饰的纳米球不能进入肿瘤细胞内,而锰-硅核壳纳米复合物能进入肿瘤细胞内,具备良好的肿瘤靶向性,显著提高肿瘤荧光成像效果,可作为新型的肿瘤成像剂。     

以交叉分子束及时间切片离子速度成像法研究产物成对相关讯息

A novel experimental technique has been developed to measure the attributes of product pair correlation of bimolecular reactions under the crossed molecular beam condition. The first system that we picked is F + CD4/CHD3 / CH4 reactions. By combining a crossed molecular beam method with a time-sliced ion velocity imaging technique,the product state-resolved pair-correlated differential cross sections were revealed directly from the measurements. Several facets of the product pair correlation have been explored. The dependence on the collisional energy has been elucidated. The pair-correlated angular distributions show strong dependences on the HF/DF vibrational quantum numbers,and weaker yet not negligible dependences on the methyl radical vibrational quantum numbers. For the F + CH4 reaction at collisional energies close to the reaction threshold,the first experimental evidences of a reactive resonance in a polyatomic reaction were discovered. The product pair-correlated information helps us to unravel the complexity of polyatomic reactions and offers the important link between A + BC type of reactions and more general polyatomic reactions.     

电化学发光成像技术及其在阵列传感分析和潜在指纹成像分析中的应用

电化学发光成像技术作为一种新的生化分析手段,具有设备简单、反应可控、多信息化和可视化等优点. 目前,该技术已被用于便携式、微型化、高通量的电化学发光传感器中,并取得了一系列创新性成果. 本文结合作者课题组的研究进展,简要介绍了电化学发光成像技术在阵列传感分析和潜在指纹检测中的应用,并尝试着展望了今后的发展趋势.     

Extracellular matrix alterations in low‐grade lung adenocarcinoma compared with normal lung tissue by imaging mass spectrometry

Lung adenocarcinoma (LUAD) is the second most common cancer, affecting both men and women. Fibrosis is a hallmark of LUAD occurring throughout progression with excess production of extracellular matrix (ECM) components that lead to metastatic cell processes. Understanding the ECM cues that drive LUAD progression has been limited due to a lack of tools that can access and report on ECM components within the complex tumor microenvironment. Here, we test whether low‐grade LUAD can be distinguished from normal lung tissue using a novel ECM imaging mass spectrometry (ECM IMS) approach. ECM IMS analysis of a tissue microarray with 20 low‐grade LUAD tissues and 20 normal lung samples from 10 patients revealed 25 peptides that could discriminate between normal and low‐grade LUAD using area under the receiver‐operating curve (AUC) ≥0.7, P value ≤.001. Principal component analysis demonstrated that 62.4% of the variance could be explained by sample origin from normal or low‐grade tumor tissue. Additional work performed on a wedge resection with moderately differentiated LUAD demonstrated that the ECM IMS analytical approach could distinguish LUAD spectral features from spectral features of normal adjacent lung tissue. Conventional liquid chromatography with tandem mass spectrometry (LC‐MS/MS) proteomics demonstrated that specific sites of hydroxylation of proline (HYP) were a main collagen post translational modification that was readily detected in LUAD. A distinct peptide from collagen 3A1 modified by HYP was increased 3.5 fold in low‐grade LUAD compared with normal lung tissue (AUC 0.914, P value <.001). This suggests that regulation of collagen proline hydroxylation could be an important process during early LUAD fibrotic deposition. ECM IMS is a useful tool that may be used to define fibrotic deposition in low‐grade LUAD.     

Cyclodextrin-Based Contrast Agents for Medical Imaging

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides consisting of multiple glucose subunits. CDs are widely used in host–guest chemistry and biochemistry due to their structural advantages, biocompatibility, and ability to form inclusion complexes. Recently, CDs have become of high interest in the field of medical imaging as a potential scaffold for the development of a large variety of the contrast agents suitable for magnetic resonance imaging, ultrasound imaging, photoacoustic imaging, positron emission tomography, single photon emission computed tomography, and computed tomography. The aim of this review is to summarize and highlight the achievements in the field of cyclodextrin-based contrast agents for medical imaging.     

A tutorial on support vector machine-based methods for classification problems in chemometrics

This tutorial provides a concise overview of support vector machines and different closely related techniques for pattern classification. The tutorial starts with the formulation of support vector machines for classification. The method of least squares support vector machines is explained. Approaches to retrieve a probabilistic interpretation are covered and it is explained how the binary classification techniques can be extended to multi-class methods. Kernel logistic regression, which is closely related to iteratively weighted least squares support vector machines, is discussed. Different practical aspects of these methods are addressed: the issue of feature selection, parameter tuning, unbalanced data sets, model evaluation and statistical comparison. The different concepts are illustrated on three real-life applications in the field of metabolomics, genetics and proteomics.     

Clinical Relevance of [18F]Florbetaben and [18F]FDG PET/CT Imaging on the Management of Patients with Dementia

PET of β-Amyloid plaques (Aβ) using [¹⁸F]florbetaben ([¹⁸F]FBB) and [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) increasingly aid clinicians in early diagnosis of dementia, including Alzheimer’s disease (AD), frontotemporal disease, dementia with Lewy bodies, and vascular dementia. The aim of this retrospective analysis was to evaluate clinical relevance of [¹⁸F]FBB, [¹⁸F]FDG PET and complimentary CSF measurements in patients with suspected dementia. In this study, 40 patients with clinically suspected or history of dementia underwent (1) measurement of Aβ peptides, total tau, and p-tau protein levels in the cerebrospinal fluid (CSF) compared with healthy controls (HC); (2) clinical and neuropsychological assessment, which included Consortium to Establish a Registry for Alzheimer’s Disease neuropsychological assessment battery (CERAD-NAB); (3) [¹⁸F]FBB and [¹⁸F]FDG PET imaging within an average of 3 weeks. The subjects were within 15 days stratified using PET, CSF measurements as HC, mild cognitive impaired (MCI) and dementia including Alzheimer´s disease. The predictive dementia-related cognitive decline values were supporting the measurements. PET images were evaluated visually and quantitatively using standard uptake value ratios (SUVR). Twenty-one (52.5%) subjects were amyloid-positive (Aβ+), with a median neocortical SUVR of 1.80 for AD versus 1.20 relative to the respective 19 (47.5 %) amyloid-negative (Aβ-) subjects. Moreover, the [¹⁸F]FDG and [¹⁸F]FBB confirmed within a sub-group of 10 patients a good complimentary role by correlation between amyloid pathology and brain glucose metabolism in 8 out of 10 subjects. The results suggest the clinical relevance for [¹⁸F]FBB combined with [¹⁸F]FDG PET retention and CFS measurements serving the management of our patients with dementia. Therefore, [¹⁸F]FBB combined with [¹⁸F]FDG PET is a helpful tool for differential diagnosis, and supports the patients’ management as well as treatment.     

A quinoline-based selective ‘turn on’ chemosensor for zinc(II) via quad-core complex,and its application in live cell imaging

An efficient quinoline-based fluorescent chemosensor (QLNPY) was successfully developed for the detection of zinc ions (Zn²⁺). This novel chemosensor displayed higher sensitivity and selectivity toward Zn²⁺ over other competitive metal ions accompanying with obvious fluorescence enhancement. The QLNPY-Zn²⁺ complex can be further used as a new fluorescent “turn-off” sensor for pyrophosphate (PPi) and sulfur ion (S^2?) via a Zn²⁺ displacement approach. The limits of detection were calculated to be 3.8 × 10^?8 M for Zn²⁺, 3.7 × 10^?7 M for PPi and 4.9 × 10^?7 M for S^2?. The binding mechanism of QLNPY and Zn²⁺ was investigated through NMR, HR-MS analysis and further studied by crystallographic analysis. Additionally, further application of QLNPY for sequential bioimaging of Zn²⁺ and PPi was studied in HepG2 cells, suggesting that the quinoline-based chemosensor possesses great potential applications for the detection of intracellular Zn²⁺ and PPi in vivo.