Dendritic upconverting nanoparticles for multiphoton imaging and sensing

用于多光子成像和传感的树突上转换纳米颗粒

• 批准号: 8932692
• 负责人: SERGEI VINOGRADOV
• 金额: $ 35.72万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-24 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8932692
• 关键词: Address; Angiography; Architecture; Back; Binding; Biocompatible; Biological; Biological Process; Blood flow; Brain; Cerebrovascular Circulation; Cerebrum; Coupled; Dendrimers; Detection; Dyes; Electric Stimulation; Energy Transfer; Evaluation; Fluorescence; Frequencies; Functional Magnetic Resonance Imaging; Goals; Health; Image; Imagery; Imaging Techniques; Ions; Lanthanoid Series Elements; Lasers; Ligands; Light; Measurement; Methods; Microscopic; Microscopy; Modification; Morphology; Mus; Neurosciences; Optics; Oxygen; Partial Pressure; Photons; Physiologic pulse; Physiological; Pilot Projects; Posterior Pituitary Gland; Problem Solving; Property; Radiation; Resolution; Risk; Rodent; Rodent Model; Route; Sampling; Scheme; Shapes; Signal Transduction; Solutions; Source; Stroke; Surface; Technology; Testing; Time; Tissues; Toxic effect; Variant; Vesicle; Visible Radiation; Water; absorption; base; bioimaging; blood rheology; carboxylate; chemical property; chromophore; cost; design; extracellular; feeding; imaging modality; imaging probe; in vivo; luminescence; macromolecule; nanoparticle; neurotransmitter release; prevent; ratiometric; research study; two-photon

DESCRIPTION (provided by applicant): In this project we address the need in probes for two-photon microscopy - the leading imaging technique for dynamic visualization and quantification of biological processes in vivo in 3D with micron-scale spatial resolution. We propose to develop a new class of multiphoton probes, termed dendritic UCNPs, which comprise lanthanide-based up converting nanoparticles (UCNPs) and dendritic ligands. The key advantage of UCNPs is their enormously high multiphoton absorption cross-sections, which exceed those of the most efficient multiphoton probes available today by several orders of magnitude. Recently, we demonstrated that due to this remarkable property, in vivo two-photon depth-resolved microscopic imaging with UCNPs can be accomplished using simple low-power continuous-wave (CW) infrared light sources, which is in contrast to conventional two-photon experiments requiring very expensive pulsed femtosecond lasers. This remarkable advantage comes on top of other benefits of UCNPs, which include record-high photo stability, zero background fluorescence (due to CW infrared excitation) and greatly diminished risk of photo damage. However, lack of robust methods of UCNP solubilization and functionalization has been a major obstacle preventing their inclusion into the toolkit of modern imaging methods. We propose to solve this problem by using dendritic macromolecules. Our key proposition is that modification of UCNP surfaces with hydrophilic shape-persistent dendrimers will make up an efficient and general route to soluble bio-compatible UCNPs, whose luminescence will be coupled to analyte detection via UCNP-to-dendrimer excitation energy transfer (EET). Our approach capitalizes on unique structural features of dendritic architecture, i.e. intrinsic polyvalency and pseudo- globular shape. Both "colorless" probes for morphologic angiographic two-photon imaging and dedicated probes for imaging of specific analytes (pH and Ca2+) will be developed. To test the probes we will perform: (a) angiographic imaging in vivo in rodent brain, determining changes in blood rheology upon functional stimulation; (b) simultaneous in vivo multiphoton imaging of alterations in tissue pH and partial pressure of oxygen (pO2) in stroke rodent models; d) imaging of extracellular Ca2+ flux in mouse neurohypophysis upon electrical stimulation. All these experiments will differ from conventional multiphoton imaging in that the cost of the excitation sources will be lower by ca 1000 fold. These applications will demonstrate the ability of the new probes to a) replace currently used expensive multiphoton setups; and b) go beyond and address questions and hypotheses in neuroscience for which no alternative solutions are currently available.

描述（由申请人提供）：在该项目中，我们解决了双光子显微镜探针的需求，双光子显微镜是一种领先的成像技术，用于以微米级空间分辨率对体内生物过程进行 3D 动态可视化和定量。我们建议开发一类新型多光子探针，称为树突状 UCNP，其包含基于镧系元素的上转换纳米粒子（UCNP）和树突配体。 UCNP 的主要优势是其极高的多光子吸收截面，比当今最有效的多光子探针高出几个数量级。最近，我们证明，由于这种显着的特性，使用 UCNP 进行体内双光子深度分辨显微成像可以使用简单的低功率连续波 (CW) 红外光源来完成，这与需要非常昂贵的脉冲飞秒激光器的传统双光子实验形成鲜明对比。这一显着优势超越了 UCNP 的其他优势，包括创纪录的高光稳定性、零背景荧光（由于连续波红外激发）以及大大降低的光损伤风险。然而，缺乏可靠的 UCNP 溶解和功能化方法一直是阻碍其纳入现代成像方法工具包的主要障碍。我们建议通过使用树枝状大分子来解决这个问题。我们的关键主张是，用亲水性形状持久的树枝状聚合物对 UCNP 表面进行修饰，将形成一条有效且通用的可溶性生物相容性 UCNP 的途径，其发光将通过 UCNP 到树枝状聚合物的激发能量转移 (EET) 与分析物检测耦合。我们的方法利用了树突结构的独特结构特征，即内在的多价性和伪球状形状。将开发用于形态学血管造影双光子成像的“无色”探针和用于特定分析物（pH 和 Ca2+）成像的专用探针。为了测试探针，我们将执行：（a）啮齿动物大脑体内血管造影成像，确定功能刺激后血液流变学的变化； (b) 中风啮齿动物模型中组织 pH 值和氧分压 (pO2) 变化的同时体内多光子成像； d) 电刺激后小鼠神经垂体细胞外 Ca2+ 通量的成像。所有这些实验都与传统的多光子成像不同，因为激发源的成本将降低约 1000 倍。这些应用将展示新探针的能力： a) 取代目前使用的昂贵的多光子装置； b) 超越并解决目前没有替代解决方案的神经科学问题和假设。