Ln3+ doped nanoparticles: new optical and magnetic properties

Ln3 掺杂纳米粒子：新的光学和磁性特性

• 批准号: RGPIN-2018-03743
• 负责人: vanVeggel, Frank
• 金额: $ 3.5万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667554
• 关键词: Ln3+; doped; nanoparticles; new; optical

The lanthanides, elements La-Lu, are fascinating because of their optical and magnetic properties and their practical use permeates our society (e.g. strong magnets, MRI contrast agents). My inter- and multidisciplinary research programme will explore new directions, all based on colloidally stable (doped) nanoparticles (NPs):***1) singly doped NPs: stable single-photon sources that operate in the telecommunication window are much sought after for optical quantum computing and cryptography. Methods will be developed to dope a NP with one Er3+, which emits at 1.55 micron. Such singly doped NPs also allow to determine the photophysics of one Er3+ ion;***2) photoluminescence through two-photon excitation of doped NPs: preliminary data show that this is possible with Eu3+, Tb3+, Dy3+, and Sm3+. This is a hardly explored field and promises some new and exciting photophysics, e.g. there is theoretical work that concludes that the two-photon intra-4f transition of the Ln3+ ions is allowed, unlike the one-photon process. It may pave the way for optical correlation spectroscopy with non-overlapping emissions;***3) upconversion (core-shell) NPs that convert two or more low-energy photons into one of higher energy (usually near-infrared irradiation to red, green, and blue light) are much studied. However, the quantum yields are still much lower than their bulk counterparts, for which the reasons remain elusive. I hypothesize that the low-temperature synthesis, i.e. around 300 degrees C, of the NPs leads to internal defects that are main quenching sites. UVic's scanning transmission electron holography microscope (STEHM) will be used.***4) MRI correlation: contrast in MRI is often enhanced by adding a T1 or T2 contrast agent. It seems possible to perform magnetic resonance correlation imaging if “T1-only” and “T2-only” contrast agents can be developed. We have some data to support this hypothesis;***5) magnetic NPs as “single molecule magnets”: the field of single molecule magnets, SMMs, has made huge progress over the last two decades, but getting stable SMMs at temperatures above liquid nitrogen remains a formidable unresolved issue. I propose to make SmCo2, NdFeB, and the-like NPs. It should be possible to make these NPs large enough and still a single magnetic domain such that the blocking temperature is above liquid nitrogen;***6) the X-ray radiation dose quantification during in-vivo studies (e.g. cancer diagnosis and treatment) is an unresolved issue. I propose to make NPs that have a T2 contrast that is not susceptible to a change in its oxidation state by X-ray induced processes, e.g. Dy3+, and a T1 contrast that is and turns on by X-ray induced photo-electrons (e.g. Eu3+, which is impotent as contrast agent, to Eu2+ which is a potent T1 contrast agent). The T2 contrast then serves as an internal standard. An internal standard is necessary for one never knows how much NPs localize in a tumour because of heterogeneity.

镧系元素，La-Lu元素，由于其光学和磁性而令人着迷，并且其实际用途渗透到我们的社会中（例如强磁体，MRI造影剂）。我的跨学科和多学科研究计划将探索新的方向，所有这些都基于胶体稳定（掺杂）纳米粒子（NP）：*1）单掺杂NP：在电信窗口中运行的稳定单光子源对于光学量子计算和密码学来说是非常受欢迎的。 将开发用一种Er 3+掺杂NP的方法，其在1.55微米处发射。这种单掺杂的NP还允许确定一个Er 3+离子的光致物理;*2）通过掺杂的NP的双光子激发的光致发光：初步数据显示，这对于Eu 3+、Tb 3+、Dy 3+和Sm 3+是可能的。这是一个很难探索的领域，并承诺一些新的和令人兴奋的电子物理学，例如，有理论工作得出结论，双光子内4f跃迁的Ln 3+离子是允许的，不像单光子过程。它可以为具有非重叠发射的光学相关光谱铺平道路;*3）将两个或更多个低能量光子转换为更高能量的一个的上转换（核-壳）NP（通常近红外辐射为红光、绿色和蓝光）被大量研究。然而，量子产率仍然远低于其本体对应物，原因仍然难以捉摸。我推测，低温合成，即约300摄氏度，纳米粒子导致内部缺陷，是主要的淬灭位点。将使用UVic的扫描透射电子全息显微镜（STEHM）。* 4)MRI相关性：MRI中的对比度通常通过添加T1或T2造影剂来增强。如果能够开发出“仅T1”和“仅T2”造影剂，似乎可以进行磁共振相关成像。我们有一些数据支持这一假设;*5）磁性纳米粒子作为“单分子磁体”：单分子磁体领域，SMM，在过去的二十年里取得了巨大的进展，但在液氮以上的温度下获得稳定的SMM仍然是一个艰巨的未解决的问题。我建议制造SmCo 2、NdFeB和类似的NP。应该可以使这些NP足够大并且仍然是单个磁畴，使得阻断温度高于液氮;*6）在体内研究（例如癌症诊断和治疗）期间的X射线辐射剂量定量是一个未解决的问题。我建议制备具有T2对比度的NP，该T2对比度不易受X射线诱导过程（例如Dy 3+）的氧化态变化的影响，并且具有T1对比度，该T1对比度通过X射线诱导的光电子开启（例如作为对比剂无效的Eu 3+，对于作为有效的T1对比剂的Eu 2+）。然后，T2造影剂用作内标。内标物是必要的，因为由于异质性，人们永远不知道肿瘤中有多少纳米颗粒定位。