應用於光源與顯影之近紅外光二區奈米材料

Abstract

近年，近紅外光材料之設計與應用日益增加，其相較紫外光與可見光，於組織內之低自發螢光、低散射及低組織吸收之特性，組織穿透能力佳，為生醫影像領域提供前景。其中以近紅外光二區(NIR-II; 900–1800 nm)材料，尤為受注目，其為影像提供優異之訊噪比與高空間解析度，為具應用潛力之螢光材料。 本研究分為兩部分，第一部分以NIR-II光源應用為核心，使用中孔洞二氧化矽限制無機螢光粉於奈米尺度，以部分反尖晶石MgGa2O4結構為發光材料，摻雜Cr3+與Ni2+離子作為發光中心，利用兩離子間之能量轉移，大幅增加能量轉換效率，故提升Ni2+離子NIR-II之內部量子效率達55.8%，NIR全區放光達79.2%。次毫米發光二極體(mini-LED)具極高亮度、長使用壽命及節省能源之特性，為高解析顯示器之熱門選項，本研究之材料發光效率佳與尺寸小之特性作為其螢光體，其對於提升mini-LED對比度具發展潛力。 第二部分以NIR-II顯影劑應用作為核心，開發奈米Gd2O3氧化物，摻雜Yb3+與Er3+離子作為發光中心。以常見之808與980 nm雷射激發，實現高量子效率之NIR-IIb與NIR-IIx放光，期望增加影像之訊噪比，並由組織穿透深度測試與體內肝臟成像，揭示此窗口卓越之穿透能力達1公分與其應用潛力。本研究亦詳細探討Yb3+-Er3+系統NIR-II範圍之詳細光學特性與材料作為核磁顯影劑之可行性。 本研究之新穎性在於結合NIR-II光源與顯影劑之材料開發，為NIR-II之應用提供嶄新選項。第一部分著重於開發具優異光學特性與高效能之奈米螢光粉材料，並首度將其應用於NIR-II次毫米發光二極體，展現潛力於生醫影像與光電元件領域。第二部分則探討鑭系氧化物作為螢光/核磁雙模式顯影劑之可行性，並由光譜分析深入研究Yb³⁺-Er³⁺系統之下轉換發光機制，以建立針對肝臟成像之顯影策略，期望提升臨床非侵入式成像之準確性與可靠性。

In recent years, the design and application of near-infrared (NIR) materials have garnered increasing attention. Compared to ultraviolet and visible light, NIR light offers superior tissue penetration due to its low autofluorescence, minimal scattering, and reduced absorption in biological tissues. These properties render NIR materials highly advantageous for biomedical imaging. Notably, materials operating in the near-infrared-II window (NIR-II) have emerged as promising, providing exceptional signal-to-noise ratios and high spatial resolution, thus representing a class of fluorescent probes with significant potential for biomedical applications. This study is divided into two parts. The first part focuses on the application of NIR-II light sources. Mesoporous silica is employed to confine the inorganic phosphors at the nanoscale. The luminescent material is based on a partially inverse spinel structure of MgGa₂O₄, doped with Cr³⁺ and Ni²⁺ ions as emission centers. The energy conversion efficiency is significantly enhanced through energy transfer between these two ions. As a result, the internal quantum efficiency of Ni²⁺ emission in the NIR-II region reaches 55.8%, with a total NIR emission efficiency across the full region of 79.2%. Mini-LEDs, known for their high brightness, long operational lifetime, and energy efficiency, are considered promising candidates for next-generation high-resolution displays. The developed phosphor materials, featuring high luminescence efficiency and nanoscale dimensions, are expected to improve contrast ratios and demonstrate strong potential for application in advanced mini-LED technologies. The second part of this study focuses on the application of NIR-II imaging agents, specifically developing Gd₂O₃-based nanomaterials doped with Yb³⁺ and Er³⁺ ions as luminescent centers. Under excitation by commonly used 808 nm and 980 nm lasers, high quantum efficiency emission in the NIR-IIb and NIR-IIx regions is achieved, aiming to enhance the signal-to-noise ratio (SNR) of imaging. Tissue penetration depth tests and in vivo liver imaging further demonstrate the exceptional penetration capability of this spectral window, reaching up to 1 cm, thereby highlighting its promising potential for biomedical applications. Additionally, the optical properties of the Yb³⁺–Er³⁺ system within the NIR-II range are thoroughly investigated, and the feasibility of these nanomaterials as dual-function magnetic resonance imaging (MRI) contrast agents is also explored. The novelty of this study lies in the integrated development of materials for NIR-II light sources and contrast agents, offering innovative options for NIR-II-related applications. The first part focuses on the synthesis of nanophosphor materials with excellent optical properties and high efficiency, which are applied in NIR-II mini-LEDs for the first time, demonstrating promising potential in biomedical imaging and optoelectronic devices. The second part explores the feasibility of lanthanide oxides as dual-modal contrast agents for fluorescence and magnetic resonance imaging (MRI). Through spectroscopic analysis, the downshifting luminescence mechanisms of the Yb³⁺-Er³⁺ system are thoroughly investigated to develop an imaging strategy specifically for liver diagnostics. This approach is expected to enhance the accuracy and reliability of clinical non-invasive imaging techniques.