本研究旨在利用表面增強拉曼散射技術（Surface-enhanced Raman Scattering, SERS）來量化人體血漿中的抗氧化劑——類胡蘿蔔素。實驗中，透過有機金屬化學氣相沉積法（Metal-Organic Chemical Vapor Deposition, MOCVD）在藍寶石基板上生長氮化銦鎵/氮化鎵（InGaN/GaN）量子井，將高濃度的電荷侷限在SERS晶片表面，並藉由晶片表面的鋁金屬與InGaN量子井之間形成的電漿耦合(plasmonic coupling)，大幅增加SERS的有效範圍。
　　相比於傳統用於類胡蘿蔔素量化的高效液相層析法（High-Performance Liquid Chromatography, HPLC），SERS 具備更簡易、直觀且快速的操作與量測方式。本技術僅需將10 μL 的血漿檢體滴在晶片表面，並於 30 °C、40% 相對濕度下乾燥約 10 分鐘，即可進行光譜量測，從抽血到完成量測分析，可於 30 分鐘內完成。
　　實驗選用488奈米波長的雷射光源，因該波長在類胡蘿蔔素的吸光範圍內，能藉由共振拉曼(resonance Raman)增強類胡蘿蔔素的光譜強度。結果顯示，將類胡蘿蔔素的乙醇溶液與人體血漿均勻混合後，所得的SERS訊號強度與胡蘿蔔素濃度呈線性相關。因此，我們可透過SERS光譜推算血漿中的類胡蘿蔔素濃度，為胡蘿蔔素的檢測技術提供一種快速、準確的新選擇。

This study aims to quantify β-carotene, a key antioxidant present in human plasma, using surface-enhanced Raman scattering (SERS) technology. In this work, InGaN/GaN quantum wells were grown on sapphire substrates via metal-organic chemical vapor deposition (MOCVD) to enhance electron confinement and increase the surface charge density of the SERS chip. To further boost Raman signals, the substrate surface was coated with nanostructured aluminum, forming densified and expanded hot spots.
Compared with high-performance liquid chromatography (HPLC), the conventional technique for β-carotene analysis, the SERS method is simpler and faster. This is because SERS requires no solvents, but only a plasma droplet of 10 μL, which is dried at 30 °C and 40% humidity for 10 minutes. The whole process, from preparation to data collection, can be completed in 30 minutes.
A 488-nm laser was used to excite the strong resonance Raman spectra of β-carotene, as the blue light is within the absorption range of β-carotene. SERS spectra of the plasma diluted in ethanol show three major peaks at 1525, 1160 and 1010 cm-1, whose intensities are linearly correlated with β-carotene concentration. The result allows us to quantify the level of β-carotene in plasma. This study presents a new approach for fast and sensitive analysis of the antioxidant in human blood.

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