本研究探索表面增強拉曼散射（Surface-enhanced Raman scattering, SERS）技術在生物醫學感測方面的應用。這種技術依賴金屬/分子界面上的電子共振，可增強拉曼訊號數百萬倍。SERS具備高靈敏度、高分子特異性、無標記等優點，在生物醫學、環境監測、食品安全等領域具有廣泛的應用前景。然而，SERS檢測依賴奈米尺度的熱點（< 10 nm），為了擴展熱點的有效面積以提升SERS訊號的穩定性，我們利用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InGaN/GaN量子井，以增加SERS晶片表面的電荷密度。氮化物量子井不僅能擴大熱點的範圍，還能增強待測物的SERS訊號。我們展示了氮化物SERS磊晶片於循環腫瘤DNA檢測中的應用，並通過磊晶結構和量測參數的優化，極大化DNA的SERS訊號。
我們發現，三層量子井的結構設計提供了最佳的電子和電洞侷限性，再加上將DNA置於20°C、50% 濕度的環境中，可在最快的乾燥時間45分鐘內使 DNA 分子充分與基板表面相互作用，形成穩定的吸附結構。最後，搭配8 mW的488-nm雷射功率進行量測，避免了樣品過熱而碳化，並提供相對最強的激發能量。因此這一組合使得ctDNA檢測能產生最強的訊號。

This study explores the application of Surface-enhanced Raman Scattering (SERS) technology in biomedical sensing. This technique relies on electron resonance at metal/molecule interfaces to amplify Raman signals by millions of times. SERS biosensing is sensitive, molecular-specific, and label-free, making it ideal for biomedical, environmental, and food safety applications. SERS detection depends on highly localized (<10 nm) hotspots. To expand these hotspots and stabilize the Raman signal, we used metal-organic chemical vapor deposition to grow InGaN quantum wells (QWs), which not only expand the hotspot area but also intensify SERS signals.
We applied the nitride SERS biosensor to detect circulating tumor DNA (ctDNA) for cancer diagnosis. After optimizing the QW structure and measurement conditions, we found that a three-layer QW structure, combined with 8-mW 488-nm laser power and a 45-minute drying time, led to the highest SERS signals of DNA. Placing DNA on the substrate in a 20°C, 50% humidity environment allowed full immobilization of nucleotide within 45 minutes. Using the 488-nm laser of 8 mW, we can attain strong and stable SERS signals without overheating the ctDNA.

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