賴昆佑
簡汎清

Surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful analytical technique since it reveals detailed insights into the vibrational modes of molecules, which is often regarded as the molecular fingerprints. DNA sequencing is the process of determining the precise order of nucleobases (adenine, cytosine, guanine, and thymine) within a DNA molecule. Because of its excellent specificity, SERS can be a potential tool for DNA sequencing. In this study, we explore the viability of using SERS to differentiate nucleobases. To achieve the goal, InGaN quantum wells were employed to build the SERS substrates. The nitride quantum wells enhance the Raman signals via two mechanisms in SERS, namely localized surface plasmon resonance (LSPR) and charge transfer (CT), which result in the distinct SERS spectrum of each nucleobase. In addition, the quantum wells produce the SERS images with multiple “bright” regions, attributed to the much densified hot spots. With the SERS images, we recorded the characteristic bands (the “fingerprints”) for each nucleobase, including 1000 cm-1 for Adenine, 1241 cm-1 for Cytosine, 1668 cm-1 for Thymine and 1478 cm-1 for Guanine. The four vibrational modes are of the relaxation time (approximately 0.30 ps for the C-C stretching of Cytosine, N-H and C-H bending of Thymine, C=N stretching of Guanine and 0.21 ps for the PO43- stretching of Adenine). These distinct signals can be used to identify the nucleobases in DNA’s with different sequences.