Strong Surface-Enhanced Raman Scattering Signals From Nanoconjugate Comprised of Popcorn-Shaped Gold Nanoparticles and Semiconductor Quantum Dots and the Application In Protein Detection

Strong surface-enhanced Raman scattering (SERS) signals of 4-mercaptobenzoic acid (4-MBA) are detected from nanoconjugates comprised of popcorn-shaped gold nanoparticles (PS-AuNP) and CdSe\ZnS core\shell quantum dots (QDs). The presence of QD, which is bond to PS-AuNP via an amide bond, is important for the large enhancement factor of the Raman signals. According to finite-difference time-domain (FDTD) simulation, the electromagnetic field enhancement factor near the surface of PS-AuNP can be as high as 400, which means the theoretical Raman signal enhancement due to the electromagnetism enhancement could be 10¹⁰, Electrodynamics calculation confirms that the presence of the QD near a spherical gold particle can generate much higher electromagnetic field enhancement compared with the situation when just spherical gold particle alone in an electromagnetic field. Protein conjugation detection was also applied based on biotin-avidin interaction using the PS-AuNP-QD nanoconjugates. The SERS spectrum illustrated rich molecular vibration information of the conjugated avidin. The new PS-AuNP-QD nanoconjugate can be employed as a single particle SERS platform, which has potential application in biomolecular detection.