Yan Jiahao, Liu Pu, Lin Zhaoyong, Yang Guowei
State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, School of Physics & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P. R. China.
Nanoscale. 2016 Mar 21;8(11):5996-6007. doi: 10.1039/c5nr07871g.
Sensing is regarded as one of the most important applications of noble metal-based nanoplasmonics. However, all previous designs have been based on the wavelength-shift of the localized surface plasmon resonance, in which the sensitivity is intrinsically limited by the low quality factors induced by metal losses, and meanwhile the large ohmic loss, high cost and inevitable toxicity and biofouling for detection in vivo greatly hinder their further applications in biosensors. Beyond noble metals, high-refractive index dielectric materials (HRDMs) like silicon with low-loss and strong magnetic response have drawn more attention. Here, for the first time, we proposed a HRDM nanosphere as a new nanosensor for biomolecule detection, and experimentally demonstrated a HRDM sensor working on the intensity-shift but not wavelength-shift of the scattering. The sensing mechanism based on the synergistic effect of the broadening electric mode shift of HRDMs and the Kerker's scattering intensity-shift is beneficial to achieve higher sensitivity. We validated the efficacy of our sensor to detect refractive index changes and trace amounts of streptavidin molecules, and the sensitivity can reach 27 times as high as the highest sensitivity reported to date for nanoplasmonic structures. These findings showed that monitoring the change of the scattering intensity of HRDM nanostructures is superior to monitoring the wavelength-shift of nanoplasmonic structures, as is widely used in nanoplasmonic sensors, for biosensing, meaning HRDM nanosensors could be an important tool in biomolecule detection.
传感被视为基于贵金属的纳米等离子体学最重要的应用之一。然而，以往所有的设计都是基于局域表面等离子体共振的波长偏移，其中灵敏度本质上受到金属损耗引起的低品质因数的限制，同时，大的欧姆损耗、高成本以及体内检测时不可避免的毒性和生物污垢极大地阻碍了它们在生物传感器中的进一步应用。除了贵金属，具有低损耗和强磁响应的高折射率介电材料（HRDMs），如硅，已受到更多关注。在此，我们首次提出将HRDM纳米球作为一种用于生物分子检测的新型纳米传感器，并通过实验证明了一种基于散射强度偏移而非波长偏移工作的HRDM传感器。基于HRDMs展宽电模偏移和克尔散射强度偏移协同效应的传感机制有利于实现更高的灵敏度。我们验证了我们的传感器检测折射率变化和痕量链霉亲和素分子的功效，其灵敏度可达迄今报道的纳米等离子体结构最高灵敏度的27倍。这些发现表明，监测HRDM纳米结构的散射强度变化优于监测纳米等离子体结构广泛应用于生物传感中的波长偏移，这意味着HRDM纳米传感器可能成为生物分子检测的重要工具。
