Kazuma Emiko, Tatsuma Tetsu
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Nanoscale. 2014 Feb 21;6(4):2397-405. doi: 10.1039/c3nr05846h. Epub 2014 Jan 17.
Localized surface plasmon resonance (LSPR) sensors serve as sensitive analytical tools based on refractive index changes, which can be applied to affinity-based chemical sensing and biosensing. However, to select the monitoring wavelength, monodisperse Au or Ag nanoparticles must be synthesized. Here we developed LSPR sensors that operate at arbitrary wavelengths after preirradiation at the corresponding wavelength. Polydisperse plasmonic Ag nanospheroids or nanorods are photocatalytically deposited on TiO2. The nanoparticle ensemble shows a broad absorption band over the visible and near infrared regions, and absorption dips can be formed at desired wavelengths simply by photoexciting the ensemble at the wavelengths, on the basis of plasmon-induced charge separation. The dips redshift linearly in response to a positive change of refractive index, and the refractive index sensitivity linearly increases with increasing dip wavelength (e.g., 356 nm RIU(-1) at 1832 nm). The dip-based sensor is applied to monitoring of selective binding between biotin and streptavidin. The present system would allow development of miniaturized and cost-effective sensors that operate at the optimum wavelength at which the sensitivity is highest within the optical window of the sample.
局域表面等离子体共振（LSPR）传感器作为基于折射率变化的灵敏分析工具，可应用于基于亲和力的化学传感和生物传感。然而，为了选择监测波长，必须合成单分散的金或银纳米颗粒。在此，我们开发了一种LSPR传感器，其在相应波长预辐照后可在任意波长下工作。多分散的等离子体银纳米球或纳米棒通过光催化沉积在TiO₂上。纳米颗粒集合体在可见光和近红外区域显示出宽吸收带，并且基于等离子体诱导的电荷分离，只需在所需波长对集合体进行光激发，就能在所需波长处形成吸收凹陷。这些凹陷随着折射率的正向变化而线性红移，并且折射率灵敏度随着凹陷波长的增加而线性增加（例如，在1832 nm处为356 nm RIU⁻¹）。基于凹陷的传感器应用于监测生物素和链霉亲和素之间的选择性结合。本系统将有助于开发小型化且经济高效的传感器，这些传感器可在样品光学窗口内灵敏度最高的最佳波长下工作。
