Localized surface plasmon resonance sensors based on wavelength-tunable spectral dips

Abstract

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.

Plasmon-induced charge separation: chemistry and wide applications

“…PICS oxidation of Ag is decelerated by appropriate donors or by protecting the NPs with a self-assembled monolayer (SAM) of an alkanethiol or fluoroalkanethiol. 36 Au–Ag alloy NPs are more stable than pure Ag NPs. 29 Ag NPs can also be used stably by coating them with a semiconductor ( e.g.…”

“…10b). Since the absorption dip redshifts with increasing local refractive index, as does the absorption peak, 36 it allows LSPR sensing.…”

Plasmon-induced charge separation at two-dimensional gold semishell arrays on SiO2@TiO2 colloidal crystals

“…2 We found that exposure of metal-semiconductor nanocomposite to light at LSPR wavelength induced PICS, which was realized by electron transfer from photoexcited metal nanoparticles to semiconductor. 9,10 In order to further meet the requirements of practical application, a number of studies have focused on how to improve PICS efficiency and photoresponse window, which depend on the shape and size of metal nanoparticles, the interparticle distance, and the contact area between metal and TiO 2 . However, for disordered metal-TiO 2 nanocomposites in the most studied systems, it is difficult to control above mentioned factors exactly and reproducibly.…”

Emerging Cytokine Biosensors with Optical Detection Modalities and Nanomaterial-Enabled Signal Enhancement

“…Compared to the relatively inflexible arrangements required for momentum matching in SPR, LSPR works in a simpler configuration as shown in Figure 14C. The measured signal from LSPR is often based on the shift in the spectral peak due to the changes in the maximum extinction condition [114] following analyte binding.…”