Localized Surface Plasmon Resonance LSPR

The shift of the LSPR absorbance peak from metallic nanoparticles can also be used to detect the dielectric constant change of the environment, in very similar maimer to the SPR detection technique [53]. However, the set-up for LSPR sensor is fairly simple. There are two basic measurement configurations nanoparticle 

SPR- and LSPR-based sensors utilize the property that nanostructured thin film or particles are very sensitive to the dielectric constant change of their local environment, and the enhanced detection sensihvity really depends on how the nanostructures respond to such change. Although some of these techniques (especially SPR) are already available commercially, their sensihvity and specificity are relatively poor, especially for trace amounts of biomolecules or complicated systems such as viruses and bacteria. As stated above, metallic nanostructures-especially particles-may also enhance the local electric field when the incident wavelength is close to the LSPRW, and this provides yet another means of designing enhanced spectroscopic sensors, especially the so-called surface-enhanced vibrational spectroscopy (SEVS) sensors. 

---

Long period gratings modified by the deposition of a self-assembled colloid monolayer of gold have been shown to enhance SRI sensitivity, which was attributed to the localized surface plasmon resonance (LSPR) of gold nanoparticles61. The system was used after functionalization of the gold nanoparticles with dini-trophenyl (DNP) antigen, for the detection of anti-(DNP) with a limit of detection as low as 9.5 x 10 10 M. 

The overall goal of my thesis work is to elucidate the sensing mechanism of the localized surface plasmon resonance (LSPR) of triangular Ag nanoparticle biosensors and to apply that knowledge to optimize their use as a novel analytical tool. 

Ghosh SK, Nath S, Kundu S, Esumi K, Pal T (2004) Solvent and ligand effects on the localized surface plasmon resonance (LSPR) of gold colloids. J Phys Chem B 108 13963-13971... 

Surface plasmons, or surface plasmon polaritons, are surface electromagnetic waves that propagate inside a metal along a metal/dielectric (or metal/ vacuum) interface their excitation by light is surface plasmon resonance (SPR) for planar surfaces or localized surface plasmon resonance (LSPR) for nanometer-sized metal particles. 

While it is safe to say that SPR is a mature technique from the historical perspective, new driving forces appear to challenge traditional SPR for various needs that traditional SPR sensors fail to satisfy. In particular, a novel SPR biosensor that attempts to capitalize on the nanotechnology, by which to localize surface plasmons (SPs), has emerged and thus has been appropriately called a localized surface plasmon resonance (LSPR) biosensor. In this chapter, 1 focus on the LSPR biosensor by reviewing its operating principles and properties in a systematic way and venture into future directions along which LSPR biosensors evolve. 

A parallel development in sensor technology is the use of gold nanoparticles (AuNPs) and their localized surface plasmon resonances (LSPR) [41] for sensing purposes. Mirkin et al. [42] showed how single nanoparticles (NPs) in solution can... 

Localized surface plasmon resonance (LSPR) at the metal surface has been exploited to enhance the signal obtained from optical biochips and thereby lower the limits of detection. There are two main enhancement factors (i) an increase in the excitation of the fluorophore by localizing the optical field on the nanoparticles near the fluorophore and (ii) an increase in quantum efficiency of the fluorophore. The plasmon resonance wavelength should coincide with the fluorophore absorption band to obtain the maximum emission efficiency. Several parameters concerning the signal detection enhancement are as follows (84)... 

In recent years, it has become accepted within the SERS community that hot spots primarily arise from intense and highly localized electromagnetic fields caused by local surface plasmon resonances (LSPR). However, questions over the precise magnitude of the enhancement present at such locations have led some to suggest that there must be a chemical aspect to hot spots. In this section, the key results from recent work focusing on the fundamentals of hot spots with regard to these two components are summarized. 

For centuries, metal nanoparticles have never ceased to attract scientists and artists from many diverse cultures. In this section we briefly introduce a phenomenon of metal nanoparticles that still inspires scientists localized surface plasmon resonance (LSPR) (Hutter and Fendler, 2004). Metal nanoparticles show nonlinear electronic transport (single-electron transport of Coulomb blockade) and nonlinear/ultrafast optical response due to the SPR. Conduction electrons (—) and ionic cores (-F) in a metal form a plasma state. When external electric fields (i.e., electromagnetic waves, electron beams etc.) are applied to a metal, electrons move so as to screen perturbed charge distribution, move beyond the neutral states, return to the neutral states, and so on. This collective motion of electrons is called a plasma oscillation. SPR is a collective excitation mode of the plasma localized near the surface. Electrons confined in a nanoparticle conform the LSPR mode. The resonance frequency of the surface plasmon is different... 

Shin, Y-B., Lee, J-M., Park, M-R., Kim, M-G., Chung, B. H., Pyo, H-B., Maeng, S. (2007). Analysis of recombinant protein expression using localized surface plasmon resonance (LSPR). Biosens Bioelectron 22, 2310-2307. 

Localized surface plasmon resonance (LSPR) of Ag nanopartieles... 

Metal-based nanomaterials have been regarded as the most widely and deeply studied photothermal agents. The metal nanoparticles exhibit excellent localized surface plasmon resonance (LSPR) properties, caused by nanoscale oscillations of free electrons on the surface of metal particles. The intriguing LSPR property makes metal nanoparticles absorb light in visible and NIR regions and convert the optical energy to heat. This characteristic of metal nanoparticles has greatly motivated the research on metal-based... 

---