Sensing using localised surface plasmon resonance sensors

Abstract

The bright colours of noble metal particles have attracted considerable interest since historical times, where they were used as decorative pigments in stained glass windows. More recently, the tuneable optical properties of metal nanoparticles and their addressability via spectroscopic techniques have brought them back into the forefront of fundamental and applied research fields. Much of the recent attention concerning metal nanoparticles such as gold and silver has been their use as small-volume, ultra-sensitive label-free optical sensors. Plasmonic nanoparticles act in this case as transducers that convert changes in the local refractive index into spectral shifts of the localized surface plasmon resonance (LSPR) band. This LSPR-shift assay is a general technique for measuring binding affinities and rates from any molecule that induces a change in the local refractive index around the metallic nanostructures. By attaching molecular recognition elements (chemical or biological ligands) on the nanostructures, specificity and selectivity to the analyte of interest are introduced into the nanosensor. In this review, we will discuss the different methods used to fabricate plasmonic nanosensors. A special emphasis will be given to techniques used to link plasmonic nanostructures to surfaces. While the difference between colorimetric and refractive index sensing approaches will be briefly described, the importance to distinguish between bulk refractive index (RI) sensing and molecular near-field refractive index sensing will be discussed. The recent progress made in the development of novel surface functionalization strategies together with the formation of optically and mechanically stable LSPR sensors will be highlighted.

Plasmonic photothermal cancer therapy with gold nanorods/reduced graphene oxide core/shell nanocomposites

“…Among the nanoparticles currently considered for cancer, gold nanostructures are particularly well-suited. [5][6][7][8][9][10][11] The localized surface plasmon resonance (LSPR) of gold nanoparticles 12 endows them with the capability to strongly absorb light at a specific wavelength, which can be controlled and tuned through synthetic means. Photo-excitation of gold nanostructures at their LSPR band can efficiently convert photon energy into heat and can be used for the photothermal ablation of cancer cells.…”

Coupling between plasmonic films and nanostructures: from basics to applications

“…Plasmonics emerged mostly in the 1990s as an extremely rich new domain in optics, exciting due to its many applications ranging from simply down-scaling the conduction of light in subwavelength devices [1], to designing nanosources of light [2], new single-molecules biosensors [3], developing innovative treatment in cancer therapy [4], efficient and cheap solar cells [5], or designing an entirely new type of metamaterials, where "atoms" are artificially built as complex optical nanostructures allowing for the manipulating of light at will in ways not found in nature [6]. Specifically, surface plasmons are optical modes bound to the interface between a dielectric and a metal nano-object, which originate from the resonant coupling between a surface-charge oscillation and the electromagnetic field that it scatters.…”

Advancements on the molecular design of nanoantibiotics: current level of development and future challenges

“…92,93 Due to their small size, large surface area to volume ratio, stability over high temperature and translocation into the cells, inorganic nanoparticles are considered as a viable alternative for carrying a large amount of antibiotics and the efficacy of metallic NPs conjugated with antibiotics has thus been the subject of intense investigations. These studies showed that gold nanostructures 94,95 used in combination with antibiotics exhibit enhanced bactericidal activity on a range of Gram-positive and Gramnegative bacteria and higher stability over an extended storage compared to the free antibiotics (Table 6).…”