Emerging use of nanostructure films containing capped gold nanoparticles in biosensors

Abstract

The localized surface plasmon resonance (LSPR) property of gold nanoparticles (GNP) has been exploited in a variety of optical sensor configurations including solution-based bioassays, paper-based colorimetric detection, surface-confined nanoparticle film/array-based sensing, etc. Amongst these, gold nanostructured films are of great interest because of their high stability, good reproducibility, robustness, and cost-effectiveness. The inherent optical characteristics of GNP, are attributed to parameters like size and shape (eg, nanospheres, nanorods, nanostars), eg, LSPR spectral location sensitivity to the local environment, composition (eg, gold-silver or silica-gold nanoshells), sensing volume, mesospacing, and multiplexing. These properties allow sensor tunability, enabling enhanced sensitivity and better performance of these biosensors. Ultrasensitive biosensor designs were realized using gold nanostructured films fabricated by bottom-up as well as top-down approaches. In this review, we describe the past, present, and future trends in the development of GNP-LSPR-based sensors, concentrating on both design (fabrication) and application. In the process, we have discussed various combinations of GNP size and shape, substrate, and application domains.

Comparison of the Mechanical Properties of Self-Assembled Langmuir Monolayers of Nanoparticles and Phospholipids

“…Phospholipids have been used as a model to study the mechanical properties of cell membranes and pulmonary surfactants. , Recently, there has also been a developing interest in a different class of Langmuir monolayers, composed of inorganic nanoparticles capped with organic surfactants. Like amphiphilic molecules, these capped nanoparticles self-assemble into 2D lattices at the air–water interface. − Nanoparticles exhibit remarkable physical properties including quantum confinement, plasmon resonance, ,− and superparamagnetism. , Thin films composed of nanoparticles have shown potential applications in biosensors, ,, high sensitivity resonators, filtration devices, magnetoresistive devices, and flexible electronics. − …”

“…Like amphiphilic molecules, these capped nanoparticles self-assemble into 2D lattices at the air-water interface. [3][4][5][6][7][8][9][10][11][12][13][14] Nanoparticles exhibit remarkable physical properties including quantum confinement, 15 plasmon resonance 9,[16][17][18][19] and superparamagnetism 5,20 Thin films composed of nanoparticles have shown potential applications in biosensors 16,19,21 , high sensitivity resonators 14 , filtration devices 22 , magnetoresistive devices 10 , and flexible electronics. [23][24][25] Langmuir monolayers in particular have remarkable mechanical properties as two-dimensional materials that can extend into the third dimension.…”

Interaction-tailored organization of large-area colloidal assemblies

“…Another critical parameter affecting both the sensitivity and the electromagnetic field distribution around plasmonic nanostructures is the interparticle spacing. Higher wavelength sensitivity and larger sensing volume have been theoretically and experimentally demonstrated for nanostructured system characterized by greater average interparticle spacing, owing to the wider distribution of the electric field when the resonance conditions are satisfied [ 35 – 36 ].…”

Optical Detection of the Viruses by Gold Nanoparticles (AuNPs)

“…Furthermore, fluorescence is one of the most commonly studied optical sensors and they typically use dyes, quantum dots, and fluorescent proteins as labels [43] because quantum dots have a narrow excitation wavelength that has been successfully used to simultaneously detect separate pathogens [11]. Fluorescence-based biosensors have been explored for various applications such as medical diagnostics, drug delivery, drug discovery, environmental monitoring, and food safety.…”

“…AuNP is widely desired for optical biosensors due to its strong absorption coefficient, scattering flux, and luminescence characteristics [10]. Additionally, the surface plasmon resonance (SPR) is brought about by the oscillation of electrons on the surface of AuNPs, and this produces various absorption and scattering bands depending on the size, shape, and surface of AuNPs [11]. The resonance wavelength of SPR in a gold nanoparticle is highly dependent on the environment around the particles.…”