Silver Nanocube Aggregates in Cylindrical Pores for Higher Refractive Index Plasmonic Sensing

Abstract

We report on silver nanocubes (AgNCs) infiltrated into cylindrical nanopores of porous alumina membranes (PAM) with an outstanding chemical sensitivity based on refractive index sensing (RIS) measurements. Numerical simulations performed using the finite‐difference time‐domain (FDTD) method suggested that the enhanced sensitivity is based mainly on the inter‐pore coupling plasmonic effect. This effect is related to plasmonic amplification based on localized surface plasmon resonance (LSPR) coupling between AgNCs located at the pore walls of neighboring cylindrical pores and separated by a nanoscale wall. Results are discussed for different aggregation scenarios ranging from individual nanocubes through pentamers on a flat glass surface, a flat alumina surface, and a concave local shape representing the experimental conditions. An experimental RIS sensitivity of about 770 nm per refractive index unit was found to be more than an order of magnitude higher for silver nanocube aggregates within cylindrical pores than that observed for ordinary planar substrates.

Self‐Organization of Gold Nanoparticle Assemblies with 3D Spatial Order and Their External Stimuli Responsiveness

“…However, due to statistical distribution of the monomers and aggregates the extinction cross‐section intensity is different from modeling to experiment. With a statistical method established by König et al, the experimental measured envelop function could be deconvoluted in a weighted function of dipolar modes caused by monomers, transversal/longitudinal modes caused by dimers, and super radiant mode caused by particle lines …”

“…With a statistical method established by König et al, the experimental measured envelop function could be deconvoluted in a weighted function of dipolar modes caused by monomers, transversal/longitudinal modes caused by dimers, and super radiant mode caused by particle lines. [ 41 ] The systematic variation of the AuNP/4VP ratio in the solid state was followed by transmission electron microscopy (TEM) analysis ( Figure 2 ). The TEM images of AuNP@ S 26 4VP 1 and AuNP@S 77 4VP 1 showed evidence of a coreshell structure with a dense coverage of AuNP with short 4VP units as ligands when a low amount of AuNP of 0.5 and 1.0 μmol was used (Figure 2 were irregular in shape but upon solvent evaporation, the AuNP form a hexagonal order within a 2D arrangement.…”

Label‐free diagnosis for colorectal cancer through coffee ring‐assisted surface‐enhanced Raman spectroscopy on blood serum

“…The signal amplification through electromagnetic enhancement, the ability to provide molecule‐specific vibrational data and the inherent swiftness of the optical method make SERS a powerful candidate for the development of sensitive diagnostic strategies . Particularly, in the pursuit of rapid, noninvasive and precise cancer diagnosis, SERS has received an enormous amount of attention in recent years . Different classes of nanostructured metal probes and substrates based on scalable bottom‐up and reproducible top‐down fabrication have been explored for boosting the SERS signal intensities through electric field enhancement via localized surface plasmon resonances (LSPRs).…”

Examining the Gilded Cage: Synthesis, Optical Properties and Plasmonic Applications of Gold Nanocages

“…Comparisons have been made between planar substrate, those with shallow concave facets, and those with high aspect ratio cylindrical pores to observe the induced changes to the LSPR modes of silver nanocubes. 30 The highest sensitivity by these substrate designs was observed using the substrate made with cylindrical pores. The increase is suspected to be caused by inter-particle coupling across a wall between two pores.…”