Shape and Size Control of Substrate-Grown Gold Nanoparticles for Surface-Enhanced Raman Spectroscopy Detection of Chemical Analytes

Abstract

Anisotropic gold nanoparticles often exhibit superior optical properties compared to spherical ones, in part due to intense electric field localization near sharp geometric features and a broadly tunable localized surface plasmon resonance. As a result, anisotropic nanoparticles are attractive building blocks for surface-enhanced Raman spectroscopy (SERS) substrates. To unlock the full potential of such substrates, one should be able to (1) generate a sufficient number of SERS hotspots with structures of controlled shape and size and (2) remove ligands so that analytes can easily access nanoparticle surface sites. Here, we develop a synthetic strategy for the shape- and size-controlled anisotropic growth of gold nanoparticles (concave rhombic dodecahedra and concave cubes, 70–135 nm characteristic length) from spherical seeds anchored on a structurally complex surface (common filter paper) and subsequently combine electrodynamics and electronic structure calculations with experiment to systematically characterize these substrates using SERS. Furthermore, we explore the generalizable functionality of these substrate-stabilized nanoparticles by using a continuous extraction method to partially remove surface ligands that were necessary for anisotropic growth, enabling the specific SERS detection of serotonin, a molecular neurotransmitter with a weak affinity for gold.

Intratumoral generation of photothermal gold nanoparticles through a vectorized biomineralization of ionic gold

“…Variations in the reducing agent molecule as well as reaction conditions (e.g. pH, temperature, incubation time) will result in different morphologies, sizes, and functionalities of the resulting nanoparticles [5][6][7][8] . For biomedical applications, these variations in morphology, size, and functionality are directly correlated to their cellular internalization [9][10][11] , biodistribution, biological half-life [11][12][13] , renal secretion [11][12][13][14][15] , and plasmon optical properties [1][2][3][4][5][6][7][8] .…”

Application of Gold Nanoparticle to Plasmonic Biosensors

“…This results in a 2–5-order magnitude enhancement of the local electromagnetic (EM) field intensity at the nanoparticle surface, which is the key to the huge enhancement in SERS [ 28 , 29 ]. Moreover, recent studies of SERS on metal nanoparticles demonstrated the importance of having local field “hotspots” due to surface roughness [ 30 , 31 ], nanogaps between aggregated plasmonic NPs [ 32 , 33 ], or NP-metal surfaces [ 34 ] which can induce higher EM enhancements, and the SERS contribution to such hotspots often dominates the observed response [ 31 ]. To generate homogeneous “hotspots” using GNPs, researchers have fabricated GNP arrays [ 35 , 36 ].…”

Strategies for the Development of Metallic‐Nanoparticle‐Based Label‐Free Biosensors and Their Biomedical Applications

“…[114] EM enhancement of SERS depends more on the local refractive index and arrangement of NPs, which is related to the LSPR value. [115] These factors affect the SERS and need to be tuned for ap roperu nderstanding of the differenceb etween healthy and disease-containings amples. This technique is emerging in the biosensor field because it is very specific and sensitivef or differentchemical and molecular vibrations.…”