Tuning the interparticle distances in self-assembled gold nanoparticle films with their plasmonic responses

Ultrasensitive Detection of Exosome Using Biofunctionalized Gold Nanorods on a Silver-Island Film

“…After deposition, the GNR assemblies showed an island pattern, while on glass substrates the distribution was wider due to the impact of charging (Figure S1c). Overall, careful analysis yields gap sizes ranging from 0.2 to ∼1.5 nm, which is consistent with previous studies demonstrating that such gaps promote plasmon coupling between particles, which leads to emission enhancement. − Hence, it is expected that the interparticle gap will have a large effect on optical properties. The optical properties of the silver-island film, GNR on the silver-island film, and GNR on the glass substrate were determined using a UV–vis–NIR spectrophotometer.…”

Self-assembly of colloidal nanoparticles into 2D arrays at water–oil interfaces: rational construction of stable SERS substrates with accessible enhancing surfaces and tailored plasmonic response

“…In this context, the most widely researched area has been the fine tuning of the gap distance between adjacent nanoparticles. [113][114][115] For example, by modifying the surface of the Au nanoparticles with acrylamine, Huang and Tao et al demonstrated that the size of the interfacial films formed with these particle can shrink by more than 50 % upon UV light irradiation due to the crosslinking of acrylamine on the surface of neighbouring particles (Figure 10a). [116] In their work, the authors showed that the crosslinking led to gradual decrease in gap between adjacent nanoparticles from ca.…”

“…Similarly, other groups have demonstrated that the gap distance between nanoparticles in interfacial arrays can be tuned by changing the length of ligands, such as alkyl thiols, alkyl amines and polymers, adsorbed on the surface of the plasmonic nanoparticles. [113,115,117] While adjusting the length of ligands on the surface of Au nanoparticles provides a simple method to manipulate the interparticle distance of 2D nanoparticle interfacial arrays, the addition of strongly adsorbing ligands inevitability decreases the accessibility of the plasmonic surface, which is undesirable for SERS. In an effort to circumvent this issue, Kang et al recently demonstrated a method based on Au@SiO 2 nanoparticles which allowed the distance between the plasmonic cores in interfacial arrays to be controlled without the use of surface-passivating molecular modifiers.…”

Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy

“…The plasmonic coupling of metallic nanostructures under the excitation of incident light has not only drawn substantial interest − but also looks promising for applications in optical sensing, − solar energy, biomedical therapy, , and especially surface-enhanced Raman spectroscopy (SERS). − The vibrational Raman fingerprints of target molecules can be enhanced several orders of magnitude because of the synergistic coupling of localized surface plasmon resonances (LSPR) of nanoparticles (NPs), , surface modified planar substrates, or a combination of both. ,, Previous reports based on deposited NPs or lithographic features , on dry substrates have beautifully demonstrated that the surrounding media, metal species, size, shape, interparticle distance, , and the gap between the substrate and NPs are crucial for the resonance strength, frequency, and the resultant SERS signals. The latter is caused by the local near-field enhancement (“hot spots”) inside or around these nanostructures.…”

“…10−16 The vibrational Raman fingerprints of target molecules can be enhanced several orders of magnitude because of the synergistic coupling of localized surface plasmon resonances (LSPR) of nanoparticles (NPs), 17,18 surface modified planar substrates, 19 or a combination of both. 3,20,21 Previous reports based on deposited NPs 22 or lithographic features 10,23 on dry substrates have beautifully demonstrated that the surrounding media, 24 metal species, 11 size, 25 shape, 26 interparticle distance, 24,27 and the gap between the substrate and NPs 3 are crucial for the resonance strength, frequency, and the resultant SERS signals.…”