Effects of nanoparticle sizes, shapes, and permittivity on plasmonic imaging

Abstract

Plasmonic imaging has exhibited superiority in label-free and fast detection to single nanoparticles due to its high sensitivity and high temporal resolution, which plays an important role in environmental monitoring and biomedical research. As containing plenty of information associated with particle features, plasmonic imaging has been used for identifying the particle sizes, shapes, and permittivity. Yet, the effects of the nanoparticle features on plasmonic imaging are not investigated, which hinders the in-depth understanding to plasmonic imaging and its applications in particle identification. In this work, we analyzed five types of nanoparticles, including polystyrene (PS), Au, silicon nanospheres as well as PS and Ag nanowires. We illustrated the effects of nanoparticle sizes, shapes, and permittivity on spatial resolution, imaging contrast, and interference fringes. We found that nanoparticle sizes and permittivity influenced the imaging contrast. Via introducing size parameter relevant to interference fringes, the connection between particle shape and reduction rate of size parameter is built, and the effects of particle shapes on the interference patterns are revealed. Our research provides a basis for improving the plasmonic imaging and presents guidance for applications on particle identification in nano-detection, biosensor, and environmental monitoring.

Refractive Index of Single Surface Nanobubbles

“…In order to simplify the description, we defined SPR contrast of NPs to be (I NP − I BG )/I BG , where the I NP is the mean value of 40 pixels (4 × 10, 247 nm per pixel, marked by blue rectangle in Figure 2a) around the point of maximum contrast, the I BG is mean value of the same area, but calculated using SPRM images of blank gold film without binding of NPs. We further confirmed the reverse in SPRM image contrast using commercial Finite Difference Time Domain (FDTD) software from Lumerical Solutions, Inc. 49 The model simulation demonstrated that the adsorption of NPs with different RIs on the gold-water interface could produce SPRM images consistent with the experimental observation, i.e., wavelike patterns of bright center for NPs with ΔRI > 0 and wavelike patterns of dark center for NPs with ΔRI < 0 (Figure 2c, d). In a previous study by Corn and co-workers, gas vesicles, i.e.…”

Flexible hyperspectral surface plasmon resonance microscopy

“…The PS spheres with diameter of 0.6–1.0 μm (2.5% w/v) were purchased from Shanghai Aladdin, and dispersedly immobilized on the gold film by a reported method 38 . First, the gold-film chip was preheated at 160 °C for 10 min.…”

Label-Free Imaging of Subwavelength SiO2 Nanoparticle Arrays Using Evanescent Wave-Assisted Dark-Field Microscopy

“…However, this prediction still needs to be further experimentally verified. Currently, the leakage radiation microscopy based on the excitation of SPPs has been used for label-free imaging samples such as single nanoparticles; − defects in 2D materials, viruses, proteins, and exosomes; cell membranes; , etc. However, due to the propagation of SPPs, it is difficult to directly observe close-packed dielectric nanoparticle arrays through the leakage radiation microscope, and these arrays also have important applications.…”