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Theoretical Comparison of Optical Properties of Near-Infrared Colloidal Plasmonic Nanoparticles

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ABSTRACT

We study optical properties of near-infrared absorbing colloidal plasmonic nanostructures that are of interest for biomedical theranostic applications: SiO2@Au core-shell particles, Au nanocages and Au nanorods. Full-wave field analysis is used to compare the absorption spectra and field enhancement of these structures as a function of their dimensions and orientation with respect to the incident field polarization. Absorption cross-sections of structures with the same volume and LSPR wavelength are compared to quantify differential performance for imaging, sensing and photothermal applications. The analysis shows that while the LSPR of each structure can be tuned to the NIR, particles with a high degree of rotational symmetry, i.e. the SiO2@Au and nanocage particles, provide superior performance for photothermal applications because their absorption is less sensitive to their orientation, which is random in colloidal applications. The analysis also demonstrates that Au nanocages are advantaged with respect to other structures for imaging, sensing and drug delivery applications as they support abundant E field hot spots along their surface and within their open interior. The modeling approach presented here broadly applies to dilute colloidal plasmonic nanomaterials of arbitrary shapes, sizes and material constituents and is well suited for the rational design of novel plasmon-assisted theranostic applications.

No MeSH data available.


Local field enhancement of the SiO2@Au core-shell particle (Rc = 27.3 nm and ts = 3.7 nm) at the LSPR wavelength of 800 nm.(a,d) Illustrate four designated planes. (b,c,e,f) plot the profiles of LSPR-induced local field enhancement. The incidence is polarized along x direction.
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f4: Local field enhancement of the SiO2@Au core-shell particle (Rc = 27.3 nm and ts = 3.7 nm) at the LSPR wavelength of 800 nm.(a,d) Illustrate four designated planes. (b,c,e,f) plot the profiles of LSPR-induced local field enhancement. The incidence is polarized along x direction.

Mentions: In Fig. 4, we plot the spatial profile of E field intensity enhancement (/E/2//E0/2) for the SiO2@Au core-shell particle across four different cut planes. As shown in Fig. 4a, two yz-planes (perpendicular to the field polarization) are labelled X1 and X2 where X1 is a symmetry plane through the center of the particle and X2 is parallel to X1 and tangential to the SiO2 core. Figure 4b shows a weakly confined mode within the Au shell in X1 and Fig. 4c shows a relatively strong mode distributed around the outer surface of Au shell in X2. The latter is due to the resonant dipolar moment of the Au core-shell.


Theoretical Comparison of Optical Properties of Near-Infrared Colloidal Plasmonic Nanoparticles
Local field enhancement of the SiO2@Au core-shell particle (Rc = 27.3 nm and ts = 3.7 nm) at the LSPR wavelength of 800 nm.(a,d) Illustrate four designated planes. (b,c,e,f) plot the profiles of LSPR-induced local field enhancement. The incidence is polarized along x direction.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035923&req=5

f4: Local field enhancement of the SiO2@Au core-shell particle (Rc = 27.3 nm and ts = 3.7 nm) at the LSPR wavelength of 800 nm.(a,d) Illustrate four designated planes. (b,c,e,f) plot the profiles of LSPR-induced local field enhancement. The incidence is polarized along x direction.
Mentions: In Fig. 4, we plot the spatial profile of E field intensity enhancement (/E/2//E0/2) for the SiO2@Au core-shell particle across four different cut planes. As shown in Fig. 4a, two yz-planes (perpendicular to the field polarization) are labelled X1 and X2 where X1 is a symmetry plane through the center of the particle and X2 is parallel to X1 and tangential to the SiO2 core. Figure 4b shows a weakly confined mode within the Au shell in X1 and Fig. 4c shows a relatively strong mode distributed around the outer surface of Au shell in X2. The latter is due to the resonant dipolar moment of the Au core-shell.

View Article: PubMed Central - PubMed

ABSTRACT

We study optical properties of near-infrared absorbing colloidal plasmonic nanostructures that are of interest for biomedical theranostic applications: SiO2@Au core-shell particles, Au nanocages and Au nanorods. Full-wave field analysis is used to compare the absorption spectra and field enhancement of these structures as a function of their dimensions and orientation with respect to the incident field polarization. Absorption cross-sections of structures with the same volume and LSPR wavelength are compared to quantify differential performance for imaging, sensing and photothermal applications. The analysis shows that while the LSPR of each structure can be tuned to the NIR, particles with a high degree of rotational symmetry, i.e. the SiO2@Au and nanocage particles, provide superior performance for photothermal applications because their absorption is less sensitive to their orientation, which is random in colloidal applications. The analysis also demonstrates that Au nanocages are advantaged with respect to other structures for imaging, sensing and drug delivery applications as they support abundant E field hot spots along their surface and within their open interior. The modeling approach presented here broadly applies to dilute colloidal plasmonic nanomaterials of arbitrary shapes, sizes and material constituents and is well suited for the rational design of novel plasmon-assisted theranostic applications.

No MeSH data available.