(186t) Light Absorption from Gold Nanoparticle Agglomerates

Gold nanoparticles have shown significant potential for biomedical applications, such as in-vivo photothermal treatment of cancer [1]. This is due to their light absorption enhanced by collective oscillations of their surface electrons during interaction with light [2]. These oscillations are efficiently converted to heat, killing cancer cells that may surround gold nanoparticles [3]. Since the electromagnetic wave transmittance through human skin reaches a maximum at near-infrared (NIR) wavelengths, it is crucial to optimize the light absorption of gold nanoparticles in this spectrum [4]. The light absorption of single gold spheres reaches a maximum at a wavelength of 530 nm, i.e. far away from the NIR spectrum. Non-spherical gold nanoparticles, such nanorods [5], have enhanced NIR light absorption. Similarly, agglomerates of gold nanoparticles formed by coagulation have enhanced NIR absorption due to plasmonic coupling effects between their constituent primary particles [1].

Here, discrete element modeling (DEM) is coupled with discrete dipole approximation (DDA) [6] to investigate numerically the evolution of gold light absorption during nanoparticle agglomeration. The DDA model is validated against simulations and experiments for single spheres and nanorods [5]. The evolution of agglomerate size distribution and morphology are derived by a DEM for agglomeration of gold primary particles. The dynamics of gold light absorption derived by DEM-DDA are in good agreement with those measured from gold nanoparticle agglomerates. The gold nanoparticle agglomerate morphology and size distribution with the optimal NIR light absorption are determined and benchmarked against those of single spheres and nanorods [5].

References:

[1] Sotiriou, G. A., Starsich, F., Dasargyri, A., Wurnig, M. C., Krumeich, F., Boss, A., Leroux, J. C., & Pratsinis, S. E. (2014) Adv. Funct. Mater. 24, 2818-2827.

[2] Willets, K. A., & Van Duyne, R. P. (2007) Annu. Rev. Phys. Chem. 58, 267-297.

[3] Radt, B., Smith, T. A., & Caruso, F. (2004) Adv. Mater. 16, 2184-2189.

[4] Weissleder, R. (2001) Nat. Biotechnol. 19, 316-317.

[5] Qin, Z., Wang, Y., Randrianalisoa, J., Raeesi, V., Chan, W.C.W., Lipinski, W., & Bishof, J.C. (2016) Sci. Rep. 6, 29836-1-13.

[6] Kelesidis, G. A., & Pratsinis, S. E. (2019). Proc. Combust. Inst. 37, 1177-1184.