Theoretical and Experimental Study of Photoacoustic Excitation of Silica-Coated Gold Nanospheres in Water

Genny A. Pang, Florian Poisson, Jan Laufer, Christoph Haisch, Emmanuel Bossy

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19 Scopus citations

Abstract

Silica-coated gold nanoparticles are commonly employed in biomedical photoacoustic (PA) imaging applications. The PA signal generation by silica-coated gold nanospheres in water was investigated theoretically and experimentally. The influence of interfacial thermal (Kapitza) resistance at the gold-water boundary and the influence of the silica coating on PA signal generation were investigated with a theoretical model considering thermoelastic expansion and a finite-difference in time domain solution to the thermoelastic equations. Our results indicate that for the several-nanosecond long pulses commonly employed in PA imaging, Kapitza resistance has a negligible effect on PA signal generation. Moreover, the model shows that the presence of a silica coating causes a reduction in the PA signal amplitude, with the magnitude of signal reduction increasing with thicker silica coating. The theoretical predictions are qualitatively consistent with the experimental results, where suspensions of silica-coated gold nanosphere suspensions were excited with nanosecond-pulsed laser illumination. The PA signal amplitudes from silica-coated nanospheres were found to be lower than the signal amplitudes for uncoated gold nanospheres of the same core gold diameter. The amount of reduction of the measured PA signal amplitude due to the silica coating increases with thicker silica coating, in agreement with the theoretical predictions.

Original languageEnglish
Pages (from-to)1088-1098
Number of pages11
JournalJournal of Physical Chemistry C
Volume124
Issue number1
DOIs
StatePublished - 9 Jan 2020

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