Photostability enhancement of silica-coated gold nanostars for photoacoustic imaging guided photothermal therapy

Abstract

Gold nanostars (GNSs) are promising contrast agents for simultaneous photothermal therapy and photoacoustic imaging (PAI) owing to their excellent photothermal conversion efficiency. However, GNSs are easily reshaped under transient high-intensity laser pulses, which can cause a rapid shift in the light absorption peak, resulting in a decrease in both therapeutic and monitoring effects. In this work, we synthesized GNSs without toxic surfactants and coated them with a silica shell to retain their shape, thus maintaining their photostability. The excellent performance of these silica-coated GNSs was verified through both in vitro and in vivo PAI experiments. The silica-coated GNSs exhibited a threefold improvement in photoacoustic stability, as compared with the non-coated GNSs. The proposed silica coating method for GNSs was found to improve the photostability of GNSs, making them efficient, safe, and reliable nanoparticles for PAI.

Significantly amplified photoacoustic effect for silica-coated gold nanoparticles by interface heat transfer mechanisms

“…Even though differences in the surface area to volume ratios between the different AuNP shapes may alter the importance of interface heat transfer, there are three other effects noted in the literature that may contribute to PA response enhancement of AuNPs with a silica coating including: i) a reduction in the energy threshold for cavitation and a resulting increased contribution of cavitation effects to the PA signal, 24,48 ii) a shift in the absorbance peak that increases the AuNP power generation, 49 and iii) an increase in the photothermal stability of the particles which reduces degradation of the PA signal during repeated laser pulse applications. 50 Experimentally discerning the impact of interface heat transfer on the PA amplification of nonspherical silica-coated AuNPs will likely require additional measures like those implemented in our study to mitigate these effects. We have also summarized the literature for theoretical studies of PA signal alteration from Au@SiO2 nanoparticles in Table S3.…”

Advances of gold nanoclusters for bioimaging

“…AuNPs exhibiting surface plasmon resonance effects and NIR absorption have attracted much attention as exogenous contrast agents ( Li and Chen, 2015 ). AuNPs commonly used for PA imaging include Au nanorods, Au nanoflowers, Au nanocages, vesicles, and oversized spherical AuNPs (>5 nm in diameter) ( Chen et al., 2021 ; Huang et al., 2013 ; Santos et al., 2021 ; Wang et al., 2021 ; Yan et al., 2021 ).…”

Photoacoustic Imaging Probes for Theranostic Applications

“…The experimental results clearly indicate that Ce6/PDA-GNSs can inhibit the growth of 4T1 tumor cells and restrain their metastasis. To improve the photostability of GNSs, Chen et al coated the GNSs with silica at different shell thicknesses [ 37 ]. The result showed that a 25 nm-thick silica shell coated GNSs maintain their shape after laser irradiation.…”