Table 5.

AuNPs responsive to ultrasound.

Structure and Size of AuNP	In Vitro Effects	In Vivo Effects	Ref.
PLGA nanocapsule 690 nm PDA/PLGA 725 nm AuNPs@PDA/PLGA 930 nm	Low cytotoxicity on ECA-109 cells. Increased echogenicity with increased concentration. AuNPs@PDA/PLGA suitable for US imaging.	Highly efficient US guided HIFU ablation ex vivo on degassed bovine liver.	[93]
AuNPs 82 ± 6 nm embedded in 7% acrylamide gel phantom	Cavitation activity dependence on HIFU pressure and laser energy was studied.	None	[95]
Nanosphere 82 nm Nanorods 25 nm × 81 nm	PA cavitation vs US pressure and NP concentration was studied. Cavitation threshold fluences decreased with the presence of US. Indicated feasibility of producing PA cavitation in deep tissue within the safe range of US and laser irradiation.	None	[98]
7 nm	None	AuNP-PpIX in combination with US had higher antitumor efficacy.	[102]
Mesoporous silica nanocapsules 250 nm, with 50 nm shell, AuNP 5–10 nm	Increased cytotoxicity via US induced thermal effect and US induced PFH bubble cavitation and pyrene release (L929 cells). Enhanced grayscale value on US imaging.	Enhanced US imaging of tumor after subcutaneous injection and enhanced HIFU efficacy and accuracy (rabbit VX2 liver tumors).	[99]
Nanorods 10 × 41 nm, Aspect ratio 4:1 Definity microbubbles	Additive cytotoxicity of US + microbubble and mPEG-Au nanorods + laser.	None	[100]
Nanocage outer edge length 60 ± 11 nm, thickness 7.5 ± 2.8 nm	Dye release by HIFU via thermal phase transition of PCM.	None	[103]
Nanoporous Au wire 250 ± 20 nm	US-powered approaching to HeLa cells. NIR triggered release of Dox.	None	[104]
Nanocage edge length 52 nm	Triggered release of R6G by HIFU in gelatin phantom.	Controlled release up to 30 mm covering phantom with chicken breast tissue (ex vivo).	[105]
AuNP 6.3 nm AuNP-PEG 15 nm Unmodified Ad 117 nm Ad-AuNP-PEG 149 nm	Increased density of Ad-AuNP-PEG increased response to US induced acoustic cavitation	Higher tumoral accumulation and antitumor effect of Ad-AuNP-PEG + US (HepG2 xenograft).	[106]

PDA, polydopamine; PLGA, poly(lactic-co-glycolic acid); US, ultrasound; HIFU, high intensity focused ultrasound; PA, photoacoustic; PpIX, Protoporphyrin IX; PHF, perfluorohexane; mPEG, methoxy polyethylene glycol; PCM, phase-changing material; NIR, near infrared; Dox, doxorubicin; and Ad, adenovirus.