Multifunctionalized Microscale Ultrasound Contrast Agents for Precise Theranostics of Malignant Tumors

Table 1

Difference between nanosized UCAs and submicron/microsized UCAs.

	Nanosized UCAs	Submicron/microsized UCAs
Size	(i) <500 nm	(i) >500 nm
Raw materials	(i) High and special requirements on material structure and property	(i) Cheap and widely available
Stability	(i) Easy to aggregate; (ii) Easy to collapse under the action of ultrasound owing to high surface energy	(i) No aggregation; (ii) Easy to collapse under the action of ultrasound owing to strong oscillation
Loading efficiency	(i) Low loading efficiency limited by the small core size	(i) High loading efficiency that benefits from the large volume
Capability of cell uptake	(i) Easy to be taken by the cell	(i) Very difficult to the cell uptake
Ultrasonic imaging effect	(i) Very weak, especially to blood pool imaging	(i) Very strong
	(ii) Very difficult for clinical application	(ii) Commercial products for clinical application
Multifunctionalization	(i) Practicable	(i) Practicable