Development of novel ST68/PLA-PEG stabilized ultrasound nanobubbles for potential tumor imaging and theranostic.

Nanobubbles (NBs) have received wide attention as theranostic agents and been extensively explored in various applications, especially in cancer. The aim of this study was to develop a novel kind of NBs which possess high echogenicity and good stability. This novel ultrasonic nanobubbles (ST68/PLA-PEG NBs) consist of perfluoropropane gas stabilized by Span 60 and Tween 80 (ST68) surfactant and synthesized PLA-PEG-NH2 block copolymers, and were prepared through the methods of mechanical shaking and low-speed centrifugation. A series of experiments were carried out to evaluate the physicochemical properties, echogenicity and cytotoxicity of this novel NBs. According to the amount ratio of copolymers to surfactant, the NBs were divided into 5 groups (0%, 5%, 10%, 15% and 20%). Group "10%" were the optimum NBs, with a size of 675.6 nm, polydispersity index of 0.39. Moreover, these NBs gave a maximum contrast intensity of 31.0 ± 0.2 dB over baseline and little loss of contrast signal after 10 min. In conclusion, this novel kind of ST68/PLA-PEG NBs which exhibited a high echogenicity and good stability were successfully prepared, and they may offer a potential strategy for drug delivery and tumor-targeted theranostic.