Microbubble Delivery Platform for Ultrasound-Mediated Therapy in Brain Cancers

Abstract

The blood-brain barrier (BBB) is one of the most selective endothelial barriers that protect the brain and maintains homeostasis in neural microenvironments. This barrier restricts the passage of molecules into the brain, except for gaseous or extremely small hydrophobic molecules. Thus, the BBB hinders the delivery of drugs with large molecular weights for the treatment of brain cancers. Various methods have been used to deliver drugs to the brain by circumventing the BBB; however, they have limitations such as drug diversity and low delivery efficiency. To overcome this challenge, microbubbles (MBs)-based drug delivery systems have garnered a lot of interest in recent years. MBs are widely used as contrast agents and are recently being researched as a vehicle for delivering drugs, proteins, and gene complexes. The MBs are 1–10 μm in size and consist of a gas core and an organic shell, which cause physical changes, such as bubble expansion, contraction, vibration, and collapse, in response to ultrasound. The physical changes in the MBs and the resulting energy lead to biological changes in the BBB and cause the drug to penetrate it, thus enhancing the therapeutic effect. Particularly, this review describes a state-of-the-art strategy for fabricating MB-based delivery platforms and their use with ultrasound in brain cancer therapy.

Sono-processes: Emerging systems and their applicability within the (bio-)medical field

“…When comparing their composition with the skull of humans, the required penetration depth and resulting attenuation of ultrasonic waves of the significantly bigger skull could potentially hinder the applicability of this system [206] , [207] . For a comprehensive overview of the application of MBs in opening the BBB, a recent review by Kim et al is then of interest [208] .…”

Research Progress in Sonochemistry for Biomedical Applications★

“…除此之外, 空化效应还是超声其他效应的基础. 声 空化效应能将超声的能量转化为热能, 导致超声热效应 和声致发光 [69] ; 气泡破裂产生的微射流和剪应力可以 破坏周围物体, 是超声辅助催化、超声机械消融和超声 机械化学的原理之一 [70] ; 声空化效应还能在细胞膜等 屏障上打开微孔, 增强细胞膜或血脑屏障等的透过 性 [71] , 能协助药物的运输和吸收等. 除了上述间接作用 之外, 声空化效应还能裂解水产生 ROS, 发挥抗癌抑菌 的作用.…”