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Why can microbubbles effectively penetrate the blood-brain barrier and open a new era of cancer treatment?
Microbubbles are bubbles with a diameter less than one hundredth of a millimeter but greater than one micron. These small bubbles are widely used in industry, medical care, life sciences and food technology. The design characteristics of microbubbles, such as buoyancy, pressure resistance, thermal conductivity and acoustic properties, are determined by the composition of the bubble shell and internal filler. In medical diagnosis, microbubbles are used as contrast agents in ultrasound imaging to help doctors observe the internal conditions of the human body more clearly.
Microbubbles oscillate under the action of ultrasound, which is an important factor that distinguishes them from surrounding tissues. This characteristic gives microbubbles potential advantages in imaging and drug delivery.
Microbubbles are usually filled with a gas, such as air or perfluorocarbon gas, and are carefully designed to improve stability. The shell is usually made of lipids, albumin or proteins, and the combination of a hydrophilic outer layer and a hydrophobic inner layer of these materials allows the microvesicles to remain stable in the blood. These properties make microbubbles not only an auxiliary tool for imaging, but also show potential applications in drug delivery, biofilm removal, and water treatment.
Acoustic response and therapeutic application of microbubbles
In ultrasound imaging, the key to the acoustic properties of microbubbles is the difference between their density and that of the surrounding tissue. The core density of microbubbles is much lower than that of surrounding tissue, which allows them to effectively reflect sound waves when stimulated by ultrasound, thereby improving the contrast of imaging.
Microbubbles will undergo two oscillation phenomena when exposed to ultrasound, and these phenomena have a significant impact on drug delivery and tumor treatment.
When microbubbles are stimulated by ultrasound, their oscillations can form tiny holes, a phenomenon called increased cell permeability. This not only helps drugs better enter target cells, but also opens up new ideas for cancer treatment. The oscillation and collapse of microbubbles can be used as carriers for drug delivery and release drugs during treatment, greatly improving the therapeutic effect.
Application of microbubbles in cancer treatment
Drug delivery modes of microbubbles can be diverse, including encapsulating fat-soluble drugs within their lipid shells or conjugating them to nanoparticles and liposomes. This method not only improves the localization effect of drugs, but also reduces systemic toxic reactions.
Breakthrough of the blood-brain barrier
The brain is protected by the blood-brain barrier, which, while beneficial to health, creates challenges in cancer treatment. Research has found that using a combination of ultrasound and microbubbles can temporarily break the blood-brain barrier, allowing drugs to enter the brain, which has been demonstrated in multiple clinical trials over the past few years.
Clinical trials have shown that the use of microbubbles combined with ultrasound can safely and effectively deliver therapeutic drugs into the brain, which is of great significance for the treatment of cancer patients.
Adjunct to immunotherapy
In addition to drug delivery, microbubbles combined with ultrasound therapy have shown potential for use in immunotherapy. High-intensity focused ultrasound (HIFU) can promote immune response, and combined with the use of microbubbles, it can also help activate the immune system.
However, microbubbles also face some challenges in clinical application, such as their large size, which makes them difficult to flow out directly from blood vessels. This has led scientists to explore alternatives, such as the use of nanodroplets, which might be able to overcome some of the limitations of microbubbles.
The use of microbubbles shows new hope in drug delivery and disease treatment. It can not only help cross the blood-brain barrier but also regulate the tumor microenvironment. However, as this technology develops, can we expect more breakthroughs in the future to improve cancer treatment?
