Nanocolloids & Ultrasound Applications in Imaging & Treatment of Cancer

The thesis has dealt with two different applications of ultrasound and extra small (nano sized) colloids. First, we focused on uses of ultrasound for imaging of the human body. We created new colloids that act as enhancers of ultrasound imaging and obtained results showing that the contrast agents work as we expected in tissue phantoms.

We hope that these contrast agents can be applied in the future in imaging of liver cancer. Then we incorporated a drug used for the chemotherapy of liver cancer, which is called sorafenib, in the same colloid that enhanced ultrasound imaging. We hoped to create a pharmaceutical formulation, which could be used both for imaging and treatment of liver cancer.

We obtained results showing that the colloids we created were toxic against liver cancer cells. We also showed that some of the components of the formulations had unexpected toxic effects on cancer cells. We propose the use of these components in other formulations to treat cancer. Then we focused on a known use of ultrasound for the therapy of different diseases, such as cancer as well as diseases of the brain.

In this application, ultrasound is used together with contrast agents used clinically at the moment, microbubbles. When microbubbles are ‘hit’ with intense ultrasound they oscillate and even implode. When this happens close to a tumor or the blood brain barrier, the result is that more circulating drug or colloid can penetrate the tissue.

We used this effect in two ways. First, we combined it with novel colloids that respond to the special environment of tumors. We used the combination to treat a human prostate cancer model in mice. We showed that our proposed treatment was in general effective against the tumors, and only slightly less effective than the commercially available colloids.

Then, we tested whether ultrasound and microbubbles could be combined with colloids specifically targeting the brain, to increase the amount of a drug present inside the colloids in the brain. We compared the novel targeted colloids with commercially available colloids. We found that there were very small differences between the two colloids.

Due to these observations, we propose that changing the chemistry of the colloid in a different way and not adding targeting properties will likely increase the amount of colloid found in the brain.