Engineering news
Scientists at Nanyang Technological University (NTU Singapore) have invented a new method to create micro-sized gas bubbles and ultrasound to deliver cancer drugs deep into tumour cells.
The NTU scientists developed micro-sized gas bubbles coated with cancer drug particles and iron oxide nanoparticles, and then use magnets to direct these bubbles to gather around a specific tumour.
Ultrasound is then used to vibrate the microbubbles, providing the energy to direct the drug particles into a targeted area in just a few milliseconds.
This technique was developed by a multidisciplinary team of scientists, led by assistant professor Xu Chenjie from the School of Chemical and Biomedical Engineering and associate professor Claus-Dieter Ohl from the School of Physical and Mathematical Sciences.
NTU’s microbubbles were successfully tested in mice and the study has been published by the Nature Publishing Group in Asia Materials.
Chenjie said their new method may solve some of the most pressing issues with chemotherapy drugs that are largely non-targeted, meaning that the drug particles flow in the bloodstream, damaging both healthy and cancerous cells. Typically, these drugs are flushed away quickly in organs such as the lungs and liver, limiting their effectiveness.
The remaining drugs are also unable to penetrate deep into the core of the tumour, leaving some cancer cells alive, which could lead to a resurgence in tumour growth.
“The first unique characteristic of our microbubbles is that they are magnetic. After injecting them into the bloodstream, we are able to gather them around the tumour using magnets and ensure that they don’t kill the healthy cells,” said Chenjie, who has been working on cancer diagnosis and drug delivery systems since 2004.
The microbubbles can penetrate a depth of 50 cell layers or more – which is about 200 micrometres, twice the width of a human hair. This helps to ensure that the drugs can reach the cancer cells on the surface and also inside the core of the tumour.
Clinical associate professor Chia Sing Joo, consultant for the study, said that currently targeted cancer drugs tend to be administered by a direct injection into the tumour, or by administering a large dosage of cancer drugs, which can be painful, expensive, impractical and might have various side effects.
Joo added: “If successful, I envisage this can be a good alternative treatment in the future, one which is low cost and yet effective for the treatment of cancers involving solid tumours, as it might minimise the side effects of drugs.”
Ohl said: “Most prototype drug delivery systems on the market face three main challenges before they can be commercially successful: they have to be non-invasive, patient-friendly and yet cost-effective.
“Using the theory of microbubbles and how their surface vibrates under ultrasound, we were able to come up with our solution that addresses these three challenges.”
Moving forward, the team will be adopting this new drug delivery system in studies on lung and liver cancer using animal models, and eventually clinical studies.
They estimate that it will take another eight to ten years before it reaches human clinical trials.