Chemotherapeutic coatings enhance 'tumour-frying' nanoparticles
Researchers deposit a thin layer of hydrogels on the surface of nanoshells, which when heated lose their water content and release any molecule trapped within
Researchers at Duke University in the US have devised a method for making a promising nanoscale cancer treatment even more deadly to tumours.
The invention allows an extremely thin layer of hydrogels (similar to contact lenses) to be deposited on the surface of nanoshells – particles about a 100nm wide which absorb infrared light and generate heat. When heated, these hydrogels lose their water content and release any molecules (such as drugs) trapped within.
By depositing the hydrogels on tumour-torching nanoshells and loading the new coating with chemotherapeutic drugs, a formidable one-two punch is formed.
The technique is described in the journal ACS Biomaterials Science & Engineering.
'The idea is to combine tumour-destroying heat therapy with localised drug delivery, so that you can hopefully have the most effective treatment possible,' said study author Jennifer West, the Fitzpatrick Family University Professor of Engineering at Duke University. 'And many chemotherapeutic drugs have been shown to be more effective in heated tissue, so there’s a potential synergy between the two approaches.'
The idea is to combine tumour-destroying heat therapy with localised drug delivery
The photothermal therapy is already being tested for several types of cancers in clinical trials conducted by Nanospectra Biosciences, a company based in Houston, Texas, which was founded by West. The nanoshells are tuned to absorb near-infrared light, which passes harmlessly through water and tissue. The nanoshells, however, quickly heat up enough to destroy cells, but only where the light shines.
In addition to being able to accurately target specific locations in the body with the light, the treatment also hinges on the fact that nanoshells tend to accumulate within a tumour due to leaky vasculature.
'But you have to keep their size under about 500nm,' said West. 'We had to come up with a new process to create a very thin polymer coating on the surface of these nanoparticles to keep them under that threshold.'
In the new study, West and doctoral student Laura Strong loaded the newly coated nanoshells with a potent chemotherapeutic drug and delivered them to tumour cells in the laboratory. The treatment worked as planned; the nanoshells heated up and destroyed most of the tumour cells while releasing the drugs, which cleaned up the survivors. Completely eradicating every cancerous cell is extremely important, as the escape of even a single cell capable of metastasising could prove deadly later on.
Testing the treatment in live animals is in progress, but human trials are at least a two years away.
But West said the technology need not be limited to cancer therapy.
'The hydrogels can release drugs just above body temperature, so you could potentially look at this for other drug-delivery applications where you don’t necessarily want to destroy the tissue,' she said. 'You could do a milder warming and still trigger the drug release.'
