London: Scientists in Britain have designed microscopic "grenades" that can explode their cancer-killing load into tumours.
The Manchester-based team will present its findings at the National Cancer Research Institute conference in Liverpool next week.
The team plan to use liposomes, tiny bubbles of fat which carry materials round the body, to release toxic drugs when their temperature is raised.
These so-called "grenades" are intended to avoid side- effects by ensuring the drugs target only the tumour.
"This is still early work but these liposomes could be an effective way of targeting treatment towards cancer cells while leaving healthy cells unharmed," said Professor Charles Swanton, the chairman of the conference.
Cancer experts believe such technology, which has been effective in animal experiments, was the "holy grail of nanomedicine".
They are trying to harness the transporting abilities of these fatty spheres by getting them to carry toxic drugs to tumours.
"The difficulty is, how do you release them when they reach their target," Professor Kostas Kostarelos, from the University of Manchester, told BBC.
The Nanomedicine Lab in Manchester has designed liposomes that are water-tight at normal body temperature. But when the temperature increases to 42C they become leaky.
"The challenge for us is to try to develop liposomes in such a way that they will be very stable at 37C and not leak any cancer drug molecules and then abruptly release them at 42C," Mr Kostarelos added.
He suggests heat pads could be used to warm tumours on the body surface such as skin, head or neck cancers.
Probes can heat tumours inside the body, and there is also discussion about using ultra sound to warm tumours.
In early tests on mice with melanoma there was "greater uptake" of drugs in tumours using the thermal grenades and that resulted in a "moderate improvement" in survival rates.
Mr Kostarelos said similar techniques were being trialled in patients.