New technique may detect cancer early

Scientists have developed a new technique of weighing microscopic particles such as single atoms or protons, as well as cancer DNA, which may lead to early diagnosis of the disease.
Researchers led by Zhu Kadi from the Shanghai Jiaotong University, proposed the optical mass sensing technique to measure the masses of tiny objects, a method several times more sensitive than previous techniques.
The technology may be used for early detection of cancer cells.
"The mass of cancer DNA molecules should be different from that of normal ones. So the technology could be used to find these cells," Zhu predicted.
"The technique is still theoretical. We are looking for partners to carry out experiments," said Zhu.

Traditional measurement method can only weigh a bunch of atoms, and then estimate the mass of a single atom, state-run Xinhua news agency reported.

"We propose a system consisting of a nanoscale vibrating bar containing an embedded quantum dot and a metal nanoparticle sphere.
"When a tiny object, such as an atom or a strand of DNA, is placed onto the bar, the extra mass of the tiny object will change the bar's vibration frequency, which could be measured with lasers," Zhu said.
"There is no new physical theory being applied. But nobody has thought about the measurement in this way," Zhu said.

"Using lasers, rather than wires, is the key of the new technique," said Zhu.
In recent years, many researchers have been exploring nanotechnologies to create more sensitive measuring instruments, but they have all relied on electrical circuitry to communicate with the sample.
"Those techniques cannot be used to measure uncharged particles. For example, the DNA molecules will be destroyed if they are charged," Zhu said.
Also, electric wires can soak up energy by heating up, and they don't work well at the highest frequencies, where measurements often have the best sensitivity to small changes.
The study was published in journal Physics Reports.