Nanoprobes effective in delivering cancer drugs

Scientists in the US have shown that tiny nanoprobes are effective in delivering cancer drugs more directly to tumour cells and the correct cellular compartments.

Purdue University Professor Joseph Irudayaraj and graduate student Jiji Chen said they've determined the nanoprobes, or nanorods, when coated with the breast cancer drug Herceptin, are reaching the endosomes of cells, mimicking the delivery of the drug on its own.

Endosomes perform a sorting function to deliver drugs and other substances to the appropriate locations.

"We have demonstrated the ability to track these nanoparticles in different cellular compartments of live cells and show where they collect quantitatively," said Irudayaraj.

"Our methods will allow us to calculate the quantities of a drug needed to treat a cancer cell because now we know how these nanoparticles are being distributed to different parts of the cell," Irudayaraj added.

The nanoprobes, which are about 1,000 times smaller than the diameter of a human hair, are made from gold and magnetic particles.

An MRI machine can track the magnetic portions of the nanoprobes while a more sensitive microscopy process can detect the gold. The nanoprobes were inserted into live human tumour cells during laboratory testing.

Using fluorescent markers to differentiate organelles, or sub-units of cells, Irudayaraj's group was able to determine the number of nanoprobes accumulating in the endosomes, lysosomes and membranes of those cells.

Cancer treatments often use high drug concentrations that damage healthy cells near a tumour. While Herceptin is attracted to and attaches to the proteins on the surface of breast cancer cells, healthy surrounding cells absorb some of the chemotherapy drugs through normal fluidic intake.

Irudayaraj said targeting only tumour cells with nanoprobes would require less drugs and mitigate the side effects of cancer chemotherapy drugs.

"Each nanoparticle acts like a deliverer of a mail package, or dose, of the drug directly to the appropriate location," Irudayaraj said.

The results were published early online in the journal ACS Nano