Light-activated drugs offer precise strikes on tumours

The research findings by UCLA Jonsson Comprehensive Cancer Center’s Jeffrey Zink, a professor of chemistry and biochemistry, and Fuyu Tamanoi, a professor of microbiology, immunology and molecular genetics, and their colleagues appear online in Small.

Light-activated drug delivery holds promise for treating cancer because it give doctors control over precisely when and where in the body drugs are released.

Delivering and releasing chemotherapy drugs so that they hit only tumour cells and not surrounding healthy tissues can greatly reduce treatment side effects and increase the drugs’ cancer-killing effect but the development of a drug-delivery system that responds to tissue-penetrating light has remained challenging.

To address this, the teams of Tamanoi and Zink, which included scientists from the Jonsson Cancer Center’s cancer nanotechnology and signal transduction and therapeutics programs, collaborated with Jean-Olivier Durand from France’s University of Montpellier to develop a new type of nanoparticle that can absorb energy from tissue-penetrating light.

These new nanoparticles are equipped with thousands of pores that can hold chemotherapy drugs. The ends of the pores are capped with nanovalves that keep the drugs in. The nanovalves contain special molecules that respond to energy from two-photon light exposure, which prompts the valves to open and release the drugs.

The operation of the nanoparticles was demonstrated in the laboratory using human breast cancer cells.

Because the effective range of the two-photon laser in the infrared red wavelength is 4cm from the skin surface, this delivery system would work best for tumours within that range, which possibly include breast, stomach, colon and ovarian tumours, the researchers said in a statement.

In addition to their light sensitivity, the new nanoparticles are fluorescent and can be monitored in the body using molecular imaging techniques, allowing researchers to track the progress of the nanoparticle into the targeted cancer cell before light activation.