NIR light-activated biomarker detects tumor cells, delivers drugs

A team of researchers at Nanyang Technological University (NTU; Singapore) has developed a biomarker made from a nanophosphor particle that, when activated by near-infrared (NIR) light, detects tumor cells to allow scientists to take a better look. And it can also release anti-cancer drugs at the same time to the specific cells.

Related: Silicon quantum dots promising for clinical deep-tissue imaging

NTU associate professors Zhang Qichun and Joachim Loo have found a way to make the nanoparticle light up when it is activated by NIR light emitted by an imaging device and only if tumor cells release small signaling molecules.

Zhang says that the use of NIR light, which is invisible to the human eye, is unique, as most imaging techniques use ultraviolet (UV) light or visible light.

"Near-infrared light can penetrate 3 to 4 cm beyond the skin to deep tissue, much deeper than visible light. It also does not cause any damage to healthy cells, unlike ultraviolet or visible light," Zhang, a materials expert, explains. "Visible light also causes photobleaching, which is the destruction of the fluorescence dye that reduces the amount of time doctors and scientists have to image a tissue sample. Our new biomarker has effectively eliminated such key limitations, which exist in existing biological markers."

Loo says their new biomarker can also release anti-cancer drugs by creating a layer of coating loaded with drugs on the outside of the nanoparticle. The drugs are released when the biomarker lights up in response to the NIR light. "This is the first time we are able to do bioimaging and potentially target the delivery of drugs at the same time, as proven in small animal tests," says Loo, a nanotechnology and bioimaging expert. "Our breakthrough will open up new doors in the various fields of nanomedicine, bioimaging, and cancer therapeutics."

The new biomarker also has other advantages. It has twice the contrast of conventional dyes and is able to emit up to three different colors of light. This means that it allows for better differentiation between healthy cells and tumor cells.

Unlike other new biomarkers used for imaging such as quantum dots, the NTU biomarker has also been shown to be non-toxic, staying in the body for up to two days before it is passed out harmlessly.

Moving forward, the team from NTU's School of Materials Science and Engineering will be looking to load multiple layers of drugs into their biomarker. If successful, doctors will be able to release sequentially two or more drugs through it. This will benefit cancer patients, as there will be fewer side effects due to the small doses administered. Also, there will be higher efficacy, as the biomarker has the ability to accurately target tumor cells.

Full details of the work appear in the journal Small; for more information, please visit http://dx.doi.org/10.1002/smll.201401867.

-----

Follow us on Twitter, 'like' us on Facebook, connect with us on Google+, and join our group on LinkedIn

Subscribe now to BioOptics World magazine; it's free!