doi:10.1038/nindia.2015.10 Published online 21 January 2015
Researchers have synthesized chitosan-modified fluorescent nanoparticles that can be used as biomarkers for imaging human breast cancer cells1. Besides imaging, these nanoparticles are potentially useful for developing anticancer therapies.
Fluorescent nanoparticles are widely used in bioimaging and drug delivery. In particular, lanthanum fluoride nanoparticles doped with rare-earth ions fluoresce, converting near-infrared light to visible light. But these nanoparticles are toxic and insoluble in water.
The researchers coated rare-earth-ion-doped lanthanum fluoride nanoparticles (less than 50 nanometres in diameter) with natural biopolymer chitosan. While studying their fluorescence properties, the researchers found that the nanoparticles converted near-infrared light to strong green fluorescence.
They then tested the biocompatibility of the nanoparticles by mixing human breast cancer cells with solutions having different nanoparticle concentrations. More than 90 per cent of the breast cancer cells survived when the nanoparticle concentration was between 12.5 and 100 micrograms per millitre. Furthermore, the nanoparticles did not show any toxic effects on the cancer cells for concentrations up to 200 micrograms per millitre over a period of two days.
The scientists attribute this biocompatibility to the chitosan linking the nanoparticles with the molecules in the cancer cells. They say that these nanoparticles could potentially be used in photodynamic therapy, which kills cancer cells by exposing them to a combination of an anticancer drug and a specific type of light.
1. Gayathri, S. et al. Chitosan conjugation: a facile approach to enhance the cell viability of LaF3: Yb,Er upconverting nanotransducers in human breast cancer cells. Carbohydr. Polymers 121, 302–308 (2015)