Nanoparticles with two-photon fluorophores for imaging and treatment of tumors

Currently, tumor imaging is based on the use of fluorescence emitted by chemical groups that absorb the energy of a single photon. These molecules – fluorophores – are excited when exposed to radiation in the ultraviolet region of the spectrum, so single-photon tomography provides relatively inaccurate results.

Scientists from several laboratories that are part of the French National Center for Scientific Research (CNRS) have managed to overcome this disadvantage. They have created porous nanoparticles capable of absorbing the energy of two photons of near-infrared light and emitting radiation suitable for detecting tumor cells.

The researchers synthesized organic two–photon fluorophores - aromatic molecules capable of simultaneously absorbing the energy of two photons in the near-infrared region of the spectrum. These molecules were incorporated into porous silicon nanoparticles that ensure their circulation in the biological environment. The advantage of this method is that, unlike ultraviolet radiation, infrared waves are less active and penetrate deeper into the thickness of tissues, which provides a more thorough search for tumors without tissue damage.

Moreover, two-photon fluorophores can be used to obtain a three-dimensional image, which will increase the effectiveness of tumor detection and targeted drug delivery. One of the possible options is the simultaneous encapsulation of nanoparticles of a fluorescent agent and chemotherapy drugs into the pores.

Scientists are also working on the functionalization of nanoparticles using biological markers that selectively interact with breast and cervical cancer cells. To do this, a monolayer of a hydrophilic polymer of polyethylene glycol and folic acid is applied to the surface of the nanoparticles, which forms a ligand binding to receptors expressed on the surface of HeLa (cervical cancer) and MCF7 (breast cancer) cell lines. Such modified nanoparticles make it possible to obtain a three-dimensional image of tumors. Other options for modifying nanoparticles for imaging other types of tumors are also possible.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily

08.04.2008