Synthesis of anisotropic plasmonic nanoparticles with core-shell structure and prospects of their application in laser treatment of tumors

Aggregative stable dispersions of particles with anisotropic cores of iron(III) oxyhydroxide and gold or silver nanoshells are synthesized. They feature maximum plasmonic absorption at about 1000 nm (i.e., in the “optical window” of biological tissues). Such composite particles are of considerable interest for their potential use in cancer therapy. The possibility of finely tuning the position of localized surface plasmon resonance to the required wavelength is demonstrated for the FeOOH core/Au(Ag) shell nanostructures through a controlled variation of the metal shell thickness with a very small step (up to 1 nm). The surface modification of such composite particles by polyethylene glycol (PEG) considerably enhances the aggregative stability of their aqueous dispersions. Quantitative information about the distribution dynamics of the PEG-conjugated composite FeOOH core/Au shell particles in various organs and tissues of tumor-bearing mice has been obtained after an intravenous injection of a colloid solution of these particles. It is shown that composite particles can remain for a rather long time in a bloodstream without aggregation; moreover, their accumulation in a tumor takes place. Preliminary in vivo experiments have shown that PEGylated FeOOH core/Au(Ag) shell particles are effective thermosensibilizers in the pulse laser therapy of tumors.