Nano-radiogold-decorated composite bioparticles.

Hybrid composite bioparticles modified with stable and radioactive gold nanoparticles were prepared via reduction of tetrachloroauric acid within Lactobacillus rhamnosus cells. The resulting biocomposite material was characterized using a number of physicochemical techniques, including microscopic, spectroscopic and thermal methods. The bacterial particles act as a type of template for gold deposition. Gold nanoparticles of approximately 3.7 nm diameter are formed and are uniformly distributed within the bacterial cell, including its hydrogel outer shell. For radioactive gold-198, the β radiation emitted from the biocomposite particles can be used for therapeutic purposes, as demonstrated in vitro in cancer cell cultures. The antitumor activity can be further enhanced by incorporation of doxorubicin, a cytostatic drug, within composite particles. The cell viability data indicate the considerable synergistic effect of β radiation and doxorubicin on breast cancer cells (MCF-7). The antitumor action of the biocomposite particles is very promising for new anticancer therapies.