Destruction of tumor mass by gadolinium-loaded nanoparticles irradiated with monochromatic X-rays: Implications for the Auger therapy.

Synchrotron generated monochromatic X-rays can be precisely tuned to the K-shell energy of high Z materials resulting in the release of the Auger electrons. In this work, we have employed this mechanism to destruct tumor spheroids. We first loaded gadolinium onto the surface of mesoporous silica nanoparticles (MSNs) producing gadolinium-loaded MSN (Gd-MSN). When Gd-MSN was added to the tumor spheroids, we observed efficient uptake and uniform distribution of Gd-MSN. Gd-MSN also can be taken up into cancer cells and localize to a site just outside of the cell nucleus. Exposure of the Gd-MSN containing tumor spheroids to monochromatic X-ray beams resulted in almost complete destruction. Importantly, this effect was observed at an energy level of 50.25 keV, but not with 50.0 keV. These results suggest that it is possible to use precisely tuned monochromatic X-rays to destruct tumor mass loaded with high Z materials, while sparing other cells. Our experiments point to the importance of nanoparticles to facilitate loading of gadolinium to tumor spheroids and to localize at a site close to the nucleus. Because the nanoparticles can target to tumor, our study opens up the possibility of developing a new type of radiation therapy for cancer.

Anticancer Drug Delivery Capability of Biodegradable PMO in the Chicken Egg Tumor Model.

Biodegradable PMO (Periodic Mesoporous Organosilica) has emerged as a promising type of mesoporous silica based nanoparticles for clinical translation. We as well as others have synthesized and characterized three types of nanoparticles containing disulfide, tetrasulfide or peptide-like bonds within their framework. Biodegradable PMO has high drug loading efficiency and can be taken up into cancer cells. Our experiments utilizing the chicken egg tumor model uncovered excellent capability to accumulate and deliver anticancer drugs to the tumor. These results will be described and their significance will be discussed. The chicken egg tumor model provides a convenient and versatile model for characterizing nanoparticles.