WE‐E‐108‐01: BEST IN PHYSICS (THERAPY) ‐ Radiotherapy Enhancement with a Novel Class of Hollow Nanoconstructs

Abstract

Purpose: Gold nanoparticles have been studied as radiation sensitizers to enhance radiotherapy. It has been reported that hollow shell‐shaped nanoparticles may lead to higher radiation enhancement than solid nanoparticles. We have developed a new gold nanoparticle in the shape of a hollow capsule. In this work we investigate the radiotherapy enhancement of this NanoCapsule system. Methods: Hollow shells nanoconstructs with a diameter of approximately 120 nm were synthesized and used for all experiments. Radiotherapy enhancement was evaluated through cytotoxicity of gold NanoCapsules in MDA‐MB‐231 human breast cancer cells in‐vitro. 100–4000 cells were plated in P60 Petri‐dishes and incubated for 24 hours. Sterilized gold nanoparticles were subsequently added to the cultures, in concentrations ranging from 0–350 μM. 48 hours after plating, cell colonies were irradiated using x‐rays from a small animal irradiator (Precision X‐ray, North Branford, CT) or a 6 MV x‐rays in flattening‐filter free mode from a commercial linear accelerator (Truebeam, Varian Medical Systems, Palo Alto, CA). The cell colonies were fixed 8 days after irradiation, stained, and counted. Results: The total intracellular Au concentration was confirmed by ICP‐Mass spectrometry. Control experiments demonstrated no significant cytotoxicity of Au‐NanoCapsules up to an Au concentration of 350 μM. The radiation enhancement was quantified by analyzing the survival fraction, the ratio between the between the numbers of survival colonies of irradiated samples and control samples (no irradiation). The survival fraction dropped from 0.37 to 0.24 using a Truebeam and from 0.17 to 0.03 with a small animal irradiator at a dose of 4 Gy with an Au concentration of 140 μM. Conclusion: Taking advantage of this novel Au‐NanoCapsule geometric configuration allows for gold nanoparticles to permeate the cell membrane and deliver dose locally, greatly reducing the amount of radiation required to achieve the same local control, whereby minimizing dose to sensitive structures.