Expression of Concern: An accurate closed-form analytical model of single nanoshells for cancer treatment

Recently, there have been significant experimental advances in cancer treatment using metallic nanoshells, which are silica spheres coated with gold. Nanoshells posses an excellent tunability of their resonance frequency as a function of the relative sizes of the core and the thickness of the shell, consequently offering much improved sensitivity, specificity, and cost-effectiveness in cancer treatment. In this paper, we develop an accurate analytical closed-form model for the frequency resonance and scattering characteristics of single nanoshells. The closed-form model helps to intuitively explain the optical properties of the nanoshells. Simulation results show that the new model matches very closely with the exact solution for typical nanoshell configurations used in cancer treatment. The developed model ultimately allows for the real-time detection, monitoring and treatment of cancer using nanoshells.