Superparamagnetic iron oxide-enclosed hollow gold nanostructure with tunable surface plasmon resonances to promote near-infrared photothermal conversion

This review focuses on the synthesis, protection, functionalization, and application of magnetic nanoparticles, as well as the magnetic properties of nanostructured systems. Substantial progress in the size and shape control of magnetic nanoparticles has been made by developing methods such as co-precipitation, thermal decomposition and/or reduction, micelle synthesis, and hydrothermal synthesis. A major challenge still is protection against corrosion, and therefore suitable protection strategies will be emphasized, for example, surfactant/polymer coating, silica coating and carbon coating of magnetic nanoparticles or embedding them in a matrix/support. Properly protected magnetic nanoparticles can be used as building blocks for the fabrication of various functional systems, and their application in catalysis and biotechnology will be briefly reviewed. Finally, some future trends and perspectives in these research areas will be outlined.

Significance Prostate cancer is the most common nonskin cancer in the United States, where approximately 1 in 9 men will be diagnosed in their lifetime. The prostate is near several vital structures, such as the urethra and neurovascular bundle, and whole gland treatments for prostate cancer can disrupt normal urinary, bowel, and sexual functioning. Here we report the initial results of a clinical trial for nanoparticle-based photothermal cancer therapy. The trial was designed to perform ultrafocal photothermal ablation of cancerous tumors within the prostate. Gold-silica nanoparticles designed to absorb near-infrared light at wavelengths of high tissue transparency provide a highly localized light-based strategy for the treatment of prostate cancer, with substantially reduced risks for deleterious treatment-related side effects.

Visible radiation at resonant frequencies is transduced to thermal energy by surface plasmons on gold nanoparticles. Temperature in