Nanoparticle enhanced optical imaging and phototherapy of cancer

Nanoparticle research has seen advances in many fields, including the imaging and treatment of cancer. Specifically, nanotechnology has been investigated for its potential to be used as a tool to deliver well-tested drugs in potentially safer concentrations through both passive and active tumor targeting, while additionally providing means for a secondary therapy or imaging contrast. In particular, the use of light in conjunction with nanoparticle-based imaging and therapies has grown in popularity in recent years due to advances in utilizing light energy. In this review, we will first discuss nanoparticle platforms that can be used for optical imaging of cancer, such as fluorescence generation with quantum dots and surface-enhanced Raman scattering with plasmonic nanoparticles. We then analyze nanoparticle therapies, including photothermal therapy, photodynamic therapies, and photoacoustic therapy and their differences in exploiting light for cancer treatment. For photothermal therapies in particular, we have aggregated data on key variables in gold nanoparticle treatment protocols, such as exposure energy and nanoparticle concentration, and hope to highlight the need for normalization of variable reporting across varying experimental conditions and energy sources. We additionally discuss the potential to co-deliver chemotherapeutic drugs to the tumor using nanoparticles and how light can be harnessed for multifunctional approaches to cancer therapy. Finally, current in vitro methods of testing these therapies is discussed as well as the potential to improve on clinical translatability through 3D tissue phantoms. This review is focused on presenting, for the first time, a comprehensive comparison on a wide variety of photo based nanoparticle interactions leading to novel treatments and imaging tools from a basic science to clinical aspects and future directions.