Polypeptide based nanoparticles for photothermal therapy of cancer

Abstract

Treatment of cancer is still a grand challenge due to the side-effects related to the currently available therapies. These include surgical intervention, radiation, and chemotherapy, which kill healthy cells along with the cancerous cells leading to several side effects such as hair loss, weight loss, etc. To overcome the limitations related to the techniques mentioned above, a new laser-based cancer therapy, i.e., photothermal therapy (PTT) has been adopted as an alternative due to its minimal side-effect. This technique requires laser light as a radiation source for treating cancer. In PTT, the radiation of laser results in the thermal ablation of the cancerous cells. However, it has been shown that the inclusion of the photosensitizers such as gold, platinum, benzoporphyrin derivative, a cyanine dye, etc.could increase the efficacy of PTT for cancer treatments. Currently, Indocyanine green (ICG), the only U.S. food and drug administration (FDA) approved exogenous chromophore, is being used for various clinical applications. In addition to other clinical applications, ICG also shows the photothermal effect and could be used as a sensitizer for PTT. However, the application of the ICG is limited due to its short circulation lifetime and poor optical stability. These limitations could be addressed by nanoencapsulation of the ICG within nanoparticles (NPs). In this study, we have encapsulated ICG within poly-L-lysine based nanoparticles for PTT. The synthesis of these nanoparticles was done by using a two-step self-assembly method. These nanoparticles were spherical with ~225 nm diameter. The encapsulated ICG showed high photostability and improved cellular uptake in comparison to free ICG. These NPs show significant photothermal effect than free ICG.