Graphene-based nanovehicles for photodynamic medical therapy

Graphene and its derivatives such as graphene oxide (GO) have been widely explored as promising drug delivery vehicles for improved cancer treatment. In this review, we focus on their applications in photodynamic therapy. The large specific surface area of GO facilitates efficient loading of the photosensitizers and biological molecules via various surface functional groups. By incorporation of targeting ligands or activatable agents responsive to specific biological stimulations, smart nanovehicles are established, enabling tumor-triggering release or tumor-selective accumulation of photosensitizer for effective therapy with minimum side effects. Graphene-based nanosystems have been shown to improve the stability, bioavailability, and photodynamic efficiency of organic photosensitizer molecules. They have also been shown to behave as electron sinks for enhanced visible-light photodynamic activities. Owing to its intrinsic near infrared absorption properties, GO can be designed to combine both photodynamic and photothermal hyperthermia for optimum therapeutic efficiency. Critical issues and future aspects of photodynamic therapy research are addressed in this review.