PEGylated carbon nanoparticles for efficient in vitro photothermal cancer therapy

Photothermal therapy (PTT) is an emerging technique for effective cancer elimination in animal experiments. The key to the success of the PTT is to develop efficient and safe photosensitive agents. Activated carbon (AC), a widespread material safely used in routine and emergent medical services, is emerging as a nascent PTT agent. Here we report for the first time synthesis and in vitro PTT application of carbon nanoparticles (CNPs, less than 10 nm) derived from AC. In our strategy, CNPs are obtained via chemical oxidation and transferred to PEGylated CNPs (PCNPs) to reduce nonspecific adsorption and to improve biocompatibility. Fluorescein isothiocyanate is conjugated to PCNPs to examine time-dependent uptake by human breast cancer cells (MCF-7). The photothermal effect experiment demonstrates that PCNPs possess much stronger photothermal conversion ability than carbon dots (CDs). In the dark, PCNPs pose negligible threats to cell viability and membrane integrity, while upon near infrared (NIR) irradiation PCNPs can effectively kill cancer cells. The current work demonstrates that PCNPs can be used as an efficient and safe PTT agent.