A comparative study of antioxidant-loaded carbon nanoparticles as drug delivery vehicles

Chronic obstructive pulmonary disease (COPD) describes chronic lung diseases that cause limitations in lung airflow. Reactive oxygen species (ROS) play a central role in causing COPD and scavenging of ROS holds great promise to alleviate the symptoms of COPD. Antioxidant proteins such as catalase are good therapeutic drug candidates; however, they are easily degraded by proteases in vivo. Here, we investigated the characteristics of carbon nanoparticles as vehicles for delivering antioxidant proteins to macrophages. A direct comparison using catalase was conducted from zero to three dimensional carbon nanoparticles, namely: fullerene (zero dimensional (0D)), carbon nanotubes (CNTs, one dimensional (1D)), graphene oxide (GO, two dimensional (2D)), and graphene aerogel (GA, three dimensional (3D)). Over 90% of catalase was encapsulated in CNTs, GO, and GA. GA released less than 3% catalase in 24 hours, which is useful for long-term release. Fullerene delivered catalase inside macrophages with high efficiency although the encapsulation of catalase in the fullerene was 39.7%. Functionalization of carbon nanoparticles can modify the chemical properties that affect the characteristics of drug delivery vehicles. The release rate of catalase from functionalized carbon nanoparticles, CNTs with 2.0 wt% (percent by weight) of -COOH and GO, is 15-20% in 4 hours, which is much higher than GA. As drug delivery vehicles, carbon nanoparticles are very promising due to their high loading efficiency of therapeutic drugs and tunable surface properties. We also anticipate numerous applications of porous carbon nanoparticles for treating lung diseases, since low density nanoparticles can reach the deep lung efficiently.