A folic acid conjugated polyethylenimine-modified PEGylated nanographene loaded photosensitizer: photodynamic therapy and toxicity studies in vitro and in vivo

Targeted cancer therapies are currently a strong focus in biomedical research. Our recent studies have demonstrated that polyethylenimine-modified PEGylated nanographene loaded chlorin e6 (PPG-Ce6) shows excellent photodynamic efficacy because of the significantly enhanced intracellular targeted delivery of Ce6 to lysosomes. Based on our previous research, in this work, a novel nanographene-based tumor targeting delivery system was developed to selectively transport the photosensitizer into the tumor cells. In brief, we describe that the folic acid (FA) conjugated polyethylenimine-modified PEGylated nanographene system (PPG-FA) delivered in a targeted manner chlorin e6 (Ce6) to the tumor to simultaneously achieve targeted photodynamic therapy and biological imaging. The cellular internalization and the cellular uptake of PPG-FA-Ce6 were assessed, which indicated that the intracellular uptake of PPG-FA-Ce6 was target-specific. In vitro and in vivo photodynamic therapy results showed that PPG-FA-Ce6 exhibits excellent targeted delivery of Ce6, leading to simultaneous significant targeted photodynamic therapy and imaging. More importantly, the toxicity studies showed that PPG-FA-Ce6 had low toxicity as evidenced by blood biochemistry, hematological analysis, and histological examination. Our present work demonstrates that PPG-FA-Ce6 has high photodynamic therapy efficacy with no obvious toxicity because of its good tumor targeting property which can be potentially utilized in the biomedicine field.