Size-Dependent In Vitro Biocompatibility and Uptake Process of Polymeric Carbon Nitride

PPolymeric carbon nitride (PCN), which demonstrates unique properties, has been widely explored, mostly in photocatalysis, however, the evaluation of its biocompatibility is still needed. Herein, the cytocompatibility of PCN with different lateral size distribution (A-PCN with 160 nm –, B-PCN with 20 nm – and C-PCN with 10 nm dominating lateral size) was investigated. Three cell lines (L929, MCF-7 and HepG2) viability has been determined using cell counting kit-8 (CCK-8), neutral red uptake (NRU) and lactate dehydrogenase (LDH) leakage assays. It was found that the highest cytotoxicity of PCN was observed for flakes with lateral size of ~20 nm (B-PCN) in three cell lines after 48-hour of exposition. The uptake process of B-PCN sheets labelled with FITC by cells was also the most effective. Confocal laser scanning microscopy and atomic force microscopy revealed the nanomaterials distribution throughout the whole cytoplasm and perinuclear region. The results demonstrated the correlation between size, intern...