Carbonized Polymer\nDots: Influence of the Carbon Nanoparticle\nStructure on Cell Biocompatibility

Carbonized polymer dots (CPDs) were obtained by using\nmicrowave\nirradiation under the same conditions. However, different carbogenic\nprecursors were used, such as aromatic diamine molecules, <i>ortho</i>-phenylenediamine (<i>o</i>-OPDA), and 3,4-diaminobenzoic\nacid (3,4-DABA). Both carbon nanoparticles showed different structural\nresults based on Fourier transform infrared spectroscopy, Raman spectroscopy,\nX-ray diffraction, and atomic force microscopy analyses. However,\nthere are similar spectroscopic (UV–visible and fluorescence\nemission) profiles. The photophysical results, like quantum yield\n(QY) and fluorescence lifetime, were not identical; CPDs-OPDA has\na higher QY and fluorescence lifetime than CPDs-3,4-DABA. CPDs-3,4-DABA\npresents a more hydrophobic character than CPDs-OPDA and has a more\nnegative superficial charge. Cell viability studies in both standard\nand tumor lines demonstrated higher cytotoxicity from CPDs-OPDA than\nthat from CPDs-3,4-DABA. The oxidative stress identified in cells\ntreated with CPDs-OPDA was based on reactive oxygen species and associated\nwith nitric oxide production. CPDs-3,4-DABA showed more DPHH inhibition\nthan CPDs-OPDA, indicating the antioxidant activity of CPDs.