N-doped graphene quantum dots from graphene oxide and dendrimer and application in photothermal therapy: An experimental and theoretical study

Abstract

The present study was conducted to synthesize nitrogen-doped graphene quantum dots (N-GQDs) through amidative/oxidative cutting of graphene oxide using H2O2 and G0 PAMAM dendrimer as oxidizing and amidative agents, respectively. G0 PAMAM dendrimer, as a multiamine, was utilized for doping N into GQDs and passivation of the active surface of GQDs to obtain N-doped GQDs and amine-modified GQDs. The N-GQDs exhibited a broad absorption band from the visible to the first near infra-red (NIR) region with a photoluminescence. Interestingly, the prepared the N-GQDs exhibited reasonable photothermal conversion efficiency (η = 53.45% upon 808 nm laser irradiation). The structures of N-GQDs were investigated by a series characterization method. Moreover, a theoretical study was carried out employing quantum mechanical (QM) method on the structures of the designed graphene oxide and N-GQDs profiles to obtain the energy gap. Subsequently, the absorption and photoluminescence mechanisms of the N-GQDs were proposed. Following the evaluation of biocompatibility, the N-GQDs were evaluated to their photothermal application.