RESUMEN
Nitrogen-doped carbon dots (NCD) were synthesized using a simple and fast hydrothermal route, employing citric acid and urea as precursors. The resulting NCDs were non-covalently functionalized (conjugated) with aromatic amino acids, namely phenylalanine (Phe) and tryptophan (Trp). Atomic force microscopy revealed that the NCDs exhibit a disk-like morphology with an average diameter of approximately 60â¯nm and an average height of about 0.5â¯nm. Following conjugation, the particle height increased to around 3â¯nm. UV-vis spectroscopy analysis indicated successful conjugation of the amino acids to the NCD nanostructures. Additionally, DFT numerical calculations based on three differently N-doped clusters were performed to elucidate the nature of the non-covalent interactions between NCDs and the corresponding amino acids. Photoluminescent spectra demonstrated a stable and strong fluorescence signal for both hybrids in the UV region. The most significant changes were observed in the case of Trp-conjugation. In contrast to phenylalanine, the non-covalent bonding of tryptophan to NCDs strongly influenced the visible emission (around 500â¯nm) originating from surface states of the dots.
Asunto(s)
Aminoácidos Aromáticos , Carbono , Nanoestructuras , Nitrógeno , Carbono/química , Nitrógeno/química , Aminoácidos Aromáticos/química , Nanoestructuras/química , Puntos Cuánticos/química , Propiedades de Superficie , Fenilalanina/química , Tamaño de la Partícula , Triptófano/química , Microscopía de Fuerza Atómica , Fenómenos Ópticos , Teoría Funcional de la DensidadRESUMEN
Carbon nanotubes are unique one-dimensional macromolecules with promising application in biology and medicine. Since their toxicity is still under debate, here we describe an investigation of genotoxic properties of purified single-walled carbon nanotubes (SWCNT), multiwall carbon nanotubes (MWCNT), and amide-functionalized purified SWCNT. We used two different cell systems: cultured human lymphocytes where we employed cytokinesis-block micronucleus test and human fibroblasts where we investigate the induction of DNA double-strand breaks (DSBs) employing H2AX phosphorylation assay.