Biogenic preparation of undoped and heteroatoms doped carbon dots: effect of heteroatoms doping in fluorescence, catalytic ability and multicolour in-vitro bio-imaging applications - A comparative study

Abstract

The proficient carbon nanocatalysts and incredible fluorescent bio-imaging probes have been successfully fabricated and compared their remarkable efficiencies in this work. The work describes the preparation of undoped and heteroatoms (N, B & S) doped carbon dots from the Syzygium malaccense (S. malaccense) fruit extract via a simple and low cost hydrothermal carbonization method. The obtained pure and heteroatoms doped CDs were characterized and confirmed spectrometrically through various analytical techniques. The size of the obtained CDs, NCDs, B-CDs and S-CDs were found to be 4.68, 4.50, 3.71 and 3.10 nm, respectively. HR-TEM studies explored that the synthesized CDs were spherical in shape and the size of the CDs was reduced during doping of heteroatoms. The photophysical properties of the dissimilar CDs were enlightened through UV–Vis spectroscopy and spectrofluorometer. The quantum yield (QY) was found to be 0.32, 0.41, 0.35 and 0.36 for synthesized CDs, NCDs, B-CDs and S-CDs, respectively. The XRD, Raman and SAED results exposed the amorphous nature of the heteroatoms doped CDs. FT-IR, EDAX and XPS studies helped to confirm the doping of heteroatoms (N, B and S) were doped over the CDs surface. The proficient catalytic ability of the various CDs was revealed and compared towards the methylene blue (MB) reduction using NaBH4. Among the synthesized CDs, the NCDs showed better catalytic ability and efficiently reduced the MB within 10 min. Furthermore, the fluorescent staining ability of the prepared CDs was examined and compared in the in-vitro multicolour HeLa cell imaging. The NCDs were found to give high intense HeLa cell imaging compared to other synthesized CDs.