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

•Undoped and heteroatoms doped CDs was biogenically synthesized from S. malaccense.•Effect of heteroatoms doping on fluorescence and catalytic ability of the CDs was studied.•Profound catalytic ability of the obtained CDs was utilized through methylene blue reduction.•Highly fluorescent heteroatoms doped CDs were used as bio-imaging probe to detect hela cells.•Catalytic and fluorescent staining ability of heteroatoms doped CDs were compared and reported.