Bioactive carbon dots lights up microtubules and destabilises cell cytoskeletal framework - A robust imaging agent with therapeutic activity.

A class of bioactive, microtubule specific, self-targeted carbon dots (CDs) has been synthesised by simple one-step hydrothermal treatment with Catharanthus roseus as the precursor. Apart from excitation dependent multicolour fluorescence of as-prepared CDs, they were also attributed with an inherent affinity for microtubules of cell cytoskeletal framework. As prepared CDs in-vitro bio-labelling and live cell imaging studies in NIH 3T3 cells illustrates their tubulin specific bio-labelling potential which lights up the cell microtubule framework prominently under all filters. The ability of as-prepared CDs to simultaneously label tubulin and effectuate microtubule depolymerisation and fragmentation enables us to track its therapeutic potential on a real time basis. The cascade of events starting from cellular uptake, microtubule labelling and subsequent cytoskeletal changes (microtubule fragmentation, depolymerisation and cytoplasmic constriction) have been investigated comprehensively in this work by flow cytometer, confocal microscope, AFM microscopy (Peak Force QNM) and FE-SEM analysis. In summary, this work outlines the synthesis, characterization and application of a new class of highly fluorescent self-targeted microtubule specific CDs as a potent bioactive imaging nanotags.