Full color emitting fluorescent carbon material as reversible pH sensor with multicolor live cell imaging

Carbon-based nano materials are developed as a cytocompatible alternative to semiconducting quantum dots for bioimaging and fluorescence-based sensing. The green alternatives for the synthesis of carbon materials are imminent. The present study demonstrates microwave based one step quick synthesis of fluorescent carbon material (FCM) having three variants: (i) un-doped fluorescent carbon material (UFCM) (ii) nitrogen doped FCM ([email protected]), and (iii) nitrogen & phosphorus co-doped FCM ([email protected]) using sugarcane extract as a carbon source. The N doping was performed using ethylenediamine and phosphoric acid was used for P doping. The heteroatom doped FCM were synthesized due to insolubility of UFCM in water. Unlike, UFCM, the [email protected] and N[email protected] were found to be highly soluble in water. The [email protected] shows highest quantum yield among the three. The N[email protected] was explored for alkaline pH sensing and it shows a quenching of fluorescence in the pH range 09–14. The sensing behaviour shows reversibility and high selectivity. Further, the sensor was also investigated for their biocompatibility and hence employed as a promising multicolour probe for cancer cell imaging. The generality in cell imaging was investigated by flow cytometry. The hetero-atom doped green carbon-dots may open new avenues for sensing and selective cellular targeting.