Nitrogen doped carbon dots with antibacterial activity for dual mode fluorescence and smartphone-assisted...

The treatment of cancer can be improved by optimising the drug dose during therapy. To meet the challenge, simple and sensitive techniques are essential to monitor the concentrations of an anticancer drug like epirubicin (EPR) in the patient's blood. In this work, we synthesised nitrogen-doped carbon dots (N-CDs) for dual mode fluorometric and smartphone assisted colorimetric detection of EPR. The synthesised N-CDs exhibited usual excitation dependent fluorescence, high aqueous solubility and excellent photostability properties. The blue fluorescence emission was effectively quenched by addition of EPR through the inner filter effect. In addition, the observed colour change of N-CDs with addition of EPR was quantified by using a portable and easy to handle smart phone device. The N-CD based dual mode sensing technique was successfully applied for detection of EPR in real human blood samples with satisfactory recovery. Furthermore, these N-CDs showed antibacterial activities against both Gram-positive (S. aureus) and Gram-negative (S. flexneri and K. pneumonaie) bacteria.