pH-responsive zwitterionic carbon dots for detection of rituximab antibody.

Zwitterionic carbon dots (CDs) have received much attention as a result of good photostability, high biocompatibility, and high quantum yield. In this study, novel zwitterionic CDs were synthesized using a simple hydrothermal method of citric acid (CA) and l-histidine as carbon and nitrogen precursors, respectively. Prepared zwitterionic CDs have an average particle size of 4 nm diameter and showed green fluorescence with a peak at 530 nm when excited at 470 nm; quantum efficiency was 39.34% using rhodamine 6G as a baseline. The fluorescence intensity of zwitterionic CDs was quenched by rituximab in the range 0-400 μmol L , with a limit of detection of 27 μmol L . In addition, the synthesized zwitterionic CDs had low toxicity, good stability, and high selectivity and sensitivity sensing for rituximab, therefore zwitterionic CDs are a promising candidate for practical applications.