Multicolour dual-emission Photoluminescent Carbon Dots à la carte for biomedical applications

Dual-emission fluorescence probes that provide high sensitivity are key for biomedical diagnostic applications. Non-toxic carbon dots (CDs) are a good alternative to traditional fluorescent probes, however robust and reproducible synthetic strategies are still needed to access materials with controlled emission profiles and improved fluorescence quantum yields (FQYs). Herein, we report a practical and general synthetic strategy to access dual-emission multicolour CDs with FQYs as high as 0.67 and green/blue, yellow/blue or red/blue excitation dependent emission profiles using common starting materials such as citric acid, cysteine and co-dopants to bias the synthetic pathway. Structural and physicochemical analysis is used to elucidate the material’s composition which is responsible for the unique observed photoluminescence properties. Moreover, the utility of the probes is demonstrated in the clinical setting by the synthesis of green/blue emitting antibody-CD conjugates which are used for the immunohistochemical staining of human brain tissues of glioblastoma patients, showing detection under two different emission channels.