Facile construction of carbon dots via acid catalytic hydrothermal method and their application for target imaging of cancer cells

To solve the problem of high temperature or long reaction time in hydrothermal synthesis of carbon dots (CDs), a novel method based on the promoting carbonization by hydrochloric acid as catalysis was developed in present work. The acid catalyzed carbon dots (ACDs) were prepared facilely from tryptophan and phenylalanine at 200 ℃ for 2 h. In our findings, the acids could promote significantly the formation of the ACDs' carbon core, as a result of the accelerating of the carbonization due to the easy deoxidation. The ACDs showed an average size of 4.8 nm, and consisted of high carbon crystalline core and various surface groups. The ACDs exhibited good optical properties and pH-dependent photoluminescence (PL) intensities. Furthermore, the ACDs were safe and biocompatible. The experimental results demonstrated that such new ACDs were connected with DNA-aptamer by EDC/NHS reaction maintaining both the bright fluorescence and recognizing ability on the cancer cells, which so could be served as an effective PL sensing platform. The resultant DNA-aptamer with ACDs (DNA-ACDs) could stick to human breast cancer cells (MCF-7) specifically, and exhibited high sensitivity and selectivity, indicating the potential applications in the cancer cells targeted imaging fields.