Application of fluorescent carbon nanodots in fluorescence imaging of human serum proteins

In our studies, fluorescent carbon nanodots (C-dots) imaging was established for the on gels-detection of human serum proteins and Escherichia coli proteins after polyacrylamide gel electrophoresis (PAGE). The water-soluble C-dots were synthesized by a one-step microwave pyrolysis method, and emit bright, stable luminescence at 450 nm. For imaging, the fluorescent C-dots solution acted as the direct incubating solution, which was diluted with acetic acid (pH 2.7). After staining, fluorescence signals of proteins in the gel were obtained by ultraviolet illumination at 365 nm. The sensitivity of C-dots imaging was evaluated by the comparison of the signal intensities of transferrin obtained by different imaging methods, which resulted in 8 times higher sensitivity than the traditional CBB-R250 staining. Identified by mass spectrometry (MS), some proteins such as isoform 1 of alpha-1-antichymotrypsin (ACT), zinc-alpha-2-glycoprotein (ZAG) and complement C3 (fragment), can be easily detected by C-dots imaging after 2-D PAGE. However, they could not be detected by CBB-R250 staining. As a new fluorescence method for protein detection, C-dots imaging is simple, fast and sensitive, showing potential for proteome research.