1,5-Diaminonaphthalene functionalized carbon nanodots as a novel matrix for the analysis of small molecules by matrix-assisted laser desorption/ionization mass spectrometry

1,5-Diaminonaphthalene functionalized carbon nanodots (DAN-CDs) were explored as a novel matrix for direct detection of small molecules by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) in negative ion mode. By using DAN-CDs as the matrix, we could detect not only biological small molecules such as fatty acids (FAs), amino acids, peptide Gly-Gly and dopamine, but also anticancer drug erlotinib. By comparison with the performance of CDs, DAN, and their binary matrix, DAN-CDs were favored because of their lower matrix background interference and good detection sensitivity. In addition, the DAN-CDs matrix displayed good salt tolerance and was further applied for plasma detection and qualitative detection of endogenous FAs in a plasma sample. Furthermore, the covalent amide bonds in the DAN-CDs matrix reduced signal interference from the matrix. These results demonstrated that DAN-CDs are a novel negative ion mode matrix for the analysis of small molecules in bio-samples by MALDI-MS.