A homogeneous carbon nanosphere film-spot: For highly efficient laser desorption/ionization of small biomolecules

In this work, a novel strategy for highly efficient detection of small molecules with a homogeneous carbon nanosphere film-spot (HCNFs) was carried out for the first time by negative surface-assisted laser desorption/ionization time-of-flight mass spectroscopy (SALDI-TOF MS). The HCNFs was fabricated by monolayer oxidized carbon nanospheres (OCS) self-assembling on laser desorption/ionization (LDI) target. With the HCNFs, no background interference and exclusive deprotonated ([M−H]−) peaks of analytes were obtained for a wide range of small biomolecules including fatty acids, amino acids, nucleobases, traditional Chinese medicines, and anti-cancer drugs in the negative SALDI-TOF MS. Comparing with other carbon-based matrices as well as the organic matrix, the monolayer OCS film exhibited various advantages including fewer interfering fragments, stronger signal intensities, and higher detection sensitivity. Moreover, with the improved spotting homogeneity of the HCNFs, “sweet-spot” searching on LDI target was avoided and good reproducibility was obtained in the LDI-TOF MS analysis. This study is expanding the application of carbon nanospheres and providing a promising approach for rapid analysis of small molecules with none-interference and good reproducibility.

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