Facile synthesis of organic matrix-incorporated polydopamine layer for efficient laser desorption/ionization time-of-flight mass spectrometric analysis and imaging

Self-oxidative copolymerization of dopamine with organic matrices such as 3,4-dihydroxybenzoic acid (3,4-DHB) and 3,4-dihydroxycinnamic acid (3,4-DHC) leads to formation of homogeneous organic matrix incorporated polydopamine (pDA/OM) layers on both SiO₂ nanoparticles and Si substrates. The 3,4-DHB and 3,4-DHC incorporated pDA (DHB-pDA and DHC-pDA) layers are exhibited homogeneous mass signals and high laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS) efficiency with soft ionization characteristics compared to pDA layer for various small molecules as well as synthetic polymers. Therefore, the limit of detection (LOD) values of various analytes are improved on pDA/3,4-DHB and pDA/3,4-DHC layers compared to pure pDA layer. In addition, the pDA/3,4-DHC layers are also uniformly formed on Si substrates and successfully harnessed for LDI-TOF-MS imaging of fingerprints due to their high efficiency and homogeneity in LDI-TOF-MS analysis.