• Acidic solutions;
  • Amino-functionalized macroporous silica;
  • Mass spectrometry;
  • Nanoproteomics;
  • Peptide mass fingerprinting

Amino-functionalized macroporous silica foam (NH2-MOSF) has been developed as a host reactor to realize highly efficient proteolysis in acidic solutions where normal tryptic reactions cannot occur. The digestion protocol consists simply of adding the functionalized NH2-MOSF into the protein and trypsin solutions without altering the bulk pH or preloading the enzymes on the materials. With this protocol, digestion of sample fractions from LC can be efficiently realized in the acidic solutions directly. Digestion of a protein fraction extracted from rat liver tissue after LC separation was performed to illustrate this principle, where 103 proteins were successfully identified at pH 3 after 1.5 h of tryptic digestion.