Functionalized periodic mesoporous organosilicas for enhanced and selective peptide enrichment

The analysis of peptides by the mass spectrometry (MS) technique is important in modern life science. The enrichment of peptides can increase the detection efficiency and is sometimes indispensable for collecting the information on proteins with low-abundance. Herein, we first report that functionalized periodic mesoporous organosilica (PMO) materials have a superior peptide enrichment property. It is demonstrated that the PMO materials with an organo-bridged (-CH₂-) hybrid wall composition display a highly enhanced peptide enrichment ability compared to the pure silica material (SBA-15) with similar mesostructured parameters and morphology. More importantly, by surface modification of PMO with amino groups (denoted NH ₂-PMO), PMO and NH₂-PMO with opposite charged surfaces (-25.2 and +39.0 mV, respectively) show selective affinities for positively and negatively charged peptides, respectively. By directly adding PMO, NH ₂-PMO as well as pure silica materials to the peptides solution with a low concentration (1-2 fmol/μL), 36 and 28 peptides can be detected from the BSA digestion in the presence of PMO and NH₂-PMO, respectively, while only 6 and 4 are monitored in the case of SBA-15 enrichment and from solution without enrichment, respectively. Moreover, 69.4% (25 of 36) of enriched peptides by PMO have pI ≥ 6 and 80% (21 of 28) of enriched peptides by NH₂-PMO possess pI ≤ 6. Combining the results from the NH ₂-PMO and PMO enrichment together, 51 peptides can be identified with a MOWSE score of 333. It is also noted that similar conclusions can also be obtained from the peptides solution originated from other proteins. This might be an important contribution to the understanding of the interaction between peptides and porous hosts, and the proposed method is promising for the development of both material science and biotechnology.