Nanoprobe Based Mass Spectrometry

Matrix-Aassisted Laser Desorption/Ionization mass spectrometry(MALDI-MS) is a soft ionization technique with the potential for the analysis of biomolecules using the conventional organic matrix. However, analysis of complex biological samples as well as enzymatic digested proteins at low concentrations by MALDI-MS is difficult because high sensitivity is required for detection. Recently, we have developed multifunctional nanoprobes by using a variety of nanomaterials for the separation and enrichment of peptides and proteins for MALDI-MS. We have focused on developing simple, straight forward, washing or separation free techniques by using a variety of nanomaterials including Au nanoparticles (NPs)¹, Ag NPs², SiO₂ NPs, carbon nanotubes, functionalized ZnS NPs³ and CdSe QDs⁴ as the matrix, affinity probes and desalting approach to increase the detection sensitivity of proteins, peptides or drugs or environmental toxicants in the MALDI-MS. Our main contributions are in two aspects: (1) To develop nanoparticle based liquid phase microextraction techniques^1-2 as preconcentrating probes for complex sample analysis. (2) To develop on particle ionization/enrichment (OPIE) technique⁵ to accelerate the microwave-enzymatic digestion of proteins and to enrich the tryptic digested proteins for direct MALDI-MS analysis.