Silicon NAPA chips provide highly efficient ion production for ultratrace analysis and molecular imaging by mass spectrometry without an ionization matrix. Matrix-assisted laser desorption ionization (MALDI) is an established ionization technique for mass analysis of large biomolecules, but analysis of small biomolecules (m/z < 1000) suffers from matrix-related interferences. For this reason, a number of matrix-free ionization platforms are in development. Nanopost arrays capture the energy from ultraviolet laser light thereby promoting efficient sample ionization and sub-femtomolar sensitivity and quantitative response with over three orders of magnitude dynamic range. NAPA chips facilitate structural identification of biomolecules and peptides in their ability to adjust the degree of their fragmentation by simply changing the laser intensity.
Chemical modifications to the surface of NAPA chips enable customized bioassays. Multiple peer-reviewed scientific publications demonstrate applications of NAPA chips for chemical and mixture identification and molecular imaging of cells (even single cells) and biological tissue sections.
Figure: Molecular images of a mouse kidney section on a NAPA chip. a) optical image b) heme b c) PE(40:8) d) PC(32:0) e) composite.