Enhanced Spatially Resolved Proteomics Using On-Tissue Hydrogel-Mediated Protein Digestion

The identification of proteins from tissue specimens is a challenging area of biological research. Many current techniques for identification forfeit some level of spatial information during the sample preparation process. Recently, hydrogel technologies have been developed that perform spatially localized protein extraction and digestion prior to downstream proteomic analysis. Regiospecific protein identifications acquired using this approach have thus far been limited to 1–2 mm diameter areas. The need to target smaller populations of cells with this technology necessitates the production of smaller diameter hydrogels. Herein, we demonstrate hydrogel fabrication processes that allow hydrogel applications down to a diameter of ∼260 μm, approximately 1/15 of the area of previous approaches. Parameters such as the percent polyacrylamide used in hydrogel construction as well as the concentration of trypsin with which the hydrogel is loaded are investigated to maximize the number of protein identifications f...