Schematic illustration of the Azo-enabled ECM proteomics strategy. (1) Tissues are collected, cryo-pulverized, and (2) undergo rapid decellularization in 2% Triton X-100. After centrifugation, the supernatants are collected, precipitated, and reconstituted in 0.5% Azo labeled as “Decell extract 1” for downstream analysis. (3) Azo was added to the remaining tissue pellet to extract the remaining proteins, resulting in “Azo extract 2”. (4) Both Decell Extract 1 and Azo extract 2 were reduced, alkylated, and digested with trypsin. (5) Azo was degraded by UV-irradiation and (6) the digested peptides were analyzed by RPLC-MS/MS.