Covalent organic framework-coated magnetic graphene as a novel support for trypsin immobilization

Deep and efficient proteolysis is the critical premise in mass spectrometry-based bottom-up proteomics. It is difficult for traditional in-solution digestion to meet the requirement unless prolonged digestion time and enhanced enzyme dosage are employed, which makes the whole workflow time-consuming and costly. The abovementioned problems could be effectively ameliorated by anchoring many proteases on solid supports. In this work, covalent organic framework-coated magnetic graphene (MG@TpPa-1) was designed and prepared as a novel enzyme carrier for the covalent immobilization of trypsin with a high degree of loading (up to 268 μg mg^-1). Profiting from the advantages of magnetic graphene and covalent organic frameworks, the novel trypsin bioreactor was successfully applied for the enzymatic digestion of a model protein with dramatically improved digestion efficiency, stability, and reusability. Complete digestion could be achieved in a time period as short as 2 min. For the digestion of proteins extracted from Amygdalus pedunculata, a total of 2833 protein groups were identified, which was slightly more than those obtained by 12 h of in-solution digestion (2739 protein groups). All of the results demonstrate that MG@TpPa-1-trypsin is an excellent candidate for sample preparation in a high-throughput proteomics analysis. Graphical abstract Covalent organic frameworks-coated magnetic graphene was prepared as novel carrier for highly efficient tryptic immobilization.