Functionalizing P622-N-Cys with Tetrazine and trans-cyclooctene for the use of interfacial bioorthogonal cross-linking

• Caleb Lavallee, Chemical Engineering, University of Delaware

• Xinqiao Jia, Materials Science and Engineering, University of Delaware

The peptide chain P622-N-Cys has been designed and studied for its unique behavior of forming tetramer bundles in aqueous solution; however, conjugating P622-N-Cys with tetrazine and tri-cyclooctene in order to facilitate a tetrazine ligation which forms peptide-encapsulating matrices has yet to be accomplished. Reported are the methods and results for the synthesis, purification, characterization, and conjugation with tetrazine and tri-cyclooctene of P622-N-Cys. The relationship between purity and yield of the peptide product was taken into account in the synthesis and purification process. Tetrazine and tri-cyclooctene were attached to P622-N-Cys using Inverse-electron-demand Diels-Alder Reactivity chemistry with the thiol group of Cysteine. A microfluidic chip was used to flow the functionalized peptides and allow them to react, forming a fiber. The microfluidic chip was first tested with the reaction between Na-Alg and CaCl2. The formation of a semi-flexible linker between two P622-N molecules is a step of progress in the creation of bioorthogonal materials with complex properties dependent on the specific amino acids in the peptide chains.