Construction of shape memorable imprinted cavities for protein recognition using oligo-l-lysine-based peptide crosslinker

Protein-imprinted polymers are artificial receptors capable of recognizing protein. They are highly promising for applications in important bio-related areas, however, their development was severely retarded by two problems: difficult template removal and low imprinting efficiency. The two problems could be overcome by constructing shape-memorable imprinted cavities using peptide crosslinker. Here a new oligo-l-lysine-based peptide crosslinker was designed and synthesized. A novel cytochrome c (Cyt C)-imprinted polymer was synthesized using the new peptide crosslinker. When switching pH between 12 and 7.4, the peptide segments incorporated in the polymer underwent reversible helix-coil transition. Because of the precise folding of the peptide segments, the imprinted cavities in the polymer could be enlarged when lowering pH to 7.4 to release the template protein, but restore their original size and shape at pH 12 to recognize the template protein. Therefore complete template removal was achieved under mild conditions. Meanwhile the imprinting efficiency was improved significantly. Compared to polymer crosslinked with the commonly used crosslinker N, N-methylenebisacrylamide, the imprinting efficiency of the peptide-crosslinked polymer was increased by 15 times. The new imprinted polymer presented not only a high adsorption capacity (454.4 mg g−1), a high imprinting factor (6.3), high selectivity towards Cyt C, and excellent reusability, but also could preserve the fragile secondary structure of the eluted protein, and therefore had high potential in bioseparation. As a demonstration, Cyt C added into fetal bovine serum was separated from the sample using the polymer via a simple adsorption-desorption cycle. The recovery rate was as high as 92.7%.