Conditional DNA-protein interactions confer stimulus-sensing properties to biohybrid materials

Abstract

Interactive materials that specifically respond to environmental stimuli hold high promise as energy-autonomous sensors and actuators in biomedicine, analytics or microsystems engineering. However, the implementation of materials specifically responsive to a given small molecule has so far been hampered by a lack of generically applicable stimulus sensors. In this study, a novel and likely general strategy for the synthesis of biohybrid materials with desired stimulus specificity is established. The strategy is based on allosterically regulated DNA-binding proteins, a conserved protein family that has evolved in prokaryotes to sense and respond to most diverse molecules in order to enable bacterial survival in a changing environment. The novel hydrogel design concept is demonstrated with the example of single-chain TetR, a protein that binds the tetO DNA motif and dissociates thereof in the presence of the antibiotic tetracycline. Therefore, linear polyacrylamide is crosslinked via the TetR/tetO interaction to a biohybrid material that can subsequently be dissolved by tetracycline in a dose-dependent manner. This drug-induced dissolution is applied for the adjustable release of the cytokine interleukin 4 in a tetracycline-dependent manner. The design concept developed in this study might serve as a blueprint for the synthesis of biohybrid materials responsive to drugs, metabolites or toxins by replacing TetR/tetO with another protein/DNA pair showing the desired stimulus specificity. A biohybrid hydrogel is synthesized for the drug-inducible release of biopharmaceuticals. The hydrogel consists of linear polyacrylamide crosslinked by the interaction of the tetracycline repressor scTetR with its target DNA sequence tetO. Addition of tetracycline dissociates the protein-DNA interaction and triggers the release of a previously embedded payload protein. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.