Abstract
Spatiotemporal control over engineered tissues is highly desirable for various biomedical applications as it emulates the dynamic behavior of natural tissues. Current spatiotemporal biomaterial functionalization approaches are based on cytotoxic, technically challenging, or non-scalable chemistries, which has hampered their widespread usage. Here we report a strategy to spatiotemporally functionalize (bio)materials based on competitive supramolecular complexation of avidin and biotin analogs. Specifically, an injectable hydrogel is orthogonally post-functionalized with desthiobiotinylated moieties using multivalent neutravidin. In situ exchange of desthiobiotin by biotin enables spatiotemporal material functionalization as demonstrated by the formation of long-range, conformal, and contra-directional biochemical gradients within complex-shaped 3D hydrogels. Temporal control over engineered tissue biochemistry is further demonstrated by timed presentation and sequestration of growth factors using desthiobiotinylated antibodies. The method’s universality is confirmed by modifying hydrogels with biotinylated fluorophores, peptides, nanoparticles, enzymes, and antibodies. Overall, this work provides a facile, cytocompatible, and universal strategy to spatiotemporally functionalize materials.
Highlights
Spatiotemporal control over engineered tissues is highly desirable for various biomedical applications as it emulates the dynamic behavior of natural tissues
Temporal control and cytocompatibility are demonstrated by reversibly sequestering growth factors from reporter cells using desthiobiotinylated VHH type antibodies, which could be on-demand displaced by pristine biotin
We primarily focused on the complexation of neutravidin with desthiobiotin and biotin compounds as they interact strongest with avidin, which enabled the biochemical functionalization of materials that remained relatively stable for numerous days, which matches with the desired timeframe of most biological and life science applications
Summary
Spatiotemporal control over engineered tissues is highly desirable for various biomedical applications as it emulates the dynamic behavior of natural tissues. We report a strategy to spatiotemporally functionalize (bio)materials based on competitive supramolecular complexation of avidin and biotin analogs. Biotin has a non-sulfur containing analog, desthiobiotin, which interacts with avidin and its analogs, but with a binding affinity that is approximately an order of magnitude lower than biotin (Kd,biotin–avidin ~ 10−15 M versus Kd,desthiobiotin–avidin ~ 10−14 M in solution)[26] The difference between these binding affinities has, for example, been used to achieve the displacement of desthiobiotin by biotin for the reversible labeling and affinity-based isolation of proteins[27,28]. Temporal control and cytocompatibility are demonstrated by reversibly sequestering growth factors from reporter cells using desthiobiotinylated VHH type antibodies, which could be on-demand displaced by pristine biotin. Postfunctionalizing hydrogel constructs with biotinylated fluorophores, peptides, nanoparticles, enzymes, and antibodies confirms the universality of the competitive supramolecular complexation strategy
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