Directed Evolution Enables Simultaneous Controlled Release of Multiple Therapeutic Proteins from Biopolymer-Based Hydrogels

Carter J. Teal, Marian H. Hettiaratchi, Margaret T. Ho, Arturo Ortin-Martinez, Ahil N. Ganesh, Andrew J. Pickering, Alex W. Golinski, Benjamin J. Hackel, Valerie A. Wallace, Molly S. Shoichet

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


With the advent of increasingly complex combination strategies of biologics, independent control over their delivery is the key to their efficacy; however, current approaches are hindered by the limited independent tunability of their release rates. To overcome these limitations, directed evolution is used to engineer highly specific, low affinity affibody binding partners to multiple therapeutic proteins to independently control protein release rates. As a proof-of-concept, specific affibody binding partners for two proteins with broad therapeutic utility: insulin-like growth factor-1 (IGF-1) and pigment epithelium-derived factor (PEDF) are identified. Protein–affibody binding interactions specific to these target proteins with equilibrium dissociation constants (KD) between 10−7 and 10−8 m are discovered. The affibodies are covalently bound to the backbone of crosslinked hydrogels using click chemistry, enabling sustained, independent, and simultaneous release of bioactive IGF-1 and PEDF over 7 days. The system is tested with C57BL/6J mice in vivo, and the affibody-controlled release of IGF-1 results in sustained activity when compared to bolus IGF-1 delivery. This work demonstrates a new, broadly applicable approach to tune the release of therapeutic proteins simultaneously and independently and thus the way for precise control over the delivery of multicomponent therapies is paved.

Original languageEnglish (US)
Article number2202612
JournalAdvanced Materials
Issue number34
StatePublished - Aug 25 2022

Bibliographical note

Funding Information:
The authors are grateful to members of the Shoichet lab for their thoughtful review. The authors are grateful to the following for partial funding of this research: NSERC (Discovery and Herzberg to M.S.S.; PGSD to C.J.T.; Vanier to M.T.H.; PDF to M.H.H.), CIHR (Foundation to M.S.S.) CFREF to Medicine by Design (to M.S.S.), and Vision Science Research Program (Scholarship to C.J.T. and M.T.H.).

Publisher Copyright:
© 2022 Wiley-VCH GmbH.


  • affibodies
  • controlled release
  • directed evolution
  • yeast display


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