Bio-Orthogonal Cross-Linking Chemistry Enables In Situ Protein Encapsulation and Provides Sustained Release from Hyaluronic Acid Based Hydrogels

• Published in: Molecular pharmaceutics Vol. 14; no. 6; pp. 1961 - 1968
• Main Authors: Famili, Amin, Rajagopal, Karthikan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.06.2017
• Subjects: Click Chemistry - methods; Delayed-Action Preparations; Hyaluronic Acid - chemistry; Hydrogels - chemistry; Kinetics; Protein Stability; Proteins - chemistry; bio-orthogonal chemistry; hydrogels; protein delivery; protein stability
• ISSN: 1543-8384; 1543-8392
• DOI: 10.1021/acs.molpharmaceut.7b00067

Chemically cross-linked hydrogels are promising systems for protein delivery applications, but their utility may be limited due to the possibility of protein reaction with hydrogel precursors. Herein, a catalyst-free inverse-demand Diels–Alder reaction between tetrazine and norbornene groups was used to demonstrate the bio-orthogonal nature of cross-linking chemistry that is chemically inert to proteins. Tetrazine-modified hyaluronic acid and norbornene-modified polyethylene glycol were used as hydrogel precursors for in situ encapsulation of a model protein, Fab1. Measurement of gelation kinetics demonstrates that network formation and gel stiffness are temperature-dependent but independent of Fab1 concentration. In vitro release testing shows that Fab1 is completely released from the hydrogel matrix over a period of several weeks. Analytical characterization suggests that Fab1 is released without any physical or chemical modifications and retains its antigen binding capacity. Thus, the bio-orthogonal and catalyst-free aqueous phase chemistry enables efficient in situ protein encapsulation in a single step and provides sustained protein release.