title: Cleavable carbamate linkers for controlled protein delivery from hydrogels.
abstract: The reversible attachment of proteins to polymers is one potential strategy to control protein release from hydrogels. In this study, we report the reversible attachment of lysozyme to poly(ethylene glycol) (PEG) by degradable carbamate linkers. Phenyl groups with different substituents were used to control the rate of carbamate hydrolysis and the resulting protein release. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed modification with 1-3 PEG chains per lysozyme molecule. Protein PEGylation and PEG chain elimination occurred without changes in secondary protein structure, as demonstrated by circular dichroism spectroscopy. The lytic activity of lysozyme was restored to 73.4±1.7%-92.5±1.2% during PEG chain elimination. Attached PEG chains were eliminated within 24h to 28days, depending on the used linker molecule. When formulated into hydrogels, a maximum of about 60% of the initial dose was released within 7days to 21days. Linker elimination occurs 'traceless', so that the protein is released in its native, unmodified form. Altogether, we believe that tethering proteins by degradable carbamate linkers is a promising strategy to control their release from hydrogels.
authors.affiliation: University of Regensburg, Department of Pharmaceutical Technology, 93040 Regensburg, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Hammer
authors.affiliation: University of Regensburg, Department of Pharmaceutical Technology, 93040 Regensburg, Germany; Massachusetts Institute of Technology, David H. Koch Institute for Integrative Cancer Research, Cambridge 02139, USA.
authors.forename: Ferdinand P
authors.initials: FP
authors.lastname: Brandl
authors.affiliation: University of Regensburg, Department of Pharmaceutical Technology, 93040 Regensburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Kirchhof
authors.affiliation: University of Regensburg, Department of Pharmaceutical Technology, 93040 Regensburg, Germany. Electronic address: achim.goepferich@chemie.uni-regensburg.de.
authors.forename: Achim M
authors.initials: AM
authors.lastname: Goepferich
mesh_terms: D002219:Carbamates / Q000138:chemical synthesis / Q000737:chemistry*; D002942:Circular Dichroism; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry*; D065546:Drug Liberation; D020100:Hydrogels / Q000737:chemistry*; D015394:Molecular Structure; D009113:Muramidase / Q000008:administration & dosage*; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013997:Time Factors
chemical_list: D002219:Carbamates; D004337:Drug Carriers; D020100:Hydrogels; D011092:Polyethylene Glycols; D009113:Muramidase
keywords: Cleavable linker; Hydrogel; Poly(ethylene glycol); Protein tethering; Release; Reversible PEGylation