Tyrosine-bearing polyphosphazenes

Harry R. Allcock, Anurima Singh, Archel M.A. Ambrosio, Walter R. Laredo

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Tyrosine-functionalized polyphosphazenes were synthesized, and their hydrolytic stability, pH-sensitive behavior, and hydrogel-forming capabilities were investigated. The physical and chemical properties of the polymers varied with the type of linkage between the tyrosine unit and phosphazene backbone. Poly[(ethyl glycinat-N-yl)(ethyl tyrosinat-N-yl)phophazenes] (linkage via the amino group of tyrosine) were found to be hydrolytically erodible. The rate of hydrolysis was dependent on the ratio of the two side groups, the slowest rate being associated with the highest concentration of tyrosine. The hydrolysis products were identified as phosphates, tyrosine, glycine, ammonia, and ethanol derived from the ester group. The hydrolytically stable phenolic-linked tyrosine derivatives were prepared from N-t-BOC-L-tyrosine methyl ester and alkoxy-based cosubstituents. Polyphosphazenes with both propoxy and phenolic-linked tyrosine side groups showed a pH-sensitive solubility behavior, which was dependent on the ratio and nature of the two side groups. The polymer was soluble in aqueous media below pH 3 and above pH 4. From pH 3-4, the polymer was insoluble. Replacement of propoxy by trifluoroethoxy units yielded a polymer that was insoluble in aqueous media at all pH values. Replacement of propoxy by methoxyethoxyethoxy groups gave a polymer that was soluble at all pH values. Exposure of both the propoxy and methoxyethoxyethoxy polymers to calcium ions in aqueous media caused gel formation due to ionic cross-linking through the carboxylate groups.

Original languageEnglish (US)
Pages (from-to)1646-1653
Number of pages8
JournalBiomacromolecules
Volume4
Issue number6
DOIs
StatePublished - Nov 1 2003

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Bearings (structural)
Tyrosine
Polymers
Hydrolysis
Esters
Hydrogels
Chemical properties
Amino acids
Hydrogel
Calcium
Ammonia
Phosphates
Ethanol
Gels
Solubility
Physical properties
Glycine
Derivatives
Ions

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Allcock, H. R., Singh, A., Ambrosio, A. M. A., & Laredo, W. R. (2003). Tyrosine-bearing polyphosphazenes. Biomacromolecules, 4(6), 1646-1653. https://doi.org/10.1021/bm030027l
Allcock, Harry R. ; Singh, Anurima ; Ambrosio, Archel M.A. ; Laredo, Walter R. / Tyrosine-bearing polyphosphazenes. In: Biomacromolecules. 2003 ; Vol. 4, No. 6. pp. 1646-1653.
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Allcock, HR, Singh, A, Ambrosio, AMA & Laredo, WR 2003, 'Tyrosine-bearing polyphosphazenes', Biomacromolecules, vol. 4, no. 6, pp. 1646-1653. https://doi.org/10.1021/bm030027l

Tyrosine-bearing polyphosphazenes. / Allcock, Harry R.; Singh, Anurima; Ambrosio, Archel M.A.; Laredo, Walter R.

In: Biomacromolecules, Vol. 4, No. 6, 01.11.2003, p. 1646-1653.

Research output: Contribution to journalArticle

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Allcock HR, Singh A, Ambrosio AMA, Laredo WR. Tyrosine-bearing polyphosphazenes. Biomacromolecules. 2003 Nov 1;4(6):1646-1653. https://doi.org/10.1021/bm030027l