Synthesis and characterisation of ferrocenylalcohols anchored onto polyphosphazene polymeric supports for biomedical applications

Introduction Polyphosphazenes are inorganic-organic hybrid polymers consisting of a phosphorous and nitrogen backbone. When hydrolysed, these polymers decompose into a low toxicity medium consisting of phosphates and ammonia,... [ view full abstract ]

Introduction

Polyphosphazenes are inorganic-organic hybrid polymers consisting of a phosphorous and nitrogen backbone. When hydrolysed, these polymers decompose into a low toxicity medium consisting of phosphates and ammonia, making them suitable for biomedical applications (eg. polymeric drug delivery systems).¹ Ferrocenylalcohols have been found to exhibit cytotoxic activity against the HeLa cell line, whereby ferrocene-containing alcohols with longer alkyl chains exhibit higher cytotoxicity.² Therefore, ferrocenylalcohols of the type Fc(CH₂)_nOH, where n = 1, 2, 3 and 4, were anchored onto polyphosphazene polymers as a possible drug delivery system.

Methods

Ferrocenylalcohols, Fc(CH₂)_nOH where n = 1, 2, 3 and 4, have been synthesised according to literature.³ Trichloro(trimethylsilyl)phosphoranimine monomer and polydichlorophosphazene were synthesised utilising a living cationic polymerisation also found in literature.^4,5 Ferrocenylalcohols were then anchored onto the polyphosphazene support by substitution of the chloro group with ferrocenylalkoxide and trifluoroethoxide substituents in a ratio of 1:3.

Results and Discussion

Poly(2,2,2-trifluoroethoxy)(ferrocenylalkoxy)phosphazenes were synthesised with yields between 10.3 – 13.5 %. Molecular weight of the synthesised polyphosphazenes determined by intrinsic viscosity measurements yielded values in the range 0.016 – 0.0083 dL/g. Characterisation of the polymers were carried out by ¹H and ³¹P Nuclear Magnetic Resonance Spectroscopy and the atomic content (P, N, Fe, F) by X-ray Photoelectron Spectroscopy.

References

[1] N. L. Morozowich, A. L. Weikel, J. L. Nichol, C. Chen, L. S. Nair, C. T. Laurencin, H. R. Allcock, Macromolecules, 2011, 44, 1355 – 1364.

[2] R.F.Shago, J. C. Swarts, E. Kreft and C. E. J. van Rensburg, Anticancer Res., 2007, 27, 3431 – 3433.

[3] W. L. Davis, R. F. Shago, E. H. G. Langner, J. C. Swarts, Polyhedron, 2005, 24, 1611 – 1616.

[4] B. Wang, E. Rivard, I. Manners, Inorg. Chem. 2002, 41, 1690 – 1691.

[5] C. H. Honeyman, I. Manners, C. T. Morrissey, H. R. Allcock, J. Am. Chem. Soc. 1995. 117, 7035 – 7036.