The synthesis of β-CD polymer phosphate sodium salts was worked out to be used for coating of metal-organic framework (MOF) nanoparticles.  Epichlorohydrin was used as crosslinking agent and phosphorus pentoxide was applied for introducing phosphate groups. The phosphorylated CD polymers have high affinity to iron atoms within nanoMOF resulting in 26% weight increase caused by the coating shell (compared to 20% with the unphosphorylated CD polymer). The grafted phosphate moieties enabled a firm anchorage of the coating to the nanoMOFs. Coating stability was directly related to the density of grafted phosphate groups, and did not alter nanoMOFs morphology or drug release kinetics.
Phosphated beta-CD polymers were prepared by crosslinking BCD and BCD/dextran mixture with sodium trimetaphosphate, a non-toxic cyclic triphosphate. [2,3] The resulting soluble CD polymer phosphates with molecular weights (Mw) higher than 104 g.mol-1 can form inclusion complexes, and show strong interactions with a divalent cation, Ca2+. The strong affinity between these novel phosphorus-containing cyclodextrin polymers and hydroxyapatite was demonstrated by adsorption studies. Polymers that combine cyclodextrin and phosphorus functionalities is suitable for biomedical applications that jointly require calcium affinity and delivery of lipophilic bioactive molecules.
Beta-CD and b-glycerophosphate were crosslinked with hexamethylenediisocyanate to obtain cyclodextrin polyurethanes containing phosphate groups.  The CD cavities within this polymer preserved the ability for complex formation and showed controlled release of ciprofloxacin, as model drug.
A polyionic derivative of an alpha-, beta-, or gamma-CD polymer (water-insoluble) in which the ionic group is sulfate, phosphate, carboxylate, or nitrate was patented by Weisz et al. These ionic derivatives of CD polymers were found useful for purification of proteins, such as heparin-binding growth factor, from mixtures. 
- Aykaç, A., Noiray, M., Malanga, M., Agostoni, V., Casas-Splvas, J.M., Fenyvesi, É., Gref, R., Vargas-Berenguel, A. A non-covalent “click chemistry” strategy to efficiently coat highly porous MOF nanoparticles with a stable polymeric shell. Biochimica et Biophysica Acta – General Subjects, 2017, 1861(6), 1606-1616. DOI: https://doi.org/10.1016/j.bbagen.2017.01.016
- Wintgens, V.. Sebille, B., Amiel C. Novel phosphorus-containing cyclodextrin polymers: affinity for calcium cations and hydroxyapatite. Carbohydrate Polymers, 2013, 98(1), 896–904 , DOI: http://dx.doi.org/10.1016/j.carbpol.2013.06.073
- Wintgens, V., Lorthioir, C., Dubot, P., Sébille, B., Amiel, C. Cyclodextrin/dextran based hydrogels prepared by cross-linking with sodium trimetaphosphate. Carbohydrate Polymers, 2015, 132, 80–88
- Moreira, M.P., Andrade, G.R.S., De Araujo, M.V.G., Kubota, T., Gimenez, I.F. Ternary cyclodextrin polyurethanes containing phosphate groups: Synthesis and complexation of ciprofloxacin. Carbohydrate Polymers, 2016, 151, 557–564
- Weisz, P.B., Shing, Y.W., Folkman, J. Cyclodextrin polymers and cyclodextrins immobilized on a solid surface. US5183809, 1993
This post is a part of the paper published in the Cyclodextrin News 2018, 32(6).