Novel phosphorus-containing cyclodextrin polymers and their affinity for calcium cations and hydroxyapatite

Area of Science:

• Polymer Chemistry
• Green Chemistry
• Materials Science

Background:

• Cyclodextrins (CDs) are versatile cyclic oligosaccharides with a hydrophobic cavity and hydrophilic exterior.
• Phosphorylated polymers offer unique binding properties for various molecules and ions.
• Developing sustainable synthesis methods for functional polymers is crucial.

Purpose of the Study:

• To synthesize novel phosphorous-containing β-cyclodextrin polymers (CDPs) under green chemistry conditions.
• To characterize the binding affinities of these CDPs towards amphiphilic molecules, divalent cations, and hydroxyapatite.
• To explore the potential applications of CDPs in nanoparticle recovery.

Main Methods:

• Green polycondensation of β-cyclodextrin (βCD) with sodium trimetaphosphate (STMP) under basic conditions.
• Characterization of polymer molecular weight and structure.
• Isothermal titration microcalorimetry (ITC) to determine binding strengths.
• Transmission electron microscopy (TEM) and quantitative analysis for hydroxyapatite binding.

Main Results:

• Soluble, non-reticulated CDPs with Mw > 10(4) g mol(-1) were successfully synthesized.
• CDPs exhibited strong binding affinities for amphiphilic probes (e.g., 1-adamantyl acetic acid) and divalent cations (e.g., Ca2+).
• High affinity of CDPs for hydroxyapatite (HA) was observed, enabling efficient recovery of HA nanoparticles.

Conclusions:

• Green synthesis of phosphated β-cyclodextrin polymers is feasible and efficient.
• These novel CDPs demonstrate significant potential for applications involving molecular recognition and nanoparticle sequestration.
• The ability to easily recover hydroxyapatite nanoparticles using CDPs opens avenues for advanced material processing.