Spontaneous Assembly into Pseudopolyrotaxane Between Cyclodextrins and Biodegradable Polyphosphoester Ionomers

Abstract

The development of novel biodegradable supermolecules is of importance in designing functionalized biomaterials utilized in the field of tissue engineering and drug delivery. In this regard, the focus here is on biocompatible and biodegradable polyphosphoester ionomers, and their pseudopolyrotaxane (PPRX) formation with α‐, β‐, or γ‐cyclodextrins (CDs) is examined. Poly(2‐hydroxy‐2‐oxo‐1,3,2‐dioxaphosphorane) (PHP) is found to form a precipitate upon mixing with α‐CD in water. Also, precipitation is observed by mixing PHP and γ‐CD, although its yield is lower than with α‐CD. The stoichiometry ratio of PHP monomer unit:α‐CD is determined to be 1:1 from the 1H NMR spectra of the precipitate. The wide‐angle X‐ray diffraction pattern of the precipitate between PHP and α‐CD clearly supports the formation of PPRX, and its crystalline structure is well consistent with previously reported α‐CD‐based PPRXs. This finding contributes to the design of novel supramolecular biomaterials.

How Does PHEMA Pass through the Cavity of γ-CDs to Create Mismatched Overfit Polypseudorotaxanes?

“…Consequently, the transmittance changes of mixed aqueous solutions of γ-CD with PHEMA as a function of incubation time provided visual evidence confirming the occurrence and evalution of the self-assembly of γ-CDs with PHEMA. This observation was also consistent with studies undertaken by Yui et al…”

“…Consequently, the transmittance changes of mixed aqueous solutions of γ-CD with PHEMA as a function of incubation time provided visual evidence confirming the occurrence and evalution of the self-assembly of γ-CDs with PHEMA. This observation was also consistent with studies undertaken by Yui et al 35 To gain insight into the particle sizes of self-aggregates of γ-CD, PHEMA, and their inclusion complexes in aqueous solutions, the DLS measurements were performed at 25 °C, and the results are illustrated in Figure 3 and Table 2. Not surprisingly, a solution of 0.40 wt ‰ γ-CD exhibited a bimodal distribution of particle sizes of aggregates, with the main peak attributed to the γ-CD aggregates with an R h,app range of 50 to 90 nm and the small one corresponding to a single free CD molecule with R h,app = ∼1 nm in a scattering angle range of 30 to 90°, which was conceived to be crucial to the formation of PPRs composing CDs and incoming linear polymers.…”

Synthesis of the anionic hydroxypropyl-β-cyclodextrin:poly(decamethylenephosphate) polyrotaxane and evaluation of its cholesterol efflux potential in Niemann–Pick C1 cells

“…54 Polymeric phosphodiesters have already been used as prodrugs, hydrogels and drug carriers. 51,55,56 A pseudopolyrotaxane based on biodegradable polyphosphoester ionomers obtained by ring opening polymerization has been described by Tamura et al 53 Polyrotaxane formation was only observed with α and γ-CD and the resulting polyrotaxanes formed precipitates in aqueous solution. No inclusion complexes were obtained with β-CD.…”

Polyphosphoester‐based paclitaxel complexes

“…The phosphoryl group (PO) is a good proton acceptor (about 2 orders of magnitude stronger than the CO group) and forms strong hydrogen bonds with phenols and alcohols . It is established that the PO group of poly(hydroxyalkylene phosphate) participates in hydrogen bonding with POH and OH groups . Besides, poly(hydroxyoxyethylene phosphate)s are biodegradable, biocompatible, water soluble and low toxic polymers .…”

“…[25][26][27] It is established that the P@O group of poly (hydroxyalkylene phosphate) participates in hydrogen bonding with PAOH and OH groups. [28][29][30] Besides, poly(hydroxyoxyethylene phosphate)s are biodegradable, biocompatible, water soluble and low toxic polymers. 31 Polyphosphoesters degraded through hydrolysis of the PAOAC ester bonds under acidic or basic conditions [31][32][33] and this can be particularly accelerated in the presence of phosphoesterase.…”