Poly(phosphoester) ionomers as tissue‐engineering scaffolds

Abstract

Regenerative medicine requires scaffolds of divergent physicochemical properties for different tissue-engineering applications. To this end, a series of biodegradable poly(phosphoester) ionomers of the general composition [p(BHET-EOP-HOP/TC)] was synthesized, with BHET(bis-hydroxyl ethylene phosphate):EOP(ethylene phosphate):HOP(free phosphate) ratios of 60:20:20, 70:10:20, and 75:5:20, respectively. The 60/20/20 ionomer possessed the best tensile properties, exhibiting an average tensile modulus of 68 MPa and strain at break of 31%. Calcium treatment of the ionomer films led to significantly higher hardness and elastic moduli as measured by indentation. Calcium binding was evident from the increase in glass transition and melting temperatures, and a shift in the P-->O absorption in the FTIR spectrum. Stable N-hydroxysuccinimide ester (NHS) of the ionomers could be synthesized to facilitate derivatization, as demonstrated by conjugation of GRGDS in this study. The polymers conjugated with NHS were hydrolyzed in a biphasic mode, with a fast initial phase occurring in the first few hours, followed by a slower phase in the next few days. These ionomers represent a novel class of biomaterials with readily controllable physical and chemical attributes for tissue engineering.

Spontaneous Assembly into Pseudopolyrotaxane Between Cyclodextrins and Biodegradable Polyphosphoester Ionomers

“…Figure shows the FTIR spectra of α‐CD, PHP, the PHP/α‐CD complex, and the physical mixture of PHP and α‐CD (the amount of PHP and α‐CD was adjusted to the same as PHP/α‐CD complex). In the spectrum of PHP, the characteristic peaks assignable to phosphodiesters were observed; hydrogen bonded P=O stretching at around 1190 cm −1 , non‐hydrogen bonded P=O stretching at around 1160 cm −1 , and asymmetric P–O–C stretching at around 970 cm −1 . These peaks were diminished in the spectrum of the PHP/α‐CD complex, and the spectrum resembled that of α‐CD.…”

Biodegradable poly(terephthalate-co-phosphate)s: synthesis, characterization and drug-release properties

“…For instance, drugs with hydroxyl groups may be coupled to the phosphorus via an ester bond, which is hydrolyzable. Cell-adhesion molecules can be conjugated to the surface of the poly (terephthalate-co-phosphate) scaffolds, improving the cell adhesion for tissue-engineering applications [30]. These poly(phosphoester)s are natural candidates for a completely biodegradable pendant delivery system.…”

“…Phosphate ion incorporating polymer was prepared by synthesizing co-polymers with methoxy side chains and then cleaving the methoxy side chain with NaI [30]. Replacing all the EOP with methyl phosphorodichloridate (MOP) yielded a co-polymer P(BHET-MOP/TC, 80 : 20) with relatively low molecular weight, maybe due to the increased instability of MOP compared with EOP (reacting to moisture).…”

“…The molecular weights of these two co-polymers were slightly lower than P(BHET-EOP/TC, 80 : 20). Furthermore, converting the methoxy groups into sodium salt renders the polymer less soluble in chloroform and methylene chloride [30].…”

Phosphorous-containing polymers for regenerative medicine

“…To improve the biological function of some PPEs, cell-adhesive peptides, such as the GRGDS peptide, can be attached to the polymer backbone following polymerization via reaction with free P-OH groups. [23] Thermoresponsive polymers can be useful in regenerative medicine applications because they have the potential to deliver cells and growth factors to form scaffolds in situ . [32] Thermoresponsive PPEs have been synthesized by ring opening co-polymerization of cyclic phosphoester monomers with differing pendant groups.…”