Synthesis and biomimetic mineralization of l‐proline substituted polyphosphazenes as bulk and nanofiber

Abstract

This work presents the synthesis of polyphosphazenes bearing L-proline methyl ester (ProOMe) and 4-hydroxy-Lproline methyl ester (HypOMe), aiming for new bioactive polymers for bone repair. The polymers were characterized by 1 H and 31 P NMR, FTIR, DSC, and TGA. Electrospun fibers were prepared using poly[bis(L-proline methyl ester)phosphazene] (PProP), and their potential for biomimetic mineralization, as well as the bulk material, were tested in simulated body fluid (13SBF). Samples were analyzed between 24 h and 3 weeks of incubation using SEM/EDS and FTIR. After 24 h, spherical and flower-like shapes of calcium phosphates (CaP) were crystallized on the bulk samples. The nanofibers presented spherical CaP crystals attached to them after 48 h of incubation. The Ca/P molar ratio of the crystals varied from 1.5 to 1.6. According to this study, PProP presents bioactivity in vitro, and its fibers offer sites for CaP nucleation like the collagen fibers in bone.

An efficient and stable star-shaped plasticizer for starch: cyclic phosphazene with hydrogen bonding aminoethoxy ethanol side chains

“…This may not become a surprise as also other studies show a regioselectivity in the macromolecular substitution of bifunctional nucleophiles, with preferred substitution via an amine rather than an alcoholic hydroxyl. [46][47][48][49] In fact, the above suggested statistical mixture of both reaction topographies may even be favorable to promote plasticization, as suppression of regularity is attractive for suppressed crystallization and efficient plasticization. Also, whether the aminoethoxy ethanol NH 2 -(CH 2 ) 2 -O-(CH 2 ) 2 -OH reacts onto the phosphazene ring from its amine or hydroxyl group, the opposite peripheral hydroxyl or amine end groups can still allow hydrogen bonding with starch.…”

Cyclo- and Polyphosphazenes for Biomedical Applications

“…Eletrospun fibers have been prepared using polyphosphazene bearing l -proline methyl ester and 4-hydroxy- l -proline methyl ester as side arms to achieve a new bioactive material for bone repair. The biomimetic mineralization was tested on the fibers and on the bulk polymer, observing in both cases bioactivity with the formation of an abundant calcium phosphate layer after 24 h and the adhesion of calcium phosphate crystals to the fiber mimicking the hydroxyapatite growth in collagen fibers [ 177 ]. Poly[(ethyl alanato)(p-methyl-phenoxy)phosphazene] has been used to modify the surface of the electrospun fibers of poly(ε-caprolactame) for tendon tissue engineering, to improve the hydrophobicity of the matrix, and to enhance the protein synthesis by seeded Human Mesenchymal Cells (hMSCs).…”

Glycine integrated zwitterionic hemocompatible electrospun poly(ethylene-co-vinyl alcohol) membranes for leukodepletion

“…Glycine also offer tactics for modification of drug carriers suited for clinically challenging and poorly water-soluble drugs [15]. Recent advancements have presented numerous polyphosphazenes containing esters of glycine for tissue regeneration applications [16][17][18][19][20][21]. On the basis of current knowledge, it can be understood that glycine is the least contemplated zwitterion for the furtherance of hemocompatibility of blood contacting medical devices.…”