Two novel methods for synthesizing poly (propylene fumarate): Technical aspects and role of vacuum and N2 purging effects‏

Poly (propylene fumarate) (PPF), a linear unsaturated polyester consisting of alternating propylene glycol and fumaric acid units, can be cured in vivo to fill the skeletal defects with minimal surgical intervention. Many different methods have been reported for synthesizing PPF, but none of them gives a clear method. The present paper introduces two new methods in PPF synthesis: Modified reflux system (MRS) and mixed reflux-distillation system (MRDS). Similarly, the effects of applying vacuum (vacuum sequence, time, vacuum applying position, and the distance between vacuum applying position and reactor) as well as nitrogen gas (used continuously or only as an N2 blanket) on the PPF synthesis have been studied. The PPF obtained using optimum reaction condition has been characterized by using NMR, FTIR, and GPC analyses. It is demonstrated that the efficiency of MRDS in synthesizing PPF is higher than that of MRS. Nitrogen gas, vacuum applying position, continuously/stepwise-continuously applying vacuum and other parameters show an important role in the polymerization of PPF in both the MRDS and MRS systems

In vitro study of a new biodegradable nanocomposite based on poly propylene fumarate as bone glue.

A novel poly propylene fumarate (PPF)-based glue which is reinforced by nanobioactive glass (NBG) particles and promoted by hydroxyethyl methacrylate (HEMA) as crosslinker agent, was developed and investigated for bone-to-bone bonding applications. In-vitro bioactivity, biodegradability, biocompatibility, and bone adhesion were tested and the results have verified that it can be used as bone glue. In an in-vitro condition, the prepared nanocomposite (PPF/HEMA/NBG) showed improved adhesion to wet bone surfaces. The combined tension and shear resistance between two wet bone surfaces was measured, and its maximum value was 9±59MPa. To investigate the bioactivity and biodegradability of the nanocomposite, it has been immersed in simulated body fluid (SBF). After 14days exposure to SBF, a hydroxyapatite (HA) layer formed on the surface of the composite confirms the bioactivity of this material. In the XRD pattern of the nanocomposite surface, the HA characteristic diffraction peak at θ=26 and 31.8 were observed. Also, by monitoring the weight change after 8weeks immersion in SBF, the mass loss was about 16.46wt%. It has been confirmed that this nanocomposite is a biodegradable material. Also, bioactivity and biodegradability of nanocomposite have been proved by SEM images. It has been showed that by using NBG particles and HEMA precursor, mechanical properties increased significantly. The ultimate tensile strength (UTS) of nanocomposite which contains 20% NBG and the ratio of 70/30wt% PPF/HEMA (PHB.732) was approximately 62MPa, while the UTS in the pure PPF/HEMA was about 32MPa. High cell viability in this nanocomposite (MTT assays, 85-95%) can be attributed to the NBG nature which contains calcium phosphate and is similar to physiological environment. Furthermore, it possesses biomineralization and biodegradation which significantly affected by impregnation of hydrophilic HEMA in the PPF-based polymeric matrix. The results indicated that the new synthesized biodegradable PPF/HEMA/NBG composite is suitable for biomedical applications especially as biodegradable bone glue in orthopedic surgeries

High aspect ratio phospho-calcified rock candy-like cellulose nanowhiskers of wastepaper applicable in osteogenic differentiation of hMSCs

info:eu-repo/semantics/publishe