ABSTRACT
Storage stability was evaluated on a biodegradable salicylate-based poly(anhydride-ester) to elucidate the effects of storage conditions over time. The hydrolytically labile polymer samples were stored in powdered form at five relevant storage temperatures (-12 °C, 4 °C, 27 °C, 37 °C, 50 °C) and monitored over four weeks for changes in color, glass transition temperature, molecular weight, and extent of hydrolysis. Samples stored at lower temperatures remained relatively constant with respect to bond hydrolysis and molecular weight. Whereas, samples stored at higher temperatures displayed significant hydrolysis. For hydrolytically degradable polymers, such as these poly(anhydride-esters), samples are best stored at low temperatures under an inert atmosphere.
ABSTRACT
Fast-degrading, salicylate-based poly(anhydride-esters) were designed to degrade and release the active component, salicylic acid (SA), within 1 week. The polymer degradation was enhanced by using shorter or oxygen-containing aliphatic chains. A copolymer of diglycolic acid was also made with a salicylate-based diacid for comparison of polymer properties, including SA release. Both methods resulted in polyanhydrides with molecular weights ranging from 14 500 to 27 800 Da and displayed glass transition temperatures near physiological conditions, namely 33-40 degrees C. the homo- and copolymers completely degraded within one week releasing the chemically incorporated SA.
ABSTRACT
Antiseptics based on phenol and phenolic derivatives were chemically incorporated into polyanhydrides as pendant groups via ester linkages. Polyanhydrides with antiseptic loadings of 46-58 wt.-% were obtained with molecular weights ranging from 9 400-23 000. In general, polymers with the bulkier antiseptics were more difficult to polymerize and yielded lower molecular weights. All polyanhydrides were amorphous with glass transition temperatures ranging from 27-58 °C. Polymers were deemed noncytotoxic after culturing L929 mouse fibroblast cells in media containing the polymers at two concentrations (0.10 and 0.01 mg · mL(-1) ) over three days. In summary, mono-functional bioactives can be chemically incorporated into noncytotoxic polyanhydrides.
ABSTRACT
Poly(anhydride-esters) based on iodinated versions of salicylic acid were synthesized via both melt-condensation and solution polymerization techniques to generate radiopaque biomaterials. The poly(anhydride-esters) from iodinated salicylates were highly X-ray opaque compared to poly(anhydride-esters) from salicylic acid. Molecular weight and Young's modulus of polymers prepared by melt-condensation were typically two-to-three times higher than polymers prepared by solution methods. The glass transition temperatures of the polymers were dependent on the iodine concentration; polymers containing more iodine had higher glass transition temperatures. Cytotoxicity studies using mouse fibroblasts indicated that iodinated salicylate-based poly(anhydride-esters) prepared by both polymerization methods are biocompatible with cells at low polymer concentrations (0.01 mg/mL).