Designing biomaterials for bone tissue regeneration that are also capable of eluting drugs is challenging. Poly(ester amide)s are known for their commendable mechanical properties, degradation, and cellular response. In this regard, development of new poly(ester amide)s becomes imperative to improve the quality of lives of people affected by bone disorders. In this framework, a family of novel soybean oil based biodegradable poly(ester amide)s was synthesized based on facile catalyst-free melt-condensation reaction. The structure of the polymers was confirmed by FTIR and (1)H -NMR, which indicated the formation of the ester and amide bonds along the polymer backbone. Thermal analysis revealed the amorphous nature of the polymers. Contact angle and swelling studies proved that the hydrophobic nature increased with increase in chain length of the diacids and decreased with increase in molar ratio of sebacic acid. Mechanical studies proved that Young's modulus decreased with decrease in chain lengths of the diacids and increase in molar ratio of sebacic acid. The in vitro hydrolytic degradation and dye release demonstrated that the degradation and release decreased with increase in chain lengths of the diacids and increased with increase in molar ratio of sebacic acid. The degradation followed first order kinetics and dye release followed Higuchi kinetics. In vitro cell studies showed no toxic effects of the polymers. Osteogenesis studies revealed that the polymers can be remarkably efficient because more than twice the amount of minerals were deposited on the polymer surfaces than on the tissue culture polystyrene surfaces. Thus, a family of novel poly(ester amide)s has been synthesized, characterized for controlled release and tissue engineering applications wherein the physical, degradation, and release kinetics can be tuned by varying the monomers and their molar ratios.

We have developed nanocomposites based on galactitol/adipic acid in the molar ratio of 1:1 with different weight percentages of graphene oxide (GO). The objective of this study was to analyze the effect of enhanced physicochemical properties achieved due to the addition of GO to the polymers on cellular responses. The chemical structures of the polymer and composites were confirmed by Fourier transform infrared spectroscopy. Scanning electron microscopy revealed the uniform distribution of GO in the polymers. Differential scanning calorimetry showed no significant variation in the glass-transition temperature of the nanocomposites. Dynamic mechanical analysis demonstrated the increase of Young’s modulus with the increase in the addition of GO to the polymer from 0.5 to 1 wt % and a dramatic decrease in modulus with the addition of 2 wt % GO to the polyester. Contact angle analysis illustrated a slight increase in hydrophilicity with the addition of GO to the polyester. Investigations on the hydrolytic degradation and dye release were performed and revealed that the degradation and release decreased with the increase in the weight percentages of GO but increased for 2 wt % GO with the polymer. The rates of degradation and dye release followed first-order and Higuchi kinetics, respectively. The initial in vitro cytocompatibility studies exhibited minimal toxicity. Mineralization studies proved that these nanocomposites stimulated osteogenesis. This study has salient implications for designing biodegradable polymers for use as scaffolds with tailored release.

A family of high molecular weight castor oil (CO)-based biodegradable polyanhydrides was synthesized by a catalyst-free melt−condensation reaction between prepolymers of CO and sebacic acid (SA). The structure of the polymers was characterized by 1 H NMR and Fourier transform infrared spectroscopy, which indicated the formation of the anhydride bond along the polymer backbone. Thermal analysis and X-ray diffraction confirmed the semicrystalline nature of the polymers. Incorporation of SA enhanced the crystallinity of the polymer. The hydrophobic nature of these polymers was revealed by contact angle goniometry. Water wettability decreased with increase in SA content. Compressive tests demonstrated a sharp increase in strength and decrease in ductility with increasing SA content. In vitro hydrolytic degradation studies indicated surfaceeroding behavior. The degradation rate decreased with an increase of SA content in the polymers because of increased crystallinity. The release studies of both hydrophobic and hydrophilic dyes followed zero-order kinetics. In vitro cell studies to assess the cytotoxicity of the polymer confirmed minimal toxicity of the degradation products. Thus, a family of CO-SA polyanhydrides have been synthesized and characterized for controlled release applications where the physical, mechanical, and degradation kinetics can be modulated by varying the weight fraction of the prepolymers.

Despite extensive research performed in the area of drug delivery and tissue engineering, the search for a perfect biomaterial remains an ongoing process. In an effort to find this material, novel maltitol-based polyesters using three different dicarboxylic acids (DCAs; adipic acid, dodecanedioic acid and suberic acid) were synthesized and their properties were investigated. The chemical structure of the polymers was confirmed using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies.Thermal characterization revealed that the polymers were amorphous and that the glass transition temperature decreased with an increase in the chain length and molar ratio of maltitol : DCAs.Mechanical studies showed that the moduli of these polymers were comparable to those of the components of the skeletal system. Contact angle goniometry confirmed that the hydrophobicity of the polymers increased with increase in chain length and the molar ratio of maltitol : DCAs. The polymer degradation followed first order kinetics whereas dye release from these polymers followed zero order kinetics. Both the degradation and dye release studies demonstrated that the degradation and release decreased with increase in chain length and molar ratio of maltitol : DCA. The degradation and dye release can be modulated based on the chain length and the molar ratio of acids. Preliminary cytocompatibility studies showed that these polymers were cytocompatible. Mineralization studies revealed that these polymers showed increased mineralization when compared to results obtained with controls. Thus, this family of polyesters can serve as effective biomaterials for bone tissue engineering with tunable degradation and controlled release properties.Scheme 1 Reaction scheme for the synthesis of the polyesters in the molar ratio of 1 : 1. Red dots near the -OH groups indicate that these groups may also be involved in esterification because it is a random polymerization.40542 | RSC Adv., 2016, 6, 40539-40551This journal is