The objective of this work was to develop a versatile strategy for preparing biodegradable polymers with tunable properties for biomedical applications. A family of xylitol-based cross-linked polyesters was synthesized by melt condensation. The effect of systematic variation of chain length of the diacid, stoichiometric ratio, and postpolymerization curing time on the physicochemical properties was characterized. The degradation rate decreased as the chain length of the diacid increased. The polyesters synthesized by this approach possess a diverse spectrum of degradation (ranging from ∼4 to 100% degradation in 7 days), mechanical strength (from 0.5 to ∼15 MPa) and controlled release properties. The degradation was a first-order process and the rate constant of degradation decreased linearly as the hydrophobicity of the polyester increased. In controlled release studies, the order of diffusion increased with chain length and curing time. The polymers were found to be cytocompatible and are thus suitable for possible use as biodegradable polymers. This work demonstrates that this particular combinatorial approach to polymer synthesis can be used to prepare biomaterials with independently tunable properties.

The purpose of this work was to develop a family of cross-linked poly(xylitol adipate salicylate)s with a wide range of tunable release properties for delivering pharmacologically active salicylic acid. The synthesis parameters and release conditions were varied to modulate polyester properties and to understand the mechanism of release. Varying release rates were obtained upon longer curing (35% in the noncured polymer to 10% in the cured polymer in 7 days). Differential salicylic acid loading led to the synthesis of polymers with variable cross-linking and the release could be tuned (100% release for the lowest loading to 30% in the highest loading). Controlled release was monitored by changing various factors, and the release profiles were dependent on the stoichiometric composition, pH, curing time, and presence of enzyme. The polymer released a combination of salicylic acid and disalicylic acid, and the released products were found to be nontoxic. Minimal hemolysis and platelet activation indicated good blood compatibility. These polymers qualify as "bioactive" and "resorbable" and can, therefore, find applications as immunomodulatory resorbable biomaterials with tunable release properties.

Polyols are multifunctional alcohols, with branched structures, where each arm terminates with an -OH group. These free -OH groups have been utilised to make a variety of polymer structures ranging from cross-linked to linear to starshaped. This review presents a comprehensive account of polyol-based polymers in biomedical applications. The advantages afforded by polyolbased biodegradable polymers are detailed in this review, alongside a general historical perspective on the development of biodegradable polymers. The major advantage of these polyols is that they are endogenous to the human body. Synthesis strategies and fabrication techniques to mould these materials into three-dimensional (3D) scaffolds are discussed. Modifications to the conventionally used polyol-based polyesters have been achieved by chemically incorporating drugs/ bioactives or by preparing nanocomposites. This review discusses the physicochemical properties and biological responses of these polymers relevant in biomedical applications and further outlines the need for improving their processability and performance.

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.

Controlled and sustained release of antibacterial drugs is a promising approach to address challenges related to bacterial infections in biomedical implants. Biocompatible polyols like xylitol and mannitol are frequently used to synthesize cross-linked, biodegradable polyesters. Xylitol-based adipoyl and sebacoyl polyesters were synthesized by a catalyst free melt polyesterification technique. Unlike traditional drug delivery systems, the objective of this work was to develop biodegradable polymers with usnic acid (UA), a known antibacterial agent, entrapped in the polymer network. Apart from offering a wider control of the release kinetics and improved processability, the hydrolytic degradation results in the concomitant resorption of the polymer. Polymer properties such as degradation, modulus, and drug release were tuned through a subtle change in the chain length of the diacid. In 1 week, the xylitol based adipoyl ester degrades 41% and releases 25% of its initial drug loading whereas the sebacoyl ester degrades 23% in and releases 9% of the loaded drug. A kinetic model has been used to understand the UA release profiles and determine degradation and release parameters that influence release from the polymers. These polyesters are cytocompatible and exhibit excellent bactericidal activity against Staphyloccus aureus by inducing oxidative stress. This work enables a strategy to synthesize biodegradable polymers for potential to inhibit biofilm formation in vivo with tunable mechanical and degradation properties, and variable controlled release.