Synthesis and characterization of L‐tyrosine based polyurethanes for biomaterial applications

Abstract

The use of amino acid based polymers for biomaterial applications enhance biocompatibility and ensure biodegradability. Two polyurethanes based on L-tyrosine based diphenolic dipeptide, desaminotyrosyl tyrosine hexyl ester as chain extender are synthesized with polyethylene glycol (PEG) and polycaprolactone diol (PCL) as soft segment and hexamethylene diisocyanate as diisocyanate. The chemical structure and molecular characteristics of the polymers were studied by 1H NMR, FTIR, and gel permeation chromatography. Results of DSC and TGA analysis were used for examining the thermal behavior of the polyurethanes. In addition, DSC results were used to analyze the morphology of the polymers, which shows characteristic microphase behavior of the polyurethanes. The tensile properties of the polyurethanes are primarily controlled by the soft segment and are higher in PCL based polymers. Contact angle, water vapor permeation, release of model drug, and water absorption characteristics of the polymers were studied and analyzed in terms of structure of the polyurethanes. In vitro degradation studies show that PEG based polyurethane is more degradable than PCL based polyurethane. The difference in the soft segment structure offers significant variation in the properties of the polyurethanes. These polyurethanes show the potential for use in a variety of biomaterial applications including tissue engineering.

Structure‐property relationship of L‐tyrosine‐based polyurethanes for biomaterial applications

“…The results show that PEGbased polyurethanes are relatively weaker in mechanical properties compared with PCL-based polyurethanes because of relative crystallinity. 11,12,16 The effect of soft segment's molecular weight can be seen for both PEG-and PCL-based polyurethanes. For PU1, PU2, and PU3, increasing PEG's molecular weight shows increased mechanical properties although the hard segment content of the polyurethanes is decreasing.…”

“…The additional endotherms of PU5 represent soft segment and hard segment melting. 16 Comparison of endotherms for PU4 and PU5 shows that PCL soft segment with higher molecular weight exhibits soft segment crystallinity and also leads to a more crystalline and ordered hard segment. Although the change in soft segment T g is not appreciable, the phase mixed morphology of PU4 is evident from the absence of melting endotherms.…”

“…PEG-based polyurethanes degrade at a faster rate compared with PCL-based polyurethanes. 7,11,16 Since PEG is hydrophilic and absorbs more water, the degradation rate in PEG-based polyurethanes is faster than PCL polyurethane. Moreover, PCL is relatively crystalline compared with PEG.…”

“…The details of the synthetic process are described elsewhere. 16 Briefly, polydiol and diisocyanate were added to 50 mL dry DMF (solvent) in the molar ratio of 1 : 2 and were allowed to react for 3 h at 1108C in the presence of 0.1% stannous octoate 11 as catalyst and subsequently cooled down to room temperature. DTH was added to the solution in the molar ratio of 1 : 1 to the polydiol and the reaction was allowed to continue at 808C for another 12 h. After 12 h the reaction was quenched by precipitating the polyurethanes in concentrated aqueous solution of sodium chloride.…”

Characteristics of novel polymer based on pseudo-polyamino acids GluLa-DPG-PEG600: binding of albumin, biocompatibility, biodistribution and potential crossing the blood-brain barrier in rats

“…Pseudo-poly amino acids based on glycine, asparagine, arginine and lysine in complex with lactic acid are biodegra dable and have advanced cell adhesion [7][8][9]. Pseu dopolyamino acids based on tyrosine in complexes with ZnO can be used in anticancer therapy [10,11]. The main advantages of this class of polymers as drug transporters are their biodegradability and prolonged time of degradation that correlates with releasing of drugs active components (for example, polymers based on glycine and lactic acid are de composed for about 10 weeks) [7,8].…”