Microbial degradation, cytotoxicity and antibacterial activity of polyurethanes based on modified castor oil and polycaprolactone

Abstract

The objective of this study was to assess the effects of type of polyol and concentration of polycaprolactone (PCL) in polyurethanes (PUs) on microbial degradability, cytotoxicity, biological properties and antibacterial activity to establish whether these materials may have biomedical applications. Chemically modified and unmodified castor oil, PCL and isophorone diisocyanate in a 1:1 ratio of NCO/OH were used. PUs were characterized by stress/strain fracture tests and hardness (ASTM D 676-59). Hydrophilic character was determined by contact angle trials and morphology was evaluated by scanning electron microscopy. Degradability with Escherichia coli and Pseudomonas aeruginosa was evaluated by measuring variations in the weight of the polymers. Cytotoxicity was evaluated using the ISO 10993-5 (MTT) method with mouse embryonic fibroblasts L-929 (ATCC® CCL-1) in direct contact with the PUs and with NIH/3T3 cells (ATCC® CRL-1658) in indirect contact with the PUs. Antimicrobial activity against E. coli and P. aeruginosa was determined. PUs derived from castor oil modified (P0 and P1) have higher mechanical properties than PUs obtained from castor oil unmodified (CO). The viability of L-929 mouse fibroblasts in contact with polymers was greater than 70%. An assessment of NIH/3T3 cells in indirect contact with PUs revealed no-toxic degradation products. Finally, the antibacterial effect of the PUs decreased by 77% for E. coli and 56% for P. aeruginosa after 24 h. These results indicate that PUs synthesized with PCL have biocidal activity against Gram-negative bacteria and do not induce cytotoxic responses, indicating the potential use of these materials in the biomedical field.

Polyurethanes from modified castor oil and chitosan

“…al. 14 Alternatively, chitosan is a heteropolysaccharide consisting of linear β-1,4-linked units and a de-N-acetylated analogue of chitin 15 . This allows the formation of an ionic complex with other natural and synthetic materials such as lipids, proteins and some polymers.…”

Polyurethane-based bioadhesive synthesized from polyols derived from castor oil (Ricinus communis) and low concentration of chitosan

“…The tensile strength results from a previous study with polymer matrices synthesized using the same polyols (CO, P0 and P1) with isophorone diisocyanate 20 show lower values when HDI is used instead of diisocyanate. This may be due to the chemical structure of the HDI because it is a linear aliphatic diisocyanate, whereas and the isophorone diisocyanate has a cyclic structure that allows for higher tensile strength than materials from linear diisocyanates.…”

“…Castor oil is characterized by hydroxyl groups in the chain that react with isocyanates generating different morphological and mechanical properties. 20,21 PUs derived from castor oil may exhibit antibacterial activity and applications of these polymers for wound closure have been reported. 11 According to the previously information there are works related to biodhesive design.…”

Castor Oil Polyurethanes as Biomaterials

“…Those materials also demonstrated promising prospects for bone repair and regeneration. Also, using pentaerythritol for castor oil modification, Uscategui et al [24] compared polyurethanes from transesterification reaction with castor oil-based polyurethanes. Though mechanical behavior was increased in alcoholyzed castor oil due to increase of cross-linking density, cell viability of those polymers had lower values than castor oil.…”

“…In that context, Uscategui et al [24], additionally, studied the effect of polycaprolactone diol (PCL) incorporation into modified castor oil-based polyols, obtained from transesterification reaction with pentaerythritol. They studied the effect of three concentrations of PCL (5, 10, 20% w/w).…”