The objective of this research was to synthesize biocompatible polyurethanes, with suitable mechanical properties to be used as biomaterials. Polyurethanes were synthesized with polyols derived from castor oil and isophorone diisocyanate (IPDI), hexamethylene diisocyanate and 4,4’-methylenebis (cyclohexyl isocyanate), with the addition of polycaprolactone/chitosan (PCL/Ch). The materials were evaluated for their mechanical properties by determining the stress-strain curves, thermogravimetric analysis, differential scanning calorimetry analysis and contact angle. The biological response of the materials was evaluated by measuring in vitro cell viability on the L-929 mouse fibroblast cell line. The mechanical properties of polyurethanes vary according to the type of polyol and diisocyanate used. The best results were obtained with transesterification-modified polyols with cycloaliphatic diisocyanates. The best results were found for polyurethane synthesized with IPDI and the modified polyol (P.3): 17 MPa of maximum stress at break, 0.937 MPa of Young’s modulus, elongation greater than 250%. Polyurethanes do not have toxic effects and cell viability values exceed 70% on the L-929 fibroblast line. The addition of PCL/Ch improves the cell viability of polyurethanes. The results indicate that the polyurethanes synthesized with polyols derived from castor oil can be used in the design of biomaterials due to the mechanical and biological properties obtained.

Polyurethanes (PUs) are generating increasing interest in the biomedical field due to its characteristic properties. The objective of this article was review general properties of PUs and related with their biomedical applications, also to show the importance of the synthesis of PUs and how each one of the reagents used influences both mechanical properties and biological response of the designed medical devices. It is important to look for a correlation between mechanical properties and biological properties from the synthesis process of the PUs which allow to maintain the biocompatibility required by each medical device. In this work, the PUs are evaluated into three groups of applications: equipment and surgical instruments, temporary applications within the body, and permanent applications within the body. This review can show the broad field of use of PUs in biomedical applications.

Biological activities from polyurethanes (PUs) synthesized from polyols (derived from castor oil) and isophorone diisocyanate were evaluated. In vitro degradability was evaluated by phosphate buffered saline (PBS) and antibacterial degradation with Escherichia coli and Pseudomonas aeruginosa. The biocompatibility was analyzed by: i) the antimicrobial activity against E. coli, S. aureus and P. aeruginosa, and ii) in vitro cytotoxicity assays using mouse embryonic fibroblast cell line L-929 in direct contact with the PUs and with NIH/3T3 cells in indirect contact with the PUs degradation products. PUs with polyol P1 (2,64% molar relation of pentaerythritol and castor oil) was the material with better biodegradation properties: 1.125±0.110% in 72 h by PBS at 100 ºC. In general, all materials were degraded up to 1.000±0.223% and 2.251±0.010% in 72 h by E. coli and P. aeruginosa, respectively. On the other hand, it was determined a close relationship between functionality of polyol and bacterial inhibition. The antibacterial effect of the PUs decreased by 67% for E. coli, 55% for S. aureus and 56% for P. aeruginosa after 24 h. Chemical modification of castor oil did not generate a cytotoxic effect on the tested cell lines. The evaluated materials are suggested as candidates to obtain biomaterials due to their mechanical properties and biocompatibility presented in untransformed cells.

Se sintetizaron bioadhesivos tipo poliuretano a partir del aceite de higuerilla y almidón modificado por glucosilación con etilenglicol, y metil éster diisocianato de lisina (LDI). Los bioadhesivos se caracterizaron mediante espectroscopia infrarroja por transformada de Fourier (FTIR), análisis termogravimétrico (TGA) y se determinaron las propiedades mecánicas y de adhesión. Finalmente se determinó el módulo de almacenamiento y la tan(δ) mediante ensayos dinamomecánicos (DMTA). La degradación in vitro del material se llevó a cabo en solución de PBS y se determinó la pérdida de masa. También se realizaron mediciones del ángulo de contacto y absorción de agua con el fin de determinar el cambio en el carácter hidrofílico del material. Finalmente se realizaron pruebas de adsorción de proteínas para determinar la biocompatibilidad del material. El objetivo del estudio fue evaluar el cambio en la estructura del material y el efecto en las propiedades mecánicas y de adhesión, degradabilidad y biocompatibilidad del material con el fin de determinar si los bioadhesivos tipo poliuretano sintetizados pueden ser candidatos en aplicaciones biomédicas.

Polyurethanes were synthesized from castor oil, starch modified via glycosylation with ethylene glycol and lysine methyl ester diisocyanate (LDI). A degradation study of the polyurethanes in PBS solution was performed, and the mass loss was determined for each. The results were compared with homologous material obtained in previous studies using isophorone diisocyanate (IPDI). The degraded polyurethanes were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). The objective of the study was to evaluate the biodegradation characteristics and proteins adsorption of the materials under various conditions and to evaluate the changes in their mechanical and thermal properties caused by the modification of the structures of the hard and soft segments of the polyurethanes with respect to the structure of the diisocyanate used in the synthesis. This study provided an evaluation of segmented polyurethanes with possible biomedical applications.

Biodegradable polyurethanes (PUR) were prepared from polyols derived from castor oil by transesterification of pentaerythritol-modified castor oil and lysine polyisocyanates (LDI and LTI). The polyurethanes obtained were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The mechanical behavior of the polyurethanes was measured by Shore A hardness and tensile testing (stress-strain curves). The biodegradable nature of the material was determined by contact angle, water absorption tests, and in vitro degradation in PBS solution. This study aims to examine the effect of the structure and functionality of diisocyanate on the mechanical properties and in vitro degradation of the material. The results were compared with homologous materials obtained from isophorone diisocyanate (IPDI) used in previous works. The objective was to evaluate candidate materials that can be potentially used in tissue engineering.

Las metaloproteinasas 2 y 9 (MMP-2 y MMP-9) y el inhibidor-1 de MMP (TIMP-1) podrían contribuir a la regulación del comportamiento invasivo de las células trofoblásticas, efecto que podría ser mediado por el factor de crecimiento similar a la insulina tipo II (IGF-II), el cual regula el desarrollo y la función del trofoblasto en la interfase materno-fetal. El objetivo de este estudio fue investigar el rol de la vía de señalización PI3K/AKT activada por IGF-II en la expresión de MMP-2 y MMP-9 involucradas en el proceso de invasión en la línea celular JEG-3, de coriocarcinoma humano. La expresión del mARN de MMP-2, MMP-9 y TIMP-1 fue evaluada, en dichas células, por la técnica de RT-PCR empleando diferentes dosis de IGF-II y diferentes condiciones, mientras que la vía de señalización fue evaluada usando la técnica de Western blot. Se encontró que el IGF-II no contribuye a la proliferación de las células trofoblásticas; sin embargo, este promueve la expresión del mARN de MMP-9 y TIMP-1 pero no de MMP-2, de forma dependiente de la dosis. El efecto en la expresión de MMP-9 es mediado a través de IGF-II por la activación de la vía de señalización PI3K/ AKT después de la fosforilación del receptor de IGF-I (IGF-IR). De acuerdo con los resultados, se propone un modelo en el cual la interacción de IGF-II con IGF-IR conduce a la activación de PI3K/AKT y la subsecuente expresión y activación de MMP-9. Esta activación es un requisito esencial para el proceso invasivo.

Metalloproteinases 2 and 9 (MMP-2 and MMP-9) and TissueInhibitor-1 ofMMPs (TIMP-1) could contribute to regulate the invasive behaviour of trophoblastic cells, effect which could be mediated by Insulin-like growth factor type II (IGF-II), which regulates the development and function of trophoblast at the foetal-maternal interface. The aim of this study was to investigate the role of the PI3K/AKT signalling pathway activated by IGF-II in the expression of MMP-2 and MMP-9 involved in the invasion process in the human choriocarcinoma cell line JEG-3. MMP-2, MMP-9 and TIMP-1 mARN expression in those cells were evaluated by RT-PCR using different IGF-II doses and conditions while signalling pathway was evaluated using Western blot. It was found that IGF-II does not contribute to trophoblastic cells proliferation, however, it promotes mARN expression of MMP-9 and TIMP-1, but not of MMP-2, in a dose-dependent way. The effect on MMP-9 expression is mediated through IGF-II activation of PI3K/AKT signalling pathway after phosphorylation of the IGF-I receptor (IGF-IR). According with the results a model is proposed in which the interaction of IGF-II with IGF-IR leads to PI3K/AKT activation and subsequent expression and activation of MMP-9. This activation is an essential requirement for the invasive process.

As metaloproteinasas 2 y 9 (MMP-2 y MMP-9) e o inibidor-1 de MMPs (TIMP-1) poderiam contribuir à regulação do comportamento invasivo das células trofoblásticas, efeito que poderia ser mediado pelo Factor de Crescimento Similar à Insulina tipo II (IGF-II), o qual regula o desenvolvimento e função do trofoblasto na interface materno-fetal. O objectivo deste estudo foi investigar o papel da via de sinalização PI3K/AKT activada por IGF-II na expressão de MMP-2 e MMP-9 envolvidos no processo de invasão na linha celular JEG-3, de coriocarcinoma humano. A expressão do mARN de MMP-2, MMP-9 y TIMP-1, foi avaliada, em ditas células, pela técnica de RT-PCR utilizando diferentes doses de IGF-II e diferentes condições, enquanto que a via de sinalização foi avaliada usando a técnica de Western-blot. Foi encontrado que o IGF-II não contribui à proliferação das células trofoblásticas, no entanto, este promoveu a expressão do mARN de MMP-9 e TIMP-1 mas não de MMP-2, de forma dependente da dose. O efeito na expressão de MMP-9 é mediado através de IGF-II pela activação da via de sinalização PI3K/AKT depois da fosforilação do receptor de IGF-I (IGF-IR). De acordo aos resultados é proposto um modelo, no qual a interacção de IGF-II com IGF-IR conduz à activação de PI3K/AKT e à subsequente expressão e activação de MMP-9. Esta activação é um requisito essencial para o processo invasivo.