Antonio Martínez-Richa

Low-temperature, organocatalyzed ring-opening polymerization (ROP) of deep eutectic solvent (DES) and noneutectic mixtures composed of l-lactide (LLA) and ε-caprolactone (CL) was carried out under solvent-free conditions using ethyl lactate and butyl lactate as biobased initiators. Unlike previously reported DES-mediated ROP systems, this work integrates lactate-based initiators, selective sequential organocatalysis, and fused salt templating to achieve simultaneous polymerization and scaffold formation under mild conditions. This approach allows the direct formation of biodegradable three-dimensional macroporous polyester scaffolds, in which polymer synthesis and structural organization occur in a single step. The eutectic nature of the LLA–CL system was investigated by density functional theory, ¹H NMR spectroscopy, and thermal analysis, providing insight into the intermolecular interactions governing phase behavior. Structural characterization of the resulting polyesters by ¹H NMR, X-ray diffraction, and differential scanning calorimetry confirmed successful polymerization and the formation of semicrystalline PLLA/PCL scaffolds. Mechanical testing showed that the compressive properties of the scaffolds can be systematically adjusted through control of molar mass and crystallinity by varying initiator type and concentration. Hydrolytic degradation studies revealed gradual mass loss consistent with scaffold composition, while cytotoxicity assays using MC3T3-E1 preosteoblasts indicated suitable cytocompatibility. Overall, this work establishes a solvent-free, low-temperature strategy for the preparation of macroporous biodegradable polyester materials with controllable physicochemical properties.

"Se llevó a cabo la síntesis de polímeros base poliuretano conteniendo aminoácidos mediante la reacción entre PCL-diol y diisocianato de hexametileno incorporando seis aminoácidos diferentes, para evaluar su efecto sobre las propiedades, térmicas, mecánicas y de liberación de fármacos de los poliutretanos, siendo ciprofloxacina como fármaco elegido. Los estudios de liberación se llevaron a cabo a pH 5 y pH 12. Los poliuretanos y sus derivados se caracterizaron mediante espectroscopía FT-IR y calorimetría diferencial de barrido, además de pruebas específicas de las matrices para liberación de fármacos. Finalmente se evidenció que los polímeros sintetizados permitieron la liberación de ciprofloxacina en diversos perfiles, lo cual se asocia a su estructura y propiedades inherentes de cada aminoácido. Asimismo, se realizaron pruebas para extracción por método Soxhlet del aceite esencial de muestras de Ricinus communis, obteniendo buenosrendimientos del aceite extraído. El extracto"

This study investigated the chemical, thermal, and mechanical properties of segmented polyurethanes (SPUs) synthesized using less common biodegradable polyester polyols, specifically poly(adipate) (PAD) and poly(sebacate) (PSC), to evaluate their potential as nerve guidance conduits (NGCs) in peripheral nerve regeneration. The synthesis of novel 4,4′ methylene-bis-cyclohexyl diisocyanate (HMDI) SPUs was conducted in a two-step process: prepolymer formation and chain extension with 1,4-butanediol (BO) or 1,4-butanediamine (BA). SPUs were synthesized with two molar ratios—polyol:HMDI:BA/BO at 1:2:1 and 1:3:2 for the PAD:HMDI:BA system—to optimize mechanical properties. 1HRMN analysis verified the expected chemical structure of SPUs, whereas Raman and IR spectroscopy confirmed successful polyurethane synthesis. X-ray diffractograms showed that PAD-based SPUs (SPUPAD) were amorphous while PSC-based SPUs (SPUPSC) exhibited semi-crystalline behavior. SPUPAD showed only one degradation stage by TGA, while DSC showed one thermal event. In contrast, SPUPSC exhibited two degradation stages and three thermal events that confirmed phase separation. The longitudinal tensile properties of an NGC fabricated from SPUA-PAD-2 (PAD:HMDI:BA (1:3:2)) after 30 days of immersion in water (25 °C) showed a lower modulus (4.46 ± 0.5 MPa) than native intact nerves (15.87 ± 2.21 MPa) but a similar modulus to extracted nerves (8.19 ± 7.27 MPa). This system exhibited a longitudinal tensile force of 11.1 ± 1.6 N, which is lower than that of peripheral nerves (19.85 ± 7.21 N) but higher than that of commercial collagen-based nerve guide conduits (6.89 ± 2.6 N). The observed properties suggest that PUA-PAD-2 has potential as a biomaterial for nerve regeneration applications.

Synthetic and commercial carboxymethyl cellulose (CMC) sodium salts were analyzed by CP‐MAS ¹³C‐NMR and plasma emission analysis. CMC was synthesized in the lab from cotton alkali cellulose and sodium chloroacetate. The progressive changes in the chemical composition and morphology (and reflected in the degree of substitution, DS) were followed by solid‐state NMR. Observed differences in solid‐state NMR spectra are discussed in terms of DS, chemical composition, dynamics, and polymorphism. The effect of molecular weight in CMC morphology and dynamics can be assessed by small differences observed in peak shapes and peak positions in the CP‐MAS spectra.

El PET (tereftalato de polietileno en español) es un polímero ampliamente utilizado en envases plásticos y presenta una gran oportunidad para ser reciclado y reutilizado en formas de alto valor agregado, la sobreproducción y desecho de este conlleva impactos significativos en el medio ambiente, desde el consumo de recursos no renovables hasta la acumulación de desechos plásticos en los ecosistemas terrestres y acuáticos. En esta investigación nos centramos en la obtención de poliuretano a partir de la degradación del PET, ofreciendo una alternativa prometedora y sostenible para mitigar la contaminación plástica. El proceso de degradación del PET se convierte así en una fuente viable de materias primas para la síntesis de poliuretano (PUs) derivados de la reacción entre un poliol y un diisocianato, que es un material versátil con aplicaciones en diversas industrias.

Nanocomposites prepared with a terpolymer of poly(L–lactide) (PLLA)–poly(ε–caprolactone) (PCL)–poly(ethylene glycol) (PEG) and partially oxidized carbon nanotubes (CNTs_po) were synthesized and characterized to evaluate their ability to act as an effective nanocarrier of the anticancer drug methotrexate. The homopolymers of PLLA and PCL were synthesized through ring-opening polymerization (ROP) and characterized through gel permeation chromatography (GPC). The PLLA–PCL–PEG terpolymers were synthesized through a four-step chemical route using oxalyl chloride as a linker agent and analyzed with ¹H–NMR, ¹³C–NMR, and FTIR spectroscopies. Additionally, the nanocomposites were characterized through FTIR, and X-ray photoelectron spectroscopy (XPS), as well as the differential scanning calorimetry (DSC) technique. XPS analysis revealed that PLLA–PCL–PEG terpolymer chains are grafted onto CNTs_po. Moreover, evaluations through FTIR and DSC strongly suggest that the PCL-rich domains are preferentially oriented toward CNTs_po. The release tests exhibited a “burst effect” profile, which was more evident in the terpolymers than in the nanocomposites. Five models were used to assess methotrexate’s in vitro release. For the nanocomposites, the best fit to the experimental data was obtained using the first-order model, whereas the results obtained from the Korsmeyer–Peppas model indicated that Fickian diffusion drives methotrexate’s release.

Nanocomposites prepared with a terpolymer of poly(L-lactide) (PLLA)–poly(-caprolactone) (PCL)–poly(ethylene glycol) (PEG) and partially oxidized carbon nanotubes (CNTspo) were synthesized and characterized to evaluate their ability to act as an effective nanocarrier of the anticancer drug methotrexate. The homopolymers of PLLA and PCL were synthesized through ring-opening polymerization (ROP) and characterized through gel permeation chromatography (GPC). The PLLA–PCL–PEG terpolymers were synthesized through a four-step chemical route using oxalyl chloride as a linker agent and analyzed through 1H-NMR, 13C-NMR, and FT-IR spectroscopies. Also, the nanocomposites were characterized through FT-IR, 1H-NMR, and X-ray photoelectron spectroscopy (XPS) spectroscopies and, using the differential scanning calorimetry (DSC) technique. XPS analysis revealed that CNTspo is grafted to PLLA–PCL–PEG terpolymer. Besides, evaluation through FT-IR and DSC strongly suggests that the CNTspo are preferentially oriented to the PCL-rich domains. The release tests exhibited a “burst effect” profile, which was more evident in the terpolymers than in the nanocomposites. Five models were used to assess the methotrexate in vitro release. For the nanocomposites, the best fit to the experimental data was obtained using the first-order model, whereas the results obtained from the Korsmeyer–Peppas model indicated that a Fickian diffusion drives the methotrexate release.