In vitro hydrolytic degradation of polyester-based scaffolds under static and dynamic conditions in a customized perfusion bioreactor

Creating biofunctional artificial scaffolds could potentially meet the demand of patients suffering from bone defects without having to rely on donors or autologous transplantation. Three-dimensional (3D) printing has emerged as a promising tool to fabricate, by computer design, biodegradable polymeric scaffolds with high precision and accuracy, using patient-specific anatomical data. Achieving controlled degradation profiles of 3D printed polymeric scaffolds is an essential feature to consider to match them with the tissue regeneration rate. Thus, achieving a thorough characterization of the biomaterial degradation kinetics in physiological conditions is needed. Here, 50:50 blends made of poly(e-caprolactone)–Poly(D, L-lactic-co-glycolic acid (PCL-PLGA) were used to fabricate cylindrical scaffolds by 3D printing (Ø 7 × 2 mm). Their hydrolytic degradation under static and dynamic conditions was characterized and quantified. For this purpose, we designed and in-house fabricated a customized bioreactor. Several techniques were used to characterize the degradation of the parent polymers: X-ray Photoelectron Spectroscopy (XPS), Gel Permeation Chro-matography (GPC), Scanning Electron Microscopy (SEM), evaluation of the mechanical properties, weigh loss measurements as well as the monitoring of the degradation media pH. Our results showed that flow perfusion is critical in the degradation process of PCL-PLGA based scaffolds implying an accelerated hydrolysis compared to the ones studied under static conditions, and up to 4 weeks are needed to observe significant degradation in polyester scaffolds of this size and chemical composition. Our degradation study and characterization methodology are relevant for an accurate design and to tailor the physicochemical properties of polyester-based scaffolds for bone tissue engineering

Towards eco-friendly crop protection: natural deep eutectic solvents and defensive secondary metabolites

Plant science

Effect of nitrogen doping method on the activity of Fe-N-C catalysts based on carbon xerogels for fuel cells

3 figures, 1 table.-- Work presented at the EHEC 2022, European Hydrogen Energy Conference, 18-20 May, 2022. Madrid, Spain.The development of active and inexpensive non-precious metal catalysts is a necessary and essential requirement to replace currently used Pt-based catalysts, in order to reduce the cost of polymer electrolyte fuel cells(PEFC). [1] Catalysts based on the Fe-N-C structure develop high electroactivity towards the oxygen reduction reaction (ORR), the limiting reactionin fuel cells. To increase the catalysts activity, Fe must be dispersedin acarbon material with a high surfacearea.In this context, carbon xerogels are excellent candidates, as their main properties can be easily tailored: porosity, electrical conductivity and surface chemistry. [2] The meso/macroporosity of carbon xerogels can be designed by modifying the conditions of the synthesis process, while microporosity can be generated by subsequent carbonization/activation treatments [3].In the present work, on the basis of carbon xerogels with an optimal ratio of micro/meso/macroporosity, we investigate the effect of two different methods of nitrogen-doping in the catalytic activity of Fe-N-C catalysts. Catalysts are evaluated both in half-cell and single-cell configurations and their activity is correlated to their physical-chemical features.The authors wish to thank the Ministry of Science and Innovation and the AEI(MCIN/AEI/10.13039/501100011033) for the funding received with the reference project PID2020-115848RB-C21 and the Government of Aragon for funding the T06-20R group. L. Álvarez-Manuel wish to thank the Government of Aragon for her pre-doctoral contract.Peer reviewe

Catalizadores Fe-N-C basados en xerogeles de carbono para pilas de combustible

2 figuras.-- Resumen de la comunicación oral presentada en la XV Reunión del Grupo Español del Carbón, 24-27 abril 2022, Granada (España).-- O59.-- D.L. GR 695-2022Una de las principales desventajas de las pilas de combustible (PEMFCs) es su elevado coste, debido principalmente a los catalizadores de Pt empleados. Se han investigado numerosos materiales como posibles alternativas al Pt, siendo los catalizadores basados en metales como el hierro coordinado con nitrógeno y carbono (Fe-N-C), los más activos para la reacción de reducción de oxígeno (ORR), la reacción limitante en las PEMFCs. Generalmente, estos catalizadores emplean negros de carbono microporosos como matrices carbonosas. Un estudio detallado de la micro/meso/macroporosidad de esta estructura carbonosa es esencial para el desarrollo de catalizadores de Fe-N-C. En este trabajo se ha modificado la microporosidad de estos xerogeles de carbono mediante diferentes tratamientos de activación y se ha estudiado su efecto en la actividad de los catalizadores Fe-N-CXG para la ORR.Los autores agradecen la financiación del Gobierno de Aragón al grupo T06-20R. L. Álvarez agradece también al Gobierno de Aragón su contrato pre-doctoral DGA.Peer reviewe

Mitochondrial long chain fatty acid oxidation, fatty acid translocase/CD36 content and carnitine palmitoyltransferase I activity in human skeletal muscle during aerobic exercise

Mitochondrial fatty acid transport is a rate-limiting step in long chain fatty acid (LCFA) oxidation. In rat skeletal muscle, the transport of LCFA at the level of mitochondria is regulated by carnitine palmitoyltransferase I (CPTI) activity and the content of malonyl-CoA (M-CoA); however, this relationship is not consistently observed in humans. Recently, fatty acid translocase (FAT)/CD36 was identified on mitochondria isolated from rat and human skeletal muscle and found to be involved in LCFA oxidation. The present study investigated the effects of exercise (120 min of cycling at ∼60% V̇(O(2)peak)) on CPTI palmitoyl-CoA and M-CoA kinetics, and on the presence and functional significance of FAT/CD36 on skeletal muscle mitochondria. Whole body fat oxidation rates progressively increased during exercise (P < 0.05), and concomitantly M-CoA inhibition of CPTI was progressively attenuated. Compared to rest, 120 min of cycling reduced (P < 0.05) the inhibition of 0.7, 2, 5 and 10 μm M-CoA by 16%, 21%, 30% and 34%, respectively. Whole body fat oxidation and palmitate oxidation rates in isolated mitochondria progressively increased (P < 0.05) during exercise, and were positively correlated (r = 0.78). Mitochondrial FAT/CD36 protein increased by 63% (P < 0.05) during exercise and was significantly (P < 0.05) correlated with mitochondrial palmitate oxidation rates at all time points (r= 0.41). However, the strongest (P < 0.05) correlation was observed following 120 min of cycling (r= 0.63). Importantly, the addition of sulfo-N-succimidyloleate, a specific inhibitor of FAT/CD36, reduced mitochondrial palmitate oxidation to ∼20%, indicating FAT/CD36 is functionally significant with respect to LCFA oxidation. We hypothesize that exercise-induced increases in fatty acid oxidation occur as a result of an increased ability to transport LCFA into mitochondria. We further suggest that decreased CPTI M-CoA sensitivity and increased mitochondrial FAT/CD36 protein are both important for increasing whole body fatty acid oxidation during prolonged exercise

Can the extract of Aristolochia argentina Griseb affect the foraging decisions of the leaf cutting ant Acromyrmex lundi (Guérin)? Preliminary assays

The aim of this study was to evaluate whether foraging decisions of Acromyrmex lundi in the field are affected by the extract of Aristolochia argentina. A free choice test was performed using Rosa x hybrida leaves treated with the extract and control with acetone. Two leaves (treated and control) were presented on either side of a foraging trail. The percentage of removed material was recorded for 90 minutes of observation on two consecutive days. Dry weight and repellency index were calculated. Ant activity, the percentage of carried leaves and weight data were analyzed using a “t”-test for paired data, and a General Linear Mixed Model test was used to evaluate the different variables and their interactions. A. argentina extract (1%) did not affect the foraging activity of A. lundi, whereas the 5% dose caused significant differences in foraging activity as well as between the factors and the interactions. A repellency index of above 95% was obtained at the 5% dose. The extract of A. argentina could be considered for future management of this insect.Fil: Defagó, María Teresa. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Investigaciones Entomológicas de Córdoba; ArgentinaFil: Nolli, Laura. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Investigaciones Entomológicas de Córdoba; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Diaz Napal, Georgina Natalia. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palacios, Sara Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Buffa, Liliana María. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Investigaciones Entomológicas de Córdoba; Argentin