Estudio de transiciones líquido‐líquido en disoluciones acuosas de polipéptidos sensibles a estímulos

Los nuevos biomateriales, como los polímeros recombinantes de tipo elastina, prometen multitud de aplicaciones médicas, desde el transporte de fármacos a la regeneración de tejidos dañados. Si bien la separación en dos fases líquidas de la elastina es un proceso conocido, poco se sabe sobre su efecto en la migración celular. Se ha teorizado que los agregados poliméricos podrían arrastrar a las células presentes en el medio, al producirse la coacervación y separación en dos fases líquidas. Para estudiar la viabilidad de este proceso, se ha propuesto realizar un estudio con un polímero recombinante de tipo elastina, el HRGD6, caracterizado por la secuencia de adhesión celular RGD. En este trabajo se ha caracterizado físicamente dicho polímero, analizado su similitud con la elastina mediante espectroscopía infrarroja. Se ha determinado, por medio de mediciones de calorimetría diferencial de barrido, que se produce la coacervación de este polímero a temperatura fisiológica, y se ha seguido este proceso mediante medidas de turbidimetría y dispersión dinámica de la luz, así como de forma visual. Se ha observado que el autoensamblado proteico origina gotas del orden de 1,2μm, que, al coalescer entre sí, forman una separación de fases líquido-líquido pasada media hora. Además de la caracterización del polímero y de su proceso de coacervación, se le ha realizado una modificación química, añadiendo el fluoróforo Cy5, y se ha hecho una caracterización preliminar de la modificación. Esto permitirá realizar futuros estudios sobre el proceso de coacervación en presencia de células, ayudando a determinar, mediante microscopía de fluorescencia, la influencia de este proceso en la migración celular, así como su posible aplicación en la regeneración de tejidos dañados.New biomaterials, such as elastin-like recombinamers, promise a broad variety of medical applications, from drug delivery to tissue regeneration. While the liquid-liquid phase separation of elastin is a known process, little is known about its effect on cell migration. It has been theorized that polymeric aggregates could drag the cells from the medium, by coacervation and liquid two-phase separation. To study the feasibility of this process, it has been proposed to perform a study with a recombinant elastin-like polymer, HRGD6, characterized by the cell adhesion sequence RGD. In this work, this polymer has been physically characterized, and its similarity to elastin has been analyzed by infrared spectroscopy. It has been determined, by means of differential scanning calorimetry measurements, that coacervation of this polymer occurs at physiological temperature, and this process has been followed by means of turbidimetry and dynamic light scattering measurements, as well as visually. It has been observed that the protein self-assembly originates droplets of about 1.2μm, which, upon coalescence, form a liquid-liquid phase separation after half an hour. In addition to the characterization of the polymer and its coacervation process, a chemical modification has been carried out, adding the Cy5 fluorophore, and a preliminary characterization of the modification has been made. This will allow future studies on the coacervation process in the presence of cells, helping to determine, by means of fluorescence microscopy, the influence of this process on cell migration, as well as its potential application in tissue regeneration.Departamento de Física de la Materia Condensada, Cristalografía y MineralogíaGrado en Físic

Cation dynamics as structure explorer in hybrid 0erovskites─The case of MAPbI3

Published as part of Crystal Growth & Design virtual special issue “Lattice Dynamics”.Hybrid organic–inorganic perovskites exhibit remarkable potential as cost-effective and high-efficiency materials for photovoltaic applications. Their exceptional chemical tunability opens further routes for optimizing their optical and electronic properties through structural engineering. Nevertheless, the extraordinary softness of the lattice, stemming from its interconnected organic–inorganic composition, unveils formidable challenges in structural characterization. Here, by focusing on the quintessential methylammonium lead triiodide, MAPbI3, we combine first-principles modeling with high-resolution neutron scattering data to identify the key stationary points on its shallow potential energy landscape. This combined experimental and computational approach enables us to benchmark the performance of a collection of semilocal exchange–correlation functionals and to track the local distortions of the perovskite framework, hallmarked by the inelastic neutron scattering response of the organic cation. By conducting a thorough examination of structural distortions, we introduce the IKUR-PVP-1 structural data set. This data set contains nine mechanically stable structural models, each manifesting a distinct vibrational response. IKUR-PVP-1 constitutes a valuable resource for assessing thermal behavior in the low-temperature perovskite phase. In addition, it paves the way for the development of accurate force fields, enabling a comprehensive understanding of the interplay between the structure and dynamics in MAPbI3 and related hybrid perovskites.Financial support from the Spanish Ministry of Science and Innovation (grant PID2020-114506GB-100 funded by MCIN/AEI/10.13039/501100011033) and the Basque government (grant PIBA-2021-0026) is gratefully acknowledged. Grant PRE2021-097712 to support P.M.V. has been funded by MCIN/AEI/10.13039/501100011033 and the European Social Fund Programme “Investing in Your Future”. We acknowledge generous HPC resources from PL-Grid Infrastructure (grant IDs: plghybrids; plghybrids2022; and plghybrids2023). We further acknowledge the Spanish Supercomputing Network (RES Activity: QHS-2023-1-0027) and the computational resources from the Donostia International Physics Center (DIPC; Atlas Facility). M.G. wishes to thank Chiara Milanese (University of Pavia) for the support. We gratefully acknowledge the financial support received from the IKUR Strategy under the collaboration agreement between the Ikerbasque Foundation and the Materials Physics Center, on behalf of the Department of Education of the Basque government.Peer reviewe

Supplementary Information for Publication: Cation Dynamics as Structure Explorer in Hybrid Perovskites – the Case of MAPbI3

Collection of CASTEP *.phonon files according to IKUR-PVP-1 dataset, delivered as a part of the publication: Cation Dynamics as Structure Explorer in Hybrid Perovskites – the Case of MAPbI3 by Kacper Druzbicki, Pablo Gila-Herranz, Pelayo Marin-Villa, Mattia Gaboardi, Jeff Armstrong, and Felix Fernandez-Alonso

Cation Dynamics as Structure Explorer in Hybrid Perovskites – the Case of MAPbI3

Hybrid organic-inorganic perovskites exhibit remarkable potential as cost-effective and high-efficiency materials for photovoltaic applications. Their exceptional chemical tunability opens further routes for optimizing their optical and electronic properties through structural engineering. Nevertheless, the extraordinary softness of the lattice, stemming from its interconnected organic-inorganic composition, unveils formidable challenges in their structural characterization. Here, by focusing on the quintessen tial methylammonium lead triiodide, MAPbI3, we combine first-principles modeling with high-resolution neutron scattering data to identify the key stationary points on its shallow potential energy landscape. This combined experimental and computa tional approach enables us to benchmark the performance of a collection of semi-local exchange-correlation functionals and to track the local distortions of the perovskite framework, hallmarked by the inelastic neutron scattering response of the organic cation. By conducting a thorough examination of structural distortions, we introduce the IKUR-PVP-1 structural dataset. This dataset contains nine mechanically stable structural models, each manifesting a distinct vibrational response. IKUR-PVP-1 con stitutes a valuable resource for assessing the thermal behavior in the low-temperature perovskite phase. In addition, it paves the way for the development of accurate force fields, enabling a comprehensive understanding of the interplay between structure and dynamics in MAPbI3 and related hybrid perovskites

Association between Maternal Postpartum Depression, Stress, Optimism, and Breastfeeding Pattern in the First Six Months

Early breastfeeding cessation is a major public health problem. Several factors can affect breastfeeding pattern, and psychological aspects have been poorly explored. We hypothesize that psychological factors and breastfeeding pattern have a relationship. We have assessed in mothers during the first six months of lactation if breastfeeding pattern is associated with maternal stress, postpartum depression, and dispositional optimism, and if these psychological factors play a role on breastfeeding adherence. In total, 711 women participated, answering online the following questionnaires: sociodemographic, perceived stress scale, Edinburgh postpartum depression scale, life orientation test, and breastfeeding adherence score. Women were categorized according to infant feeding practices as exclusive breastfeeding (EBF) or mixed breastfeeding (MBF). The EBF group had a lower score of perceived stress compared to those giving MBF (first month: EBF = 1.5 [1.1; 1.9], MBF = 1.8 [1.5; 2.0]; p-Value = 0.030; third month: EBF = 1.6 [1.2; 2.0], MBF = 1.8 [1.5; 2.4]; p-Value = 0.038) and also had a lower score of postpartum depression (third month: EBF = 8.0 [6.0; 11.0], MBF = 11.0 [9.0; 15.0]; p-Value = 0.001). The breastfeeding adherence score showed a positive correlation with maternal perceived stress (first month: ρ = 0.27; p-Value = 0.018), and postpartum depression (third month: ρ = 0.30; p-Value < 0.001), and a negative correlation with maternal dispositional optimism (second month: ρ = −0.20; p-Value = 0.028). MBF was positively associated with breastfeeding adherence score (odd ratio (OR) = 1.4 [1.2–1.6]; p-Value < 0.001) and with postpartum depression (OR = 1.1 [1.0; 1.1]; p-Value = 0.020). In the third month of breastfeeding, women with MBF exhibited higher perceive stress and postpartum depression compared to those with EBF and no difference in dispositional optimism. The maternal psychological aspects are associated with breastfeeding pattern. Evaluation of maternal psychological concerns and providing support to lactating mothers may help improving breastfeeding adherence

Influence of Maternal Age and Gestational Age on Breast Milk Antioxidants During the First Month of Lactation

Breast milk (BM) is beneficial due to its content in a wide range of different antioxidants, particularly relevant for preterm infants, who are at higher risk of oxidative stress. We hypothesize that BM antioxidants are adapted to gestational age and are negatively influenced by maternal age. Fifty breastfeeding women from two hospitals (Madrid, Spain) provided BM samples at days 7, 14 and 28 of lactation to assess total antioxidant capacity (ABTS), thiol groups, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities, lipid peroxidation (malondialdehyde, MDA + 4-Hydroxy-Trans-2-Nonenal, HNE), protein oxidation (carbonyl groups) (spectrophotometry) and melatonin (ELISA). Mixed random-effects linear regression models were used to study the influence of maternal and gestational ages on BM antioxidants, adjusted by days of lactation. Regression models evidenced a negative association between maternal age and BM melatonin levels (β = −7.4 ± 2.5; p-value = 0.005); and a negative association between gestational age and BM total antioxidant capacity (β = −0.008 ± 0.003; p-value = 0.006), SOD activity (β = −0.002 ± 0.001; p-value = 0.043) and protein oxidation (β = −0.22 ± 0.07; p-value = 0.001). In conclusion, BM antioxidants are adapted to gestational age providing higher levels to infants with lower degree of maturation; maternal ageing has a negative influence on melatonin, a key antioxidant hormone