Smart systems related to polypeptide sequences

Increasing interest for the application of polypeptide-based smart systems in the biomedical field has developed due to the advantages given by the peptidic sequence. This is due to characteristics of these systems, which include: biocompatibility, potential control of degradation, capability to provide a rich repertoire of biologically specific interactions, feasibility to self-assemble, possibility to combine different functionalities, and capability to give an environmentally responsive behavior. Recently, applications concerning the development of these systems are receiving greater attention since a targeted and programmable release of drugs (e.g. anti-cancer agents) can be achieved. Block copolymers are discussed due to their capability to render differently assembled architectures. Hybrid systems based on silica nanoparticles are also discussed. In both cases, the selected systems must be able to undergo fast changes in properties like solubility, shape, and dissociation or swelling capabilities. This review is structured in different chapters which explain the most recent advances on smart systems depending on the stimuli to which they are sensitive. Amphiphilic block copolymers based on polyanionic or polycationic peptides are, for example, typically employed for obtaining pH-responsive systems. Elastin-like polypeptides are usually used as thermoresponsive polymers, but performance can be increased by using techniques which utilize layer-by-layer electrostatic self-assembly. This approach offers a great potential to create multilayered systems, including nanocapsules, with different functionality. Recent strategies developed to get redox-, magnetic-, ultrasound-, enzyme-, light-and electric-responsive systems are extensively discussed. Finally, some indications concerning the possibilities of multi-responsive systems are discussed.Postprint (published version

Temperature induced structural changes in even-odd nylons with long polymethylene segments

Structural transitions of nylons 8 9 and 12 9 heating and cooling processes were investigated using calorimetric, spectroscopic during and real time X-ray diffraction data. These even-odd nylons had three polymorphic forms related to structures where hydrogen bonds were established in two planar directions. Heating processes showed a first structural transition at low temperature where the two strong reflections related to the packing mode of the low temperature structure (form I) disappeared instead of moving together and merging into a single reflection, as observed for conventional even-even nylons. The high temperature structure corresponded to a typical pseudohexagonal packing (form III) attained after the named Brill transition temperature. Structural transitions were not completely reversible since an intermediate structure (form II) became clearly predominant at room temperature in subsequent cooling processes. A single spherulitic morphology with negative birefringence and a flat-on edge-on lamellar disposition was obtained when the two studied polyamides crystallized from the melt state. Kinetic analyses indicated that both nylons crystallized according to a single regime and a thermal nucleation. Results also pointed out a secondary nucleation constant for nylon 12 9 higher than that for nylon 8 9, suggesting greater difficulty in crystallizing when the amide content decreased. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2494–2506Peer ReviewedPostprint (author's final draft

Degradable Poly(ester amide)s for biomedical aplications

Poly(ester amide)s are an emerging group of biodegradable polymers that may cover both commodity and speciality applications. These polymers have ester and amide groups on their chemical structure which are of a degradable character and provide good thermal and mechanical properties. In this sense, the strong hydrogen‑bonding interactions between amide groups may counter some typical weaknesses of aliphatic polyesters like for example poly(e-caprolactone). Poly(ester amide)s can be prepared from different monomers and following different synthetic methodologies which lead to polymers with random, blocky and ordered microstructures. Properties like hydrophilic/hydrophobic ratio and biodegradability can easily be tuned. During the last decade a great effort has been made to get functionalized poly(ester amide)s by incorporation of a-amino acids with hydroxyl, carboxyl and amine pendant groups and also by incorporation of carbon-carbon double bonds in both the polymer main chain and the side groups. Specific applications of these materials in the biomedical field are just being developed and are reviewed in this work (e.g., controlled drug delivery systems, hydrogels, tissue engineering and other uses like adhesives and smart materials) together with the main families of functionalized poly(ester amide)s that have been developed to date.Peer ReviewedPostprint (published version

Biodegradable Poly(Ester Amide)s: Synthesis and Applications

Postprint (published version

Performance-enhancing materials in medical gloves

Medical gloves, along with masks and gowns, serve as the initial line of defense against potentially infectious microorganisms and hazardous substances in the health sector. During the COVID-19 pandemic, medical gloves played a significant role, as they were widely utilized throughout society in daily activities as a preventive measure. These products demonstrated their value as important personal protection equipment (PPE) and reaffirmed their relevance as infection prevention tools. This review describes the evolution of medical gloves since the discovery of vulcanization by Charles Goodyear in 1839, which fostered the development of this industry. Regarding the current market, a comparison of the main properties, benefits, and drawbacks of the most widespread types of sanitary gloves is presented. The most common gloves are produced from natural rubber (NR), polyisoprene (IR), acrylonitrile butadiene rubber (NBR), polychloroprene (CR), polyethylene (PE), and poly(vinyl chloride) (PVC). Furthermore, the environmental impacts of the conventional natural rubber glove manufacturing process and mitigation strategies, such as bioremediation and rubber recycling, are addressed. In order to create new medical gloves with improved properties, several biopolymers (e.g., poly(vinyl alcohol) and starch) and additives such as biodegradable fillers (e.g., cellulose and chitin), reinforcing fillers (e.g., silica and cellulose nanocrystals), and antimicrobial agents (e.g., biguanides and quaternary ammonium salts) have been evaluated. This paper covers these performance-enhancing materials and describes different innovative prototypes of gloves and coatings designed with them.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Electrospun biodegradable polymers loaded with bactericide agents

Development of materials with an antimicrobial activity is fundamental for different sectors, including medicine and health care, water and air treatment, and food packaging. Electrospinning is a versatile and economic technique that allows the incorporation of different natural, industrial, and clinical agents into a wide variety of polymers and blends in the form of micro/nanofibers. Furthermore, the technique is versatile since different constructs (e.g. those derived from single electrospinning, co-electrospinning, coaxial electrospinning, and miniemulsion electrospinning) can be obtained to influence the ability to load agents with different characteristics and stability and to modify the release behaviour. Furthermore, antimicrobial agents can be loaded during the electrospinning process or by a subsequent coating process. In order to the mitigate burst release effect, it is possible to encapsulate the selected drug into inorganic nanotubes and nanoparticles, as well as in organic cyclodextrine polysaccharides. In the same way, processes that involve covalent linkage of bactericide agents during surface treatment of electrospun samples may also be considered.; The present review is focused on more recent works concerning the electrospinning of antimicrobial polymers. These include chitosan and common biodegradable polymers with activity caused by the specific load of agents such as metal and metal oxide particles, quaternary ammonium compounds, hydantoin compounds, antibiotics, common organic bactericides, and bacteriophages.Peer ReviewedPostprint (published version

Análisis del Riesgo de sufrir Trastornos Alimentarios en jóvenes universitarios de Extremadura (España)

Eating disorders (ED), anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder are disorders of great concern in western world countries. Their rising tendencies have led researchers to try to explain the factors involved, their causes, and their effects, as a way of contributing to the efforts to stop the growing trends. Our research project focuses on the study of the risk of suffering ED amongst a sample of 600 students from the University of Extremadura (Spain). Said students are enrolled in twelve of the degrees offered by the University. The assessment tools used for the purposes of this research are the Eating Disorder Inventory-3 RF (EDI-3 RF) and the Spanish questionnaire, IMAGEN (Evaluation of Dissatisfaction with Body Image). The most significant results show the existence of a high percentage of students at risk of suffering ED. Young female students evidence higher rates of body dissatisfaction and drive for thinness than their male classmates who, conversely, demonstrate more characteristics of bulimia. Those studying education present higher rates of risk factors for suffering ED, such as the drive for thinness and their own body dissatisfaction, in the opposite situation are the health degrees in particular the nursing students, as a result of a greater bio health knowledge caused.Los Trastornos de la Alimentación (TA), la Anorexia Nerviosa (AN), Bulimia nerviosa (BN) y trastorno por atracón son trastornos de gran preocupación en el mundo occidental. Sus tendencias crecientes han llevado a los investigadores a tratar de explicar los factores implicados, sus causas y sus efectos, como una forma de contribuir a los esfuerzos para detener las tendencias de crecimiento.Nuestro proyecto de investigación se centra en el estudio del riesgo de padecer TA entre una muestra de 600 estudiantes de la Universidad de Extremadura (España). Dichos estudiantes están matriculados en doce de los grados ofertados por dicha Universidad.Los instrumentos de evaluación utilizados para los fines de esta investigación están el inventario-3 trastorno del RF (RF de EDI-3) y el cuestionario en español, IMAGEN (evaluación de la insatisfacción con la imagen corporal).Los resultados más significativos demuestran la existencia de un alto porcentaje de estudiantes en riesgo de sufrir TA. En las jóvenes alumnas se evidencia mayores tasas de insatisfacción corporal y de delgadez que sus compañeros masculinos que, por el contrario, demuestran más características de bulimia. Además quienes estudian grados de educación presentan tasas más altas de los factores de riesgo para sufrir tales como TC, la unidad de la delgadez y la insatisfacción de su propio cuerpo, en la situación opuesta se encuentran los grados de ciencias de la salud en particular los estudiantes de enfermería, probablemente como consecuencia de un mayor conocimiento biosanitario. &nbsp

Incorporation of biguanide compounds into poly(GL)-b-poly(GL-co-TMC-co-CL)-b-poly(GL) monofilament surgical sutures

A new biodegradable coating was developed for bioabsorbable monofilament sutures. Specifically, a random copolymer having 35 wt-% and 65 wt-% of lactide and trimethylene carbonate units showed appropriate flexibility, stickiness and degradation rate, as well as capability to produce a complete and uniform coating. Monofilament sutures of polyglycolide-b-poly(glycolide-co-trimethylene carbonate-co-e-caprolactone)-b-polyglycolide were loaded with chlorhexidine (CHX) and poly(hexamethylene biguanide) (PHMB) to explore the possibility to achieve antimicrobial activity without adverse cytotoxic effects. To this end, two processes based on single drug adsorption onto the suture surface and incorporation into the coating copolymer were used and subsequently evaluated. Although the second process could be considered more complex, clear benefits were observed in terms of drug loading efficiency, antimicrobial effect and even lack of cytotoxicity. In general, drugs could be loaded in an amount leading to a clear bacteriostatic effect for both Gram-negative and Gram-positive bacteria without causing significant cytotoxicity. Release profiles of PHMB and CHX were clearly different. Specifically, adsorption of the drug onto the fiber surface which prevented complete release was detected for PHMB. This polymer had advantages derived from its high molecular size, which hindered penetration into cells, thus resulting in lower cytotoxicity. Furthermore, bacterial growth kinetics measurements and bacterial adhesion assays showed greater effectiveness of this polymer.Peer ReviewedPostprint (author's final draft

PROCEDIMIENTO PARA LA ADMINISTRACIÓN DEL CAPITAL DE TRABAJO. CASO DE ESTUDIO

Procedimiento para la administración del capital de trabajo. Caso: Hotel N-H Krystal Laguna Villas & Resort, es de gran importancia, pues las decisiones de inversión a corto plazo tomadas por la entidad radica la mayor responsabilidad de su administración financiera. Tales disposiciones, cuando se relacionan con el corto plazo tendrían que ver con los niveles de inversión en activos circulantes, en otras palabras con su Capital de Trabajo, resulta una herramienta disponible en aras de contribuir al control y planificación de dichos recursos, por lo que contó con la aceptación por parte de la administración del negocio. La misma abarca fundamentos teóricos del Capital de Trabajo, características generales y específicas del sector turístico cubano. En su desarrollo se elaboró un procedimiento que permitió demostrar e identificar las fluctuaciones cíclicas del Capital de Trabajo de la entidad objeto de estudio en el período de fluctuación estacional. Esto permitió definir su repercusión en el modelo de cálculo del saldo óptimo de efectivo y a la vez precisó los niveles requeridos en ingresos y en algunos gastos relacionados con dicha estación cíclica. El procedimiento utilizado puede ser aplicado a cualquier entidad relacionada con la actividad turística que experimente fluctuaciones cíclicas y es aplicable a cualquier período deseado. Con esta investigación se abre un campo al perfeccionamiento de la financiación de los activos circulantes en entidades con fluctuaciones estaciónales

Improvement of biodegradability and biocompatibility of electrospun scaffolds of poly(butylene terephthalate) by incorporation of sebacate units

Incorporation of aliphatic units to poly(butylene terephthalate) (PBT) gives rise to biodegradable copolymers with tunable properties (e.g., degradability), depending on the selected comonomer and the specific composition. Specifically, a low molecular weight poly(butylene sebacate-co-terephthalate) (PBSeT) with a high ratio of aliphatic sebacate units (i.e., 70 mol-% with respect to the total dicarboxylate content) has been employed in this work to get new electrospun biodegradable scaffolds. Appropriate electrospinning conditions have been found despite the limited copolymer molecular weight. In addition, PBSeT has been employed to improve biocompatibility and biodegradability of scaffolds based on the PBT homopolymer. Scaffolds with different properties have been prepared following two strategies: Electrospinning of single solutions of PBT and PBSeT mixtures and co-electrospinning of independent PBT and PBSeT solutions. Characterization involved spectroscopic (FTIR, NMR), calorimetric (DSC, TGA) and surface hydrophobicity analyses. Hydrolytic and enzymatic degradation studies demonstrated the success of the approach due to the susceptibility of the PBSeT component towards the enzymatic attack with lipases from Pseudomonas cepacia and even towards high temperature hydrolysis.Peer ReviewedPostprint (author's final draft