Biomimetic miniaturized platform able to sustain arrays of liquid droplets for high-throughput combinatorial tests

The development of high-throughput and combinatorial technologies is helping to speed up research that is applicable in many areas of chemistry, engineering, and biology. A new model is proposed for flat devices for the high-throughput screening of accelerated evaluations of multiplexed processes and reactions taking place in aqueous-based environments. Superhydrophobic (SH) biomimetic surfaces based on the so-called lotus effect are produced, onto which arrays of micro-indentations allow the fixing of liquid droplets, based on the rose-petal effect. The developed platforms are able to sustain arrays of quasi-spherical microdroplets, allowing the isolation and confinement of different combinations of substances and living cells. Distinct compartmentalized physical, chemical, and biological processes may take place and be monitored in each droplet. The devices permit the addition/removal of liquid and mechanical stirring by adding magnetic microparticles into each droplet. By facing the chip downward, it is possible to produce arrays of cell spheroids developed by gravity in the suspended droplets, with the potential to be used as microtissues in drug screening tests.The authors acknowledge the financial support from the FCT- Fundacao para a Ciencia e para a Tecnologia through the Ph.D. grants with the references SFRH/BD/73119/2010, SFRH/BD/69529/2010 and SFRH/BD/61390/2009. We also acknowledge the financial support of FEDER through the program Operacional Factores de Competitividade COMPETE and from FCT - the Fundacao para a Ciencia e para a Tecnologia under the project PTDC/CTM-Bio/1814/2012

Effect of the ultrastructure of chitosan nanoparticles in colloidal stability, quorum quenching and antibacterial activities

We have fabricated two types of crosslinked chitosan-based nanoparticles (NPs), namely (1) ionically crosslinked with tripolyphosphate (TPP), designated as IC-NPs and (2) dually co-crosslinked (ionically and covalently with TPP and genipin, respectively) termed CC-NPs. The two types of NPs were physichochemically characterized by means of DLS-NIBS, synchrotron SAXS and M3-PALS (zeta potential). First, we found that covalent co-crosslinking of ionically pre-crosslinked nanoparticles yielded monodisperse CC-NPs in the size range of ∼200 nm, whereas the parental IC-NPs remained highly polydisperse. While both types of chitosan nanoparticles displayed a core-shell structure, as determined by synchrotron SAXS, only the structure of CC-NPs remained stable at long incubation times. This enhanced structural robustness of CC-NPs was likely responsible of their superior colloidal stability even in biological medium. Second, we explored the antimicrobial and quorum sensing inhibition activity of both types of nanoparticles. We found that CC-NPs had lower long-term toxicity than IC-NPs. In contrast, sub-lethal doses of IC-NPs consistently displayed higher levels of quorum quenching activity than CC-NPs. Thus, this work underscores the influence of the NP’s ultrastructure on their colloidal and biological properties. While the cellular and molecular mechanisms at play are yet to be fully elucidated, our results broaden the spectrum of use of chitosan-based nanobiomaterialsin the development of antibiotic-free approaches against Gram-negative pathogenic bacteria

Mapas conceptuales y redes semánticas como estrategias de aprendizaje en la asignatura de química para los alumnos de 2º de Bachillerato

Las estrategias de aprendizaje constituyen una de las líneas de investigación más importantes dentro de la Psicología de la Educación de los últimos años y engloban todo un conjunto de procedimientos y recursos cognitivos que los alumnos ponen en marcha para aprender. Entre las estrategias para la reorganización constructiva de la información se pueden distinguir los mapas conceptuales y redes semánticas que permiten una jerarquización y organización de los conceptos y palabras para una mejor comprensión por parte del alumno. El objetivo de investigación del presente trabajo consiste en analizar si el uso de dichas mapas conceptuales y redes semánticas en la asignatura de química de Bachillerato sirven para un aprendizaje más significativo. Se presenta una investigación que se realizó en una institución privada de educación de secundaria con un grupo de 36 estudiantes (20 chicas y 16 chicos) que cursan la asignatura de química en 2º de Bachillerato y su correspondiente profesor. Los resultados obtenidos muestran que los mapas conceptuales y redes semánticas generados por los alumnos ayudan a conseguir un aprendizaje más significativo para los alumnos de Bachillerato en la asignatura de química, por lo que se concluye que las estrategias utilizadas ayudan a una mejor comprensión, interés y aprendizaje de los conceptos en química

Wound Healing: Biologics, Skin Substitutes, Biomembranes and Scaffolds

This review will explore the latest advancements spanning several facets of wound healing, including biologics, skin substitutes, biomembranes and scaffolds