Evaluation of Bioactive Release Kinetics from Crosslinked Chitosan Films with Aloe Vera

Thermocompression was employed to prepare citric acid-crosslinked chitosan films with Aloe vera (AV) as bioactive compound. Films were easy to handle and mechanical properties did not change with the addition of AV up to 10 wt%, although both TS and EAB decreased for the films with 15 wt% AV, indicating that high AV contents would hinder intermolecular interactions among the formulation components. Maillard reaction occurred between chitosan and citric acid at the processing temperature used (115 °C), while physical interactions took place with AV, as shown by FTIR analysis. All films were insoluble but displayed hydration and limited swelling due to both physical and chemical interactions promoted by AV and citric acid, respectively. A slow AV release, governed by a Fickian diffusion controlled mechanism, and an increase of surface hydrophilicity, which favors cell adhesion, were observed.This research was funded by MCIU/AEI/FEDER, UE (RTI2018-097100-B-C22). Iratxe Zarandona thanks the Quality and Food Industry Department of the Basque Government for her fellowship (22-2018-00078

Chitosan Films Incorporated with Exopolysaccharides from Deep Seawater Alteromonas sp.

Two Alteromonas sp. strains isolated from deep seawater were grown to promote the production of exopolysaccharides (EPS, E611 and E805), which were incorporated into chitosan solutions to develop films. The combination of the major marine polysaccharides (chitosan and the isolated bacterial EPS) resulted in the formation of homogenous, transparent, colorless films, suggesting good compatibility between the two components of the film-forming formulation. With regards to optical properties, the films showed low values of gloss, in the range of 5–10 GU, indicating the formation of non-glossy and rough surfaces. In addition to the film surface, both showed hydrophobic character, with water contact angles higher than 100 º, regardless of EPS addition. Among the two EPS under analysis, chitosan films with E805 showed better mechanical performance, leading to resistant, flexible, easy to handle films.This research was funded by the Economic Development and Infrastructures Department of the Basque Government (grant number KK-2019/00076) and the Quality and Food Industry Department of the Basque Government (grant number 22-2018-00078)

Magnetically responsive chitosan-pectin films incorporating Fe3O4 nanoparticles with enhanced antimicrobial activity.

Chitosan-pectin films with iron oxide (Fe3O4) magnetic nanoparticles were prepared by solution casting in order to produce biopolymer based magnetically active materials. Infrared (FTIR) spectra indicated physical interactions between the matrix and nanoparticles, corroborated by differential scanning calorimetry (DSC) results. In addition, thermal characterization suggested that the interactions between chitosan, pectin and the nanoparticles resulted in a less compact structure, influencing the film mechanical properties. Regarding vibrating-sample magnetometry (VSM) and electrical analysis, chitosan-pectin films with Fe3O4 nanoparticles showed ferrimagnetic behavior, with an increase of the dielectric constant as the nanoparticle concentration increased. Furthermore, films displayed enhanced antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) bacteria. Therefore, chitosan-pectin films with Fe3O4 magnetic nanoparticles provide promising results for active and intelligent food packaging applications.Grant PID2021-124294OB-C22 funded by MCI/AEI10.13039/501100011033 and by “ERDF A way of making Europe”. Biomat group thanks the Basque Government for funding (IT1658-22) and I.Z. thanks the Basque Government for her fellowship (22-2018-00078). This work was also supported by the Portuguese Foundation for Science and Technology (FCT) under strategic funding UIDB/04650/2020, UID/FIS/04650/2021, project PTDC/FIS-MAC/28157/2017, and Investigator FCT Contracts 2020.02915.CEECIND (D.M.C) and 2020.04028.CEECIND (C.M.C.) funded by national funds through FCT and by the ERDF through the COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI). Thanks are also due to the Advanced Research Facilities (SGIker) from the UPV/EHU

Design of chitosan-based materials for food applications.

321 p.En la industria alimentaria se utilizan grandes cantidades de materiales no biodegradables y no renovables para el envasado de alimentos, y la gran mayoría son de un solo uso, lo que provoca problemas medioambientales, especialmente durante su eliminación. En este contexto, el quitosano, un polisacárido que se obtiene a partir de la extracción de los residuos biológicos de crustáceos, moluscos, hongos e insectos, es un material adecuado debido a su carácter natural, biodegradable y antimicrobiano, convirtiéndose en una materia prima alternativa para la producción de envases/recubrimientos sostenibles. En este contexto, el objetivo de esta tesis es desarrollar, por diferentes métodos de procesado, materiales basados en quitosano aditivados con bioactivos naturales que mejoran las propiedades del material destinado a aplicaciones alimentarias.El capítulo 1 de la tesis presenta una visión general de las películas y recubrimientos basados en quitosano para el envasado de alimentos. En este capítulo se explican los métodos de procesado y la adición de bioactivos naturales para el envasado activo e inteligente. En los tres capítulos siguientes, se analizan las películas de quitosano preparadas por el método de casting. En el capítulo 2 se utilizan como aditivos exopolisacáridos de bacterias extraídas de aguas profundas, evaluándose las propiedades fisicoquímicas, ópticas, de barrera y mecánicas para analizar la influencia de los exopolisacáridos en las propiedades funcionales de los films de quitosano. En el capítulo 3, se utilizan ciclodextrinas para encapsular 2-fenil etanol con el fin de evitar su volatilización. En el capítulo 4 se añade ácido gálico, que tiene propiedades antioxidantes y antimicrobianas, añadiendo así nuevas funcionalidades a la película de quitosano. Teniendo en cuenta los resultados del capítulo 4, y con la motivación de implementar los materiales en aplicaciones de envasado activo de alimentos, en el capítulo 5 se estudia la extensión de la vida útil de filetes de jurel con recubrimientos de quitosano con ácido gálico. En el capítulo 6, se lleva a cabo el desarrollo de películas de quitosano mediante moldeo por compresión, utilizando ácido cítrico como reticulante y Aloe vera como bioactivo. A continuación, en el capítulo 7, se utilizan geles de pectina-quitosano para preparar películas mediante impresión 3D, evaluándose previamente las propiedades reológicas del gel. Finalmente, en el capítulo 8 se preparan películas de quitosano con nanopartículas magnéticas de Fe3O4 y se analizan sus propiedades para el envasado inteligente de alimentos

Impaired motor cortical plasticity associated with cannabis use disorder in young adults

Maladaptive cortical plasticity has been described in individuals with heroin and methamphetamine addiction and may mediate other substance abuse disorders. It is unknown whether cannabis dependence in humans alters the capacity for induction of cortical plasticity. The aim of this study was to non‐invasively investigate cortical plasticity with transcranial magnetic stimulation in young adults who meet DSM‐5 criteria for cannabis use disorder (CUD). Thirty men (ages 20– 30) who used cannabis daily over the previous 6 months (15 diagnosed of CUD) and 15 demographically matched non‐users were enrolled in this study. All participants underwent two sessions of theta burst stimulation (TBS) in which either continuous TBS (cTBS; 600 pulses, 80% active motor threshold) or intermittent TBS (iTBS; 2‐s train of cTBS repeated every 10 s for a total of 190 s, 600 pulses) was applied over the primary motor cortex. The effects of these protocols were assessed by analysing the contralateral motor evoked potentials (MEPs). The relationships between cortical plasticity and problematic cannabis use, degree of dependence, and nicotine addiction were also investigated. Significant MEP inhibition after cTBS was observed in both cannabis users without CUD and non‐users, while this inhibition was not seen in cannabis users with CUD. Strikingly, less motor cortical plasticity was observed in subjects with severe problematic cannabis use. No significant differences between users and non‐users were found in the iTBS‐induced cortical plasticity measures. Our study provides the first evidence of maladaptive cortical plasticity associated with cannabis use disorder and problematic cannabis use in humans.This work was supported by the Instituto de Salud Carlos III‐Fondo Europeo de Desarrollo Regional (ISCIII‐FEDER) (PI14/01823, PI16/01575), the Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía (CVI‐02526, CTS‐7685), the Consejería de Salud y Bienestar Social de la Junta de Andalucía (PI‐0437‐2012, PI‐0471/2013), the Fundación Progreso y Salud (FPS 2014 PI‐0055‐2014), the Sociedad Andaluza de Neurología, the Fundación Alicia Koplowitz and the Fundación Mutua Madrileña. J.F.M.‐R. was supported by the “Sara Borrell” Programme from the Instituto de Salud Carlos III and the VI PPIT‐US from the University of Seville; P.A.d.T. was supported by the FPU programme of the Ministry of Education, Culture and Sport of Spain; and M.R.‐V. was supported by Grant BAE 09/90088