Efeito da aplicação de escória de siderurgia granulada em cana-soca junto com a adubação NPK.

FERTBIO 2010

An overview of the antimicrobial properties of lignocellulosic materials

Pathogenic microbes are a major source of health and environmental problems, mostly due to their easy proliferation on most surfaces. Currently, new classes of antimicrobial agents are under development to prevent microbial adhesion and biofilm formation. However, they are mostly from synthetic origin and present several disadvantages. The use of natural biopolymers such as cellulose, hemicellulose, and lignin, derived from lignocellulosic materials as antimicrobial agents has a promising potential. Lignocellulosic materials are one of the most abundant natural materials from renewable sources, and they present attractive characteristics, such as low density and biodegradability, are low-cost, high availability, and environmentally friendly. This review aims to provide new insights into the current usage and potential of lignocellulosic materials (biopolymer and fibers) as antimicrobial materials, highlighting their future application as a novel drug-free antimicrobial polymer.This research was partially funded through the project TERM RES Hub—Infraestrutura Científica para a Engenharia de Tecidos e Medicina Regenerativa, Refª Norte-01-0145-FEDER02219015, co-financed by the European Regional Development Fund (FEDER) through the North Regional Operational Programme (NORTE2020) and national funds, by the Portuguese Foundation for Science and Technology (FCT)

Copper adsorption as a function of solution parameters of variable charge soils

Effects of pH and ionic strength (I) on copper (Cu) adsorption and the driving force of the reaction in variable charge soils were evaluated from batch studies. Experimental results of Cu adsorption fitted Langmuir model. According to adsorption isotherms, Cu affinity (K L) was greater in the subsoil (0.061-0.468 L kg-1) than in the topsoil samples (0.169-0.359 L kg-1). Maximum adsorption (Ads max) ranged from 1114-2422 mg kg-1 (topsoil) to 1002-1334 mg kg-1 (subsoil). Strong dependence of Cu adsorption on the pH was observed in subsoil samples. Adsorption edges showed sharply increase of Cu adsorption (20-90%) in the 4.0-5.0 pH range. Copper adsorption changed with increase in I and indicated different metal retention mechanisms (outer- and inner-spheres). Adsorption reaction was favorable and spontaneous, as indicated by negative values of the free energy variation (&#916;G) and the separation factor K R < 1. Soil-solution interface and Cu adsorption were also thermodynamically described by a theoretical approach

Manufacturing and characterization of coatings from polyamide powders functionalized with nanosilica

Polyamide coatings are thermoplastics with great advantages such as a good corrosion protection of the base metal and wear resistance. Their application as powder coatings is an environmentally friendly option that is currently attracting growing interest. However, during their life service, they can sometimes be exposed to conditions that they are unable to stand. In this work, a polyamide 11 (PA11) powder was reinforced with different percentages of silica nanoparticles (1â 3 wt. %). Powder mixtures were prepared through extrusion followed by compression molding processes to manufacture coatings. For the coatings under study, the effect of 500 h xenon exposure was studied in order to know their ultraviolet (UV) resistance. Attenuated total reflection-Fourier transform infrared spectroscopy (FTIR-ATR) and differential scanning calorimetry (DSC) tests were performed to study changes in polymer structure and if they are affected by nanoparticles. The effect of nanoadditions and xenon exposure on hardness and stiffness were also evaluated. Furthermore, reciprocal wear tests were performed before and after irradiation, and the wear tracks were analyzed using optoelectronic microscopy and scanning electron microscopy (SEM). Finally, the aesthetic properties were measured. The results reveal improvements in mechanical and wear properties when 1% nanosilica is added to the PA11, which then become more relevant after xenon radiation exposure.This research was funded by Interreg SUDOE, through KrEaTive Habitat project (grant SOE1/P1/E0307

Effects of high fat diet on salivary alpha-amylase serum parameters and food consumption in rats

Salivary a-amylase, a major protein in saliva, has been described as a marker for sympathetic nervous system activity, hence for metabolic energy balance. In this context, its expression in overweight and obesity is of interest. Rats fed with a diet enriched with sunflower oil differentially gained weight yielding two subgroups according to their susceptibility (OP) or resistance (OR) to obesity. Elevated plasmatic levels of leptin in the OP subgroup and altered plasmatic lipid profiles (lower triglycerides and higher total choles- terol/HDL ratio compared to controls) in OR subgroup were observed. Animals from OP subgroup presented higher a-amylase expression and activity even prior to the dietary treatment, suggesting that this salivary protein may constitute a putative indicator of susceptibility for fat tissue accumulation. After 18 weeks of high-fat diet consumption, salivary a-amylase levels did not significantly changed in OP subgroup, but increased 3-fold in OR subgroup. The raise of a-amylase for the latter might represent an adaptation to lower starch intake. These results suggest that salivary a-amylase secretion might be useful to predict susceptibility for weight gain induced by high-fat diet consumption.This paper is funded by FEDER Funds through the Operational Programme for Competitiveness Factors-COMPETE and National Funds through FCT-Foundation for Science and Technology under the Strategic Projects PEst-C/AGR/UI01, PEst-OE/AGR/ UI0115/2014, 15/2011, PEst-C/SAU/LA0001/2011 and PEst-C/QUI/ UI0062/2011. Authors acknowledge also the financial support from the Portuguese Science Foundation (FCT) in the form of Post- Doctoral grant (SFRH/BPD/63240/2009) of Elsa Lamy. The Portu- guese Science Foundation (FCT) played no role in the develop- ment of the present work or upon its submission for publication

Variations in salivary function in a rodent model of pre-diabetes

Diabetes is a widespread disease representing an enormous part of the total health costs. An early diagnostic could be of extremely importance both for the understanding and prevention of this pathology. Saliva is a fluid with increasing interest as a source of biomarkers for disease diagnostic and saliva protein composition changes have already been reported for diabetic individuals. However, the studies were performed after the onset of the disease and it is unknown if salivary changes are present in the early stages of development of the disease or a characteristic of overt diabetes. Wistar rats have been selected for their glucose intolerance (GIR). GIR females were compared with Wistar females with normal glucose tolerance (control) for changes in saliva protein composition and salivary gland histology. Fasting glycemias were observed to be normal (<95 mg/dl) in GIR animals, indicating an absence of a diabetic state. However they presented an abnormal increase in glycemia after a glucose bolus. For salivary parameters a marked increase in total protein concentration and alpha-amylase activity occurred in GIR animals, comparatively to controls. After separation of salivary proteins by SDS PAGE differences between the experimental groups for some protein bands, with apparent molecular masses ranging from 20 to 55 kDa were observed. Different expression of alphaamylase at salivary gland duct level is also apparent for pre-diabetic animals. Although preliminary, these results suggest changes in saliva occurring before the onset of diabetes, reinforcing the interest of further investigation of saliva composition for the diagnostic of pre-diabetic condition, ultimately allowing an early intervention and eventually the prevention of disease development

Design and characterization of synthetic biodegradable films for musculoskeletal tissue engineering

To repair soft tissue, it is vital to ensure that the biomaterial is able to mimic the complex elasticity of the native tissue. It has been demonstrated that substrate stiffness has a huge influence on cellular growth, differentiation, motility and phenotype maintenance. The goal of the present study is to characterize extensively a set of polymeric films with variable mechanical profiles. A range of synthetic biodegradable polymers was selected according to the physico-chemical intrinsic properties of aliphatic polymers. They have similar chemistry (absorbable polyesters made from lactic acid, glycolic acid, trimethylene carbonate, dioxanone & β-caprolactone), however show different mechanical and degradation properties. The films were manufactured by thermal presser and then characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the films were assessed by uniaxial tensile tests in wet conditions and also by atomic force microscopy (AFM) to assess the material's stiffness at a micro-level. In vitro assays were performed to assess the cell cytocompatibility, proliferation and differentiation potential of the films. The mechanical properties of the materials are within the range intended for musculoskeletal tissue repair. Biological assays showed good cell adhesion, cell proliferation and cell viability. Stem cells were able to differentiate into adipogenic, osteogenic, chondrogenic and tenogenic lineages. Overall the selection of polymers gave good options for a potential tissue repair scaffold. In the future, the combined effect of stiffness and topography will be assessed on cell phenotype maintenance

Development and characterisation of cytocompatible polyester substrates with tunable mechanical properties and degradation rate

Although it has been repeatedly indicated the importance to develop implantable devices and cell culture substrates with tissue-specific rigidity, current commercially available products, in particular cell culture substrates, have rigidity values well above most tissues in the body. Herein, six resorbable polyester films were fabricated using compression moulding with a thermal presser into films with tailored stiffness by appropriately selecting the ratio of their building up monomers (e.g. lactide, glycolide, trimethylene carbonate, dioxanone, ε-caprolactone). Typical NMR and FTIR spectra were obtained, suggesting that the fabrication process did not have a negative effect on the conformation of the polymers. Surface roughness analysis revealed no apparent differences between the films as a function of polymer composition. Subject to polymer composition, polymeric films were obtained with glass transition temperatures from -52 °C to 61 °C; contact angles in water from 81 ° to 94 °; storage modulus from 108 MPa to 2,756 MPa and loss modulus from 8 MPa to 507 MPa (both in wet state, at 1 Hz frequency and at 37 °C); ultimate tensile strength from 8 MPa to 62 MPa, toughness from 23 MJ/m3 to 287 MJ/m3, strain at break from 3 % to 278 %, macro-scale Young's modulus from 110 MPa to 2,184 MPa (all in wet state); and nano-scale Young's modulus from 6 kPa to 15,019 kPa (in wet state). With respect to in vitro degradation in phosphate buffered saline at 37 °C, some polymeric films [e.g. poly(glycolide-lactide) 30 / 70] started degrading from day 7 (shortest timepoint assessed), whilst others [e.g. poly(glycolide-co-ε-caprolactone) 10 / 90] were more resilient to degradation up to day 21 (longest timepoint assessed). In vitro biological analysis using human dermal fibroblasts and a human monocyte cell line (THP-1) showed the potential of the polymeric films to support cell growth and controlled immune response. Evidently, the selected polymers exhibited properties suitable for a range of clinical indications.This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie, grant agreement no. 676338; the Widespread: Twinning, grant agreement no. 810850; and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme, grant agreement no. 866126. This work was also supported by Science Foundation Ireland, Career Development Award, grant agreement no. 15/CDA/3629 and Science Foundation Ireland/European Regional Development Fund, grant agreement no. 13/RC/2073. We would also like to thank Darlene Nebinger, Danielle Lord and Oswaldo Fabian from Medtronic North Haven, USA, for all their technical/experimental support

Chitosan/virgin-coconut-oil-based system enriched with cubosomes: a 3D drug-delivery approach

Emulsion-based systems that combine natural polymers with vegetable oils have been identified as a promising research avenue for developing structures with potential for biomedical applications. Herein, chitosan (CHT), a natural polymer, and virgin coconut oil (VCO), a resource obtained from coconut kernels, were combined to create an emulsion system. Phytantriol-based cubosomes encapsulating sodium diclofenac, an anti-inflammatory drug, were further dispersed into CHT/VCO- based emulsion. Then, the emulsions were frozen and freeze-dried to produce scaffolds. The scaffolds had a porous structure ranging from 20.4 to 73.4 µm, a high swelling ability (up to 900%) in PBS, and adequate stiffness, notably in the presence of cubosomes. Moreover, a well-sustained release of the entrapped diclofenac in the cubosomes into the CHT/VCO-based system, with an accumulated release of 45 ± 2%, was confirmed in PBS, compared to free diclofenac dispersed (80 ± 4%) into CHT/VCO-based structures. Overall, the present approach opens up new avenues for designing porous biomaterials for drug delivery through a sustainable pathway.The authors especially acknowledge the financial support from the Portuguese FCT (grants CEECIND/01306/2018, SFRH/BPD/93697/2013, and SFRH/BPD/85790/2012). This work was also financially supported by the FCT R&D&I project, with reference PTDC/BII-BIO/31570/2017, and the R&D&I Structured Projects, with reference NORTE-01-0145-FDER-000021. We also acknowledge the financial support from São Paulo Research Foundation (FAPESP) in Brasil through projects 2015/25406-5 and 2021/12071-6, and for the postdoctoral grant to D.G.V., 2019/12665-3. The project 2018/08045-7 is part of a bilateral agreement between FAPESP and the FCT (Portugal), involving the project Nature4Health