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Abstract : Preliminary Study on the Biodegradability of Chitosan Films Emulsified with Palm Oils (Aracaceae) from the Brazilian Cerrado
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Abstract: Non-toxic products with distinguishable characteristics are desirable for use in the packaging sector. Biopolymers fit this criterion and can serve as vehicles for the addition of various compounds, such as enzymes, dyes, antioxidant agents, or monounsaturated fatty acids, to provide useful qualities to a product, such as biodegradability. A biopolymer obtained from fishing industry waste residues can be combined with fatty acids to form films and emulsions with different characteristics to be used in different drug production, packaging, and product protection. This study aimed to use a natural biopolymer, chitosan, in combination with oils from the Mauritia flexuosa L.f., (“buriti”) and Acrocomia aculeata (“macaúba”) species of palm trees to develop films that exhibit excellent biodegradability in soil. The degradation of chitosan films (CF), emulsified chitosan films with buriti oil (CFB), and emulsified chitosan films with macaúba oil (CFM) in soil was investigated, where the CFB samples showed the best protection against moisture and the largest weight reduction over 30, 60, and 90 day testing periods. Further studies are needed to test the practical application of these films, but the results of the CFB sample indicate that these chitosan films imbued with natural oils from the Mauritia flexuosa L.f. and Acrocomia aculeata species have great potential for use in the packaging sector. Keywords: Biopolymer, Soil, Palm oil, Packaging, Mauritia flexuosa L.f., Acrocomia aculeata. |
Abstract : A Review on the Physicochemical and Biological Aspects of the Chitosan Antifungal Activity in Agricultural Applications
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Abstract: The antifungal activity of the chitosan biopolymer has been extensively studied for several decades. However, the mechanisms of action associated with this process have not been fully clarified yet. To a large extent, this situation is due to the lack of systematization with which, in general terms, the subject has been approached. However, it seems to have begun to change in recent years with the appearance of several papers reviewing the accumulated knowledge on the beneficial effects shown by chitosan in agricultural applications and putting forward it in a more systematic mode. In this work, the most relevant mechanisms of action proposed for chitosan regarding its antifungal activity will be briefly presented, i.e., disruption and changes in the fungal plasma membrane, alteration of gene expression, inhibition of RNA and protein synthesis, Ca2+ channel blocker, to then address the main factors that influence this antifungal activity, observed mainly in studies focused on phytopathogenic species, which have been grouped into three main blocks: those related exclusively to the chitosan molecules, those associated to the fungal itself and those having to do with the environment where the processes take place. Additionally, a brief section addressing some possibilities on which future studies on this topic should focus is also included. Keywords: Action mode, Radial growth inhibition, Membrane disruption, Fungal chitosan, Development stage. |
Abstract : Interaction of Lipase with Lipid Model Systems
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Abstract: The aim of this work was to study the interaction of lipases (as an important biopolymer) with models of biomembranes based on the phospholipid and cholesterol. Lipases (triacylglycerolacyl hydrolases) are widely distributed enzymes and well-known by their hydrolytic activity. The study of the lipase interactions with lipid vesicles in aqueous dispersions is of fundamental and practical interest. The pure phosphatidylcholine from egg yolk (ePC) and cholesterol (Chol) were obtained from Sigma-Aldrich. Lipase was obtained from hog pancreas. Measurements of the current and equilibrium surface tension (ST and eST) values were carried out using a BPA-1P device and ADSA program. The particle sizes in the prepared colloidal solutions were determined by the method of dynamic light scattering. An addition of lipase led to some decrease both, of ST and eST for the samples of ePC:Chol (in the ratios from19:1 to 1:1). The mean particle diameter (MPD) and effective particle diameter (EPD) values for the samples of ePC:Chol changed drastically by lipase addition. The EPD/MPD ratios increased from 1.7 to 2.0, from 1.8 to 2.6, from 2.3 to 6.5, from 1.5 to 2.9 for the samples of ePC:Chol at the ratios of 19:1, 14:1, 9:1, 7:1, respectively by lipase concentration increase. This general tendency can be explained by strong interaction of lipase with lipid membrane that leads to the formation of the mixed particles ePC:Chol:lipase with more narrow particle size distribution as compared to the initial EPD/MPD ratio (for the ePC:Chol mixture without lipase) Keywords: Lipase, lipids, surface tension, particle size distribution. |
Abstract : Effect of Molybdenum Trioxide in the Behavior of Poly(vinyl alcohol) Nanocomposites Systems Focusing New Systems for Protection against COVID-19
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Abstract: The purpose of this work was to study the molecular dynamics, morphology, mechanical and thermal performance of nanomaterials formed by poly(vinyl alcohol) and molybdenum trioxide (PVA/MoO3) obtained through solution casting method, focusing new materials with therapeutic applications since the molybdenum trioxide exhibit an excellent antibacterial activity and could be a pathway to prevent viruses. The obtaining materials were characterized by conventional techniques as X-ray diffraction, thermogravimetric and dynamical-mechanical analysis. The unconventional low-field NMR relaxometry was used to evaluate the molecular dynamic and morphology of these systems. The results obtained showed that the MoO3 addition into PVA matrix promote an increase on the thermal stability at higher temperatures and a progressive increase on the rigidity of the PVA systems. Also changes in the molecular mobility of nanomaterials determined through the proton spin-lattice relaxation time showed that low proportion of molybdenum trioxide increased the intercalation of the poly(vinyl alcohol) chains between oxide lamellae while higher quantity of molybdenum trioxide caused an inverse effect on the oxide lamellae delamination. From those results the nanomaterials presented a mixed structural organization as intercalated and exfoliated morphologies. According to these first results, the nanocomposites obtained promise to be antimicrobial and antiviral agent to prevent COVID-19 and similar viruses. Keywords: COVID-19, molybdenum trioxide, PVA, nanocomposites, NMR relaxation. |
