Chitosan-TiO2: A Versatile Hybrid Composite Anaya-Esparza, Luis Miguel; Ruvalcaba-Gómez, José Martín; Maytorena-Verdugo, Claudia Ivette ...
Materials,
02/2020, Letnik:
13, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan–titanium dioxide (CS–TiO2) composites, which have interesting technological ...properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO2 nanoparticles. Their effects on structural, textural, thermal, optical, mechanical, and vapor barrier properties and their biodegradability are also discussed. Evidence shows that the incorporation of TiO2 onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS–TiO2 composite exhibits great potential applications including antimicrobial activity against bacteria and fungi; UV-barrier properties when it is used for packaging and textile purposes; environmental applications for removal of heavy metal ions and degradation of diverse water pollutants; biomedical applications as a wound-healing material, drug delivery system, or by the development of biosensors. Furthermore, no cytotoxic effects of CS–TiO2 have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS–TiO2 has also been used as an anti-corrosive material. However, the development of suitable protocols for CS–TiO2 composite preparation is mandatory for industrial-scale implementation.
The effect of 20% high degree polymerized agave fructans (HDPAF) on the induction of the defense system in avocado fruits was investigated by transcriptomic analysis at 1, 24 and 72 h after ...treatment, and the effect of HDPAF on respiration rate and ethylene production was also analyzed. Transcriptomic profiling revealed 5425 differentially expressed genes (DEGs), 55 of which were involved in the pathways related to plant defense response to pathogens. Key genes were associated with phenylpropanoid biosynthesis, mitogen-activated protein signaling, plant hormone signaling, calcium ion signal decoding, and pathogenesis-related proteins. Dysregulated genes involved in ethylene biosynthesis were also identified, and the reduction in ethylene production by HDPAF was corroborated by gas chromatography, where three days of delayed peak production was observed compared to that in water-treated fruits. These results help to understand the mechanism of induction of the avocado defense system by applying HDPAF and support the application of HDPAF as an efficient postharvest treatment to extend the shelf life of the fruit.
•Physicochemical and nutritional changes depended on maturity in all mango varieties.•IQF conserved a higher content of macro and micronutrients of mango cubes than TSF.•IQF is an excellent ...alternative to maintain the quality of mango at two ripening stages.
This research evaluated the physicochemical, nutritional and antioxidant changes of frozen cubes from four mango varieties (Tommy Atkins, Tommy Kent, Keitt, and Kent). The factors were the ripening stage (green-mature or GM and three-quarter or TQ) and freezing with the traditional slow freezing (TSF) or individual quick freezing (IQF). IQF mango cubes kept higher physicochemical, nutritional and antioxidant values (p < 0.05) than TSF mango cubes, depending on the ripening stage in each variety. IQF-GM mango cubes from all varieties exhibited the highest content of vitamin C, dietary fiber, minerals (Na, K, Ca, Mg, Cu, and Mn) and phenolic compounds, highlighting gallocatechin, gallic acid, epigallocatechin, and vanillic acid. In contrast, IQF-TQ mango cubes had the highest content of vitamin E, thiamine, riboflavin, niacin, and pyridoxine, as well as total carotenoids, including β-carotene, α-carotene, cryptoxanthin, zeaxanthin and lutein. This is the first report on changes in nutrients and antioxidants from frozen mango cubes with IQF, concluding that IQF is an excellent alternative to conserve nutrients and antioxidants of mango pulp in two ripening stages.
The postharvest application of high degree of polymerization agave fructans (HDPAF) was tested, evaluating anthracnose disease, defense-related enzyme activities, and quality attributes in avocado ...fruit. Application of a 20% HDPAF solution showed a reduction in anthracnose severity (60%) and incidence (34%) compared to the other concentrations evaluated and the water-treated control. Polyphenoloxidase activity increased 4.6 times more 24 h after treatment. In addition, peroxidase and phenylalanine ammonia-lyase enzyme activity was 4.34 and 1.7 times higher than the control at 0.5 h after treatment. HDPAF retrieves the deceleration of both firmness loss and physiological weight loss compared to the control. Regarding quality parameters such as color, pH, total soluble solids, and titratable acidity, no significant differences were observed between treatments compared to the control; therefore, these parameters were not negatively affected by HDPAF treatments, but a positive effect on the induction of the defense system is shown.
Fruit losses and wastage are mainly due to postharvest diseases; their control is reduced with pesticides. The excessive use of synthetic fungicides has caused harmful effects on human health and the ...environment, so it is therefore necessary to reduce their use. The development of new innocuous strategies has led to the use of compounds of natural or biological origin with the capacity to induce the plant defense system, which improves the fruit’s response against future pathogen attacks in addition to reducing the incidence of postharvest diseases. These compounds are known as “elicitors”. Although the use of molecular tools such as RT-qPCR or the measurement of the enzymatic activity of molecular markers makes it possible to determine the activation of the plant defense system in response to the application of an elicitor compound, in recent years, omics technologies such as the transcriptome, proteome, or metabolome have provided new and interesting information that helps to elucidate the molecular aspects involved in the activation of the plant defense system in response to the application of elicitors. This review summarizes recent advances in molecular aspects, highlighting the contribution of omics technologies to a better understanding of fruit defense mechanisms induced by different elicitors.
Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), also known as the fall armyworm, is an economically important and widespread polyphagous pest. Microorganisms associated to this insect during ...life cycle play important ecological roles. We report 3 metagenome-assembled bacterial genomes reconstructed from a metagenome dataset obtained from S. frugiperda larvae F3 3rd-instar reared using artificial diet under laboratory conditions. Genome data for Enterococcus casseliflavus indicated a genome length of 3,659,8333 bp and GC content of 42.54%. Genome data for E. mundtii indicated a genome length of 2,921,701 bp and GC content of 38.37%. Finally, genome data for Lactiplantibacillus plantarum indicated a genome length of 3,298,601 bp, GC content of 44.31%. Genome analysis allowed us to identify genus-specific protein families (PLFams), transporters and antibiotic resistance-related genes among others. DNA sequences were deposited in National Center for Biotechnology Information (https://www.ncbi.nlm.nih.gov/) as Bioproject accession PRJNA899064.
Biocontrol agents are an environmentally friendly alternative to chemical pesticides against phytopathogens. The effectiveness of metabolites produced by Bacillus atrophaeus B5 for controlling ...anthracnose produced by Colletotrichum gloeosporioides in harvested fruit and the possible action mechanisms have been studied. Avocado fruit treated with metabolites reduced 54% of anthracnose incidence and nearly 70% of the lesion than untreated fruit. The treatment enhanced the activities of peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase. Additionally, the transcription of PAL and EIN3-like genes related to defense were increased. These results suggest that metabolites produced by B. atrophaeus B5 enhance disease resistance against C. gloeosporioides in avocado fruit. In the fruit, the induced resistance is related to the priming of defense responses. Metabolites in the cell-free supernatant could also be a potential biological preservative for avocado protection.
The quality of tomato (Solanum esculentum L.) fruits is associated with their sensory characteristics and nutrient contents, among which are some secondary metabolites with biological activity. The ...aim of this study was to assess the effect of ultrasound (US) treatment on the quality and contents of polyphenols, lycopene and rutin in tomatoes after harvest. The application of US under controlled conditions of time and sonication amplitude (SA) induced a significant increase in polyphenol, lycopene and rutin contents in both the pulp and the skin of tomatoes at the beginning and end of the post-harvest evaluation period (0 and 6 days), standing out the 10 min 60% SA and 20 min 20% SA treatments. Additionally, with these treatments, no US effect was observed on the quality parameters (total soluble solids, titratable acidity, pH, firmness, and physiological weight loss). These results reveal that the US application to tomatoes is an attractive technology to increase the content of secondary metabolites in the fruit without affecting its quality.
Secondary metabolites play an important role in the avocado fruit defense system. Phenolic compounds are the main biosynthesized metabolites of this system response. Our objective in this ...investigation was to evaluate the induction of specific metabolic pathways using chitosan as an elicitor. Extracts obtained from avocado in intermediate and consumption maturity stages treated with chitosan exhibited an increase in antifungal activity, which caused inhibition of mycelial growth and a decrease in sporulation as well as spore germination of Colletotrichum gloeosporioides. Additionally, RNA from epicarp of the fruits treated and untreated with chitosan was obtained in order to evaluate the expression of genes related to phenylpropanoids and the antifungal compound 1-acetoxy-2-hydroxy-4-oxo-heneicosa-12,15-diene biosynthesis. An increased in gene expression of genes that participates in the phenylpropanoids route was observed during the stage of physiological fruit maturity, others genes such as Flavonol synthase (Fls), increased only in samples obtained from fruit treated with chitosan at consumption maturity. Our results reveal a new molecular mechanism where chitosan induces a specific accumulation of phenylpropanoids and antifungal diene; this partially explains avocado's resistance against fungal pathogens. Finally, we discuss the molecular connections between chitosan induction and gene expression to explain the biological events that orchestrate the resistance pathways in fruits.
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•Extract of fruits treated with chitosan showed a greater in vitro inhibition of C. gloesporoiodes.•Genes expression suggests that phenylpropanoid route is stimulated under chitosan treatment.•The expression of genes involved in the biosynthesis of persin increased considerably in chitosan treatments.•The avocado fruits treated with chitosan acquire resistance to fungal by the presence of persin with antifungal effect.
In recent years, a strong interest has emerged in polysaccharide-hybrid composites and their potential applications, which have interesting functional and technological properties. This review ...summarizes and discusses the reported advantages and limitations of the functionalization of conventional and nonconventional polysaccharides by adding TiO2 nanoparticles as a reinforcement agent. Their effects on the mechanical, thermal, and UV-barrier properties as well as their water-resistance are discussed. In general, the polysaccharide–TiO2 hybrid materials showed improved physicochemical properties in a TiO2 content-dependent response. It showed antimicrobial activity against bacteria (gram-negative and gram-positive), yeasts, and molds with enhanced UV-protective effects for food and non-food packaging purposes. The reported applications of functionalized polysaccharide–TiO2 composites include photocatalysts (dye removal from aqueous media and water purification), biomedical (wound-healing material, drug delivery systems, biosensor, and tissue engineering), food preservation (fruits and meat), cosmetics (sunscreen and bleaching tooth treatment), textile (cotton fabric self-cleaning), and dye-sensitized solar cells. Furthermore, the polysaccharide–TiO2 showed high biocompatibility without adverse effects on different cell lines, indicating that their use in food, pharmaceutical, and biomedical applications is safe. However, it is necessary to evaluate the structural changes promoted by the storage conditions (time and temperature) on the physicochemical properties of polysaccharide–TiO2 hybrid composites to guarantee their stability during a determined time.
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