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 white snook (Centropomus viridis) is a species with great aquaculture potential, therefore, the present study aims two objectives; 1) to characterize digestive enzymatic activity during larval ...development and; 2) characterize the diversity and functionality of digestive enzymes in an early juvenile stage of C. viridis. On first feeding, larvae were 2.75 ± 0.09 mm total length and grew to 24.35 ± 4.35 mm after 42 days. The specific activity of acid proteases was detected with low activity from day 1 (Days after hatching, DAH) to day 21, and increased at 23 DAH, reaching maximum activity at 40 DAH. Meanwhile, digestive enzymatic activity of alkaline proteases was observed from hatching to day 40. From hatching until 40 DAH, the presence of alkaline proteases, trypsin, chymotrypsin, leucine aminopeptidase, α-amylase and lipase were detected with different activity patterns. Total and specific activity of digestive enzymes on juveniles showed higher activity of acid than alkaline proteases, while α-amylase had a higher activity than lipases. The maximum activity of acid proteases was observed at 40 °C and at pH 2.0, while digestive alkaline proteases showed maximum activity at 60 °C. α-amylases and lipases showed their maximum activities at 50 °C. The maximum alkaline protease and α-amylase activities were found at pH 7 to 9. The enzymatic activity of juvenile's acid proteases was highly inhibited by Pepstatin A (96%), however the activity of alkaline proteases incubated with PHEN, TLCK, SBTI, PMFS, and OVO showed reductions of 51.29, 30.16, 27.98, 27.26, and 24.68% respectively. Lipase activity was totally inhibited with Ebelactone B, and highly inhibited by Ebelactone A, Orlistat, 1% SDS, and PMFS (96.12, 77.16, 64.22, and 51.29%, respectively). Seven bands (102.6, 65.7, 58.9, 40.6, 27.4, 21.5, and 15.8 kDa) resolved by protein electrophoresis were detected with alkaline protease activity, identified as serine proteases and metalloproteases, and three bands (57, 43.9, and 32.6 kDa) with lipase-like activity were also identified. These results show that C. viridis ontogeny entails an indirect development of its digestive system with a functional stomach on day 23, and characterized by increases in pepsin activity. Indeed, white snook ontogeny shows a similar developmental trajectory to other carnivorous marine fish, showing a diversity of alkaline proteases that work in a wide range of pH and temperatures. Thus, the identification of these enzymes provides advantages to formulate white snook aqua-feeds.
•Alkaline digestive enzymes in C. viridis larvae are active since mouth opening.•C. viridis digestive system is complete since day 23.•Seven alkaline enzymes were identified as serine and metallo-proteases.•Three lipases-like and esterases and at least two isoforms of amylases were found.•C. viridis has a diverse enzymatic set, which is functional in a wide range of conditions.
Functionalization of polysaccharide-based packaging incorporating inorganic nanoparticles for food preservation is an active research area. This review summarizes the use of polysaccharide-based ...materials functionalized with inorganic nanoparticles (TiO2, ZnO, Ag, SiO2, Al2O3, Fe2O3, Zr, MgO, halloysite, and montmorillonite) to develop hybrid packaging for fruit, vegetables, meat (lamb, minced, pork, and poultry), mushrooms, cheese, eggs, and Ginkgo biloba seeds preservation. Their effects on quality parameters and shelf life are also discussed. In general, treated fruit, vegetables, mushrooms, and G. biloba seeds markedly increased their shelf life without significant changes in their sensory attributes, associated with a slowdown effect in the ripening process (respiration rate) due to the excellent gas exchange and barrier properties that effectively prevented dehydration, weight loss, enzymatic browning, microbial infections by spoilage and foodborne pathogenic bacteria, and mildew apparition in comparison with uncoated or polysaccharide-coated samples. Similarly, hybrid packaging showed protective effects to preserve meat products, cheese, and eggs by preventing microbial infections and lipid peroxidation, extending the food product’s shelf life without changes in their sensory attributes. According to the evidence, polysaccharide-hybrid packaging can preserve the quality parameters of different food products. However, further studies are needed to guarantee the safe implementation of these organic–inorganic packaging materials in the food industry.
Introduction: Morelet’s crocodile (Crocodylus moreletii) is a species distributed in the Mexican southeast and threatened due to multiple pressures. Objective: To characterize the digestive proteases ...in the acid phase (stomach) and alkaline phase (intestine) of three life stages of C. moreletii in captivity (hatchling, juvenile, and adult). Methods: Total alkaline and acid protease activities were quantified using casein and haemoglobin as substrates. Trypsin, chymotrypsin, leucine aminopeptidase, and elastase activities were quantified using synthetic substrates. Protease profiles were analysed by SDS-PAGE and Native-PAGE. Results: The specific activity of acid and alkaline proteases showed differences between the three stages, finding the highest activity in the juveniles. Trypsin, chymotrypsin, leucine aminopeptidase, and elastase activities were higher in hatchlings. There were differences in optimum pH and temperature of acid and alkaline proteases, trypsin, and leucine aminopeptidase between the three stages, demonstrating the diversification of the enzymes according to different stages, as well as the presence of specific isoforms in each stage of C. moreletii. The acid phase zymogram showed four bands with pepsin-like acid activity in the hatchling and juvenile crocodile, while in the adult only two of the four bands were detected. The alkaline zymogram showed that the hatchling had the highest number of activity bands compared to the other stages, corresponding to the high specific activity reported in the alkaline phase. Conclusions: Digestive proteases of Morelet’s crocodile differ in their biochemical characteristics and the number of proteases between hatchling, juvenile, and adult. This could help in the future design of balanced diets as well to the sustainable management and production of this species.
Chitosan-TiO 2 : A Versatile Hybrid Composite Anaya-Esparza, Luis Miguel; Ruvalcaba-Gómez, José Martín; Maytorena-Verdugo, Claudia Ivette ...
Materials,
2020-Feb-11, Letnik:
13, Številka:
4
Journal Article
Recenzirano
In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan-titanium dioxide (CS-TiO
) composites, which have interesting technological ...properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO
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 TiO
onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS-TiO
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-TiO
have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS-TiO
has also been used as an anti-corrosive material. However, the development of suitable protocols for CS-TiO
composite preparation is mandatory for industrial-scale implementation.
Cichlasoma dimerus
is a neotropical cichlid that has been used as a biological model for neuroendocrinology studies. However, its culture is problematic in terms of larval feeding to allow having ...enough fry quantity and quality. Larviculture requires full knowledge about the digestive system and nutrition; therefore, this study was intended to assess the digestive enzymes' changes at different ages during the early ontogeny. Acid protease activity was detectable from the first day after hatching (dah), increasing to its maximum peaks on 9 dah. In contrast, alkaline proteases had low activity in the first days of life but reached their maximum activity on 17 dah. Chymotrypsin, L-aminopeptidase, and carboxypeptidase A activities increased at 6 dah, while trypsin activity was first detected on 13 dah and reached its maximum activity on 17 dah. Lipase and α-amylase activity were detectable at low levels in the first days of life, but the activity fluctuated and reaching its maximum activity at 21 dah. Alkaline phosphatase continued to oscillate and had two maximum activity peaks, the first at 6 dah and the second at 19 dah. Zymograms of alkaline proteases on day 6 dah six revealed four activity bands with molecular weights from 16.1 to 77.7 kDa. On 13 dah, two more activity bands of 24.4 and 121.9 kDa were detected, having a total of six proteases. The enzymatic activity analyzes indicate the digestive system shows the low activity of some enzymes in the first days after hatching, registering significant increases on 6 dah and the maximum peaks of activities around at 17 dah. Therefore, we recommend replacing live food with dry feed and only providing dry feed after day 17 dah.
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