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Seaweeds as Sustainable Sources for Food Packaging
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Y. S. M. Senarathna, I. Wickramasinghe, S. B. Navaratne
Agar is a red algal polysaccharide that is researched for applying in making packaging materials owing to its good film formation capability, thermoplasticity, moderate resistance for water and better transparency. However, the commercialization of agar-based films and coatings has become limited due to the lower mechanical properties, barrier properties, and thermal stability. Therefore, recent studies focus on improving its packaging properties by combining hydrophobic compounds, biopolymers and nanoparticles (Wang et al. 2018; Mostafavi and Zaeim 2020). Wongphan and Harnkarnsujarit (2020) suggested a composite formula by combining agar, starch and maltodextrin to control the water solubility of films. Based on the findings, incorporating agar has led to forming film matrices with enhanced solidity and gelation at lower temperatures that result in increased film-forming capability and hydrophobic nature. Moreover, agar has contributed to producing consistent film matrices in the starch network. Conversely, for the improvement of agar-based films, the incorporation of nano bacterial cellulose has been studied by Wang et al. (2018). According to the findings, the addition of nano bacterial cellulose could improve the film crystallinity, thermal stability and mechanical strength while decreasing the water solubility and water vapor permeability, revealing the applicability of developed film as a good material for food packaging. However, more scientific investigations should be conducted on using agar in making films and coatings to improve their mechanical, physical and barrier properties.
Genetics and Biosynthesis of Lipopolysaccharide O-Antigens
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Wendy J. Keenleyside, Chris Whitfield
The classic O-PS assembly system is the Wzy-dependent (formerly Rfc-dependent) pathway first described in Salmonella. This involves growth of the polymer at the reducing terminus by polymerization of individual repeat units en bloc. Polymerization occurs at the periplasmic face of the plasma membrane and follows export of the newly synthesized lipid-linked O units across the plasma membrane. In contrast, the ATP-binding cassette (ABC) transporter-dependent pathway (formerly the Rfe-dependent pathway) is distinguished by growth at the nonreducing terminus through the processive polymerization of nascent O-polysaccharide at the cytoplasmic face of the plasma membrane. After polymerization, nascent O-PS is exported across the plasma membrane by a process involving an ABC transporter. It is becoming increasingly apparent that the Wzy-dependent and ABC transporter-dependent pathways are widespread in bacteria. Similar systems have been reported for capsular and extracellular polysaccharides. To date, the newly described third pathway, the synthase-dependent pathway, has only been characterized for the 0:54 OPS of Salmonella, but it resembles the synthetic process for bacterial cellulose, chitin, and possibly certain streptococcal capsular polysaccharides. The critical feature of this pathway is a unique glycosyl transferase, which is proposed to catalyze a vectorial polymerization, sequentially adding monosaccharide substituents while simultaneously extruding the nascent polymer across the plasma membrane.
Catalog of Herbs
Published in James A. Duke, Handbook of Medicinal Herbs, 2018
Toxicity — Thorns from mesquite, on penetrating the eye, cause more inflammation than expected from the physical injury. The irritation may be due to waxes. Injection of cerotic acid is destructive to the eye.6 (Still Amerindians applied the leaves for conjunctivitis.) Using the wood in a fireplace has caused dermatitis, as has working with seasoned wood. The gum has irritant properties. Reports on cattle toxicity vary. Ingestion over long periods of time will result in death in cattle.11 The pollen may cause allergic rhinitis, bronchial asthma, and/or hypersensitivity pneumonitis.11 Kingsbury14 goes into some detail on mesquite poisoning in cattle, including cases where autopsies showed pods and seeds in the rumen 9 months after the cattle could have ingested them. Mesquite poisoning may induce a permanent impairment of the ability to digest cellulose.14 Felker and Bandurski275 also provide interesting detail. If Prosopis pods are the sole food source for cattle, circa 1% becomes sick, and some die with a compacted pod ball in the rumen. Death is attributed to high sugar content repressing the rumen-bacterial cellulose activity. Mesquite feeding to pigs was promising during the first 4 weeks, deteriorating thereafter, perhaps due to phytohemagglutinins and trypsin inhibition. Feeding trials with sheep show a 15% higher protein disgestibility coefficient for mesquite pods than for alfalfa hay. Trypsin inhibition has been demonstrated. Contains isorhamnetin 3-glucoside, apigenin, 6,8-diglycoside, and traces of quercitin 3’,3diOMe, leutolin 3’-OMe, and apigenin diglycoside.274 According to Morton, the gum is irritant and causes dermatitis in susceptible people. Flowers may cause respiratory irritation.42
Recent advancements in cellulose-based biomaterials for management of infected wounds
Published in Expert Opinion on Drug Delivery, 2021
Munira Momin, Varsha Mishra, Sankalp Gharat, Abdelwahab Omri
Cellulose acquired from vegetal origin is associated with residual hemicellulose, lignin, and pectin. Microbial or bacterial cellulose (BC) is a very unique biopolymer, mostly synthesized from Acetobacter xylinum, with several properties, which make it exceptionally valuable in the biomedical field [162]. The features that make it superior to plant-based cellulose are its high chemical purity, porosity, and permeability [163]. BC has many inherent properties making it an ideal scaffold for burns, tissue regeneration and as artificial skin [164]. The important characteristics are its nontoxicity, non-carcinogenicity, and biocompatibility. Moreover, it can absorb exudates from the wounds and accelerate granulation, making it a promising class of material for wound dressing [165,166]. The exceptional physical as well as mechanical properties of BC are attributed to its unique 3D structure, which is considerably different from the vegetal sources and BC aggregates to form elongated fibrils, which gives it a high surface area and more flexibility as compared to the plant-based cellulose. The fibers of BC are many folds thinner and smaller, making it highly porous Table 4 [167].
Novel chitosan and bacterial cellulose biocomposites tailored with polymeric nanoparticles for modern wound dressing development
Published in Drug Delivery, 2021
Paul-Octavian Stanescu, Ionut-Cristian Radu, Rebeca Leu Alexa, Ariana Hudita, Eugenia Tanasa, Jana Ghitman, Oana Stoian, Aristidis Tsatsakis, Octav Ginghina, Catalin Zaharia, Mikhail Shtilman, Yaroslav Mezhuev, Bianca Galateanu
Low molecular weight chitosan (50,000–190,000 Da) with a 75% percent of deacetylation, anhydrous calcium chloride, sodium hydroxide, polyvinyl alcohol (PVA) with 88% hydrolysis degree (88,000 Da), N-isopropylacrylamide (NIPAM), methyl oleate (MO), and potassium persulfate initiator were purchased from Sigma–Aldrich, 3050 Spruce Street, St. Louis, MO 63103, USA. Bacterial cellulose (BC) was provided by National Chemical-Pharmaceutical for Research and Development Institute, Bucharest, Romania. Silver sulfadiazine drug was purchased from ACROS Organics, New Jersey, USA.
Constructing artificial urinary conduits: current capabilities and future potential
Published in Expert Review of Medical Devices, 2019
Jan Adamowicz, Shane V. Van Breda, Tomasz Kloskowski, Kajetan Juszczak, Marta Pokrywczynska, Tomasz Drewa
The pioneering study of Drewa et al. sparked an idea for developing a tissue engineering approach to artificial conduit fabrication. Tubular shaped small intestinal submucosa was used as a conduit with both ureters anastomosed [20]. Seeding with 3T3 fibroblast cells was used to accelerate restoration of the ECM that was intended to support tubular configuration during changes of abdominal pressure. Due to the low SIS mechanical endurance, the biomaterial was rolled multiple times to obtain a flexible tubular construct without the tendency to collapse, hampering urine outflow. Strategies to artificial conduit fabrication have traditionally relied on applying biomaterials that closely mimic the native features of ECM in urinary tracts. In 2013 Liao et al. reported using tubular constructs made from bladder acellular matrix for urinary diversion after cystectomy in a rabbit model [27]. The critical point of the study is the 12 weeks long follow-up; the most extended experimentally reported settings using artificial urinary conduit fabrication. The authors did not detect obstruction in reconstructed urinary tracts by urography. Bio-nanotechnology routes were developed to produce entirely artificial biomaterials allowing for stable tubular structures to be adapted to an artificial urinary conduit. Bodin et al. generated a conduit from bacterial cellulose for use in urinary diversion, which was seeded with urothelial and smooth muscle cells [32]. Authors presented an attractive concept to utilize non-biodegradable scaffolds with a retained hollow structure to avoid wall kinking. Bacterial cellulose is an FDA approved biomaterial for medical use which is highly hydrophilic and causes little site fibrosis after implantation. Despite rational design, the conduit was not evaluated in the urinary tract environment; hence its potential advantages could not be confirmed. Obtaining a durable tubular structure is one the major challenge in artificial conduit construction. Multistep approaches for artificial conduit fabrication with a stable 3D structure was demonstrated by Fossum et al. Authors covered latex lumen tubes with previously harvested and minced bladder mucosa. Subsequently, the prepared grafts were implanted into the abdominal wall of subcutaneous fat for four weeks to generate an organized tubular conduit [42]. This was an intriguing concept with high translational potential to obtain a conduit built from autologous tissue.