•Cell wall polysaccharide fractions were isolated from Chinese quince fruits.•Chelator-soluble pectins exhibited a high DPPH radical scavenging activity.•1 mol/L KOH soluble hemicelluloses showed a ...high reducing power.
To investigate the composition and structural characteristics of cell wall polysaccharides, three pectic fractions and two hemicellulose fractions, namely water-soluble pectin (WSP), chelator-soluble pectin (CSP), sodium carbonate-soluble pectin (NSP), 1 mol/L KOH soluble hemicellulose (KSH-1) and 4 mol/L KOH soluble hemicellulose (KSH-2), were isolated from Chinese quince fruits. The five fractions exhibited structural and compositional variation. The results showed NSP was the predominant cell wall polysaccharide fraction in the fruit. All pectic fractions had a low degree of esterification (31.7–42.4%). WSP fraction had the highest thermal stability among the five fractions. The polysaccharide chain lengths ranged from 19.4 nm to 121.4 nm. CSP had the highest molecular weight, giving it also the highest solution viscosity. NMR spectra revealed that NSP was composed of RG-I and galacturonic acid main chains, KSH-1 was composed of 1,4-β-D-Xylp backbone attached to 1,5-α-L-Araf units. Among the five fractions, CSP has the highest DPPH radical scavenging activity while KSH-1 has the highest reducing power. This study can contribute to the applications of Chinese quince fruit polysaccharides in food and pharmaceutical industries.
Photothermal treatment (PTT) involving a combination of therapeutic modalities recently emerged as an efficient alternative for combating biofilm. However, PTT-related local high temperature may ...destroy the surrounding healthy tissues. Herein, we present an all-in-one phototherapeutic nanoplatform consisting of l-arginine (l-Arg), indocyanine green (ICG), and mesoporous polydopamine (MPDA), namely, AI-MPDA, to eliminate the already-formed biofilm. The fabrication process included surface modification of MPDA with l-Arg and further adsorption of ICG
π-π stacking. Under near-infrared (NIR) exposure, AI-MPDA not only generated heat but also produced reactive oxygen species, causing a cascade catalysis of l-Arg to release nitric oxide (NO). Under NIR irradiation, biofilm elimination was attributed to the NO-enhanced photodynamic therapy and low-temperature PTT (≤45 °C). Notably, the NIR-triggered all-in-one strategy resulted in severe destruction of bacterial membranes. The phototherapeutic AI-MPDA also displayed good cytocompatibility. NIR-irradiated AI-MPDA nanoparticles not only prevented bacterial colonization but also realized a rapid recovery of infected wounds. More importantly, the all-in-one phototherapeutic platform displayed effective biofilm elimination with an efficiency of around 100% in a abscess formation model. Overall, this low-temperature phototherapeutic platform provides a reliable tool for combating already-formed biofilms in clinical applications.
A method for conjugation of ligands to the surface of exosomes was developed using click chemistry. Copper-catalyzed azide alkyne cycloaddition (click chemistry) is ideal for biocojugation of small ...molecules and macromolecules to the surface of exosomes, due to fast reaction times, high specificity, and compatibility in aqueous buffers. Exosomes cross-linked with alkyne groups using carbodiimide chemistry were conjugated to a model azide, azide-fluor 545. Conjugation had no effect on the size of exosomes, nor was there any change in the extent of exosome adherence/internalization with recipient cells, suggesting the reaction conditions were mild on exosome structure and function. We further investigated the extent of exosomal protein modification with alkyne groups. Using liposomes with surface alkyne groups of a similar size and concentration to exosomes, we estimated that approximately 1.5 alkyne groups were present for every 150 kDa of exosomal protein.
•An alternating filtration method has been developed to prepare sandwich-like composite paper for oil/water separation.•The addition of CNF improved significantly the emulsions’ separation ...efficiency.•The thiol-mediated in situ immobilization of Ag NPs on pulp fibers endowed excellent non-leaching property.•The resulting Ag-Pulp/CNF showed efficient emulsions’ separation and anti-bacterial property.
Bio-based membranes for emulsion separation are sustainable, low-cost, renewable, biodegradable, and nontoxic. Herein, an antibacterial sandwich-like composite paper was fabricated by a facile process using Ag nanoparticles (Ag NPs)-coated pulp fibers and cellulose nanofibrils (CNFs). The obtained Ag-Pulp/CNF composite paper was superhydrophilic, allowing a 96 % separation efficiency for various oil-in-water emulsions. This outstanding separation efficiency was maintained over 20 separation cycles. The composite paper also showed satisfactory separation performance for water-in-oil emulsions after modification to render the surface hydrophobic. The CNFs provided the composite a nanoscale pore, which rejected nearly 100 % of bacteria when used to filter bacteria-contaminated emulsions due to a physical barrier effect. Attributed to the intrinsic antibacterial capability of Ag NPs, the composite paper exhibited strong antibacterial performance against Escherichia coli. Thus, the composite paper that was mainly derived from sustainable pulp fibers exhibited potential performance for oil/water separation and water purification.
In the field of tissue engineering and regenerative medicine, hydrogels are used as biomaterials to support cell attachment and promote tissue regeneration due to their unique biomimetic ...characteristics. The use of natural-origin materials significantly influenced the origin and progress of the field due to their ability to mimic the native tissues' extracellular matrix and biocompatibility. However, the majority of these natural materials failed to provide satisfactory cues to guide cell differentiation toward the formation of new tissues. In addition, the integration of technological advances, such as 3D printing, microfluidics and nanotechnology, in tissue engineering has obsoleted the first generation of natural-origin hydrogels. During the last decade, a new generation of hydrogels has emerged to meet the specific tissue necessities, to be used with state-of-the-art techniques and to capitalize the intrinsic characteristics of natural-based materials. In this review, we briefly examine important hydrogel crosslinking mechanisms. Then, the latest developments in engineering natural-based hydrogels are investigated and major applications in the field of tissue engineering and regenerative medicine are highlighted. Finally, the current limitations, future challenges and opportunities in this field are discussed to encourage realistic developments for the clinical translation of tissue engineering strategies.
Bioorthogonal reactions are chemical reactions that neither interact with nor interfere with a biological system. The participating functional groups must be inert to biological moieties, must ...selectively reactive with each other under biocompatible conditions, and, for in vivo applications, must be nontoxic to cells and organisms. Additionally, it is helpful if one reactive group is small and therefore minimally perturbing of a biomolecule into which it has been introduced either chemically or biosynthetically. Examples from the past decade suggest that a promising strategy for bioorthogonal reaction development begins with an analysis of functional group and reactivity space outside those defined by Nature. Issues such as stability of reactants and products (particularly in water), kinetics, and unwanted side reactivity with biofunctionalities must be addressed, ideally guided by detailed mechanistic studies. Finally, the reaction must be tested in a variety of environments, escalating from aqueous media to biomolecule solutions to cultured cells and, for the most optimized transformations, to live organisms. Work in our laboratory led to the development of two bioorthogonal transformations that exploit the azide as a small, abiotic, and bioinert reaction partner: the Staudinger ligation and strain-promoted azide–alkyne cycloaddition. The Staudinger ligation is based on the classic Staudinger reduction of azides with triarylphosphines first reported in 1919. In the ligation reaction, the intermediate aza-ylide undergoes intramolecular reaction with an ester, forming an amide bond faster than aza-ylide hydrolysis would otherwise occur in water. The Staudinger ligation is highly selective and reliably forms its product in environs as demanding as live mice. However, the Staudinger ligation has some liabilities, such as the propensity of phosphine reagents to undergo air oxidation and the relatively slow kinetics of the reaction. The Staudinger ligation takes advantage of the electrophilicity of the azide; however, the azide can also participate in cycloaddition reactions. In 1961, Wittig and Krebs noted that the strained, cyclic alkyne cyclooctyne reacts violently when combined neat with phenyl azide, forming a triazole product by 1,3-dipolar cycloaddition. This observation stood in stark contrast to the slow kinetics associated with 1,3-dipolar cycloaddition of azides with unstrained, linear alkynes, the conventional Huisgen process. Notably, the reaction of azides with terminal alkynes can be accelerated dramatically by copper catalysis (this highly popular Cu-catalyzed azide–alkyne cycloaddition (CuAAC) is a quintessential “click” reaction). However, the copper catalysts are too cytotoxic for long-term exposure with live cells or organisms. Thus, for applications of bioorthogonal chemistry in living systems, we built upon Wittig and Krebs’ observation with the design of cyclooctyne reagents that react rapidly and selectively with biomolecule-associated azides. This strain-promoted azide–alkyne cycloaddition is often referred to as “Cu-free click chemistry”. Mechanistic and theoretical studies inspired the design of a series of cyclooctyne compounds bearing fluorine substituents, fused rings, and judiciously situated heteroatoms, with the goals of optimizing azide cycloaddition kinetics, stability, solubility, and pharmacokinetic properties. Cyclooctyne reagents have now been used for labeling azide-modified biomolecules on cultured cells and in live Caenorhabditis elegans, zebrafish, and mice. As this special issue testifies, the field of bioorthogonal chemistry is firmly established as a challenging frontier of reaction methodology and an important new instrument for biological discovery. The above reactions, as well as several newcomers with bioorthogonal attributes, have enabled the high-precision chemical modification of biomolecules in vitro, as well as real-time visualization of molecules and processes in cells and live organisms. The consequence is an impressive body of new knowledge and technology, amassed using a relatively small bioorthogonal reaction compendium. Expansion of this toolkit, an effort that is already well underway, is an important objective for chemists and biologists alike.
Rapid increase in use of fungicides for the agricultural and industrial purposes has marked the deterioration of water resources which ultimately affects the human life. Accordingly, various attempts ...have been made in the removal of these noxious compounds. In the same context, we are presenting biopolymers based nanohydrogel sheets; guar gum-crosslinked-Soya lecithin nanohydrogel sheets (GG-crosslinked-SY NHS) used for the effective removal of a fungicide; thiophanate methyl from aqueous solution. Guar gum and soya lecithin were employed as the biopolymers in the fabrication of nanohydrogel sheets due to their non- toxic nature, easy availability, cheapness and significant properties. Due to the presence of highly reactive functional groups onto the surface of GG-crosslinked-SY NHS, good adsorption results have been obtained. Maximum adsorption capacity of 59.205mg/g was observed with 20mg GG-crosslinked-SY NHS and 25ppm thiophanate methyl solution concentration as calculated from the Langmuir isotherm. Results showed that neutral pH favoured the adsorption process. Kinetics results were indicative of the physical interactions between the thiophanate methyl and GG-crosslinked-SY NHS surface. Thermodynamic results have shown the spontaneous and endothermic adsorption process.
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•GG-crosslinked-SY nanohydrogel sheets prepared via facile greener microwave method•GG-crosslinked-SY NHS was used as an adsorbent for removal of thiophanate methyl.•The adsorption capacity was found to be 59.205mg/g.•H bonding and π-π interactions mainly governed between GG-crosslinked-SY NHS and thiophanate methyl
•Physicochemical and structural modification of starch depended on its type and annealing method.•Annealing could reduce the molecular weight of wheat starch.•Repeated annealing exhibited its ...superiority in improving crystal order of normal wheat starch.•Repeated annealing was more effective in increasing molecule interaction of starch.
Effects of repeated annealing treatments (8 cycles, 12 h each) or continuous annealing treatments (12–96 h) at 50 °C on structural, physicochemical, and digestive properties of normal and waxy wheat starches were investigated. Wheat starches retained the original crystalline structure of A-type after annealing. Annealing treatments increased crystallinity, short chain of amylopectin, viscosity, and gelatinization temperatures of starch. However, molecular weight, long chain of amylopectin, solubility, and swelling power of starch decreased after annealing. Additionally, annealing reduced the in vitro digestibility of wheat starches. The changes in properties of starch varied depending on starch type, normal or waxy, and annealing methods, repeated or continuous. The repeated annealing was found to be more effective in modification of normal wheat starch properties. However, continuous annealing efficiently modified properties of the waxy wheat starch. The obtained results may help in choosing appropriate applications of annealed wheat starches in the food industry.
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