High Grafting Degree Research Articles

Cyclic Continuous Glycation Enhanced Dispersibility of Myofibrillar Protein: Reaction Efficiency and Sites Modification.

Reaction efficiency in glycation lacks sufficient attention, leading to the waste of process costs. Cyclic continuous glycation (CCG) is an effective approach to accelerate covalent binding between myofibrillar protein (MP) and glucose. This study elucidated that CCG promoted the exposure of reactive glycated sites in MP with full unfolding of secondary and tertiary structures. Notably, the glycation rate was significantly increased by 65.43%. Physicochemical properties indicated that MP-glucose conjugates with high graft degree exhibited favorable solubility, dispersibility, and thermal stability. Furthermore, proteomics was applied to reveal the glycated sites and products in glycoconjugates of MP. Glycation preferentially acted on the tails of the myosin heavy chain. The glucosylation modification on the head region was enhanced by CCG contributing to the inhibition of the head-head interaction. Overall, this study systematically clarifies the mechanism of CCG, providing a theoretical basis for the application of glycation in innovative meat products.

Improved stability of sesame paste by peanut protein-flaxseed gum conjugation

The oil-water separation phenomenon in sesame paste poses a challenge for the storage of sauce products. In this study, soy protein isolate (SPI), peanut protein isolate (PPI) and flaxseed gum (FG) conjugates were prepared to stabilize the solid-liquid phases of sesame paste. The results indicated that the highest degree of grafting (25.07%) was observed in a ratio of PPI:FG = 4:1 (PF2). The interaction between proteins and FG generated the extension of the protein molecule and increased structural disorder. PPI-FG conjugates exhibited the lower surface hydrophobicity and higher thermal stability. The addition of 4% PF2 to sesame paste led to a reduction of 5.06% oil separation rate and showed higher storage modulus (G′), loss modulus (G″), apparent viscosity, and hardness. A stable and continuous three-dimensional network was created to physically entrap the oil, resulting in a more uniform distribution of oil droplets and a reduced particle interaction of sesame paste.

Nanocomplex of (−)-epigallocatechin-3-gallate and glycated ovalbumin based on natural deep eutectic solvents: Binding analysis and functional improvement

Natural deep eutectic solvents (NADES) are considered an efficient reaction medium for the production of glycated proteins. By optimizing the Maillard reaction conditions through response surface analysis, a glycation product (GOVA) of ovalbumin (OVA) with high grafting degree (92.2%) was prepared in choline chloride/glucose NADES. The binding information of (−)-epigallocatechin-3-gallate (EGCG) to OVA/GOVA was acquired by fluorescence spectroscopy and molecular docking. The interaction strength of GOVA + EGCG was higher than that of OVA + EGCG. Hydrogen bonding and van der Waals forces were the major driving forces in the binding process. Glycation and EGCG binding reduced the surface hydrophobicity, α-helix content and digestibility of OVA. Compared with OVA, the particle sizes of GOVA and GOVA + EGCG were increased by 54.8% and 87.7%, respectively. In addition, glycation increased the emulsifying activity index and foaming capacity of OVA by 32.6% and 20.0%, respectively, which was further increased in the presence of EGCG. The encapsulation of OVA, especially GOVA, improved the antioxidant activity, stability and bioaccessibility of EGCG. The results suggest that the glycated proteins based on NADES may provide an effective alternative for the protection and transport of bioactive ingredients in the food industries.

Revolutionizing CO2 reduction with TiO2 photocatalyst immobilized on polytetrafluoroethylene (PTFE) membrane

Slurry photocatalyst reactor is difficult to use on large scale and requires additional process to separate the catalyst. Thus, immobilizing photocatalyst titanium dioxide (TiO2) onto support ensures that the material would not be flushed away. In this study, polytetrafluoroethylene (PTFE) membranes’ surfaces were modified by grafting with carboxylic acid, wherein TiO2 was subsequently immobilized. High grafting degree of 8.5 % was achieved through wet chemistry method using 30 wt% acetic acid, at 60 °C via immersion for 2 hours. TiO2 was successfully immobilized onto the membrane (with amount of 11.32 wt%), and its presence was confirmed through FESEM-EDX. The leaching test for the first 24 hours shows less than 10 wt% was leached out; however, 59 % of the TiO2 had leached out after 4 days of the leaching test. Performance test with immobilized TiO2 shows methanol was produced from the photocatalytic CO2 reduction. Additionally, the PTFE-TiO2 membranes exhibit good reusability even after 5 cycles of use.

Biomass-based Tanning Agent for Sustainable Leather Manufacture via Cyanuric Chloride Modified Chitooligosaccharide

Developing alternative tanning agents to avoid the potential environmental and human health risks from the conventional chrome tanning is essential for the leather industry. In this work, we prepared an eco-friendly biomass-based tanning agent dichlorotriazinyl chitooligosaccharide (DTCS) by modifying chitooligosaccharide (COS) with cyanuric chloride (CC) for chrome-free leather manufacture. The synthesis of such biomass-based tanning agent was systematically optimized to obtain the target product with high grafting degree of 67% and weight-average molecular weight (Mw) of 1465 g/mol. The non-pickling tanning procedure using DTCS was investigated, and the interactions between DTCS and collagen fibers were studied. Our results showed that the hydrothermal stability of the tanned leather was significantly increased, i.e., the shrinkage temperature (Ts) exceeding 82.0°C, and the mechanical properties were improved. Moreover, the organoleptic properties of leather (e.g., fullness, softness and grain tightness) exhibited obvious improvement. This research not only offers a reliable approach for cleaner leather manufacturing while addressing the underlying ecological pressure, but also highlights the emerging use of biomass materials in the leather industry.

Effect of various reducing sugars on the structural and gelling properties of grafted myofibrillar proteins

With increasing concern about sodium-based additives, technical modifications of the protein structure have been studied. In the Maillard reaction, native proteins can be grafted with reducing sugars. The effect of reducing sugars on the structural characteristics of myofibrils and the technical properties of myofibrils grafted with various reducing sugars were determined. The highest degree of grafting was observed in the dextrose and palatinose, whereas the lowest degree of browning was observed in dextrose and lactose, followed by palatinose. However, protein solubility and surface hydrophobicity decreased after glycation with reducing sugars with the exception of dextrose due to decrease in reaction cite. The thermal stability of grafted myofibrils was improved and the highest value was observed in lactose and palatinose. Although the cooking loss of dextrose increased, the grafted myofibrils had a high water holding capacity. In the emulsifying capacity, only palatinose treatment had a similar value to the control, and the other treatments had a lower value than control. In conclusion, palatinose may have good structural characteristics when grafted with myofibrils.

Designing Strong, Tough, Fluorescent, and UV-Shielding PLA Materials by Incorporating a Phenolic Compound-Based Multifunctional Modifier.

The realization of high stiffness, high extensibility, and multi-functions for polylactic acid (PLA) is a vital issue for its practical applications. Herein, hydroxyalkylated tannin acid (mTA), a phenolic compound-based modifier with plentiful flat aromatic structures and flexible isopropanol oligomers, is designed and fabricated to act as the multifunctional modifier for PLA. The mTA exhibits the capability of emitting fluorescence and blocking UV light due to the combination of flat aromatic structures and plentiful flexible chains. Besides, mTA with high grafting degree (h-mTA) shows an excellent compatibility to PLA due to the hydrogen bonding interface and the high affinity of grafted isopropanol oligomers to PLA. As a result, the as-prepared PLA/h-mTA20 composite exhibits a strikingly improved extensibility by 61.2 times while maintaining the high yield strength of PLA. Moreover, PLA/h-mTA can serve as a fluorescent material with multi-mode responsiveness as well as a UV-shielding material with high transparency. We envision that this work opens a novel yet facile way to prepare a strong, tough, and multifunctional PLA material with expanded application scopes and will promote the practical applications of phenolic compounds in polymers.

PH-Responsive Water-Soluble Chitosan Amphiphilic Core–Shell Nanoparticles: Radiation-Assisted Green Synthesis and Drug-Controlled Release Studies

This work aims to apply water radiolysis-mediated green synthesis of amphiphilic core-shell water-soluble chitosan nanoparticles (WCS NPs) via free radical graft copolymerization in an aqueous solution using irradiation. Robust grafting poly(ethylene glycol) monomethacrylate (PEGMA) comb-like brushes were established onto WCS NPs modified with hydrophobic deoxycholic acid (DC) using two aqueous solution systems, i.e., pure water and water/ethanol. The degree of grafting (DG) of the robust grafted poly(PEGMA) segments was varied from 0 to ~250% by varying radiation-absorbed doses from 0 to 30 kGy. Using reactive WCS NPs as a water-soluble polymeric template, a high amount of DC conjugation and a high degree of poly(PEGMA) grafted segments brought about high moieties of hydrophobic DC and a high DG of the poly(PEGMA) hydrophilic functions; meanwhile, the water solubility and NP dispersion were also markedly improved. The DC-WCS-PG building block was excellently self-assembled into the core-shell nanoarchitecture. The DC-WCS-PG NPs efficiently encapsulated water-insoluble anticancer and antifungal drugs, i.e., paclitaxel (PTX) and berberine (BBR) (~360 mg/g). The DC-WCS-PG NPs met the role of controlled release with a pH-responsive function due to WCS compartments, and they showed a steady state for maintaining drugs for up to >10 days. The DC-WCS-PG NPs prolonged the inhibition capacity of BBR against the growth of S. ampelinum for 30 days. In vitro cytotoxicity results of the PTX-loaded DC-WCS-PG NPs with human breast cancer cells and human skin fibroblast cells proved the role of the DC-WCS-PG NPs as a promising nanoplatform for controlling drug release and reducing the side effects of the drugs on normal cells.

Formation of Supramolecular Gels from Host–Guest Interactions between PEGylated Chitosan andα‐Cyclodextrin

AbstractChitosan‐based hydrogels are prepared via the formation of polypseudorotaxanes (PPR), by selectively threadingα‐cyclodextrin (α‐CD) macrocycles onto polymeric chains, which, through the formation of microcrystalline domains, act as junction points for the network. Specifically, host–guest inclusion complexes are formed betweenα‐CD and PEGylated chitosan (PEG‐Ch), resulting in the formation of supramolecular gels. PEG‐grafted chitosan is obtained with a reaction yield of 79.8%, a high degree of grafting (50.9% GW) and water solubility (≈16 mg mL−1), as assessed by turbidimetry. A range of compositions for mixtures of PEG‐Ch solutions (0.2–0.8% w/w) andα‐CD solutions (2−12% w/w, or 0.04–0.2% mol) are studied. Regardless of PEG content, gels are not formed at lowα‐CD concentrations (<4%). Dynamic rheology measurements reveal stiff gels (G’ above 15k) and a narrow linear viscoelastic region, reflecting their brittleness. The highest elastic modulus is obtained for a hydrogel composition of 0.4% PEG‐Ch and 6%α‐CD. Steady‐state measurements, cycling between low and high shear rates, confirm the thixotropic nature of the gels, demonstrating their capacity to fully recover their mechanical properties after being exposed to high stress, making them good candidates to use as in‐situ gel‐forming materials for drug delivery to topical or parenteral sites.

Preparation and Properties of Graft-Modified Bagasse Cellulose/Polylactic Acid Composites

ABSTRACT Fiber reinforcement is the most common method for modifying polylactic acid (PLA). However, poor compatibility between fibers and PLA, especially at high cellulose contents, can promote cellulose agglomeration in the continuous phase, which damages the mechanical properties of composite materials. To address these issues, bagasse cellulose (BC) was used as a substrate and bifunctional glycidyl methacrylate (GMA) was used as a reactive monomer for graft modification. GMA-modified BC (BC-GMA)/PLA composite materials with different particle sizes were prepared using a blending grafting method, and the influence of the type and content of BC-GMA on the mechanical properties of the composite materials was explored. During the grafting modification of BC, a longer reaction time was found to result in smaller BC particles and a higher degree of grafting. For BC-GMA, the degree of grafting reached 27.02% with a maximum thermal decomposition temperature of 359.31°C. Furthermore, the BC-GMA/PLA composite material had a greater relative crystallinity of PLA, indicating that BC-GMA was evenly dispersed in the continuous phase. This study demonstrates that grafting modification can successfully achieve high cellulose loading in composite materials and thus reduce the production costs of PLA-based packaging materials.

Synchronous construction of high sulfonic acid grafting degree and large surface area in conjugated microporous polymer adsorbents for efficient removal of uranium (VI)

Functionalization and specific surface area (BET) are two decisive factors for conjugated microporous polymers (CMPs) as an effective uranium adsorbent, but it remains challenging to simultaneously achieve high degree of functionalization and large BET in a CMP. Herein, we innovatively adopt an ingenious molecular engineering strategy to synchronously construct high sulfonic acid grafting degree and large BET in an adsorbent. The PePy containing the pyrene-based monomer with extended π-conjugation degree and high rigidity has narrow energy band and rigid skeleton, which leads to PePy-SO3H holding a higher degree of sulfonic acid grafting while maintaining a satisfactory BET. Astonishedly, the PePy-SO3H adsorben exhibits strong affinity toward uranium with the distribution coefficient of 2.3 × 104 mL g−1 and an exceptionally high adsorption capacity of 579.0 mg g−1. This work highlights the advantages of molecular engineering strategies in optimizing the purification performance of CMPs adsorbents for uranium-containing wastewater.

Preparation of high-solubility rice protein using an ultrasound-assisted glycation reaction

To date, the poor solubility of rice protein (RP) has limited its industrial application in food products. This study aimed to prepare high-solubility RP conjugates using ultrasound-assisted glycation between RP and dextran. The conditions of glycation, treatment at 82 °C for 22 min under 600 W ultrasonic power, were optimized using single-factor experiments and response surface analysis. The solubility of the conjugates reached 90.6 %. Compared with traditional wet-heating glycation, ultrasound-assisted treatment brought more high-molecular-weight components, higher degree of graft, and less contents of arginine and lysine, indicating that ultrasound accelerated the glycation reaction. Ultrasound also resulted in a looser and more flexible structure of RP, manifesting in a 10 % reduction in β-sheets and 10.6 % increase in random coils of conjugates. The analysis of fluorescence and surface hydrophobicity indicated that ultrasound increased the exposure of hydrophobic residues towards aqueous environment. Besides solubility, the foaming and emulsifying properties of RP were improved through conformational changes. In summary, ultrasound-assisted glycation was found to be an efficient and green method for preparing high-solubility RP conjugates.

Functional Properties and Preservative Effect of P-Hydroxybenzoic Acid Grafted Chitosan Films on Fresh-Cut Jackfruit.

In the present study, p-hydroxybenzoic acid-grafted chitosan (PA-g-CS) conjugates with different grafting degrees were synthesized by a free radical-regulated grafting approach. The conjugates were further developed into films by casting, and their characteristics and preservative effects on fresh-cut jackfruit were evaluated. Compared to the CS film, the PA-g-CS film showed comprehensive performance improvements, including enhancements of water solubility, anti-ultraviolet capacity, antioxidation, and antibacterial activity. Moreover, compared with CS film, some appreciable and favorable changes of physical properties were observed in the PA-g-CS films, which included water vapor permeability, oxygen permeability, surface morphology, moisture content, and mechanical intensity. Furthermore, compared to CS alone, the application of PA-g-CS films to fresh-cut jackfruit exerted a beneficial effect on the quality of products, as indicated by the inhibition of weight loss, softening, and membrane damage, the maintenance of soluble solids and ascorbic acids contents, as well as a reduced bacterial count and a higher sensory score. Among these PA-g-CS films, the best preservation effect was achieved with the highest degree of grafting (PA-g-CS III). The results suggested that the PA-g-CS film has the potential to be explored as a new type of packaging material for the preservation of fresh-cut fruits and vegetables.

Structure and Properties of PVDF/PA6 Blends Compatibilized by Ionic Liquid-Grafted PA6.

Compatibilization of immiscible blends is critically important for developing high-performance polymer materials. In this work, an ionic liquid, 1-vinyl-3-butyl imidazole chloride, grafted polyamide 6 (PA6-g-IL(Cl)) with a quasi-block structure was used as a compatibilizer for an immiscible poly(vinylidene fluoride) (PVDF)/PA6 blend. The effects of two PA6-g-IL(Cl)s (E-2%-50K and E-8%-50K) on the morphology, crystallization behavior, mechanical properties, and surface resistance of the PVDF/PA6 blend were investigated systematically. It was found that the two types of PA6-g-IL(Cl)s had a favorable compatibilization effect on the PVDF/PA6 blend. Specifically, the morphology of the PVDF/PA6 = 60/40 blend transformed from a typical sea-island into a bicontinuous structure after incorporating E-8%-50K with a high degree of grafting (DG). In addition, the tensile strength of the PVDF/PA6/E-8%-50K blend reached 66 MPa, which is higher than that of PVDF, PA6 and the PVDF/PA6 blend. Moreover, the PVDF/PA6/E-8%-50K blend exhibited surface conductivity due to the conductive path offered by the bicontinuous structure and conductive ions offered by grafted IL(Cl). Differential scanning calorimetry (DSC) and wide-angle X-ray diffractometry (WAXD) results revealed that PA6-g-IL(Cl) exhibits different effects on the crystallization behavior of PVDF and PA6. The compatibilization mechanism was concluded to be based on the fact that the nongrafted PA6 blocks entangled with the PA6 chains, while the ionic liquid-grafted PA6 blocks interacted with the PVDF chains. This work offers a new strategy for the compatibilization of immiscible polymer blends.

Synchronous Construction of High Sulfonic Acid Grafting Degree and Large Surface Area in Conjugated Microporous Polymer Adsorbents for Efficient Removal of Uranium (Vi)

Synchronous Construction of High Sulfonic Acid Grafting Degree and Large Surface Area in Conjugated Microporous Polymer Adsorbents for Efficient Removal of Uranium (Vi)

Effect of carbohydrate type on the structural and functional properties of Maillard-reacted black bean protein.

Protein from black beans (Phaseolus vulgaris L.) has good solubility, emulsification, and antioxidant properties, with significant potential applications in the food industry. Maillard-reaction-mediated dry-heat glycosylation is a relatively safe modification method to improve the functional properties of black bean protein (BBP). Here, Maillard-reacted conjugates were prepared by applying 24-h dry-heating to induce a reaction between BBP and one of three carbohydrates (dextran, chitosan, and sodium alginate) at 70°C and 79% relative humidity. The resulting Maillard conjugates were designated as BBP-Dex, BBP-Ch, and BBP-SA, respectively. The formation of each Maillard conjugate was characterized by analyzing the grafting degree, free sulfhydryl (SH) groups content, and surface hydrophobicity, as well as the results of Fourier-transform infrared (FTIR) spectroscopy and fluorescence spectroscopy. The FTIR and fluorescence spectroscopy results provided information on the formation of the Maillard conjugates. The BBP-SA conjugate had a higher grafting degree and SH group content than the other two conjugates. The solubility, emulsifying properties, and antioxidant properties of the BBP were significantly improved after the Maillard reaction (p<0.05). Moreover, the physicochemical and functional properties of the conjugates were superior to those of the BBP-carbohydrate mixtures, indicating that covalent interactions may be stronger than noncovalent interactions. This study provides theoretical guidance for future research on protein-carbohydrate conjugates. PRACTICAL APPLICATION: This study has great potential applications in the development of new multi-functional food ingredients and the realization of functional factor homeostasis, and provides scientific and theoretical bases for the application of protein-carbohydrate conjugate in the field of functional food.

Structure and functional properties of watermelon seed protein-glucose conjugates prepared by different methods

Watermelon seed protein (WSP)-glucose conjugates were prepared by wet-heating (WH), microwave pretreatment assisted wet-heating (MWH), and ultrasonic pretreatment assisted wet-heating (UWH) methods. The effects of these methods on the structure and functional properties of WSP-glucose conjugates were investigated. Compared with WH groups, the conjugates prepared with UWH and MWH had higher grafting degree (DG).fluorescence intensity and lower content of α-helix, β-sheet structure. In addition, the conjugates prepared with UWH and MWH methods showed better solubility, foaming properties, emulsifying properties, thermal stability and antioxidant activities, which may be due to the structural changes of the conjugates. These results indicated that UWH and MWH may be effective methods for improving the functional properties of WSP-glucose conjugates.

Improving pea protein functionality by combining high-pressure homogenization with an ultrasound-assisted Maillard reaction

The functionality of many plant proteins is limited by their poor solubility characteristics. In this study, a combination of high-pressure homogenization and an ultrasound-assisted Maillard reaction were used to improve the functionality of pea protein isolate (PPI) by conjugating it with xylo-oligosaccharides (XOS). The reaction conditions with high grafting degree of PPI for producing these conjugateswere established: XOS:PPI=3:1, wt%;ultrasound power = 400 W; reaction time = 20 min; and treatment temperature = 70°C. Homogenization of the PPI solution (three times, 80 MPa) prior to the ultrasound-assisted Maillard reaction increased the grafting degree of the conjugates. In addition,the combined treatment promoted the partial unfolding of the pea proteins, increased their thermal stability, and enhanced their in vitro antioxidant activity. It also improved the solubility of PPI from pH 3 to 10, as well as its emulsifying and foaming properties. Moreover, the conjugates fabricated using the combined treatment produced emulsions containing smaller and more dispersive oil droplets that were more resistant to oxidation. This research shows that a combination of high-pressure homogenization and an ultrasound-assisted Maillard reaction can improve a variety of functional properties of pea proteins, which will be beneficial for the development of various kinds of plant-based foods in the food industry.

The Effect of Variation of Raw Material Ratio on Hydrogel Based on K-Carrageean - Acrylamide as a Carrier of Ammonium Nitrate Fertilizer

Hydrogels based on natural polymers such as carrageenan are currently being developed to improve efficiency in agriculture. By enriching hydrogels with fertilizers, they will be released slowly into the soil. Enrichment of fertilizers on carrageenan-based hydrogels was carried out and analyzed with the response of swelling ability, gel fraction value of grafting degree, to the hydrogel's ability to release the fertilizer trapped in it. Carrageenan is used because its use as a natural polymer has not been widely explored, especially in the non-food sector. The results showed that the average swelling value of carrageenan-based hydrogel to ammonium nitrate solution ranged from 750.00% - 1,633.33%. The gel fraction values obtained ranged from 74.06% to 87.51%, and the degree of grafting ranged from 85.33% to 93.59%. These values indicate a relatively high degree of tissue density and grafting of acrylamide monomer on carrageenan, which means that the carrageenan:AAm based hydrogel has strong mechanical properties. The ability to release ammonium nitrate samples from the hydrogel carrageenan-based has a value ranging from 8.86% to 44.92% in five days of observation. Interpretation of the test results, the best ratio of carrageenan:AAm is 1:1, due to its relatively low release value but still has good swelling and mechanical properties.Keywords: Hydrogel; Carrageenan; Acrilamyde; Fertilizer release

Combining ‘grafting to’ and ‘grafting from’ to synthesize comb-like NCC-g-PLA as a macromolecular modifying agent of PLA

The surface modification of nano particles is very important in nanotechnology. Grafting from (GF) and grafting to (GT) are two main methods to prepare surface modified nanoparticles like nanocellulose crystalline (NCC) grafted with polylactic acid (PLA) chains. In the GF method, the NCC can get high grafting degree but short side chains to improve its compatibility with the polymer matrix. The GT method can help obtain long side chains to increase the chain entanglements but owns low grafting density. To take the advantage of both methods, a mixed modification method combining GT and GF methods was put forward to synthesize comb-like NCC-g-PLA (NP) as a macromolecular modifying agent of PLA. Firstly, GT Method was used to obtain long side-chain NP to improve chain entanglement. Secondly, the GF method was applied to obtain NP-g-PLA (NPL) and NP-g-PDLA (NPD) with additional short side chains to improve its dispersion and compatibility in the PLA matrix. The products showed an enhanced nucleation effect, the degree of crystallinity (Xc ) of PLA composites increased almost four times with only 1 wt% NPD or NPL. What’s more, the storage modulus and loss modulus of the composite melts also increased with 1 wt% NPL or NPD. The NPD/PLA shows a higher effect than NPL/PLA owning to stronger interaction originated from the stereocomplex (SC) network of PLA matrix with PDLA short chains in NPD.