Effects of secondary cross-linking on the physicochemical properties of sodium alginate-hydrogel and in vitro release of anthocyanins.

To enhance the physicochemical properties and extend the release duration of sodium alginate (SA) hydrogels, this study explored the impact of acidifier type and the number of cross-linking on the physicochemical characteristics and in vitro anthocyanin release from SA hydrogels, utilizing calcium carbonate as the cross-linking agent. The findings revealed that the utilization of gluconolactone (GDL) as an acidifying agent in the preparation of SA hydrogels, as opposed to hydrochloric acid, resulted in a deceleration of the hydrolysis process of calcium carbonate. This deceleration led to the strengthening of hydrogen-bonding interactions and the development of a more compact network structure within the SA hydrogels. Consequently, there was a noticeable enhancement in the hardness, relaxation time, and anthocyanin encapsulation efficiency of the gels. Additionally, the release of anthocyanins in simulated intestinal fluid was delayed. Secondary cross-linking was found to facilitate ionic interactions between SA and Ca2+, further intensifying the denseness of the network structure and enhancing the physicochemical characteristics of the SA hydrogels. Overall, SA hydrogels processed with GDL as the acidifier and subjected to secondary cross-linking exhibited improved physicochemical properties, delayed release effects, and proved to be an efficient system for the delayed release of anthocyanins.

Flavonoid-rich sesame leaf extract-mediated synthesis of nanozymes: Extraction optimization, chemical composition identification and bioactivity evaluation.

Sesame leaves contain rich phenolic acids and flavonoids. However, their potential in nanozyme synthesis has not been investigated yet. Herein, we report the preparation of flavonoid-rich sesame leaf extract (SLE), composition identification, and its use in the construction of iron (Fe)-based nanozymes (Fe-SLE CPNs). SLE was obtained with an extraction yield of ∼14.5% with a total flavonoid content (TFC) of ∼850.85 mg RE/g. There were 83 flavonoid compounds in SLE, primarily including scutellarin, apigenin-7-glucuronid, narcissin, and hyperoside. Fe-SLE CPNs exhibited nanodot morphology with a hydrodynamic size of 79.34 nm and good stability in various physiological solutions, pH levels, and temperatures. The Fe-SLE CPNs were more efficient in the scavenging ability of reactive oxygen species (ROS) than SLE alone. Furthermore, a stronger anti-inflammatory effect of the Fe-SLE CPNs was shown by modulating the MyD88-NF-κB-MAPK signaling pathways. These findings imply that SLE-based nanozymes hold great potential for diverse applications.

Improving the biological activities of astaxanthin using targeted delivery systems.

The antioxidant and anti-inflammatory properties of astaxanthin (AST) enable it to protect against oxidative stress-related and inflammatory diseases with a range of biological effects. These activities provide the potential to develop healthier food products. Therefore, it would be beneficial to design delivery systems for AST to overcome its low stability, control its release, and/or improve its bioavailability. This review discusses the basis for AST's various biological activities and the factors limiting these activities, including stability, solubility, and bioavailability. It also discusses the different systems available for the targeted delivery of AST and their applications in enhancing the biological activity of AST. These include systems that are candidates for preventive and therapeutic effects, which include nerves, liver, and skin, particularly for possible cancer reduction. Targeted delivery of AST to specific regions of the gastrointestinal tract, or more selectively to target tissues and cells, can be achieved using targeted delivery systems to increase the biological activities of AST.

Controlled Nutrient Delivery through a pH-Responsive Wood Vehicle.

To lower the risk of disease and improve health, many nutrients benefit from intestinal-targeted delivery. Here, we present a nutrient-delivery system based on a pH-responsive "wood scroll", in which nutrients are stored, protected, and controllably released through the rolled structure and natural microchannels of a flexible wood substrate, thus ensuring higher bioactivity as well as prolonged steady release of the nutrient load to the intestine. We loaded the wood's natural microchannels with probiotics as a proof-of-concept demonstration. The probiotic-loaded wood scrolls can survive the simulated conditions of the stomach with a high survival rate (95.40%) and exhibit prolonged release (8 h) of the probiotic load at a constant release rate (4.17 × 108 CFUs/h) in the simulated conditions of the intestine. Moreover, by modifying the macroscopic geometry and microstructures of the wood scrolls, both the nutrient loading and release behaviors can be tuned over a wide range for customized or personalized nutrient management. The wood scrolls can also deliver other types of nutrients, as we demonstrate for tea polyphenols and rapeseed oil. This wood scroll design illustrates a promising structurally controlled strategy for the delivery of enteric nutrients using readily available, low-cost, and biocompatible biomass materials that have a naturally porous structure for nutrient storage, protection, and controlled release.

Fabrication of highly porous, functional cellulose-based microspheres for potential enzyme carriers.

Here, we present highly porous, cellulose-based microspheres using (2,2,6,6-tetramethylpiperidine-1-oxyl) TEMPO-oxidized cellulose fibers (TOCFs) as starting materials. The TOCFs were first dissolved in a NaOH/urea solvent and transformed into microspheres via an emulsification method. The carboxyl groups on the surface of TOCFs were successfully carried on the cellulose-based microspheres, which provides them numerous reacting or binding sites, allowing them to be easily functionalized or immobilized with biomolecules for multi-functional applications. Furthermore, the introduction of magnetic nanoparticles awards these microspheres magnetic properties, allowing them to be attracted by a magnetic field. As a proof of concept, we demonstrate the application of using these carboxylate cellulose-based microspheres for enzyme immobilization. The cellulose-based microspheres can successfully create stable covalent bonds with enzymes after the activation of carboxyl groups. The enhanced pH tolerance, thermal stability, convenient recovery, and reusability position the emulsified microspheres as promising carriers for enzyme immobilization.

Wet-spun nanoTiO2/chitosan nanocomposite fibers as efficient and retrievable absorbent for the removal of free fatty acids from edible oil.

Here we propose a wet-spinning assembly approach to continuously spin nanoTiO2/chitosan (CS) nanocomposite fibers, which are used directly as absorbents to remove free fatty acids (FFA) from edible oils. The morphology of nanoTiO2 and nanoTiO2/CS nanocomposite fibers was observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The structure of the fibers was studied by Fourier transform infrared spectroscopy (FTIR), and wide angel X-ray diffractometry (WAXD). Moreover, the mechanical property, thermal stability, and antibacterial activity of the fibers were evaluated. These fibers were used for the deacidification of rice bran oil and the acid value of the oil was found decreased from 4.53 ± 0.15 to 1.07 ± 0.06 mg KOH/g within 5 h with a 10 wt % load at 50 ℃. The combination of wet-spinning technology and excellent performance of nanoTiO2/CS nanocomposite fibers paves the way to eco-friendly and sustainable material for FFA removal.

A multiple signal amplified colorimetric aptasensor for antibiotics measurement using DNAzyme labeled Fe-MIL-88-Pt as novel peroxidase mimic tags and CSDP target-triggered cycles.

An ultrasensitive colorimetric aptasensor was developed for antibiotics detection, with chloramphenicol (CAP) as model target, using DNAzyme labeled Fe-MIL-88-Pt as novel peroxidase mimic signal tags and target-triggered circular strand-displacement polymerization (CSDP) for signal amplification. The system consists of two components which can partially hybridize with each other: one is capture probe which was formed through immobilizing hairpin DNA containing aptamer sequence on magnetic beads (MB-cDNA), another is signal tag which was constructed through labeling single strand DNAzyme (G-quadruplex/Hemin) which can partially hybrid with cDNA on platinum nanoparticles functionalized Fe-MIL-88 (MIL-88-Pt-DNAzyme). All components of MIL-88, Pt and DNAzyme in the tag can act as peroxidase mimic to triply catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 into a blue-colored oxidized TMB (oxTMB) for the colorimetric readout. Thus distinctive signal can be observed by naked eye even in presence of 0.02 nM tags. In the presence of target and primer, cDNA loop can open to form cDNA/CAP intermediates, enabling primer to hybridize with the exposed sequences of the cDNA, which initiated target assisted CSDP recycles. Then numerous signal tags were released into supernatant to catalyze TMB for color development. There was a liner relationship between the absorbance and the concentration of CAP in the range of 0.1 pM (0.0323 pg/mL) to 1000 pM (323 pg/mL) with the detection limit of 0.03 pM (0.0097 pg/mL). The ultra-high sensitivity was ascribed to the multiplex catalytic activities from the tags and CSDP based signal amplification. Furthermore, this method can produce signals being observed by naked eye to facilitate in-situ detection and be further extended to detect other antibiotics in food just by simply replacing cDNA on the sensing system.

Fabrication of cellulose nanowhiskers reinforced chitosan-xylan nanocomposite films with antibacterial and antioxidant activities.

Antibacterial and antioxidant chitosan-xylan/cellulose nanowhiskers (CNW) nanocomposite films were successfully prepared using CNW as nanofillers. The structure and morphology of the nanocomposite films were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The optical transmittance, thermal stability, mechanical property, and swelling property of the nanocomposite films were also evaluated. These results revealed the microstructure of the films and confirmed the good miscibility between chitosan-xylan and CNW. The improvements of tensile strength and elongation at break of the nanocomposite films confirmed the reinforcement effects of CNW. Moreover, the inhibitory effects against S. aureus and E. coli and the ABTS+ scavenging activity indicated antibacterial and antioxidant functions of the nanocomposite films. In this work, the prepared chitosan-xylan/CNW nanocomposite films, combined the antibacterial property of chitosan, the antioxidant property of xylan, and good mechanical property of CNW, could be potentially applied in food and health-related areas.

Cellulose-Based Composite Macrogels from Cellulose Fiber and Cellulose Nanofiber as Intestine Delivery Vehicles for Probiotics.

Cellulose-based composite macrogels made by cellulose fiber/cellulose nanofiber (CCNM) were used as an intestine delivery vehicle for probiotics. Cellulose nanofiber (CNF) was prepared by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation system, and the carboxyl groups in CNF acted as pore size and pH responsibility regulators in CCNMs to regulate the probiotics loading and controlled release property. The macrogel presented a porosity of 92.68% with a CNF content of 90%, and the corresponding released viable Lactobacillus plantarum (L. plantarum) was up to 2.68 × 108 cfu/mL. The porous structure and high porosity benefited L. plantarum cells to infiltrate into the core of macrogels. In addition, the macrogels made with high contents of CNF showed sustainable release of L. plantarum cells and delivered enough viable cells to the desired region of intestine tracts. The porous cellulose macrogels prepared by a green and environmental friendly method show potential in the application of fabricating targeted delivery vehicles of bioactive agents.

Development of poly (lactic acid) microspheres and their potential application in Pickering emulsions stabilization.

The aim of the present work was to study the feasibility of fabricating poly (lactic acid) (PLA) microspheres stabilized Pickering emulsions. For this purpose, the PLA microspheres were first prepared by oil-water emulsion solvent evaporation method. The effects of preparation conditions such as hydrophilic-lipophilic balance (HLB) value, emulsifier concentration, oil-water ratio and preparation temperature were evaluated by using optical microscopy. Besides, orthogonal experiments were designed to investigate the influence of preparation parameters on average diameter and uniformity, include stirring time, stirring speed, and PLA and polyvinyl alcohol (PVA) concentrations. Based on the analysis of orthogonal experimental results, an optimal level of parameters was defined for the fabrication of PLA microspheres. Furthermore, these microspheres were applied to the stabilization of Pickering emulsions, and the optimal Pickering emulsion with uniform microstructure was obtained through the adjustment of PLA microspheres concentrations. This study opens up a promising way for producing PLA microspheres stabilized Pickering emulsions.

Mimicking an Enzyme-Based Colorimetric Aptasensor for Antibiotic Residue Detection in Milk Combining Magnetic Loop-DNA Probes and CHA-Assisted Target Recycling Amplification.

A mimicking-enzyme-based colorimetric aptasensor was developed for the detection of kanamycin (KANA) in milk using magnetic loop-DNA-NMOF-Pt (m-L-DNA) probes and catalytic hairpin assembly (CHA)-assisted target recycling for signal amplification. The m-L-DNA probes were constructed via hybridization of hairpin DNA H1 (containing aptamer sequence) immobilized magnetic beads (m-H1) and signal DNA (sDNA, partial hybridization with H1) labeled nano Fe-MIL-88NH2-Pt (NMOF-Pt-sDNA). In the presence of KANA and complementary hairpin DNA H2, the m-L-DNA probes decomposed and formed an m-H1/KANA intermediate, which triggered the CHA reaction to form a stable duplex strand (m-H1-H2) while releasing KANA again for recycling. Consequently, numerous NMOF-Pt-sDNA as mimicking enzymes can synergistically catalyze 3,3',5,5'-tetramethylbenzidine (TMB) for color development. The aptasensor exhibited high selectivity and sensitivity for KANA in milk with a detection limit of 0.2 pg mL-1 within 30 min. The assay can be conveniently extended for on-site screening of other antibiotics in foods by simply changing the base sequence of the probes.

Cellulose Anionic Hydrogels Based on Cellulose Nanofibers As Natural Stimulants for Seed Germination and Seedling Growth.

Cellulose anionic hydrogels were successfully prepared by dissolving TEMPO-oxidized cellulose nanofibers in NaOH/urea aqueous solution and being cross-linked with epichlorohydrin. The hydrogels exhibited microporous structure and high hydrophilicity, which contribute to the excellent water absorption property. The growth indexes, including the germination rate, root length, shoot length, fresh weight, and dry weight of the seedlings, were investigated. The results showed that cellulose anionic hydrogels with suitable carboxylate contents as plant growth regulators could be beneficial for seed germination and growth. Moreover, they presented preferable antifungal activity during the breeding and growth of the sesame seed breeding. Thus, the cellulose anionic hydrogels with suitable carboxylate contents could be applied as soilless culture mediums for plant growth. This research provided a simple and effective method for the fabrication of cellulose anionic hydrogel and evaluated its application in agriculture.

A facile and efficient strategy for the fabrication of porous linseed gum/cellulose superabsorbent hydrogels for water conservation.

The linseed gum/cellulose composite hydrogels were successfully fabricated by mixing cellulose and linseed gum solutions dissolved in the NaOH/urea aqueous system and cross-linked with epichlorohydrin. The morphology and structure of the composite hydrogels were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). The swelling ratio and water retention properties were investigated. The results revealed that linseed gum mainly contributed to water adsorption, whereas the cellulose acted as a backbone to strengthen the porous structure. This work provided a simple way to prepare cellulose-based superabsorbent hydrogels, which could be potentially applied as an effective water conservation material in agriculture.