Frontier in gellan gum-based microcapsules obtained by emulsification: Core-shell structure, interaction mechanism, intervention strategies.

As a translucent functional gel with biodegradability, non-toxicity and acid resistance, gellan gum has been widely used in probiotic packaging, drug delivery, wound dressing, metal ion adsorption and other fields in recent years. Because of its remarkable gelation characteristics, gellan gum is suitable as the shell material of microcapsules to encapsulate functional substances, by which the functional components can improve stability and achieve delayed release. In recent years, many academically or commercially reliable products have rapidly emerged, but there is still a lack of relevant reports on in-depth research and systematic summaries regarding the process of microcapsule formation and its corresponding mechanisms. To address this challenge, this review focuses on the formation process and applications of gellan gum-based microcapsules, and details the commonly used preparation methods in microcapsule production. Additionally, it explores the impact of factors such as ion types, ion strength, temperature, pH, and others present in the solution on the performance of the microcapsules. On this basis, it summarizes and analyzes the prospects of gellan gum-based microcapsule products. The comprehensive insights from this review are expected to provide inspiration and design ideas for researchers.

Electric-field-sensitive hydrogel based on pineapple peel oxidized hydroxyethyl cellulose/gelatin/Hericium erinaceus residues chitosan and its study in curcumin delivery.

This study focused on synthesis of innovative hydrogels with electric field response from modified pineapple peel cellulose and hericium erinaceus chitosan and gelatin based on Schiff base reaction. A series of hydrogels were prepared by oxidized hydroxyethyl cellulose, gelatin and chitosan at different deacetylation degree via mild Schiff base reaction. Subsequently experiments towards the characterization of oxidized hydroxyethyl cellulose/gelatin/chitosan (OHGCS) hydrogel polymers were carried out by FTIR/XRD/XPS, swelling performances and electric response properties. The prepared hydrogels exhibited stable and reversible bending behaviors under repeated on-off switching of electric fields, affected by ionic strength, electric voltage and pH changes. The swelling ratio of OHGCS hydrogels was found reduced as deacetylation degree increasing and reached the maximum ratio âˆ¼ 2250 % for OHGCS-1. In vitro drug releasing study showed the both curcumin loading capacity and release amount of Cur-OHGCS hydrogels arrived about 90 % during 6 h. Antioxidation assessments showed that the curcumin-loaded hydrogels had good antioxidation activities, in which, 10 mg Cur-OHGCS-1 hydrogel could reach to the maximum of about 90 % DPPH scavenging ratio. These results indicate the OHGCS hydrogels have potentials in sensor and drug delivery system.

Chitin microspheres: From fabrication to applications.

Chitin microspheres (CMs) have attracted increasing attention due to their biocompatibility, uniform size and shape, large surface area, and porous structure. Considerable research efforts have been focused on developing CMs and promoting their applications in various areas. In this context, this review aims to describe the most recent progress in the fabrication and application of CMs. Different routes that can be used to prepare CMs, such as the drip method and the emulsion method, are emphatically introduced. Moreover, the applications of CMs as drug delivery systems, wound dressings, three-dimensional (3D) scaffolds, water purification, and functional supporting materials in the fields of biomedicine, tissue engineering, environmental protection, and energy storage are also highlighted. We hope this review can provide a comprehensive and useful database for further innovation of CMs.

Full-duplex cylindrical vector beam multiplexing communication using spin-dependent phase modulation metasurfaces.

Cylindrical vector beam (CVB) has recently gained attention as a promising carrier for signal multiplexing owing to its mode orthogonality. However, the full-duplex multiplexing communication has not been previously explored for the lack of effective technologies to parallelly couple and separate CVB modes. Herein, we present a full-duplex solution for CVB multiplexing communication that utilizes spin-dependent phase modulation metasurfaces. By independently phase-modulating the two spin eigenstates of CVBs with the metasurface via spin-dependent orbital interactions, and loading two binary Dammann vortex gratings, we enabled an independent and reciprocal wave vector manipulation of CVBs for full-duplex (de)multiplexing operation. To demonstrate this concept, we constructed a 16-channel (including 4 CVB modes and 4 wavelengths) full-duplex CVB multiplexing communication system and achieved the bidirectional transmission of 800 Gbit/s quadrature-phase shift-keying (QPSK) signals over a 5 km few-mode fiber. Our results demonstrate the successful multiplexing and demultiplexing of 2 radial CVB modes and 2 azimuthal CVB modes in full-duplex communication with the bit-error-rates approaching 1.87 × 10-5.

Nano-chitin reinforced agarose hydrogels: Effects of nano-chitin addition and acidic gas-phase coagulation.

Hydrogels based on natural polymers such as agarose usually show low applicability due to their weak mechanical properties. In this work, we developed a dual cross-linked agarose hydrogel by adding different amounts of TEMPO-oxidized nano-chitin (0-0.2 %) to agarose hydrogel matrices and then physically cross-linked under acidic gas-phase coagulation. The prepared hydrogels were characterized by FTIR, XRD, TGA, and SEM. The effects of nano-chitin addition and acidic gas-phase coagulation on the properties of agarose hydrogels, such as gel strength, swelling degree, rheological properties, and methylene blue (MB) adsorption capacity, were also studied. Structural characterizations confirmed that nano-chitin was successfully introduced into agarose hydrogels. The gel strength, storage modulus, and MB adsorption capacity of agarose hydrogels gradually increased with the increasing nano-chitin addition, whereas the swelling degree decreased. After acidic gas-phase coagulation, agarose/nano-chitin nanocomposite hydrogels exhibited improved gel strength and storage modulus, while the swelling degree and MB adsorption capacity were slightly reduced. The combination of oxidized nano-chitin and acidic gas-phase coagulation is expected to be an effective way to improve the properties of natural polymer hydrogels.

Nano-chitin: Preparation strategies and food biopolymer film reinforcement and applications.

Current trends in food packaging systems are toward biodegradable polymer materials, especially the food biopolymer films made from polysaccharides and proteins, but they are limited by mechanical strength and barrier properties. Nano-chitin has great economic value as a highly efficient functional and reinforcing material. The combination of nano-chitin and food biopolymers offers good opportunities to prepare biodegradable packaging films with enhanced physicochemical and functional properties. This review aims to give the latest advances in nano-chitin preparation strategies and its uses in food biopolymer film reinforcement and applications. The first part systematically introduces various preparation methods for nano-chitin, including chitin nanofibers (ChNFs) and chitin nanocrystals (ChNCs). The nano-chitin reinforced biodegradable films based on food biopolymers, such as polysaccharides and proteins, are described in the second part. The last part provides an overview of the current applications of nano-chitin reinforced food biopolymer films in the food industry.

Mediation Effect of Corporate Tax Burden and the Relationship between Environmental Regulation and Firm Performance.

This paper took the panel data of 1052 heavily-polluting listed companies from both the Shanghai and Shenzhen Stock Exchange from 2010 to 2017 to empirically analyze the impact of environmental regulation (ERG) on firm performance (FP). The article introduces a mediating effect model to test the mediating role of corporate tax burden (ETR) within the relationship between ERG on FP. The results showed that: (1) ERG has exerted a significant enhancement effect on the performance of heavily polluted firms via the ETR reduction mechanism. (2) The mediating effect of ETR depends on the duration of ERG. A significant time lag exists before the mediating effect starts to work, and the magnitude of the mediating effect increases with the time lag from the execution of the ERG. (3) The mediating effect of ETR varies significantly with the nature of corporate property rights. It is significant for the state-owned firms, while for non-state-owned firms, there is no evidence supporting the existence of the mediating effect of ETR despite ERG still having a significant direct-impact on FP. Based on these findings, we discuss the policy suggestion to optimize the impact of environmental regulation policies in terms of incentivizing the green development of polluting firms.

Green Supply Chain Management and Its Impact on Economic-Environmental Performance: Evidence from Asian Countries.

At present, with the increasing seriousness of ecological pollution, people are gradually paying more attention to the protection of the ecological environment. In the past, people only paid attention to economic growth and neglected environmental protection. Now, environmental problems have restricted economic development, leading scholars at home and abroad to reflect on it deeply. Supply chain management, as the key to the sustainable development of the current enterprise economy, can realize the key consideration of environmental factors in the complete supply chain, reduce the negative impact of economic production activities on environmental protection, and can also make better use of resources to achieve effective assessment of the impact of economic-environmental performance in the supply chain process to ensure its healthy and orderly development. This article makes an in-depth analysis of the use of a green supply chain in the impact of economic-environmental performance by using the method of a fuzzy comprehensive evaluation and provides a relatively complete calculation method. An example is given to analyze the IKEA company. The results of the example analysis show that green supply chain management not only promotes economic growth in economic-environmental performance but also plays a continuous role in the improvement of the environment. The proportion of resource consumption in regions with a high level of economic development is also high. Driven by factors of green supply chain management, green economy can effectively alleviate environmental pollution and further promote economic and green sustainable development.

A self-healing hydrogel based on oxidized microcrystalline cellulose and carboxymethyl chitosan as wound dressing material.

As the food processing by-products, hericium erinaceus residues (HER) and pineapple peel (PP) are good sources of cellulose and chitosan that can be prepared into hydrogels for structuring a drug delivery system. Hydrogel is one new type biomaterial for drug delivery with excellent absorbent ability applied in wound dressing. In this research, one composite self-healing hydrogel with pH sensitivity for drug delivery system based on the Schiff-base reaction was fabricated. Therein aldehyde group of oxidized microcrystalline cellulose (OMCC) from PP were crosslinked with amino group of carboxymethyl chitosan (CMCS) from HER via Schiff-base reaction for structuring hydrogels. The structures of the prepared hydrogels were characterized. Meanwhile, its blood clotting activity and physical properties were investigated. The hydrogels show some favorable performances with suitable gel time (54 s of minimum), distinguish swelling rate (about 31.18 g/g), good mechanical, self-healing characteristic and well coagulation effect. The cumulative release of the rutin-loaded hydrogel OMCM-54 reached about 80 % within 6 h, suggesting the well-controlled release of rutin by crosslinking degree between the modified OMCC and CMCS based on Schiff-base reaction. The novel biomaterial based on hericium erinaceus residues and pineapple peel shows its potential use as wound dressing.

pH-responsive magnolol nanocapsule-embedded magnolol-grafted-chitosan hydrochloride hydrogels for promoting wound healing.

Bacterial infection and oxidative stress seriously delay wound healing. Here, magnolol-grafted-chitosan hydrochloride (CSCl-MAG) was synthesized and crosslinked with genipin to form hydrogel (CSMH). By embedding magnolol-loaded chitosan nanocapsules (MCNGs) into CSMH, we designed a novel nanocapsule- embedded hydrogel dressing (MCNG-H) with sustained antibacterial and antioxidant properties. The swelling, rheology, cytotoxicity, antibacterial and antioxidant properties of MCNG-H were studied. MCNG-H exhibited good swelling properties and biocompatibility. The antibacterial and antioxidant assays in vitro demonstrated the corporative effect of CSM-H and MCNGs in inhibiting bacteria and eliminating reactive oxygen species (ROS). Moreover, MCNG-H revealed the pH-responsive release profiles of loaded MAG, and ensured sustained release of MAG with the dual protective effects of MCNG and CSMH, which helped to maintain long-term antibacterial and antioxidant activities. Finally, MCNG-H significantly accelerated wound healing in a splinted excisional dermal wound model, promising a competitive dressing for the treatment of infected wounds.

Preparation, properties and drug controlled release of chitin-based hydrogels: An updated review.

Chitin, as the second abundant biopolymers on earth after cellulose, has been used for synthesis of hydrogels in a wide range of applications due to its biocompatibility, biodegradability and nontoxicity. This review aims to provide an overview of the latest developments in the preparation, properties and drug controlled release of chitin-based hydrogels. In the first part, the preparation of hydrogels from native chitin, nano chitin and chitin derivatives via physical or chemical procedures was discussed in detail. The properties of chitin-based hydrogels, including gel strength, swelling degree and smart response characteristics, were described in the second part. This review also introduced how chitin-based hydrogel as a drug controlled release carrier is affected by composition, pH, temperature, magnetic field, electric field and other factors. We hope this review can provide guidelines for the rational design of chitin-based hydrogels in drug delivery systems.

Preparation, Characterization and Gelation of a Fungal Nano Chitin Derived from Hericium erinaceus Residue.

Nano chitin is a promising biocompatible material with wide applications. In this work, a fungal-derived nano chitin was prepared from Hericium erinaceus residue via mineral/protein purification and subsequent TEMPO-mediated oxidation. The structure, dispersity, and gelation ability of the prepared fungal nano chitin were studied. The results showed that the average length and width of the prepared fungal nano chitin were 336.6 nm and 6.4 nm, respectively, and the aspect ratio exceeded 50:1. The nano chitin retained the basic structure of chitin, while the crystallization index was improved. In addition, the dispersity of the nano chitin in aqueous media was evaluated by the effective diameter, and the polydispersion index was mainly affected by pH and ionic strength. Under acetic acid "gas phase coagulation", the prepared nano chitin dispersions with mass concentrations of 0.2, 0.4, 0.6, and 0.8% were converted into gels by enhanced hydrogen bond crosslinking between nano chitins.

Smart pH-Sensitive Hydrogel Based on the Pineapple Peel-Oxidized Hydroxyethyl Cellulose and the Hericium erinaceus Residue Carboxymethyl Chitosan for Use in Drug Delivery.

Pineapple and hericium erinaceus (HE) produce a lot of residues in the process of food processing. These processed residues are good potential derivative precursors. In this investigation, a simple and non-toxic method was developed to prepare one new composite hydrogel by the Schiff base reaction between the aldehyde group of oxidized hydroxyethyl cellulose (OHEC) from processed pineapple peel residue and the amino group of carboxymethyl chitosan (CMCS) from processed HE residue. Subsequently, a series of experiments toward these new hydrogel polymers including structure characterization and performances were applied. The resultant hydrogel polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy and confirmed with thermogravimetry. It was observed that the modification of cellulose and chitin was adequate, and the synthesis of OHEC/CMCS hydrogel polymers was successful. The gelation time experiments indicated that the shortest gel time was 33 s at a mass ratio of 4:6 (OHEC-70:CMCS). The hydrogel showed good swelling properties. The maximum swelling rate reached 11.58 g/g, and the swelling rate decreased with the increase of the oxidation degree of OHEC. The drug delivery applications of the prepared hydrogel were evaluated with bovine serum albumin (BSA) as a model drug releasing in vitro. It was discovered that the BSA release from the hydrogel was pH sensitive under simulated gastrointestinal conditions. All of these attributes indicate that the novel prepared hydrogel polymers have the potential as good carriers for oral delivery of protein-type drugs.

Comparison of cellulose nanocrystals from pineapple residues and its preliminary application for Pickering emulsions.

Pineapple, as a world-famous tropical fruit, is also prone to produce by-products rich in cellulose. In this study, different sections of pineapple, including pineapple core (PC), pineapple pulp (PPu), pineapple leaf (PL) and pineapple peel (PPe) were used for production of pineapple cellulose nanocrystals (PCNCs) by sulfuric acid hydrolysis. The crystallinity of PCNCs from PC, PPu, PL and PPe were 57.81%, 55.68%, 59.19% and 53.58%, respectively, and the thermal stability of PCNCs in order was PC > PL > PPe > PPu. The prepared PCNCs from PC, PPu, PL and PPe were needle like structure at the average aspect ratios of 14.2, 5.6, 5.5, and 14.8, respectively. Additionally, the differences in the structure and properties of PCNCs affected the stability of the prepared Pickering emulsions, which ranked as PPu > PPe > PL > PC. The Pickering emulsions stabilized by PCNCs prepared from PPu could be stored stably for more than 50 d. These results show the differences of PCNCs from four sections of pineapple, and provide isolated raw material selection for the further application of PCNCs.

Nanoparticles for Stem Cell Tracking and the Potential Treatment of Cardiovascular Diseases.

Stem cell-based therapies have been shown potential in regenerative medicine. In these cells, mesenchymal stem cells (MSCs) have the ability of self-renewal and being differentiated into different types of cells, such as cardiovascular cells. Moreover, MSCs have low immunogenicity and immunomodulatory properties, and can protect the myocardium, which are ideal qualities for cardiovascular repair. Transplanting mesenchymal stem cells has demonstrated improved outcomes for treating cardiovascular diseases in preclinical trials. However, there still are some challenges, such as their low rate of migration to the ischemic myocardium, low tissue retention, and low survival rate after the transplantation. To solve these problems, an ideal method should be developed to precisely and quantitatively monitor the viability of the transplanted cells in vivo for providing the guidance of clinical translation. Cell imaging is an ideal method, but requires a suitable contrast agent to label and track the cells. This article reviews the uses of nanoparticles as contrast agents for tracking MSCs and the challenges of clinical use of MSCs in the potential treatment of cardiovascular diseases.

Copper metal-organic framework embedded carboxymethyl chitosan-g-glutathione/polyacrylamide hydrogels for killing bacteria and promoting wound healing.

Bacterial infection and its induced oxidative stress as major clinical challenge during wound healing call for an urgent response for the development of medical dressings with multi-functions, such as antioxidant and antibacterial. To meet this demand, copper metal organic framework nanoparticles (HKUST NPs) and carboxymethyl chitosan-g-glutathione (CMCs-GSH) were synthesized and characterized. By embedding HKUST NPs into PAM/CMCs-GSH hydrogel (AOH), we developed a novel hydrogel dressing (HKUST-Hs) with dual effects of antibacterial and antioxidant. The morphology, swelling behavior, oxidation resistance and antibacterial properties of HKUST-Hs were investigated as well as the slow-release behavior of copper ions. Full-thickness cutaneous wound model of rats was created to assess the promoting effect of HKUST-Hs on wound healing. We found that HKUST NPs could be well dispersed in HKUST-Hs by shielding the positive charge of copper ions, and thus copper ions released were uniformly distributed and chelated with CMCs-GSH to promote the swelling stability of HKUST-Hs. Also, HKUST-Hs exhibited good free radical scavenging ability in vitro antioxidant assay. Meanwhile, a gradient sustained-release system of copper ions was formed in HKUST-Hs owing to the inhibition of HKUST NPs to copper release and the chelation of CMCs-GSH, which effectively inhibited the explosive release of copper ions and prolonged the release period, thereby reducing cytotoxicity. In vitro antibacterial test demonstrated there was synergistic antibacterial effect between the slow-released copper ions and CMCs-GSH, which improved the antibacterial activity and antibacterial persistence of HKUST-Hs. Finally, HKUST-Hs accelerated wound healing in vivo by continuously killing bacteria and inhibiting oxidative stress.

Construction of hydrogels based on the homogeneous carboxymethylated chitin from Hericium erinaceus residue: Role of carboxymethylation degree.

Carboxymethyl chitin hydrogels with different degree of substitution (DS) were prepared by the homogeneous carboxymethylation of chitin extracted from Hericium erinaceus residue. The effect of DS on gel structure and property were studied. Results showed that the DS of carboxymethyl chitin hydrogels can be increased by increasing the amount of sodium chloroacetate. The equilibrium swelling degree and pH swelling sensitivity of the hydrogels were enhanced as the increase of DS. Zeta potential, low-field nuclear magnetic resonance, contact angle and molecular dynamics simulation results suggested that the introduction of carboxymethyl functional group enhanced the negative charge, water mobility, surface hydrophilicity and the ability to form hydrogen bonds with water of the hydrogels, resulting in an increased swelling degree of the hydrogels. Moreover, the prepared hydrogels showed different adsorption capability to various dyes, and the adsorption performance of the prepared hydrogels for cationic dyes could be enhanced as the increase of DS.

Surface morphology and protective effect of Hericium erinaceus polysaccharide on cyclophosphamide-induced immunosuppression in mice.

The aim of this study was to investigate the surface morphological features and in vivo immunomodulatory activities of a hetero polysaccharide fraction (HEP-W) from Hericium erinaceus. SEM and AFM images revealed that HEP-W displayed a flexible random coil conformation, and these flexible winding chains further formed continuous fiber network structure. Meanwhile, Congo red assay and XRD further proved that HEP-W mainly exhibited amorphous structure with non-triple-helical conformation in solution. In vivo immunomodulatory experiments demonstrated that HEP-W possessed protective effects against cyclophosphamide-induced immunosuppression in mice by significantly enhancing immune organ index, splenocyte proliferation, NK cell activity, IL-2 production as well as improving the macrophage phagocytosis. These findings suggest that HEP-W could be explored as a natural and effective immunomodulatory agent.

Smart pH/magnetic sensitive Hericium erinaceus residue carboxymethyl chitin/Fe3O4 nanocomposite hydrogels with adjustable characteristics.

A smart hydrogel with pH/magnetic dual sensitivity was synthesized by in-situ synthesis of Fe3O4 inside carboxymethyl chitin hydrogel matrix prepared from Hericium erinaceus residue. The structure, pH/magnetic sensitivity, swelling and drug release behavior of the prepared hydrogels were investigated. The results showed that Fe3O4 nanoparticles were successfully synthesized and uniformly distributed within the hydrogels. The prepared hydrogels could be attracted by the magnet and exhibited sustained shrinkage behavior at low pH, with the desirable pH/magnetic sensitivity. The formed Fe3O4 could be developed inside the hydrogels by increasing the concentrations of precursor Fe2+/Fe3+ ions, and the magnetic sensitivity of hydrogels was enhanced, while the pH sensitivity and swelling degree were weakened. The Fe3O4 content-dependent behavior of the prepared hydrogels suggested the adjustable properties of hydrogels. The release of 5-Fu in simulated gastric and intestinal fluids followed the Fick diffusion mechanism and showed different release rates, indicating the pH-controlled drug release behavior.

Review on Magnetic Natural Polymer Constructed Hydrogels as Vehicles for Drug Delivery.

Hydrogels prepared from natural polymers have captured extensive attention over the past decades because of their exceptional biocompatibility and nontoxicity, ease of gelation, and functionalization. Thus, natural polymer hydrogels are considered as promising biomaterials that show great potential in the biomedical field. In drug-delivery systems, the extent and the rate with which the drugs reach their targets are highly carrier-dependent, so the demand for intelligent drug-delivery systems is gradually increasing. Recently, natural polymer hydrogels functionalized with magnetic materials have been used as a novel smart response device for drug delivery because of the quick response and remote controllability. This review aims to give the latest advances of magnetic hydrogels based on natural polymers such as polysaccharide, protein, and DNA in drug-delivery systems. Specifically, the first part compares several general synthesis strategies of magnetic natural polymer hydrogels. The applications of magnetic natural polymer hydrogels are described in the second part. For the last part, an overview of the application in drug delivery for the magnetic hydrogels constructed from several representative natural polymers is presented.