Chemical Cross-linking Agents Research Articles

Cross-Linking Agents in Three-Component Materials Dedicated to Biomedical Applications: A Review.

In biomaterials research, using one or two components to prepare materials is common. However, there is a growing interest in developing materials composed of three components, as these can offer enhanced physicochemical properties compared to those consisting of one or two components. The introduction of a third component can significantly improve the mechanical strength, biocompatibility, and functionality of the resulting materials. Cross-linking is often employed to further enhance these properties, with chemical cross-linking agents being the most widely used method. This article provides an overview of the chemical agents utilized in the cross-linking of three-component biomaterials. The literature review focused on cases where the material was composed of three components and a chemical substance was employed as the cross-linking agent. The most commonly used cross-linking agents identified in the literature include glyoxal, glutaraldehyde, dialdehyde starch, dialdehyde chitosan, and the EDC/NHS mixture. Additionally, the review briefly discusses materials cross-linked with the MES/EDC mixture, caffeic acid, tannic acid, and genipin. Through a critical analysis of current research, this work aims to guide the development of more effective and safer biopolymeric materials tailored for biomedical applications, highlighting potential areas for further investigation and optimization.

Self-assembling chitosan based injectable and expandable sponge with antimicrobial property for hemostasis and wound healing

Chitosan and chitosan derivative are widely used in hemostasis, antibiosis and wound repair for its good biocompatibility and unique effect. However, the preparation of chitosan based hemostatic materials or wound dressings generally involves chemical crosslinking agent introduction, acid residue or complicated preparation process, which limits its clinical application. In this study, an injectable and expandable chitosan sponge was constructed by chitosan (CS) and quaternized chitosan (QCS) self-assembly without acid retention and chemical crosslinker introduction. In the neutral condition, the hydrogen bond of CS molecules can act as the driving force to form cross-linking network, and the QCS was introduced to regulate the hydrogen bond of CS to avoid the excessive aggregation. The porous QCS/CS sponge was obtained by freeze-drying of the self-assembly QCS/CS hydrogel. The sponge exhibited high expansibility, injectability and water/blood triggered shape memory property. Due to the introduction of QCS, the sponge showed good antibacterial properties, which can protect the wound from bacterial invasion. The convenient and green preparation method of injectable and expandable QCS/CS sponge is a potential method for the treatment of hemostasis and wound healing.

Bovine Placentome-Derived Extracellular Matrix: A Sustainable 3D Scaffold for Cultivated Meat.

Cultivated meat, an advancement in cellular agriculture, holds promise in addressing environmental, ethical, and health challenges associated with traditional meat production. Utilizing tissue engineering principles, cultivated meat production employs biomaterials and technologies to create cell-based structures by introducing cells into a biocompatible scaffold, mimicking tissue organization. Among the cell sources used for producing muscle-like tissue for cultivated meats, primary adult stem cells like muscle satellite cells exhibit robust capabilities for proliferation and differentiation into myocytes, presenting a promising avenue for cultivated meat production. Evolutionarily optimized for growth in a 3D microenvironment, these cells benefit from the biochemical and biophysical cues provided by the extracellular matrix (ECM), regulating cell organization, interactions, and behavior. While plant protein-based scaffolds have been explored for their utilization for cultivated meat, they lack the biological cues for animal cells unless functionalized. Conversely, a decellularized bovine placental tissue ECM, processed from discarded birth tissue, achieves the biological functionalities of animal tissue ECM without harming animals. In this study, collagen and total ECM were prepared from decellularized bovine placental tissues. The collagen content was determined to be approximately 70% and 40% in isolated collagen and ECM, respectively. The resulting porous scaffolds, crosslinked through a dehydrothermal (DHT) crosslinking method without chemical crosslinking agents, supported the growth of bovine myoblasts. ECM scaffolds exhibited superior compatibility and stability compared to collagen scaffolds. In an attempt to make cultivate meat constructs, bovine myoblasts were cultured in steak-shaped ECM scaffolds for about 50 days. The resulting construct not only resembled muscle tissues but also displayed high cellularity with indications of myogenic differentiation. Furthermore, the meat constructs were cookable and able to sustain the grilling/frying. Our study is the first to utilize a unique bovine placentome-derived ECM scaffold to create a muscle tissue-like meat construct, demonstrating a promising and sustainable option for cultivated meat production.

Photo-crosslinking methacrylated-amylopectin/polyacrylamide hydrogels loading curcumin for applications as degradable, injectable, and antibacterial wound dressings

The preparation of biodegradable and antibacterial hydrogels has important clinical value. In this work, a novel strategy has been developed to prepare degradable hydrogel dressings without chemical crosslinking agent using methacrylate anhydride (MA)-modified amylopectin (APMA) and polyacrylamide (PAM). After introducing CC bonds, APMA/PAM hydrogels can be formed under light irradiation. This strategy improves the gelling ability of AP and degradation properties of the hydrogel by avoiding the addition of crosslinking agent. The degradation rate of APMA/PAM hydrogel is 74.04 ± 0.69 % within 12 weeks, while that of APMA/PAM hydrogel containing crosslinking agent is only 38.5 ± 0.1 %. The APMA/PAM hydrogel loading curcumin (Cur) (APMA/PAM-Cur) exhibits high antibacterial efficiency of 98.29 ± 0.41 % and 97.18 ± 0.81 % against S. aureus and E. coli, respectively, with light irradiation. Animal experiments show that the APMA/PAM-Cur hydrogel reduces the infiltration of inflammatory factors, increases the density of collagen, and makes the newly formed granulation tissue thicker and tighter. This study not only proves the promising potential of the APMA/PAM-Cur hydrogel as degradable and antibacterial wound dressing for clinical treatment, but also provides a new strategy for developing low-cost, degradable, and antibacterial wound dressings and reducing antibiotic abuse and environmental pollution caused by medical waste.

Structure and thermal properties of acrylic copolymer gels: effect of composition and cross-linking method

Two approaches to the synthesis of hydrogels based on polyacrylamide (pAAm) with copolymers were compared in the paper—traditional chemical cross-linking and physical cross-linking with montmorillonite (MMT). The main aim of the work was to find an adequate replacement of the chemical toxic cross-linking agent MBAAm (N,N'-methylene-bis-acrylamide) by using non-toxic—natural clay MMT for synthesis of pAAm gels, which are planned to be used as soil conditioners. A series of hydrogels based on acrylic monomers (acrylamide (AAm), acrylonitrile (AN), acrylic acid (AA)) physically cross–linked by MMT and chemically cross-linked were synthesized. For the synthesized gels, the influence of the synthesis method on the formation of the structure and the mechanism of thermal destruction in the presence of air was analyzed using a set of physicochemical methods: FTIR, XRD, SEM, DSC and TG/DTG. According to FTIR and XRD data, pAAm-MMT and pAAm-AN-MMT samples formed an intercalated/exfoliated structure, whereas pAAm-AA-MMT had an intercalated structure. The endothermic reaction of decomposition of xerogels based on acrylic polymers with and without MMT was observed using DSC and derivative thermogravimetry analyses, coupled with measurement of FTIR spectra of volatile products of thermolysis. All studied composites were relatively thermoresistant, which had three distinct regions of phase transitions and their thermal decomposition occurred at a temperature range 310–465 °C.Graphical

SYNTHESIS AND STUDY OF THE INFLUENCE OF ALKALI CONCENTRATION AND TEMPERATURE ON THE PHYSICOCHEMICAL PROPERTIES OF CRYOGELS BASED ON GELATIN AND CHITOSAN

Much of the polymer research is focused on improving existing polymers or developing new biomaterials with tunable properties. Natural polymers that have certain segments that contribute to an additional therapeutic effect are more often used as a biocompatible polymer. Polymers can be produced using a variety of methods, including covalent cross-linking, dynamic covalent cross-linking, physical cross-linking, cryopolymerization, 3D printing, electrospinning, etc. Cryopolymerization is a unique method and has several advantages over other methods. By cryofreezing it is possible to obtain a porous structure in which the size and volume of the pores can be controlled by changing the concentration of the initial monomers and temperature. The purpose of this study is to determine the effect of alkali concentration and cryopolymerization temperature on the properties of cryogels. The objects of study in this work are cryogels based on gelatin and chitosan. Methodology. The functional groups of the cryogels were determined by IR spectroscopy. The results of a study of the sorption and desorption of polymers are presented. The results of polymer degradation in phosphate-saline solution over 8 weeks are also shown. These studies were based on changes in mass, that is, they were carried out using the gravimetric method. Conclusion. The results of a study of the influence of alkali concentration and temperature on the physicochemical properties of cryogels based on gelatin and chitosan are presented. Cryogels based on gelatin and chitosan are synthesized without the use of harmful chemical cross-linking agents, which makes them attractive for tissue engineering.

In vitro chronic wound healing using collagen and plant extract along with zinc nanoparticles

INTRODUCTION: While the use of zinc nanoparticles (ZnNPs) as an antibacterial agent in the biomedical industry has recently attracted significant attention, collagen has aroused significant interest as a biomaterial in medical and tissue engineering applications.
 OBJECTIVES: In order to create biofilm loaded with biosynthesized ZnNPs for use in chronic wound healing applications, type-I collagen was extracted from the study's subject. by the acid soluble collagen technique, collagen was isolated from the fish skin of the trevally and identified by SDS-PAGE. Aqueous extract from Cassia fistula leaves was also used to greenly manufacture stable ZnNPs, which were then characterized by UV-Vis, FTIR, and XRD measurements.
 METHODS: Collagen and ZnNPs were then added to polyvinyl alcohol (PVA), creating a thin biofilm that had a high biocompatibility due to the production method's absence of a chemical reducer and crosslinking agent. When tested against the harmful bacteria, both ZnNPs alone and PVA/Collagen/ZnNPs biofilms showed potent antibacterial activity.
 RESULTS: By using the MTT test, the cytotoxic effects of collagen and ZnNPs on the Vero cell line were evaluated. With 97.76% wound closure, the PVA/Collagen/ZnNPs biofilm demonstrated strong in vitro wound scratch healing efficacy.
 CONCLUSION: The findings show that the PVA/Collagen/ZnNPs film dramatically increased cell migration by 40.0% at 24 hours, 79.20% at 48 hours, and 97.76% at 74 hours.

Recoverable and degradable carboxymethyl chitosan polyelectrolyte hydrogel film for ultra stable encapsulation of curcumin

Hydrogels have shown great potential for application in food science due to their diverse functionalities. However, most hydrogels inevitably contain toxic chemical cross-linking agent residues, posing serious food safety concerns. In this paper, a curcumin/sodium alginate/carboxymethyl chitosan hydrogels (CSCH) were prepared by self-assembly of two oppositely charged polysaccharides, carboxymethyl chitosan and sodium alginate, to form a three-dimensional network encapsulating curcumin for extending food shelf life. The network structure of the CSCH film confirmed by FTIR, XRD, and XPS was mainly formed by electrostatic interactions. The chemical stability of CSCH network encapsulated curcumin was 4.2 times greater than that of free curcumin, with excellent gas barrier, antimicrobial, antioxidant, and biosafety properties. It was found that CSCH films reduced dehydration, prevented nutrient loss, inhibited microbial growth, and lowered the respiration rate, which effectively maintained the quality of mango and prolonged its shelf-life up to 11 days. Notably, CSCH films possessed the properties of rapid recycling (10 mins) and biodegradability (53 days). This polysaccharide-based hydrogel film provides a viable strategy for the development of green and sustainable food packaging.

Emulsion synthesis of cellulose/lanthanum alginate /La (Ⅲ) composite microspheres for efficient and selective adsorption of phosphate

Phosphorus exceeding the standard will destroy the ecological environment of the freshwater resources and endanger the survival of aquatic animals. Due to the intrinsic complexation between La(Ⅲ) and alginate, in this study, lanthanum hydroxide was first prepared from lanthanum nitrate, the chemical crosslinking agent was replaced by La(Ⅲ), and cellulose/lanthanum alginate/La(OH)3 composite microspheres (CSPGs-La) were synthesized using polyethyleneimine (PEI) as a crosslinking agent through the emulsification process in one pot. In comparison, the adsorption capacity of 80 mg L−1 PO43− treated with CSPGs-La, CSPGs-Ech (Samples where the chemical crosslinking agent was not replaced by La(Ⅲ)) and La(OH)3 was 159.5 mg g−1, 57.51 mg g−1 and 137.4 mg g−1, respectively. CSPGs-La has good swelling performance, unique three-dimensional structure and mass transfer efficiency, which are the important reasons for its strong ability to capture phosphate. In the presence of coexisting anions, CSPGs-La can still accurately adsorb PO43−, showing good adsorption selectivity. Intra-surface spherical complexation and electrostatic adsorption play an important role. When the dose of CSPGs-La is 1.35 g L−1, the phosphorus pollutants in the actual domestic sewage can be reduced to 10 μg L−1 below. After five adsorption cycles, the retention rate of phosphorus removal performance is 87.7 %. This study provides a green, easy to implement, and promising solution for the preparation of efficient and selective phosphorus removal adsorbent.

A microscale 3D organ on a chip for recapitulating reciprocal neuroendocrine crosstalk between the hypothalamus and the pituitary gland

Conventional 2D or even recently developed 3D in vitro culture models for hypothalamus and pituitary gland cannot successfully recapitulate reciprocal neuroendocrine communications between these two pivotal neuroendocrine tissues known to play an essential role in controlling the body’s endocrine system, survival, and reproduction. In addition, most current vitro culture models for neuroendocrine tissues fail to properly reflect their complex multicellular structure. In this context, we developed a novel microscale chip platform, termed the ‘hypothalamic–pituitary (HP) axis-on-a-chip,’ which integrates various cellular components of the hypothalamus and pituitary gland with biomaterials such as collagen and hyaluronic acid. We used non-toxic blood coagulation factors (fibrinogen and thrombin) as natural cross-linking agents to increase the mechanical strength of biomaterials without showing residual toxicity to overcome drawbacks of conventional chemical cross-linking agents. Furthermore, we identified and verified SERPINB2 as a reliable neuroendocrine toxic marker, with its expression significantly increased in both hypothalamus and pituitary gland cells following exposure to various types of toxins. Next, we introduced SERPINB2-fluorescence reporter system into loaded hypothalamic cells and pituitary gland cells within each chamber of the HP axis on a chip, respectively. By incorporating this SERPINB2 detection system into the loaded hypothalamic and pituitary gland cells within our chip platform, Our HP axis-on-chip platform can better mimic reciprocal neuroendocrine crosstalk between the hypothalamus and the pituitary gland in the brain microenvironments with improved efficiency in evaluating neuroendocrine toxicities of certain drug candidates.

Amine-reactive crosslinking enhances type 0 collagen hydrogel properties for regenerative medicine.

Collagen is extensively utilised in regenerative medicine due to its highly desirable properties. However, collagen is typically derived from mammalian sources, which poses several limitations, including high cost, potential risk of immunogenicity and transmission of infectious diseases, and ethical and religious constraints. Jellyfish-sourced type 0 collagen represents a safer and more environmentally sustainable alternative collagen source. Thus, we investigated the potential of jellyfish collagen-based hydrogels, obtained from Rhizostoma pulmo (R. pulmo) jellyfish, to be utilised in regenerative medicine. A variety of R. pulmo collagen hydrogels (RpCol hydrogels) were formed by adding a range of chemical crosslinking agents and their physicochemical and biological properties were characterised to assess their suitability for regenerative medicine applications. The characteristic chemical composition of RpCol was confirmed by Fourier-transform infrared spectroscopy (FTIR), and the degradation kinetics, morphological, and rheological properties of RpCol hydrogels were shown to be adaptable through the addition of specific chemical crosslinking agents. The endotoxin levels of RpCol were below the Food and Drug Administration (FDA) limit for medical devices, thus allowing the potential use of RpCol in vivo. 8-arm polyethylene glycol succinimidyl carboxyl methyl ester (PEG-SCM)-crosslinked RpCol hydrogels preserved the viability and induced a significant increase in the metabolic activity of immortalised human mesenchymal stem/stromal cells (TERT-hMSCs), therefore demonstrating their potential to be utilised in a wide range of regenerative medicine applications.

Anti-freezing, tough, and stretchable ionic conductive hydrogel with multi-crosslinked double-network for a flexible strain sensor

Ionic conductive hydrogels are an ideal material for use in flexible strain sensors due to their electrical conductivity, accurate data retrieval, and extensibility. However, conventional ionic conductive hydrogels including salt/organics or salt-based hydrogels with high ionic content exhibit modest antifreeze and limited mechanical properties, hampering their practical use across diverse sectors. The preparation process is tedious due to the incorporation of toxic photoinitiator and chemical crosslinking agents. Herein, through a simple, low-cost, and environmentally friendly strategy, we have developed a multi-crosslinked double network ionic conductive hydrogel by using polyvinyl alcohol bearing styrylpyridinium groups (PVA-SbQ) and sodium alginate (SA) via UV irradiation, followed by immersion in a mixed solution of ferric chloride (FeCl3) and glycerol (Gly)/water. This synergistic effect of FeCl3 and Gly has endowed the PVA-SbQ/SA/FeCl3/Gly hydrogel with exceptional mechanical properties (tensile strength of 2.48 ± 0.45 MPa and elongation at break of 1452 ± 101 %), anti-freezing ability (-42.3 °C), and electrical conductivity of 0.38 S/m and 0.32 S/m at room temperature and −30 °C, respectively. Moreover, the hydrogel exhibits remarkable strain sensitivity (GF = 2.49), allowing it to be used as a strain sensor under both room temperature and subzero conditions. Consequently, the prepared hydrogel sensor can monitor various human motions, such as joint bending, running, and speaking. Therefore, our work offers a promising strategy for the preparation of PVA-based hydrogels with outstanding mechanical properties, electrical conductivity, and resistance to freezing, rendering them a practical option for flexible sensors. In addition, our anti-freezing method has significant potential in enhancing the accessibility of ionic conductive hydrogels.

Preparation and Application of Polyrotaxane Cross-Linking Agent Based on Cyclodextrin in Gel Materials Field.

The cross-linking point of a conventional chemical cross-linking agent is fixed. Therefore, gels that are prepared with a conventional cross-linking agent have poor deformability, strength, shear resistance, and further properties. Some researchers have prepared a new cross-linking agent using cyclodextrin (CD). In a polyrotaxane cross-linking agent, the cross-linking points can slide freely along the molecule chain. The special "slide ring" structure can provide better elongation, strength, and other properties to gels, which can effectively expand the application of the gel's materials. This paper summarizes the preparation methods and applications from different types of CD and compares the improvements of properties (swelling, viscoelastic properties, etc.). In addition, the current results of our group are presented, and some ideas are provided for the development of polyrotaxane cross-linking agents.

Degradable carrier-free spray hydrogel based on self-assembly of natural small molecule for prevention of postoperative adhesion.

Postoperative peritoneal adhesion (PPA) is frequent and extremely dangerous complication after surgery. Different tactics have been developed to reduce it. However, creating a postoperative adhesion method that is multifunctional, biodegradable, biocompatible, low-toxic but highly effective, and therapeutically applicable is still a challenge. Herein, we have prepared a degradable spray glycyrrhetinic acid hydrogel (GAG) based on natural glycyrrhetinic acid (GA) by straightforward heating and cooling without the use of any additional chemical cross-linking agents to prevent postoperative adhesion. The resultant hydrogel was demonstrated to possess various superior anti-inflammatory activity, and multiple functions, such as excellent degradability and biocompatibility. Specifically, spraying characteristic and excellent antibacterial activities essentially eliminated secondary infections during the administration of drugs in surgical wounds. In the rat models, the carrier-free spray GAG could not only slow-release GA to inhibit inflammatory response, but also serve as physical anti-adhesion barrier to reduce collagen deposition and fibrosis. The sprayed GAG would shed a new light on the prevention of postoperative adhesion and broaden the application of the hydrogels based on natural products in biomedical fields.

Enhanced sensing performance of EVA/LDPE/MWCNT piezoresistive foam sensor for long-term pressure monitoring

Conductive polymer composites (CPCs) with piezoresistive properties are smart detecting systems with high sensitivity, fast response, and low energy consumption. To enhance their sensitivity and cope with their high filler content requirements, solid CPCs are normally transformed into blends and foams, which reduces the elastic modulus, enabling larger deformations, wider detection range, and increased sensitivity. However, providing reversible and durable sensing properties remains challenging as it depends on the phase morphology, foam cell structure, and particle dispersion. To this end, we use multi-walled carbon nanotube (MWCNT) as a conductive filler with a high aspect ratio and develop CNT-filled ethylene vinyl acetate/low-density polyethylene (EVA/LDPE) blend foams. We fix the foam structure using chemical foaming and crosslinking agents in a compression molding process. To optimize the piezoresistive behavior, we follow a step-wise tuning approach, studying the blending morphology, the foaming attributes, the particle dispersion and affinity, thereby selecting the most promising formulations for further investigations. The least mechanical and electrical hysteresis is obtained at minimum foam density, which is obtained at a compromised crystallinity and crosslinking density. The higher affinity of MWCNT to EVA and the faster crosslinking of the EVA phase results in uniformly dispersed small cells at EVA-rich formulations and 4 phr MWCNT content. The final foam sensor demonstrates an impressive response and recovery times of less than 200 ms and remarkable durability thanks to the optimized cell morphology and mechanical properties. These findings expand the application of carbon-filled polyolefin foams in pressure monitoring, particularly in wearable sensors for strain and motion sensing.

Effects of TiO2 nanoparticles on the physicochemical and biological properties of oxidized sodium alginate/polyacrylamide-gelatin composite hydrogels fabricated by interpenetrating network approach

To enhance the applicability of alginate hydrogel in tissue engineering, we attempted to fabricate oxidized sodium alginate/polyacrylamide-gelatin (OSA/PAM-GT) composite hydrogels by interpenetrating network approach with the hydroxyapatite/D-glucono-δ-lactone (HAP/GDL) as the endogenous ionic cross-linking agent for oxidized sodium alginate (OSA) and N, N′-methylenebisacrylamide (MBAA) as the chemical cross-linking agent for polyacrylamide (PAM), followed by their surface coverage with gelatin. Then TiO2 nanoparticles as the reinforcing agent were added to the OSA/PAM-GT hydrogel matrix to construct organic/inorganic hybrid OSA/TiO2/PAM-GT composite hydrogels. In particular, the effects of the amount of TiO2 nanoparticles on the microscopic morphology, mechanical properties, swellability, biodegradability, bio-mineralization and biocompatibility of the composite hydrogels were studied. Experimental results indicated that the addition of TiO2 nanoparticles into the matrix of OSA/TiO2/PAM-GT composite hydrogels could effectively regulate the porosity, mechanical properties, swelling ratio, in vitro biodegradability and bio-mineralization of OSA/TiO2/PAM-GT composite. Moreover, OSA/TiO2/PAM-GT composite hydrogels had the best biocompatibility when the content of TiO2 nanoparticles was 0.5% (w/v), indicating that an appropriate amount of TiO2 nanoparticles could effectively promote cell adhesion, proliferation and differentiation. Consequently, the combined method of the interpenetrating network technology, the incorporation of TiO2 nanoparticles with the surface coverage of gelatin could overcome the defects of alginate hydrogels to some extent, making OSA/TiO2/PAM-GT composite hydrogels suitable for tissue engineering applications.

Pea Protein-Based Bioplastics Crosslinked with Genipin: Analysis of the Crosslinking Evolution

Replacing conventional plastics with other products obtained from biobased and biodegradable raw materials is an increasingly studied solution. In this line, the development of protein-based bioplastics is a promising alternative. However, for some applications, such as packaging it would be necessary to improve their properties by including an additional stage to crosslink the protein chains during the production of bioplastics. Therefore, pea protein-based bioplastics crosslinked with genipin, a natural non-toxic chemical crosslinking agent, are evaluated in this study. The bioplastics are obtained via injection moulding and genipin, is included in the initial formulation. Specifically, the concentration of genipin and the effects on the protein blends with genipin over days are evaluated. The evolution of the reaction is followed by the colour change of the blend, together with thermal analyses and infrared spectroscopy. Results showed the evolution of the crosslinking in the blends resulted in conformational changes that resulted in the modification of the initial yellowish colour to a blueish system. Respect their bioplastics, more deformable systems with a lower water absorption capability are obtained by using genipin as crosslinking agent.

Preparation and characterization of a biocompatible glucose-sensitive electrospun nanofibers scaffolds containing dexamethasone with enhanced osteogenic properties in vitro high glucose environment

Diabetes has made it challenging to repair alveolar bone defects. A successful method for bone repair utilizes a glucose-sensitive osteogenic drug delivery. This study created a new glucose-sensitive nanofiber scaffold with controlled dexamethasone (DEX) release. DEX-loaded polycaprolactone/chitosan nanofibers scaffolds were created using electrospinning. The nanofibers had high porosity (>90%) and proper drug loading efficiency (85.51 ± 1.21%). Then, glucose oxidase (GOD) was immobilized on the obtained scaffolds by a natural biological cross-linking agent, genipin (GnP), after soaking in the mixture solution containing GOD and GnP. The enzyme properties and glucose sensitivity of the nanofibers were investigated. The results showed that GOD was immobilized on the nanofibers and exhibited good enzyme activity and stability. Meanwhile, the nanofibers expanded gradually in response to the increase in glucose concentration, followed by the release of DEX increased. The phenomena indicated that the nanofibers could sense glucose fluctuation and possess favorable glucose sensitivity. In addition, the GnP nanofibers group showed lower cytotoxicity in the biocompatibility test compared with a traditional chemical cross-linking agent. Lastly, the associated osteogenesis evaluation found that the scaffolds effectively promoted MC3T3-E1 cells’ osteogenic differentiation in high-glucose environments. As a result, the glucose-sensitive nanofibers scaffolds offer a viable treatment option for people with diabetes with alveolar bone defects.

L’organisation native de la cellule révélée grâce à la cryo-microscopie à expansion

Most cellular imaging techniques, such as light or electron microscopy, require that the biological sample is first fixed by chemical cross-linking agents. This necessary step is also known to damage molecular nanostructures or even sub-cellular organization. To overcome this problem, another fixation approach was invented more than 40 years ago, which consists in cryo-fixing biological samples, thus allowing to preserve their native state. However, this method has been scarcely used in light microscopy due to the complexity of its implementation. In this review, we present a recently developed super-resolution method called expansion microscopy, which, when coupled with cryo-fixation, allows to visualize at a nanometric resolution the cell architecture as close as possible to its native state.

Preparation and Properties of Carboxymethyl Cellulose / β-Cyclodextrin Hydrogel

Carboxymethyl cellulose (CMC) based hydrogels provide superabsorbent properties but show low mechanical properties. In order to overcome this problem, β-cyclodextrin (CD) is added to improve the mechanical strength of hydrogels. Moreover, CD-containing hydrogels have the potential to encapsulate antimicrobial essential oils or drugs and give a sustained release for medical applications to treat a variety of bacterial infectious diseases causing destruction to human health. In this work, the CMC/CD hydrogels were prepared by using epichlorohydrin as a chemical crosslinking agent. The objective of this research was to study the effect of the CMC/CD weight ratio at 6:1, 7:1, and 8:1 on morphology, mechanical properties and swelling ratio in water of the CMC/CD hydrogels compared with CMC hydrogel. The weight ratio of epichlorohydrin and CMC/CD was constant at 6:1. The morphology analysis of the CMC/CD hydrogels showed an irregular porous structure with the presence of -like structure. The addition of CD content led to an increase in compressive strength whereas the swelling ratio of the hydrogel decreased. The CMC/CD hydrogel at weight ratio of 7:1 provided the highest compressive strength and also retained swelling ability.