Chitosan-based GOx@Co-MOF composite hydrogel: A promising strategy for enhanced antibacterial and wound healing effects.

A novel composite hydrogel was synthesized via Schiff base reaction between chitosan and di-functional poly(ethylene glycol) (DF-PEG), incorporating glucose oxidase (GOx) and cobalt metal-organic frameworks (Co-MOF). The resulting CS/PEG/GOx@Co-MOF composite hydrogel was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS). The results confirmed successful integration and uniform distribution of Co-MOF within the hydrogel matrix. Functionally, the hydrogel exploits the catalytic decomposition of glucose by GOx to generate gluconic acid and hydrogen peroxide (H2O2), while Co-MOF gradually releases metal ions and protects GOx. This synergy enhanced the antibacterial activity of the composite hydrogel against both Gram-positive (S. aureus) and Gram-negative bacteria (E. coli), outperforming conventional chitosan-based hydrogels. The potential of the composite hydrogel in treating wound infections was evaluated through antibacterial and wound healing experiments. Overall, CS/PEG/GOx@Co-MOF hydrogel holds great promise for the treatment of wound infections, paving the way for further research and potential clinical applications.

Polysaccharides as a Hydrophilic Building Block of Amphiphilic Block Copolymers for the Conception of Nanocarriers.

Polysaccharides are gaining increasing attention for their relevance in the production of sustainable materials. In the domain of biomaterials, polysaccharides play an important role as hydrophilic components in the design of amphiphilic block copolymers for the development of drug delivery systems, in particular nanocarriers due to their outstanding biocompatibility, biodegradability, and structural versatility. The presence of a reducing end in polysaccharide chains allows for the synthesis of polysaccharide-based block copolymers. Compared with polysaccharide-based graft copolymers, the structure of block copolymers can be more precisely controlled. In this review, the synthesis methods of polysaccharide-based amphiphilic block copolymers are discussed in detail, taking into consideration the structural characteristics of polysaccharides. Various synthetic approaches, including reductive amination, oxime ligation, and other chain-end modification reactions, are explored. This review also focuses on the advantages of polysaccharides as hydrophilic blocks in polymeric nanocarriers. The structure and unique properties of different polysaccharides such as cellulose, hyaluronic acid, chitosan, alginate, and dextran are described along with examples of their applications as hydrophilic segments in the synthesis of amphiphilic copolymers to construct nanocarriers for sustained drug delivery.

Graphene quantum dot-mediated anchoring of highly dispersed bismuth nanoparticles on porous graphene for enhanced electrocatalytic CO2 reduction to formate.

The electrocatalytic reduction of CO2 to produce formic acid is gaining prominence as a critical technology in the pursuit of carbon neutrality. Nonetheless, it remains challenging to attain both substantial formic acid production and high stability across a wide voltage range, particularly when utilizing bismuth-based catalysts. Herein, we present a novel graphene quantum dot-mediated synthetic strategy to achieve the uniform deposition of highly dispersed bismuth nanoparticles on porous graphene. This innovative design achieves an elevated faradaic efficiency for formate of 87.0% at -1.11 V vs. RHE with high current density and long-term stability. When employing a flow cell, a maximum FEformate of 80.0% was attained with a total current density of 156.5 mA cm-2. The exceptional catalytic properties can be primarily attributed to the use of porous graphene as the support and the auxiliary contribution of graphene quantum dots, which enhance the dispersion of bismuth nanoparticles. This improved dispersion, in turn, has a significantly positive impact on CO2 activation and the generation of *HCOO intermediates to facilitate the formation of formate. This work presents a straightforward technique to create uniform metal nanoparticles on carbon materials for advancing various electrolytic applications.

In situ Hydrogels Prepared by Photo-initiated Crosslinking of Acrylated Polymers for Local Delivery of Antitumor Drugs.

A triblock copolymer was synthesized by ring opening polymerization of ε-caprolactone in the presence of poly(ethylene glycol) (PEG). The resulted PCL-PEG-PCL triblock copolymer, PEG and monomethoxy (MPEG) were functionalized by end group acrylation. NMR and FT-IR analyses evidenced the successful synthesis and functionalization of polymers. A series of photo-crosslinked hydrogels composed of acrylated PEG-PCL-Acr and MPEG-Acr or PEG-Acr were prepared by exposure to visible light using lithium phenyl-2,4,6-trimethylbenzoylphosphinate as initiator. The hydrogels present a porous and interconnected structure as shown by SEM. The swelling performance of hydrogels is closely related to the crosslinking density and hydrophilic content. Addition of MPEG or PEG results in increase in water absorption capacity of hydrogels. In vitro degradation of hydrogels was realized in the presence of a lipase from porcine pancreas. Various degradation rates were obtained which mainly depend on the hydrogel composition. MTT assay confirmed the good biocompatibility of hydrogels. Importantly, in situ gelation was achieved by irradiation of a precursor solution injected in the abdomen of mice. Doxorubicin (DOX) was selected as a model antitumor drug to evaluate the potential of hydrogels in cancer therapy. Drug-loaded hydrogels were prepared by in situ encapsulation. In vitro drug release studies showed a sustained release during 28 days with small burst release. DOX-loaded hydrogels exhibit antitumor activity against A529 lung cancer cells comparable to free drug, suggesting that injectable in situ hydrogel with tunable properties could be most promising for local drug delivery in cancer therapy.

Novel chitosan based metal-organic polyhedrons/enzyme hybrid hydrogel with antibacterial activity to promote wound healing.

This work aimed to develop a novel chitosan based metal-organic polyhedrons (MOPs)/enzyme hybrid hydrogel with superior antimicrobial properties in wound healing treatment. Hybrid hydrogel was prepared by crosslinking glucose oxidase (GOx), vanadium metal-organic polyhedrons (VMOP-2) and chitosan using glutaraldehyde as crosslinker. The formed GVCS hydrogel was characterized by using various techniques, including FTIR, SEM, XPS, TGA and EDX. Data show that GVCS hydrogel was successfully obtained with uniform distribution of GOx and VMOP-2 in the hydrogel structure. Antibacterial tests show that GVCS hydrogel exhibits better bactericidal effect on both gram-negative bacteria (S. aureus) and gram-positive bacteria (E. coli) compared to other hydrogel samples because of its hydroxyl radicals generation capacity in the presence of glucose. MTT assay shows that the hydrogel presents good cell compatibility. In vivo experiments using an infected wound model indicate that GVCS hydrogel can effectively facilitate wound healing. Therefore, chitosan based MOPs/enzyme hybrid hydrogel could be most promising for antibacterial therapy in clinical applications.

Correlations between rheological and mechanical properties of fructo-polysaccharides extracted from Ornithogalum billardieri as biobased adhesive for biomedical applications.

Polysaccharides are extracted from Ornithogalum by maceration using different ultrasound (US) treatment times (0%US, 50%US, 100%US), and under optimized extraction conditions (OP%US). The total carbohydrates content (TCC) and proteins content of the extracts were determined. Data show that the extraction parameters significantly influence the extracts composition. Rheological measurements allowed determining the liquid, intermediate and gel states of the extract's solutions. The adhesion strength of the solutions was evaluated on paper and polylactide (PLA) substrates to evaluate their potential as environmentally friendly adhesive. OP%US presents the highest adhesion strength (1418.3 kPa) on paper, and is further tested on pork skin substrates. The adhesion strength is higher on skin/paper (870 kPa) than on skin/skin (411 kPa) substrate due to the capillary force of paper which allows penetration of adhesive into the micropores of paper. The correlation between rheological properties and adhesion strength indicates that the adhesion strength strongly depends on the state of adhesives and the substrate type. SEM analyses show that higher adhesion strength (intermediate and gel states) involves both cohesive and adhesive failure, whereas only adhesive failure is observed in liquid state on PLA substrates. Therefore, these polysaccharides extracts could be very promising as tissue adhesive in medical applications.

Effect of glucose substitution by low-molecular weight chitosan-derivatives on functional, structural and antioxidant properties of maillard reaction-crosslinked chitosan-based films.

In this study, the effects of different temperatures, incubation times and types of reducing sugars, including glucose and different low molecular weight (Mw) chito-oligosaccharides (COS) with varying acetylation degree (AD), on the extent of Maillard reaction (MR) on chitosan-based films were studied. Interestingly, an improvement of structural and functional properties of all MR-crosslinked films was noted, which is more pronounced by heating at higher temperature and exposure time. These findings were proved through Fourier-transform infrared and X-ray diffraction analyses. In addition, color change and Ultraviolet spectra demonstrate that glucose addition provides the high extent of MR, followed by COS1 (Mw < 4.4 kDa; AD, 18.20%) and COS2 (Mw < 4.4 kDa; AD, 10.63%). These results were confirmed by enhanced water resistance and thermal properties. Moreover, MR-chitosan/COS films showed the highest mechanical properties, whereas, glucose-loaded films were brittle, as demonstrated by scanning electron microscopy micrographs. Furthermore, MR-chitosan/COS1 films exhibited the better antioxidant behavior followed by chitosan/glucose and chitosan/COS2 films, mainly at higher heating-conditions. Thereby, MR-crosslinked chitosan/COS based films were attractive to be applied as functional and active coating-materials in various fields.

Cedrol alleviates the apoptosis and inflammatory response of IL-1ß-treated chondrocytes by promoting miR-542-5p expression.

Cedrol has been shown to exert anti-tumor, anti-inflammatory, and anti-oxidative effects, but its role in osteoarthritis (OA) is unclear. This study aimed to explore the effect of cedrol in OA. Chondrocytes were isolated from newborn rats and cultured in Dulbecco's modified Eagle's medium (DMEM). Then, Alcian blue staining was used to identify the chondrocytes. IL-1ß and cedrol were used to treat chondrocytes. Cell viability and apoptosis were measured by MTT and flow cytometry assays, respectively. The expressions of miR-542-5p, miR-26b-5p, miR-572, miR-138-5p, miR-328-3p, miR-1254, Bcl-2, Bax, iNOS, COX-2, and MMP-13 were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or western blot. NO and PGE2 levels were detected by ELISA. All the cells extracted from the newborn rats were dyed blue, indicating that the cells were chondrocytes. IL-1ß could reduce the viability and promote apoptosis and inflammatory response of chondrocytes, while cedrol could reverse the effect of IL-1ß. In addition, cedrol could significantly increase the expression of miR-542-5p in IL-1ß-treated chondrocytes. Moreover, miR-542-5p inhibitor could partly reverse the effect of cedrol in the apoptosis and inflammation response of chondrocytes. Cedrol alleviated IL-1ß-induced apoptosis and inflammatory response of chondrocytes by promoting miR-542-5p expression.

Biobased dynamic hydrogels by reversible imine bonding for controlled release of thymopentin.

Thymopentin (TP5) is widely used in the treatment of autoimmune diseases, but the short in vivo half-life of TP5 strongly restricts its clinical applications. A series of blank and TP5 loaded hydrogels were synthesized via reversible dual imine bonding by mixing water soluble O-carboxymethyl chitosan (CMCS) with a dynamer (Dy) prepared from Jeffamine and benzene-1,3,5-tricarbaldehyde. TP5 release from hydrogels was studied at 37 °C under in vitro conditions. The molar mass of CMCS, drug loading conditions and drug content were varied to elucidate their effects on hydrogel properties and drug release behaviors. Density functional theory was applied to theoretically confirm the chemical connections between TP5 or CMCS with Dy. All hydrogels exhibited interpenetrating porous architecture with average pore size from 59 to 83 µm, and pH-sensitive swelling up to 10,000% at pH 8. TP5 encapsulation affected the rheological properties of hydrogels as TP5 was partially attached to the network via imine bonding. Higher TP5 loading led to higher release rates. Faster release was observed at pH 5.5 than at pH 7.4 due to lower stability of imine bonds in acidic media. Fitting of release data using Higuchi model showed that initial TP5 release was essentially diffusion controlled. All these findings proved that the dynamic hydrogels are promising carriers for controlled delivery of hydrophilic drugs, and shed new light on the design of drug release systems by both physical mixing and reversible covalent bonding.

Brown seaweed Cystoseira schiffneri as a promising source of sulfated fucans: Seasonal variability of structural, chemical, and antioxidant properties.

A fucoidan, sulfated polysaccharide, was extracted from the brown seaweed Cystoseira schiffneri during 4 harvest periods (December, April, July, and September) and studied for its structural and chemical properties. The Cystoseira schiffneri fucoidan (CSF) showed important variation in sulfate content ranging from 7.8% in December to 34.8% in July. This was confirmed by Fourier transform infrared and nuclear magnetic resonance spectroscopies showing characteristic signals of sulfated polysaccharides. Molecular mass of the CSF varied as a function of season from 3,745 in December to 26,390 Da in July. Gas chromatography-mass spectroscopy showed that CSF fractions were "mannogalactofucans" composed mainly of mannose, fucose, and galactose with low levels of other monosaccharides. Moreover, interesting in vitro antioxidant activities that depend on the harvest season were noted for CSF. Thus, the present work might contribute to establish criteria for extracting bioactive fucoidans from an endemic Tunisian seaweed C. schiffneri.

Development of emulsion gelatin gels for food application: Physicochemical, rheological, structural and thermal characterization.

The current work aimed to prepare emulsion gels based on European eel skin gelatin (ESG). The results revealed that the ESG exhibited interesting antioxidant and functional properties in a dose-dependent manner. The ESG has a gel strength of 354.86 g and high gelling and melting temperatures of about 33 and 43 °C, respectively. Hence, based on its interesting gelling ability, the ESG-based gel was employed to stabilize European eel oil (EO) emulsions. In this context, two emulsions were prepared by homogenization or homogenization followed by sonication at EO:ESG weight ratios of 1:2 and 1:4. The physicochemical, textural, structural and thermal properties of emulsion gelatin-based gels (EGGs) were evaluated. The EGGs had a rigid and a cohesive gel network, according to the textural and microstructural analysis. Structural and thermogravimetric analyses showed the effective entrapment of EO in the ESG gel network.

Nanoparticle-mediated tumor vaccines for personalized therapy: preparing tumor antigens in vivo or ex vivo?

Tumor vaccines, focusing on tailoring individual tumor antigens, have gained much attention in personalized tumor therapy. Recently, breakthroughs have been made in the development of tumor vaccines thanks to the progress in nanotechnology. We will summarize nanoparticle-mediated tumor vaccines for personalized therapy in this review. ROS/heat generating nanoparticles and molecules could induce immunogenic cell death and tumor antigen release in vivo. This strategy often includes chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, magneto-thermal therapy, etc. On the other hand, ex vivo technologies have been applied for processing of tumor cells/tissues to form effective tumor antigens, in which nanotechnology has shown very good prospects in delivering tumor antigens. In in vivo and ex vivo strategies, nanotechnology also could improve the immune effect through enhancing the uptake by targeting cells, reducing therapeutic drugs/agents, further encapsulating immuno-modulatory molecules or combining with other therapy treatments. Thus, therapeutic vaccines based on nanoparticles have the potential to enhance the immune response and reduce the side effects.

Effect of glucose-induced Maillard reaction on physical, structural and antioxidant properties of chitosan derivatives-based films.

This work focused on studying the physicochemical and antioxidant properties changes of varying molecular weight (Mw) chitosan-depolymerization products (CDP)-based films occurring after crosslinking by heat-treatment and Maillard reaction (MR). Based on color properties and browning index, an enhancement of films properties was observed after treatment at 90 °C with a reduction in their water content, solubility and contact angle. Brown MR products were developed in heated films containing glucose thus improving their barrier properties. This effect was more pronounced in lower Mw-CDP based films. In addition, according to TGA, EAB and TS analyses an improvement in heat-treated films thermal stability and mechanical properties was detected and further confirmed through FTIR, X-ray and SEM analyses. The evaluation of the antioxidant potential through four different assays allowed to conclude that glucose addition, thermal treatment and the use of low Mw-CDP highly enhanced the MR-modified films antioxidant capacity. Consequently, MR crosslinked chitosan-based films could be potentially used as an alternative for bioactive and functional packaging effective in food oxidation inhibition, especially using low Mw chitosan derivatives.

Antioxidant Activity and Biocompatibility of Fructo-Polysaccharides Extracted from a Wild Species of Ornithogalum from Lebanon.

The present study aims to investigate the properties of biopolymers extracted from a Lebanese onion non edible plant. The extraction was performed under mild conditions by varying the percentage of ultra-sound (US) treatment duration to a total extraction time of 30 min (0, 50, 100% US). The extracts were characterized using FTIR, SEC, GC-MS, TGA, and DSC analyses. The composition of the extracts was determined from the total carbohydrate content and protein content measurements. The thermal analyses indicate that all samples have high thermal stability. The antioxidant activities of the extracts were investigated, using ß-carotene bleaching, scavenging activity of ABTS, metal chelating ability, and total antioxidant activity tests. The results indicate that the 50% US treatment leads to the best antioxidant activity. Biocompatibility of the extracts was evaluated using hemolysis and cytotoxicity assays. The results showed that 0 and 50% US samples are not toxic to human cells, in contrary to 100% US.

Development of delivery system based on marine chitosan: Encapsulationand release kinetic study of antioxidant peptides from chitosan microparticle.

The present work aims to encapsulate goby fish protein hydrolysate (GPH), endowed with antioxidant activity, through ionic gelation process using blue crab chitosan (CH) and tripolyphosphate anions and to evaluate the structural, thermal and antioxidant properties of the elaborated microparticles (MPs). The GPH-loaded MPs present spherical shape as seen by scanning electron microscopy (SEM) images and positive zeta potential. The increase of loaded GPH concentration led to the increase of encapsulation efficiency (EE) and to the reduction of the particle size. In fact, MPs, loaded with 2 and 5 mg/ml GPH, had EE values of 44 and 58% and mean particles size of 4.81 and 3.78 µm, respectively. Furthermore, thermogravimetric analysis (TGA) profiles revealed the enhanced thermal stability of encapsulated biopeptides compared to the free ones. Release kinetic data showed a Fickian diffusion behavior which follows swelling and a diffusion-controlled mechanism for peptides liberation. Finally, as opposed to unloaded MPs, an improvement of the antioxidant activity of the loaded MPs with biopeptides was observed.

Anti-bacterial dynamic hydrogels prepared from O-carboxymethyl chitosan by dual imine bond crosslinking for biomedical applications.

Imine dynamic hydrogels are synthesized via dual-imine bond crosslinking from O-carboxymethyl chitosan (CMCS) and a water soluble dynamer using a 'green' approach. Three dynamers are prepared through reaction of benzene-1,3,5-tricarbaldehyde and di-amino Jeffamine with molar mass of 500, 800 and 1900, respectively. Hydrogels, namely H500, H800 and H1900 are then obtained by mixing CMCS and dynamer aqueous solutions. FT-IR confirms the formation of hydrogels via imine bonding. H1900 presents larger pore size and higher storage modulus as compared to H500 and H800 due to the higher molar mass of Jeffamine linker. The hydrogels exhibit pH sensitive swelling behavior due to electrostatic attraction or repulsion in the pH range from 3 to 10. The highest swelling ratio is obtained at pH 8, reaching 7500% for H800. Self-healing of hydrogels is evidenced by rheological measurements with alternatively applied low and high strains, and by using a macroscopic approach with re-integration of injected filaments. Furthermore, the H1900 membrane exhibits outstanding antibacterial activity against an E. coli suspension at 108 CFU mL-1. Therefore, dynamic hydrogels synthesized from CMCS and Jeffamine present outstanding rheological, swelling, self-healing and antibacterial properties, and are most promising as healthcare material in wound dressing, drug delivery and tissue engineering.

Dynamic Hydrogels Based on Double Imine Connections and Application for Delivery of Fluorouracil.

Dynamic hydrogels have been prepared by cross-linking of O-carboxymethyl chitosan (O-CMCS) with reversibly connected imino-PEGylated dynamers. The double imine chitosan/dynamer and dynamer bonds and were used to provide tighter structures and adaptive drug release behaviors of the hydrogels. The structural and physical properties of the resulted hydrogels were examined, showing good thermal stability and higher swelling behaviors (up to 3,000%). When hydrogels with various composition ratios were further applied for delivery of anti-cancer drug fluorouracil (5-FU), high drug encapsulation rates were recorded, up to 97%. The release profile of 5-FU showed fast rate at the beginning, followed by slow increase to the maximum amount within 12 h, demonstrating potential as drug carriers for efficient drug delivery.

Synthesis of Block Copolymer Brush by RAFT and Click Chemistry and Its Self-Assembly as a Thin Film.

A well-defined block copolymer brush poly(glycidyl methacrylate)-graft-(poly(methyl methacrylate)-block- poly(oligo(ethylene glycol) methyl ether methacrylate)) (PGMA-g-(PMMA-b-POEGMA)) is synthesized via grafting from an approach based on a combination of click chemistry and reversible addition-fragmentation chain transfer (RAFT) polymerization. The resulting block copolymer brushes were characterized by 1H-NMR and size exclusion chromatography (SEC). The self-assembly of the block copolymer brush was then investigated under selective solvent conditions in three systems: THF/water, THF/CH3OH, and DMSO/CHCl3. PGMA-g-(PMMA-b-POEGMA) was found to self-assemble into spherical micelle structures as analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The average size of the particles was much smaller in THF/CH3OH and DMSO/CHCl3 as compared with the THF/water system. Thin film of block copolymer brushes with tunable surface properties was then prepared by the spin-coating technique. The thickness of the thin film was confirmed by scanning electron microscopy (SEM). Atom force microscopy (AFM) analysis revealed a spherical morphology when the block copolymer brush was treated with poor solvents for the backbone and hydrophobic side chains. The contact angle measurements were used to confirm the surface rearrangements of the block copolymer brushes.

Complicated appendicitis are common during the epidemic period of 2019 novel coronavirus (2019-nCoV).

OBJECTIVES: To assess the prevalence of complicated appendicitis (including gangrene, abscess and perforation) after the outbreak of the 2019-nCoV epidemic and to identify the risk factors associated with complicated appendicitis. METHODS: Two groups were established in the study consisting of: one group for cases of acute appendicitis before the 2019-nCoV epidemic (before January 1, 2020; pre-epidemic group) and another group for those after the epidemic outbreak (after January 1, 2020; epidemic group). These two groups were compared in terms of demographic and clinical characteristics, prevalence of complicated appendicitis, and treatment intention. A multivariate analysis model using binary logistic regression was constructed. RESULTS: A total of 163 patients were included in this study, with 105 in the pre-epidemic group and 58 in the epidemic group. In the epidemic group, the interval from the onset of symptoms to admission was 65.0 h, which is significantly longer than the 17.3 h interval noted in the pre-epidemic group (P < 0.001). The prevalence of complicated appendicitis after the epidemic outbreak was significantly higher than before the outbreak (51.7% vs. 12.4%, P < 0.001). In addition, the epidemic group had a lower score of patient's intention to seek treatment than the pre-epidemic group (9.5 ± 2.7 vs. 3.4 ± 2.6, P < 0.001). Based on the multivariate analysis, the risk factors for complicated appendicitis included the time from symptoms onset to admission (OR = 1.075) and the patients' intention to receive treatment (OR = 0.541). CONCLUSION: Complicated appendicitis was more common in patients with acute appendicitis after the outbreak of the 2019-nCoV epidemic.

Sardinelle protein isolate as a novel material for oil microencapsulation: Novel alternative for fish by-products valorisation.

The present study investigates the potential of sardinelle protein isolate (SrPI) combined to maltodextrin (MD), at different ratios (1:0, 1:1, 1:2, 1:3 and 1:4, w/w), as wall matrix to stabilize and encapsulate corn oil (1:2, oil/ wall material ratio). Emulsions were prepared by homogenization followed by sonication treatment and then dried by the spray-drying process. The obtained microcapsules were characterized regarding the encapsulation efficiency (EE), scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and thermodynamic analyses (thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC)). Data revealed that the combination of SrPI and MD resulted in very high EE compared to SrPI used alone as wall material, and the EE increased with the amount of MD incorporated to the SrPI solution. SEM images showed the production of irregular and larger particles with the increase of MD concentration. Moreover, TGA showed that microparticles obtained by 1:4 w/w ratio (SrPI/MD) displayed the highest protection of corn oil. Thus, these findings revealed the effectiveness of SrPI and MD mixture to encapsulate and protect corn oil, which offered a promote application for food and pharmaceutical industries.