Freeze-drying Method Research Articles

Effects of vacuum microwave combined with freeze-drying on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices.

The effects of freeze-drying (FD), vacuum microwave drying after freeze-drying (FD-VMD), and freeze-drying after vacuum microwave drying (VMD-FD) on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices were investigated. The results showed that FD samples had the highest crispness value (116.30 N·sec) and the lowest volume shrinkage ratio value (5.48%). Compared to FD, the VMD-FD and FD-VMD methods could save drying time without affecting the color of dried samples. FD-VMD samples had the lowest rehydration capacity and maintained a homogeneous porous structure, while the VMD-FD samples had obvious collapse. Compared to VMD-FD samples, FD-VMD samples had higher contents of ascorbic acid (20.91 mg/100 g), total phenolic (7.62 mg/g), total anthocyanin (0.21 mg/g), and gallic acid (1.21 µg/g). Moreover, FD-VMD samples showed the highest antioxidant capacity as evaluated by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging capacity, and H2 O2 content. Compared with FD and VMD-FD, FD-VMD was most effective in maintaining better quality and shortening drying time of pear fruit slices. These findings suggested that FD-VMD might be a promising drying technique in the fruits and vegetable processing industries.

Cost effective synthesis hetero-structured N-doped C-coated Ni9S8/Ni3S2/NiS1.03 nanoparticles attached on 3D reduced graphene oxide anode to exceptional Li-ion performance

In this study, nitrogen all-doped carbon-coated Ni9S8/Ni3S2/NiS1.03 (NixSy) particles with homogeneous bonds to 3D reduced graphene oxide sheets (N-NixSy@C/G) were synthesized via a using the facile hydrothermal, freeze-drying and subsequent calcination method. In this structure, the carbon layer derived from glucose was highly uniformly dispersed in an Ar atmosphere, such that the structural stability is enhanced and the volume expansion of NixSy is effectively mitigated. The Ni9S8, Ni3S2 and NiS1.03 nanoparticles were formed effectively facilitated under the existence of glucose. In situ nitrogen doping was achieved by the presence of urea containing nitrogen, such as electron conductivity was increased and fast ion intercalation was facilitated. The structural stability and cyclability can be ensured for the high flexibility and structural strength of the reduced graphene oxide wrapping layer. Under the synergistic effect exerted by the three modules, N-NixSy@C/G was further endowed with high electrical conductivity, large specific surface area as well as abundant electrochemical reaction sites. On that basis, the N-NixSy@C/G anode that was employed in the lithium-ion batteries exhibited superior rate capability and ultra-high reversible capacity (826.3 mAh g−1 at 0.5 A g−1). The capacity was kept at 703 mAh g−1 and the coulombic efficiency reached 100% after 1000 cycles at a current density of 2 A g−1. This study may contribute to the creation of a distinctive avenue for designing quick and high-capacity metal sulfide anodes and boost the growth of high-performance lithium batteries.

Nanosilver alleviates foreign body reaction and facilitates wound repair by regulating macrophage polarization.

Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds. This study explores the application of nanosilver (NAg) to reduce foreign body reactions during scaffold transplantation. An NAg hybrid collagen-chitosan scaffold (NAg-CCS) was prepared using the freeze-drying method. The NAg-CCS was implanted on the back of rats to evaluate the effects on foreign body reactions. Skin tissue samples were collected for histological and immunological evaluation at variable intervals. Miniature pigs were used to assess the effects of NAg on skin wound healing. The wounds were photographed, and tissue samples were collected for molecular biological analysis at different time points post-transplantation. NAg-CCS has a porous structure and the results showed that it could release NAg constantly for two weeks. The NAg-CCS group rarely developed a foreign body reaction, while the blank-CCS group showed granulomas or necrosis in the subcutaneous grafting experiment. Both matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were reduced significantly in the NAg-CCS group. The NAg-CCS group had higher interleukin (IL)-10 and lower IL-6 than the blank CCS group. In the wound healing study, M1 macrophage activation and inflammatory-related proteins (inducible nitric oxide synthase (iNOS), IL-6, and interferon-‍γ (IFN-‍γ)) were inhibited by NAg. In contrast, M2 macrophage activation and proinflammatory proteins (arginase-1, major histocompatibility complex-II (MHC-II), and found in inflammatory zone-1 (FIZZ-1)) were promoted, and this was responsible for suppressing the foreign body responses and accelerating wound healing. In conclusion, dermal scaffolds containing NAg suppressed the foreign body reaction by regulating macrophages and the expression of inflammatory cytokines, thereby promoting wound healing.

Effects of osmotic dehydration pre-treatment on process and quality of freeze-dried strawberries (Fragaria x ananassa var. Mencir)

The freeze-drying of fruits is one alternative to increase the added value of fresh fruit, extend the shelf life which the product, and still have properties like fresh fruit. Osmotic dehydration pre-treatment can be applied before drying techniques to produce a new product, maintain nutritional and sensory quality, and improve the drying process. In this research, the effects of osmotic dehydration on freeze-drying performance and the quality characteristics of freeze-dried strawberries were evaluated. Freeze-dried strawberries were made using fresh strawberries without pre-treatments and pre-treatments by osmotic dehydration (OD) with the freeze-drying method. The treatment of materials and processes used were the duration of storage in the freezer of 36 to 48 h; vertically cutting strawberry before OD; osmotic dehydration agents with a concentration of 50°Brix; immersion time for 30 min at temperature a 30°C; and freeze-drying time of 24 h. Results of each treatment in terms of physical quality parameters (color of skin fruit (L*a*b*), change of color (ΔE), and hardness) and phytochemical quality parameters (water content, vitamin C, total phenolic content, and antioxidant activity by DPPH) were compared and discussed. The osmotic dehydration process causes a water loss of 13%, has a significant difference on the parameters of colors (redness and color of change), hardness, vitamin C, total phenolic content, and antioxidant activity by DPPH.

DOE supported optimization of biodegradable polymeric nanoparticles based dry powder inhaler for targeted delivery of afatinib in non-small cell lung cancer

Poly (lactic-co-glycolic acid) (PLGA) based nanoparticles are increasingly being used to deliver anticancer agents directly to the lungs. This approach offers targeted delivery of the drug, which minimizes the risk of side effects associated with oral administration. Afatinib-loaded PLGA nanoparticles were fabricated with a double emulsification solvent evaporation method and optimized by a factorial design (32) approach. The optimized batch of afatinib-loaded polymeric nanoparticles exhibited suitable entrapment efficiency (78.15 ± 2.20% w/w), drug loading (3.90 ± 0.11% w/w), particle size (198.1 ± 3.5 nm), and zeta potential (−0.519 ± 0.197 mV). A dry powder-based inhaled drug delivery platform is rapid-acting, handy, and self-administered that is expected to enhance patient compliance. The lyophilization method was used to convert afatinib-loaded PLGA nanoparticles into dry powder form. The formulated afatinib-loaded PLGA nanoparticles dry powder inhaler (PLGA NDPI) demonstrated good flow properties with 77.86 ± 3.02% drug content and 6.883 ± 0.369 μm particle size distribution. With more than 85% of the dosage released from an inhaler device in the eight-stage cascade impactor through an in-vitro lung deposition investigation, the particles also proved their capacity to penetrate the deeper area of the lung. Further, the in-vitro drug release study demonstrated more than 80% drug release from PLGA NDPI at different pH of phosphate buffer solutions. A549 adenocarcinoma cell line cytotoxicity investigation revealed that PLGA NDPI has a stronger potential for suppressing tumour cell proliferation than pure drug solution. Fluorescein isothiocyanate (FITC) encapsulated afatinib PLGA NDPI formulation was more effectively absorbed intracellularly by adenocarcinoma cells than plain FITC dye. Taken together, the results suggest that, the formulated afatinib PLGA NDPI can be a promising approach for targeted lung delivery of the anticancer agent.

Bilayer Silk Fibroin/Sodium Alginate Scaffold Delivered hUC-MSCs to Enhance Skin Scarless Healing and Hair Follicle Regeneration with the IRE1/XBP1 Pathway Inhibition.

Efficient local delivery of mesenchymal stem cells (MSCs) is a decisive factor for their application in regeneration processes. Here, we prepared a biomimetic bilayer silk fibroin/sodium alginate (SF/SA) scaffold to deliver human umbilical mesenchymal stem cells (hUC-MSCs) for wound healing. An SA membrane was prepared by the casting method on the upper layer of the scaffold to simulate the dense epidermal structure. On the lower layer, porous materials simulating the loose structure of the dermis were formed by the freeze-drying method. In vitro, the scaffold was proven to have a high-density pore structure, good swelling property, and suitable degradation rate. The hUC-MSCs could survive on the scaffold for up to 14 days and maintain cell stemness for at least 7 days. In vivo, SF/SA scaffolds loaded with hUC-MSCs (M-SF/SA) were applied to full-thickness defect wounds and compared with the local injection of hUC-MSCs. The M-SF/SA group showed excellent therapeutic efficacy, characterized by induction of macrophage polarization, regulation of TGF-β expression and collagen components, and enhancement of vascular regeneration, thereby preventing scar formation and promoting hair follicle regeneration. Furthermore, the expression of endoplasmic reticulum stress markers IRE1, XBP1, and CHOP was inhibited significantly in M-SF/SA treatment. In conclusion, the bilayer SF/SA scaffold is an ideal delivery platform for hUC-MSCs, and the M-SF/SA system could locally promote scarless skin healing and hair follicle regeneration by alleviating the IRE1/XBP1 signal pathway.

Cepharanthine Dry Powder Inhaler for the Treatment of Acute Lung Injury.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) induces a severe cytokine storm that may cause acute lung injury/acute respiratory distress syndrome (ALI/ARDS) with high clinical morbidity and mortality in infected individuals. Cepharanthine (CEP) is a bisbenzylisoquinoline alkaloid isolated and extracted from Stephania cepharantha Hayata. It exhibits various pharmacological effects, including antioxidant, anti-inflammatory, immunomodulatory, anti-tumor, and antiviral activities. The low oral bioavailability of CEP can be attributed to its poor water solubility. In this study, we utilized the freeze-drying method to prepare dry powder inhalers (DPI) for the treatment of acute lung injury (ALI) in rats via pulmonary administration. According to the powder properties study, the aerodynamic median diameter (Da) of the DPIs was 3.2 μm, and the in vitro lung deposition rate was 30.26; thus, meeting the Chinese Pharmacopoeia standard for pulmonary inhalation administration. We established an ALI rat model by intratracheal injection of hydrochloric acid (1.2 mL/kg, pH = 1.25). At 1 h after the model's establishment, CEP dry powder inhalers (CEP DPIs) (30 mg/kg) were sprayed into the lungs of rats with ALI via the trachea. Compared with the model group, the treatment group exhibited a reduced pulmonary edema and hemorrhage, and significantly reduced content of inflammatory factors (TNF-α, IL-6 and total protein) in their lungs (p < 0.01), indicating that the main mechanism of CEP underlying the treatment of ALI is anti-inflammation. Overall, the dry powder inhaler can deliver the drug directly to the site of the disease, increasing the intrapulmonary utilization of CEP and improving its efficacy, making it a promising inhalable formulation for the treatment of ALI.

Effect of Selected Crosslinking and Stabilization Methods on the Properties of Porous Chitosan Composites Dedicated for Medical Applications.

Chitosan is one of the most commonly employed natural polymers for biomedical applications. However, in order to obtain stable chitosan biomaterials with appropriate strength properties, it is necessary to subject it to crosslinking or stabilization. Composites based on chitosan and bioglass were prepared using the lyophilization method. In the experimental design, six different methods were used to obtain stable, porous chitosan/bioglass biocomposite materials. This study compared the crosslinking/stabilization of chitosan/bioglass composites with ethanol, thermal dehydration, sodium tripolyphosphate, vanillin, genipin, and sodium β-glycerophosphate. The physicochemical, mechanical, and biological properties of the obtained materials were compared. The results showed that all the selected crosslinking methods allow the production of stable, non-cytotoxic porous composites of chitosan/bioglass. The composite with genipin stood out with the best of the compared properties, taking into account biological and mechanical characteristics. The composite stabilized with ethanol is distinct in terms of its thermal properties and swelling stability, and it also promotes cell proliferation. Regarding the specific surface area, the highest value exposes the composite stabilized by the thermal dehydration method.

The critical role of Ga doped Cu/Al2O3 aerogels in carbon monoxide suppression during steam reforming of methanol

Steam reforming of methanol is an effective method for providing high-purity hydrogen to polymer electrolyte membrane fuel cells, however, this technology still faces the challenge of high CO selectivity. Herein, a series of Ga2O3/Cu/Al2O3 aerogels with different Ga doping (0–50 wt%) were synthesized through freeze-drying assisted sol-gel method. Experimental studies verify that 20GaCuAl exhibits the best performance, which achieves 100% methanol conversion with no CO production. It is demonstrated that Ga doping facilitates the formation of smaller Cu crystalline size, which improves the affinity of catalyst to CO, thus inhibiting CO formation. Results also indicate that the aerogel materials have larger specific surface area and porosity, which is conducive to the homogeneous distribution of the active sites, the intensified diffusion of reactant molecules, and the suppression of their sintering and agglomeration. The methanol reforming performance, especially for CO suppression capability and long-term durability, can be comprehensively promoted, attributing to the synergy of Ga doping and aerogel material fabrication. In situ DRIFTS results illustrate that SRM on Ga2O3/Cu/Al2O3 aerogel undergoes the following process: CH3OH → CH3O* → HCHO→ monodentate HCOOH→ H2 and CO2. The strong absorbed monodentate formate is to the benefit of water-gas shift reaction, thus hindering the generation of CO.

Preparation, characterization, and application of cationic xylan-based aerogel

Adsorption is one of the most significant approaches for treatment of wastewater. An adsorbent with high mechanical strength, good renewability, and high efficiency is expected for practical applications. In this paper, a cationic xylan-based aerogel composed of xylan, polyvinyl alcohol, and agarose was fabricated to adsorb pectin, which is a typical anionic trash substance in the papermaking white water. The freeze-drying method was used to prepare the aerogel. A cationic xylan-based aerogel with high mechanical strength (34.676 MPa at 50% strain) was obtained. FT-IR results illustrated that the hydrogen bonds between three components contributed to the formation of aerogels. The addition of cationic xylan led to a slight decrease of crystallinity and thermostability of the aerogels. The maximum adsorption capacity of anionic pectin was 19.52 mg/g. Moreover, the aerogels maintained a high pectin-adsorption capacity after five recycles. This new cationic xylan-based aerogel offers potential possibilities for the development of value-added hemicellulose-based materials and the purification of papermaking white water in practical applications.

Anisotropic Polyimide/Cellulose Nanofibril Composite Aerogels for Thermal Insulation and Flame Retardancy

In this study, we report a series of lightweight, anisotropic polyimide/cellulose nanofibril (PI/CNF) composite aerogels with outstanding thermal insulation and flame retardancy via unidirectional drying and freeze drying methods. Along the axial direction, PI/CNF composite aerogels exhibit an arranged tube-like structure in parallel to ice crystal growth, thus providing superior mechanical properties. Conversely, the composite aerogels show a honeycomb-like pore structure along the radial direction, exhibiting excellent elastic properties. More importantly, the addition of CNF endows the composite aerogels with low thermal conductivity along the radial direction. The surface temperature of the composite aerogels with a thickness of 15 mm is 70% lower than that of hot stage annealing at 180 °C for 60 min. Furthermore, the composite aerogels show flame retardant and self-extinguishing performance in the combustion experiment. Therefore, the anisotropic PI/CNF composite aerogels with thermal insulation and flame retardancy are promising for expanding potential applications in aerospace fields.

Facile synthesis of corn stalks-derived carbon aerogels: Characterization, adsorption of ciprofloxacin and energy storage applications

Cellulose aerogels were fabricated from the corn stalks-derived cellulose with poly(vinyl alcohol) (PVA) as a binding agent. The aerogel structure was constructed via the freeze-drying method and then carbon aerogels (CA) were obtained via carbonization under inert gas at 700 °C. The results showed that the CA has an amorphous structure with high porosity (> 96%). Therewithal, the adsorption capacity of the CA materials was evaluated with ciprofloxacin, a persistent antibiotic. As a consequence, it is indicated that CA1 with the precursors' ratio of cellulose:PVA (5:1) performs the highest adsorption efficiency with a maximum capacity of 99.01 mg/g. The process was determined to be chemical adsorption following the Langmuir isotherm model with the investigated initial concentration in the range of 25 − 100 mg/L for ciprofloxacin. Moreover, the electrochemical properties were determined through electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge. Resultantly, the highest capacity reached 326.51 F/g at the scanning rate of 0.005 in the potential region of -0.5 to 0.5 V, corresponding to the CA3 sample with the cellulose:PVA ratio of 15:1. Furthermore, after 1000 continuous scanning cycles, the CA3 shows insignificant changes in the GCD curve, which depicts high stability as a supercapacitor. Besides, the safety of the prepared CA in energy storage application was also confirmed via the insignificant inhibitory performance on two strains of Gram-positive and Gram-negative bacteria. The aforementioned results reveal that the CA from corn stalks is potentially applicable in environmental remediation and suitable material in supercapacitors for energy storage.

Cellulose-based evaporator with dual boost of water transportation and photothermal conversion for highly solar-driven evaporation

Two-dimensional (2D) evaporation systems could significantly reduce the heat conduction loss compared with the photothermal conversion materials particles during the evaporation process. But the normal layer-by-layer self-assembly method of 2D evaporator would reduce the water transportation performance due to the highly compact channel structures. Herein, in our work, the 2D evaporator with cellulose nanofiber (CNF), Ti3C2Tx (MXene) and polydopamine modified lignin (PL) by layer-by-layer self-assembly and freeze-drying methods. The addition of PL also enhanced the light absorption and photothermal conversion performance of the evaporator due to the strong conjugation and π-π molecular interactions. After the combination process of layer-by-layer self-assembly and freeze-drying process, the as-prepared freeze-dried CNF/MXene/PL (f-CMPL) aerogel film exhibited highly interconnected porous structure with promoted hydrophilicity (enhanced water transportation performance). Benefiting these favorable properties, the f-CMPL aerogel film showed enhanced light absorption performance (surface temperature could be reached to 39 °C under 1 sun irradiation) and higher evaporation rate (1.60 kg m−2 h−1). This work opens new way to fabricate cellulose-based evaporator with highly evaporation performance for the solar steam generation and provides a new idea for improving the evaporation performance of 2D cellulose-based evaporator.

Cellulose Nanofibers/PEDOT:PSS Conductive Aerogel for Pressure Sensing Prepared by a Facile Freeze-Drying Method

The application of flexible wearable pressure sensors in the fields of pressure sensing, electronic skin, and human health monitoring has attracted a lot of attention. Herein, cellulose-nanofiber (CNF)-based aerogels with conducting polymer poly(3,4-ethylene dioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) and glutaraldehyde (GA) as cross-linking agent were designed and prepared by sol–gel cross-linking and freeze-drying. Without any special treatment, these aerogels presented good flexibility and piezoresistive properties. As the analysis of SEM, Raman spectrum, and XPS, the introduction of GA not only improves the mechanical properties of aerogel (the compressive strength at 80% strain has increased from 48 to 66 kPa) but also affects the doping state of PEDOT, which improves the sensitivity of aerogel (from 10.65 to 15.18 kPa–1). In addition, the sensor has been successfully applied to monitor human movements, including not only large movements (joint movements) but also small-scale muscle movements (cheek puffing and articulation recognition). It shows its potential as a widely used green pressure sensor.

Cellulose nanofiber/MXene/luffa aerogel for all-weather and high-efficiency cleanup of crude oil spills

The remediation of heavy crude oil spills is a global challenge because frequent crude oil spills cause long-term damage to local living beings and marine ecosystems. Herein, a solar-driven and Joule-driven self-heated aerogel were developed as an all-weather adsorbent to efficiently absorb crude oil by obviously decreasing the viscosity of crude oil. The cellulose nanofiber (CNF)/MXene/luffa (CML) aerogel was fabricated via a simple freeze-drying method using CNF, MXene, and luffa as raw materials, and then coated with a layer of polydimethylsiloxane (PDMS) to make it hydrophobic and further increase oil-water selectivity. The aerogel can quickly reach 98 °C under 1 sun (1.0 kW/m2), which remains saturated temperature after 5 times photothermal heating/cooling cycles, indicating that the aerogel has great photothermal conversation capability and stability. Meanwhile, the aerogel can also rapidly rise to 110.8 °C with a voltage of 12 V. More importantly, the aerogel achieved the highest temperature of 87.2 °C under outdoor natural sunlight, providing a possibility for promising applications in practical situations. The remarkable heating capability enables the aerogel to decrease the viscosity of crude oil substantially and increase the absorption rate of crude oil by the physical capillary action. The proposed all-weather aerogel design provides a sustainable and promising solution for cleaning up crude oil spills.

Down Fiber Reinforced Cellulose Nanofiber Aerogel toward Thermal Insulation and Pollutant Removal

Cellulose nanofiber (CNF) aerogels have the advantages of being eco-friendly, hydrophilic, and biocompatible and of having high porosity and large surface area. but low mechanical durability is a main challenge. In this regard, we proposed to fabricate a DF-x/CNF-y composite aerogel through a directional freeze-drying method using down fiber (DF) as the reinforcing filler and 1,2,3,4-butanetetracarboxylic acid (BTCA) as the cross-linking agent. Due to the good compatibility between DF and CNF, DF could effectively improve the strength of a composite aerogel by dispersing stress along the pore wall. The DF-x/CNF-y composite aerogel had significant longitudinal and transversal mechanical properties. The presence of DF in the matrix promoted crystal nucleation and provided a large surface area for crystal growth, which improved thermal stability and thermal insulation performances of the composite aerogel. The capillary effect of hollow DF and the interaction between DF and CNF significantly enhanced the DF-x/CNF-y composite aerogel adsorption performance. Methylene blue (MB) was chosen as a model pollutant. The removal rate of MB correlated well with the pseudo-second-order kinetics and Langmuir model (R2 [0.9999]), its maximum adsorption capacity for MB reached up to ∼250.21 mg/g. This work provides a strategy for the fabrication of a composite aerogel, which might have potential application prospects such as space, infrared stealth, water purification, and chemical contaminant remediation.

Three-Dimensional Graphene Aerogel Supported on Efficient Anode Electrocatalyst for Methanol Electrooxidation in Acid Media

This work attempted to improve the catalytic performance of an anodic catalyst for use in direct methanol fuel cells by coating graphene aerogel (GA) with platinum nanoparticles. A hydrothermal, freeze-drying, and microwave reduction method were used to load Pt–Ru bimetallic nanoparticles onto a graphene aerogel. The mesoporous structure of a graphene aerogel is expected to enhance the mass transfer in an electrode. XRD, Raman spectroscopy, SEM, and TEM described the as-synthesized PtRu/GA. Compared to commercial PtRu/C with the same loading (20%), the electrocatalytic performance of PtRu/GA presents superior stability in the methanol oxidation reaction. Furthermore, PtRu/GA offers an electrochemical surface area of 38.49 m2g−1, with a maximal mass activity/specific activity towards methanol oxidation of 219.78 mAmg−1/0.287 mAcm−2, which is higher than that of commercial PtRu/C, 73.11 mAmg−1/0.187 mAcm−2. Thus, the enhanced electrocatalytic performance of PtRu/GA for methanol oxidation proved that GA has excellent potential to improve the performance of Pt catalysts and tolerance towards CO poisoning.

Egyptian propolis extract for functionalization of cellulose nanofiber/poly(vinyl alcohol) porous hydrogel along with characterization and biological applications

Bee propolis is one of the most common natural extracts and has gained significant interest in biomedicine due to its high content of phenolic acids and flavonoids, which are responsible for the antioxidant activity of natural products. The present study report that the propolis extract (PE) was produced by ethanol in the surrounding environment. The obtained PE was added at different concentrations to cellulose nanofiber (CNF)/poly(vinyl alcohol) (PVA), and subjected to freezing thawing and freeze drying methods to develop porous bioactive matrices. Scanning electron microscope (SEM) observations displayed that the prepared samples had an interconnected porous structure with pore sizes in the range of 10–100 μm. The high performance liquid chromatography (HPLC) results of PE showed around 18 polyphenol compounds, with the highest amounts of hesperetin (183.7 µg/mL), chlorogenic acid (96.9 µg/mL) and caffeic acid (90.2 µg/mL). The antibacterial activity results indicated that both PE and PE-functionalized hydrogels exhibited a potential antimicrobial effects against Escherichia coli, Salmonella typhimurium, Streptococcus mutans, and Candida albicans. The in vitro test cell culture experiments indicated that the cells on the PE-functionalized hydrogels had the greatest viability, adhesion, and spreading of cells. Altogether, these data highlight the interesting effect of propolis bio-functionalization to enhance the biological features of CNF/PVA hydrogel as a functional matrix for biomedical applications.

Advanced phosphocreatine-grafted chitosan hydrogel promote wound healing by macrophage modulation.

Background: The repair of wounds usually caused by trauma or other chronic diseases remained challenging in clinics due to the potential risk of inflammation and inadequate tissue regenerative properties. Among them, the behaviour of immune cells, such as macrophages, is critical in tissue repair. Materials and methods: In this study, a water-soluble phosphocreatine-grafted methacryloyl chitosan (CSMP) was synthesized with a one-step lyophilization method, followed by the fabrication of CSMP hydrogel with a photocrosslinked method. The microstructure, water absorption and mechanical properties for the hydrogels were investigated. Then, the macrophages were co-cultured with hydrogels and the pro-inflammatory factors and polarization markers for these macrophages were detected through real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), and flow cytometry methods. Finally, the CSMP hydrogel was implanted in a wound defect area in mice to test its ability to promote wound healing. Results: The lyophilized CSMP hydrogel had a porous structure with pores ranging in size from 200 to 400μm, which was larger than the CSM hydrogel's. The lyophilized CSMP hydrogel possessed a higher water absorption rate compared with the CSM hydrogel. The compressive stress and modulus of these hydrogels were increased in the initial 7days immersion and then gradually decreased during the in vitro immersion in PBS solution up to 21days; the CSMP hydrogel showed a higher value in these parameters versus the CSM hydrogel. The CSMP hydrogel inhibited the expression of inflammatory factors such as interleukin-1β (IL-1β), IL-6, IL-12, and tumor necrosis factor-α (TNF-α) in an in vitro study cocultured with pro-inflammatory factors in pre-treated bone marrow-derived macrophages (BMM). The mRNA sequencing results showed that the CSMP hydrogel might inhibit the macrophages' M1 type polarization through the NF-κB signaling pathway. Furthermore, when compared to the control group, the CSMP hydrogel promoted more skin area repair in the mouse wound defect area, and inflammatory factors such as IL-1β, IL-6, and TNF-α were lower in the repaired tissue for the CSMP group. Conclusion: This phosphate-grafted chitosan hydrogel showed great promise for wound healing through regulating the macrophage's phenotype via the NF-κB signaling pathway.

Microencapsulation of Chia Oil Using Whey Protein and Gum Arabic for Oxidation Prevention: A Comparative Study of Spray-Drying and Freeze-Drying Methods

Encapsulation is one of the most widely utilized strategies for preventing oil oxidation. Chia oil is a source of oils that are high in omega-3s and was used as a core material in this study. Whey protein and gum arabic were used as wall materials, and the whey protein:gum arabic ratios were 1:0, 1:1, 1:2, 2:1, 1:3 and 3:1. Preparation of chia oil microcapsules was conducted by spray-drying or freeze-drying methods. All microcapsules were stored in an opaque and airtight laminate pouch for 3 and 6 months to determine the effect of time on the fatty acid composition, encapsulation efficiency and chemical properties. Encapsulation had a positive protective effect on oil quality. The two drying methods resulted in different powder characteristics: spray drying resulted in a spherical shape, whilst freeze drying led to flakes and a porous surface. Spray drying microcapsules resulted in greater encapsulation efficiency than freeze drying microcapsules. In addition, encapsulated powders stored for 6 months showed both acid and peroxide values below the Codex limit. These results indicate a possible encapsulation process to protect chia oil from oxidation.