Chitosan/alginate crosslinked hydrogels: Preparation, characterization and application for cell growth purposes

Poly(allylamine)-adorned heptylcarboxymethyl galactomannan nanocarriers of canagliflozin for controlling type-2 diabetes: Optimization by Box-Behnken design and in vivo performance

In the past three decades, the prevalence of type-2 diabetes has arisen dramatically in countries of all income levels. A novel, most effective nanotechnology-based strategy may reduce the prevalence of diabetes. Recently, the shell-crosslinked polysaccharide-based micellar nanocarriers (MNCs) have shown great promise in terms of stability, controlled drug release, and improved in vivo performance. In this study, heptyl carboxymethyl guar gum was synthesized and characterized by ATR-FTIR, 1HNMR spectroscopy, surface charge, critical micelle concentration (23.9 μg/mL), and cytotoxicity analysis. Box-Behnken design was used to optimize the diameter, zeta potential, drug entrapment efficiency (DEE), and drug release characteristics of poly (allylamine)-crosslinked MNCs containing canagliflozin. The optimized MNCs revealed spherical morphology under TEM and had 149.3 nm diameter (PDI 21.2 %), +53.8 mV zeta potential, and 84 % DEE. The MNCs released about 63 % of the drug in 12 h under varying pH of the simulated gastrointestinal fluid. DSC and x-ray analyses suggested amorphous dispersion of drugs in the MNCs. CAM assay demonstrated the biocompatibility of the MNCs. The MNCs showed hemolysis of <1 %, 85 % mucin adsorption, and stability over three months. The MNCs demonstrated excellent anti-diabetic efficacy in streptozotocin-nicotinamide-induced diabetic rats, continuously lowering blood glucose levels up to 12 h.

Development of alginate/chitosan hydrogel loaded with obestatin and evaluation of collagen type I, III, VEGF and TGF-β1 gene expression for skin repair in a rat model (in vitro and in vitro study)

BACKGROUND

Skin injuries have long been recognized as a prevalent type of physical injury. As a result, numerous research studies have been performed to discover an effective mechanism for wound healing. Therefore, tissue engineering of skin has developed as a potential solution for traditional methods of treating skin injuries.

METHODS AND MATERIALS

Alginate/Chitosan hydrogel was mixed with 1, 10, 100, and 150 µM Obestatin, and evaluated the morphology, cumulative release, hemocompatibility and cytocompatibility, water absorption, cell viability, weight loss, and antibacterial characteristics of three-dimensional (3D) alginate (Alg) and chitosan (Cs) hydrogels during the process of wound curing. Various concentrations of Obestatin (Obes) were utilized for this purpose. Finally, the hydrogels that were made were tested on a full-thickness dermal wound in a Wistar rat model. The curative effects were determined by analyzing RNA expression and examining tissue stained with Masson's trichrome (MT) and hematoxylin-eosin (H&E).

RESULTS

The biodegradability of this hydrogel was verified using weight loss testing, which demonstrated a reduction of around 90% after a period of 3 days. Furthermore, the MTT assay demonstrated that hydrogels have a beneficial effect on cell proliferation without inducing any harmful effects. Furthermore, the hydrogels produced demonstrated higher wound closure in vivo compared to the wounds treated with gauze (negative control group). Among the hydrogel groups, the chitosan/alginate/obestatin 100 µM group exhibited the apical percentage of wound closure, gene expression, and secondary epithelialization, but in 150 µM concentrations, we saw a lower rate of cell growth and proliferation and increase in hemolysis. In addition, RT-PCR analysis demonstrated that a concentration of 100 µM obestatin resulted in an upregulation in the expression of mRNA for vascular endothelial growth factor (VEGF), collagen type I & type III, and transforming growth factor-beta (TGF-β).

CONCLUSION

The present study suggests that 3D Alg/Cs hydrogels with a concentration of 100 µM obestatin have the potential for clinical application in the treatment of skin injuries.

Synthesis of biocompatible hydrogel of alginate-chitosan enriched with iron sulfide nanocrystals

This work aimed to synthesize and characterize a biocompatible hydrogel of alginate and chitosan enriched with iron sulfide nanocrystals. Three concentrations of iron sulfide nanocrystals (FeS2NCs) 0.03905, 0.0781, and 0.2343 mg/ml were used. Gel swelling was determined using phosphate-buffered saline solution at 1, 2, 4, 6, 24, 48, and 72 h. The microstructure, the morphology, and the elastic strength were determined by optical microscopy, scanning electron microscopy, and rheological studies, respectively. The functional groups were identified through Fourier Transform Infrared spectroscopy. Biocompatibility was determined in a murine model; after seven days of subdermal inoculation, histological sections stained with H&E were analyzed, and then histopathological features were evaluated. All the compounds obtained showed a loss modulus lower than the storage modulus. The 0.2343 mg/ml FeS2NCs hydrogel showed higher swelling than the control. In the in vivo evaluation, no adverse effects were found. The presence of FeS2NCs was well tolerated in the subcutaneous tissue of mice, according to histopathological analysis. The hydrogels synthesized with added FeS2NCs demonstrate a swelling ratio of 150 %, rheologically exhibiting gel-like behavior rather than viscous liquids. Furthermore, they did not present any adverse effects on the subcutaneous tissue.

Alginate-Chitosan Biodegradable and Biocompatible Based Hydrogel for Breast Cancer Immunotherapy and Diagnosis: A Comprehensive Review

Breast cancer is the most common type of cancer and the second leading cause of cancer-related mortality in females. There are many side effects due to chemotherapy and traditional surgery, like fatigue, loss of appetite, skin irritation, and drug resistance to cancer cells. Immunotherapy has become a hopeful approach toward cancer treatment, generating long-lasting immune responses in malignant tumor patients. Recently, hydrogel has received more attention toward cancer therapy due to its specific characteristics, such as decreased toxicity, fewer side effects, and better biocompatibility drug delivery to the particular tumor location. Researchers globally reported various investigations on hydrogel research for tumor diagnosis. The hydrogel-based multilayer platform with controlled nanostructure has received more attention for its antitumor effect. Chitosan and alginate play a leading role in the formation of the cross-link in a hydrogel. Also, they help in the stability of the hydrogel. This review discusses the properties, preparation, biocompatibility, and bioavailability of various research and clinical approaches of the multipolymer hydrogel made of alginate and chitosan for breast cancer treatment. With a focus on cases of breast cancer and the recovery rate, there is a need to find out the role of hydrogel in drug delivery for breast cancer treatment.

How the combination of alginate and chitosan can fabricate a hydrogel with favorable properties for wound healing

Wound management has always been a significant concern, particularly for men, and the search for effective wound dressings has led to the emergence of hydrogels as a promising solution. In recent years, hydrogels, with their unique properties, have gained considerable importance in wound management. Among the various types of hydrogels, those incorporating chitosan and alginate, two distinct chemical materials, have shown potential in accelerating wound healing. This review aims to discuss the desirable characteristics of an effective wound dressing, explore the alginate/chitosan-based hydrogels developed by different researchers, and analyze their effects on wound healing through in vitro and in vivo assessments. In vitro tests encompass a wide range of evaluations, including swelling capacity, degradation rate, porosity, Fourier Transform Infrared Spectroscopy, X-ray diffraction analysis, moisture vapor transmission rate, release studies, mechanical properties, microscopic observation, antibacterial properties, compatibility assessment, cell adhesion investigation, blood clotting capability, cell migration analysis, water contact angle determination, and structural stability. Furthermore, in vivo assessments encompass the examination of wound closure rate, modulation of gene expression, as well as histopathological and immunohistochemical studies.

Fabrication and characterization of physically crosslinked alginate/chitosan-based hydrogel loaded with neomycin for the treatment of skin infections caused by Staphylococcus aureus

Staphylococcus aureus is a pathogen widely involved in wound infection due to its ability to release several virulence factors that impair the skin healing process, as well as its mechanism of drug resistance. Herein, sodium alginate and chitosan were combined to produce a hydrogel for topical delivery of neomycin to combat S. aureus associated with skin complications. The hydrogel was formulated by combining sodium alginate (50 mg/mL) and chitosan (50 mg/mL) solutions in a ratio of 9:1 (HBase). Neomycin was added to HBase to achieve a concentration of 0.4 mg/mL (HNeo). The incorporation of neomycin into the product was confirmed by scanning electron microscopy, FTIR and TGA analysis. The hydrogels produced are homogeneous, have a high swelling capacity, and show biocompatibility using erythrocytes and fibroblasts as models. The formulations showed physicochemical and pharmacological stability for 60 days at 4 ± 2 °C. HNeo totally inhibited the growth of S. aureus after 4 h. The antimicrobial effects were confirmed using ex vivo (porcine skin) and in vivo (murine) wound infection models. Furthermore, the HNeo-treated mice showed lower severity scores than those treated with HBase. Taken together, the obtained results present a new low-cost bioproduct with promising applications in treating infected wounds.

Granulation of Lithium-Ion Sieves Using Biopolymers: A Review

The high demand for lithium (Li) relates to clean, renewable storage devices and the advent of electric vehicles (EVs). The extraction of Li ions from aqueous media calls for efficient adsorbent materials with various characteristics, such as good adsorption capacity, good selectivity, easy isolation of the Li-loaded adsorbents, and good recovery of the adsorbed Li ions. The widespread use of metal-based adsorbent materials for Li ions extraction relates to various factors: (i) the ease of preparation via inexpensive and facile templation techniques, (ii) excellent selectivity for Li ions in a matrix, (iii) high recovery of the adsorbed ions, and (iv) good cycling performance of the adsorbents. However, the use of nano-sized metal-based Lithium-ion sieves (LISs) is limited due to challenges associated with isolating the loaded adsorbent material from the aqueous media. The adsorbent granulation process employing various binding agents (e.g., biopolymers, synthetic polymers, and inorganic materials) affords composite functional particles with modified morphological and surface properties that support easy isolation from the aqueous phase upon adsorption of Li ions. Biomaterials (e.g., chitosan, cellulose, alginate, and agar) are of particular interest because their structural diversity renders them amenable to coordination interactions with metal-based LISs to form three-dimensional bio-composite materials. The current review highlights recent progress in the use of biopolymer binding agents for the granulation of metal-based LISs, along with various crosslinking strategies employed to improve the mechanical stability of the granules. The study reviews the effects of granulation and crosslinking on adsorption capacity, selectivity, isolation, recovery, cycling performance, and the stability of the LISs. Adsorbent granulation using biopolymer binders has been reported to modify the uptake properties of the resulting composite materials to varying degrees in accordance with the surface and textural properties of the binding agent. The review further highlights the importance of granulation and crosslinking for improving the extraction process of Li ions from aqueous media. This review contributes to manifold areas related to industrial application of LISs, as follows: (1) to highlight recent progress in the granulation and crosslinking of metal-based adsorbents for Li ions recovery, (2) to highlight the advantages, challenges, and knowledge gaps of using biopolymer-based binders for granulation of LISs, and finally, (3) to catalyze further research interest into the use of biopolymer binders and various crosslinking strategies to engineer functional composite materials for application in Li extraction industry. Properly engineered extractants for Li ions are expected to offer various cost benefits in terms of capital expenditure, percent Li recovery, and reduced environmental footprint.

Acer tegmentosum extract-mediated silver nanoparticles loaded chitosan/alginic acid scaffolds enhance healing of E. coli-infected wounds

This work developed Acer tegmentosum extract-mediated silver nanoparticles (AgNPs) loaded chitosan (CS)/alginic acid (AL) scaffolds (CS/AL-AgNPs) to enhance the healing of E. coli-infected wounds. The SEM-EDS and XRD results revealed the successful formation of the CS/AL-AgNPs. FTIR analysis evidenced that the anionic group of AL (-COO-) and cationic amine groups of CS (-NH3+) were ionically crosslinked to form scaffold (CS/AL). The CS/AL-AgNPs exhibited significant antimicrobial activity against both Gram-positive (G+) and Gram-negative (G-) bacterial pathogens, while being non-toxic to red blood cells (RBCs), the hen's egg chorioallantoic membrane (HET-CAM), and a non-cancerous cell line (NIH3T3). Treatment with CS/AL-AgNPs significantly accelerated the healing of E. coli-infected wounds by regulating the collagen deposition and blood parameters as evidenced by in vivo experiments. Overall, these findings suggest that CS/AL-AgNPs are promising for the treatment of infected wounds.

Cationic Azobenzenes as Light-Responsive Crosslinkers for Alginate-Based Supramolecular Hydrogels

Azobenzene photoswitches are fundamental components in contemporary approaches aimed at light-driven control of intelligent materials. Significant endeavors are directed towards enhancing the light-triggered reactivity of azobenzenes for such applications and obtaining water-soluble molecules able to act as crosslinkers in a hydrogel. Here, we report the rational design and the synthesis of azobenzene/alginate photoresponsive hydrogels endowed with fast reversible sol-gel transition. We started with the synthesis of three cationic azobenzenes (AZOs A, B, and C) and then incorporated them in sodium alginate (SA) to obtain photoresponsive supramolecular hydrogels (SMHGs). The photoresponsive properties of the azobenzenes were investigated by UV-Vis and 1H NMR spectroscopy. Upon irradiation with 365 nm UV light, the azobenzenes demonstrated efficient trans-to-cis isomerization, with complete isomerization occurring within seconds. The return to the trans form took several hours, with AZO C exhibiting the fastest return, possibly due to higher trans isomer stability. In the photoresponsive SMHGs, the minimum gelation concentration (MGC) of azobenzenes was determined for different compositions, indicating that small amounts of azobenzenes could induce gel formation, particularly in 5 wt% SA. Upon exposure to 365 nm UV light, the SMHGs exhibited reversible gel-sol transitions, underscoring their photoresponsive nature. This research offers valuable insights into the synthesis and photoresponsive properties of cationic, water-soluble azobenzenes, as well as their potential application in the development of photoresponsive hydrogels.

Alginate and Chitosan-Based Hydrogel Enhance Antibacterial Agent Activity on Topical Application

Untreated topical infections can become chronic, posing serious health issues. Optimal skin adherence is crucial in addressing such infections. In this context, chitosan and alginate emerge as promising candidates for use as a foundation in the development of topical hydrogels. The aim of this review is to examine the literature on topical hydrogel formulations that use chitosan and alginate as foundations, specifically in the context of topical antibacterial agents. The research methodology involves a literature review by examining articles published in databases such as PubMed, Scopus, ScienceDirect, and Google Scholar. The keywords employed during the research were "Alginate", "Chitosan", "Hydrogel", and "Antibacterial". Chitosan and alginate serve as bases in topical hydrogels to deliver various active ingredients, particularly antibacterial agents, as indicated by the search results. Both have demonstrated significant antibacterial effectiveness, as evidenced by a reduction in bacterial colony counts and an increase in inhibition zones. This strongly supports the idea that chitosan and alginate could be used together to make topical hydrogels that kill bacteria that work well. In conclusion, chitosan and alginate-based hydrogels show great potential in treating bacterial infections on the skin surface. The incorporation of chitosan and alginate into hydrogel formulations aids in retaining antibacterial agents, allowing for their gradual release over an optimal period. Therefore, hydrogels specifically formulated with chitosan and alginate have the potential to serve as a solution to address challenges in the treatment of topical bacterial infections.

Silver Nanoparticles-Chitosan Nanocomposites: A Comparative Study Regarding Different Chemical Syntheses Procedures and Their Antibacterial Effect

Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using various chitosan concentrations for a complex investigation. The nanocomposites were characterized by AFM and DLS regarding their dimensions, while FT-IR and UV-VIS spectrometry were used for the optical properties and to reveal the binding of silver nanoparticles with chitosan. Their antibacterial effect was determined using a disk diffusion method on two bacteria strains, E. coli and S. aureus. The results indicate that, when using both methods, the nanocomposites obtained were below 100 nm, yet the antibacterial effect proved to be stronger for the nanocomposites obtained using sodium hydroxide. Furthermore, the antibacterial effect can be related to the nanocomposites' sizes, since the smallest dimension nanocomposites exhibited the best bacterial growth inhibition on both bacteria strains we tested and for both types of silver nanocomposites.

Carvacrol Encapsulation in Chitosan-Carboxymethylcellulose-Alginate Nanocarriers for Postharvest Tomato Protection

Advancements in polymer science and nanotechnology hold significant potential for addressing the increasing demands of food security, by enhancing the shelf life, barrier properties, and nutritional quality of harvested fruits and vegetables. In this context, biopolymer-based delivery systems present themselves as a promising strategy for encapsulating bioactive compounds, improving their absorption, stability, and functionality. This study provides an exploration of the synthesis, characterization, and postharvest protection applications of nanocarriers formed through the complexation of chitosan oligomers, carboxymethylcellulose, and alginate in a 2:2:1 molar ratio. This complexation process was facilitated by methacrylic anhydride and sodium tripolyphosphate as cross-linking agents. Characterization techniques employed include transmission electron microscopy, energy-dispersive X-ray spectroscopy, infrared spectroscopy, thermal analysis, and X-ray powder diffraction. The resulting hollow nanospheres, characterized by a monodisperse distribution and a mean diameter of 114 nm, exhibited efficient encapsulation of carvacrol, with a loading capacity of approximately 20%. Their suitability for phytopathogen control was assessed in vitro against three phytopathogens-Botrytis cinerea, Penicillium expansum, and Colletotrichum coccodes-revealing minimum inhibitory concentrations ranging from 23.3 to 31.3 μg·mL-1. This indicates a higher activity compared to non-encapsulated conventional fungicides. In ex situ tests for tomato (cv. 'Daniela') protection, higher doses (50-100 μg·mL-1, depending on the pathogen) were necessary to achieve high protection. Nevertheless, these doses remained practical for real-world applicability. The advantages of safety, coupled with the potential for a multi-target mode of action, further enhance the appeal of these nanocarriers.

Antibacterial Activity Assessment of Chitosan/Alginate Lavender Essential Oil Membranes for Biomedical Applications

The demand for natural products in the treatment of dermatological pathologies has boosted the use of bioactive substances such as lavender essential oil (LEO), which stands out for its anti-inflammatory and antioxidant properties and its antimicrobial potential. Biopolymers such as chitosan (CHT) and alginate (ALG) are biodegradable and biocompatible and have proven their viability in biomedical applications such as skin regeneration. The inhibitory effect of LEO on the growth of skin-related bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and the fungus Candida albicans was studied by incorporating 1% v/v LEO encapsulated in CHT, ALG, and CHT/ALG membranes. Despite the verification of the antimicrobial effect of all type of membranes, no synergistic effect was observed following the addition of LEO. S. aureus and P. aeruginosa showed the most growth on the different substrates and C. albicans demonstrated the highest inhibition. This is a first approach using microorganisms isolated from clinical samples or skin microbiota. Further investigation would be advisable using more clinical strains for each microorganism to validate their biomedical applicability.

Advances in Chronic Wound Management: From Conventional Treatment to Novel Therapies and Biological Dressings

Chronic wounds can be classified as diabetic foot ulcers, pressure ulcers, or venous leg ulcers. Chronic wound management has become a threat to clinicians and constitutes a major healthcare burden. The healing process of chronic wounds requires many factors to work in concert to achieve optimal healing. Various treatment options, ranging from hypoxia to infection, have evolved considerably to address the challenges associated with chronic wound healing. The conventional and accelerating treatments for chronic wounds still represent an unmet medical need due to the complex pathophysiology of the chronic wound microenvironment. In clinical settings, traditional chronic wound care practices rely on nonspecific topical treatment, which can reduce pain and alleviate disease progression with varying levels of success but fail to completely cure the wounds. Conventional wound dressings, such as hydrocolloids, gauze, foams, and films, have also shown limited success for the treatment of chronic wounds and only act as a physical barrier and absorb wound exudates. Emerging advances in treatment approaches, including novel therapies (stem cells, microRNAs, and nanocarrier-based delivery systems) and multifunctional biological dressings, have been reported for chronic wound repair. This review summarizes the challenges offered by chronic wounds and discusses recent advancements in chronic wound treatment.

The application of chitosan as a carrier for fertilizer: A review

The smart combination of agriculture and other sciences can greatly reduce the limits of fertilizer use. Chitosan is a linear amino polysaccharide with a rigid structure which has hydrophilic and crystal properties. The formation of intermolecular hydrogen bonds the presence of reactive groups and cross-linking, the formation of salts with organic and inorganic acids with complexing and chelating properties ionic conductivity, film formation are the characteristics of chitosan. With the presence of amino groups, chitosan can form a complex with other compounds and also enter the vascular system of plants and lead to the activation of metabolic-physiological pathways of plants. This polymeric compound can bond with other natural polymers and in combination with fertilizers and nutritional elements, on the one hand, it can provide the nutritional needs of the plant and on the other hand, it also helps to improve the soil texture. Chitosan nanomaterials as a Next-generation fertilizers act as plant immune system enhancers through slow, controlled, and targeted delivery of nutrients to plants. Chitosan can assist agricultural researchers and has become an ideal and effective option with its many applications in various fields.

Porous Thermoformed Protein Bioblends as Degradable Absorbent Alternatives in Sanitary Materials

Protein-based porous absorbent structures can be processed and assembled into configurations suitable for single-use, biodegradable sanitary materials. In this work, a formulation based on a mixture of proteins available as industrial coproducts is processed into continuous porous structures using extrusion and assembled using conventional thermal methods. The experimental design led to formulations solely based on zein-gluten protein bioblends that could be manufactured as liquid absorbent pellets, compressed pads, and/or porous films. The processing versatility is attributed to the synergistic effect of zein as a low viscosity thermoformable protein with gluten as a readily cross-linkable high molecular weight protein. The capillary-driven sorption, the biodegradability of the materials, and the possibility to assemble the products as multilayer components provide excellent performance indicators for their use as microplastic-free absorbents. This work shows the potential of biopolymers for manufacturing sustainable alternatives to current nonbiodegradable and highly polluting disposable items such as pads and diapers.

Development of double crosslinked sodium alginate/chitosan based hydrogels for controlled release of metronidazole and its antibacterial activity

Double network sodium alginate/chitosan hydrogels were prepared using calcium chloride (CaCl2) and glutaraldehyde as the crosslinking agents by the ionotropic interaction method for controlled metronidazole release. The effect of polymer ratios and CaCl2 amount is investigated by the developing porosity, gel fraction, and extent of swelling in simulated physiological fluids. Interaction between the polymers with the formation of crosslinked structures, good stability, phase nature, and morphology of the hydrogels is revealed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. A sodium alginate/chitosan hydrogel (weight ratio of 75:25) crosslinked with two percent CaCl2 is chosen for the in-situ loading of 200 mg of metronidazole. The drug release kinetics using different models show that the best-fit Korsmeyer-Peppas model suggests metronidazole release from the matrix follows diffusion and swelling-controlled time-dependent non-Fickian transport related to hydrogel erosion. This composition displays enhanced antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Alginate-Chitosan Hydrogels Containing shRNA Plasmid for Inhibition of CTNNB1 Expression in Breast Cancer Cells

The hydrogels prepared with alginate and chitosan polymers were prepared to deliver the shRNA-encoding plasmid (pshRNA) to MDA-MB-231 cells for the inhibition of β-catenin (CTNNB1), which was reported to be overexpressed in breast cancer. Polyion complex hydrogels prepared using sodium alginate and chitosan were characterized by Fourier transform infrared spectrometry (FTIR) analysis, scanning electron microscope (SEM) analysis, swelling, and degradation properties. After the release properties and serum stability of pshRNA-loaded hydrogels were determined, their cytotoxicity, transfection efficacy, and effects on CTNNB1 expression were investigated in MDA-MB-231 cells. All hydrogels were shown to protect pshRNA from the enzymatic activity of serum and to deliver pshRNA to cells efficiently. As a result of transfection studies, pshRNA-loaded hydrogels reduced CTNNB1 expression by up to 30.25%. Cell viability also decreased by 38% in cells treated with 2.5% (w/v) alginate-chitosan hydrogel containing pshRNA targeting CTNNB1. Alginate-chitosan hydrogels were shown to be a suitable matrix system for local gene delivery.

Alginate-Chitosan Membranes for the Encapsulation of Lavender Essential Oil and Development of Biomedical Applications Related to Wound Healing

Biopolymers such as chitosan (CHT) or alginate (ALG) are among the most prominent for health-related applications due to their broad bioactivity. Their combination for the preparation of membranes is hereby proposed as an application for wound healing with the incorporation of lavender essential oil (LEO), widely known for its antioxidant and antimicrobial properties. The preparation of CHT, CHT + LEO, ALG, ALG + LEO, and CHT/ALG + LEO membranes was accomplished, and its composition was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The water absorption capacity and oil release profile of the membranes revealed higher water uptake capacity when a lower LEO release was obtained. The combined CHT/ALG + LEO film showed a water uptake percentage of 638% after 48 h and a maximum LEO release concentration of 42 mg/L. Cytotoxicity and biocompatibility of the prepared membranes were studied using a HaCaT cell line, with an assessment of cell viability regarding film leachables, DNA quantification, and DAPI-phalloidin staining. The results revealed that the indirect contact of the prepared membranes via its leachables does not compromise cell viability, and upon direct contact, cells do not adhere or proliferate on the surface of the membranes. Moreover, the CHT/ALG + LEO membrane increases cell proliferation, making it suitable for applications in wound healing.

Formulation optimization of sterilized xanthones-loaded nanoemulgels and evaluation of their wound healing activities

Xanthones (XTs) are bioactive compounds found in mangosteen trees (Garcinia mangostana Linn.). They are used as an active ingredient in various health products. However, there is a lack of data of their application in wound healing. In particular, the topical products of XTs for wound healing; they should be sterilized to minimize the risks of wound infection from contaminated microorganisms. This study thus aimed to optimize the formulation of sterilized XTs-loaded nanoemulgel (XTs-NE-G) and to investigate their wound healing activities. The XTs-NE-Gs were prepared by mixing various gels containing sodium alginate (Alg) and Pluronic F127 (F127) into a XTs-nanoemulsion (NE) concentrate according to the face-centered central composite design. The results showed that the optimized XTs-NE-G was A5-F3 containing 5% w/w Alg and 3% w/w F127. It enhanced the proliferation-, migration rates of skin fibroblasts (HFF-1 cells) with an optimal viscosity. After blending the XTs-NE concentrate and the gel that was previously sterilized by a membrane filtration and an autoclaving technique, respectively, the sterilized A5-F3 was obtained. The sterilized A5-F3 still had effective bioactivities towards the HFF-1 cells. It promoted re-epithelialization, collagen deposition and inflammation suppression in the mice' wounds. It could thus be accepted for further investigation in clinical studies.

Improved infectious burn wound healing by applying lyophilized particles containing probiotics and prebiotics

Lactiplantibacillus plantarum cells were encapsulated in a mixture of cationic and anionic polymers, with the final composition stabilized through freeze-drying. A D-optimal design was used to examine the effects of different polymer concentrations as well as adding prebiotics on the probiotic viability and swelling behavior of the formulations. Scanning electron micrographs revealed stacked particles capable of rapidly absorbing significant amounts of water. These images corresponded to initial swelling percentages of around 2000% for the optimal formulation. The optimized formula had a viability percentage of more than 82%, with the stability studies suggesting that the powders should be stored at refrigerated temperatures. The physical characteristics of the optimized formula were examined to ensure compatibility with its application. According to antimicrobial evaluations, the difference in pathogen inhibition between formulated and fresh probiotics was less than a logarithm. The final formula was tested in vivo and showed improved wound healing indicators. The optimized formula resulted in a higher rate of wound closure and infection clearance. Furthermore, the molecular studies for oxidative stress indicated that the formula could modify wound inflammatory responses. In histological investigations, the probiotic-loaded particles functioned exactly as efficaciously as silver sulfadiazine ointment did.

"Novel chitosan/alginate hydrogels as carriers of phenolic-enriched extracts from saffron floral by-products using natural deep eutectic solvents as green extraction media"

The current saffron production system is generating several hundreds of tons of tepal waste, because only stigmas are used for food. Consequently, the valorization of saffron floral by-products by developing stable functional ingredients could lead to the environmental impact minimization. Thus, the main aim of this study was to develop innovative green extraction processes from saffron floral by-products by using Natural Deep Eutectic Solvents (NaDES) and ultrasound-assisted extraction (UAE) as ecological extraction method. Response surface methodology was used to optimize process parameters. To improve the stability of the optimal extracts, they were incorporated into chitosan/alginate hydrogels, studying their water-uptake and water retention capacity and the total phenolic content (TPC) during the in vitro digestion. The results indicated that the optimal extraction, regarding total phenolic and flavonoid content, was achieved in 20 min, using 180 W ultrasound power and 90% of NaDES. The results of the DPPH assay revealed the potent antioxidant activity of saffron floral by-products. The chitosan/alginate hydrogels incorporating the as-obtained NaDES extracts showed favorable properties whereas the TPC remained stable under intestinal conditions. Therefore, NaDES combined with UAE was an efficient technique to isolate high added-value compounds from saffron flowers, succeeding also the valorization of discarded waste by using green and low-cost strategies. Furthermore, these novel hydrogels could be used as promising candidates for food or cosmetic applications.

Fabrication of a Patterned Scaffold Using Soft Lithography Technique to be Used in Cell Growth Applications

In recent years, within tissue engineering, cell growth on patterned surfaces have gained significant attention. Growing cells in patterns is important to manufacture polymeric tissues that can be used within the medical field. For this reason, the main focus of this study was to prepare patterned scaffolds using Titanium (Ti) and polyvinyl chloride (PVC) covered on microscope lamellas and examine their liability for cell growth. A polydimethylsiloxane stamp was initially prepared which was then used to transfer a predefined pattern onto PVC- and Ti-covered surfaces. Cell growth experiments were performed on the prepared materials by seeding L929 mouse fibroblasts. The growth of cells seeded on the surface of the scaffolds were spectroscopically followed using Neutral Red uptake assay. The results showed cell proliferation on both patterned surfaces, however, it was higher on Ti-covered samples. In addition, three different alkanethiols were tested for cell adhesion on patterned surfaces. A higher number of cell proliferation was observed with undecanethiol, which has a shorter alkane group among them. The morphological properties of the samples before and after cell-seeding were analyzed via scanning electron microscope and optical microscopy. Significant amount of cell proliferation was observed on all of the prepared samples.

Nanofibrous Hydrogel Nanocomposite Based on Strontium-Doped Bioglass Nanofibers for Bone Tissue Engineering Applications

Simple Summary

Currently, bone defects, diseases, and injuries are common and global problems. These defects can be treated with several surgical methods and bone grafting, but these methods have limitations, including immune disorders, risk of infection, long-term recovery, movement problems, and high costs. A promising treatment option for bone replacement is the design and construction of scaffolds that mimic the properties of bone tissue and provide a suitable environment for cell and tissue growth. Achieving successful results in this method is dependent on the composition and structure of materials used as scaffolds. Bone is a composite consisting of a mineral fraction, mainly a combination of calcium phosphate, and an organic matrix. Here, we designed and produced a porous, non-toxic, and degradable scaffold made of alginate natural polymer and bioactive glass that contains strontium as well as the common elements of bioglasses—silica, calcium, sodium, and phosphorus. The scaffold is degraded at an optimized rate with the simultaneous proliferation and growth of cells, thus providing a suitable environment for the growth and development of new tissue and blood vessels. The outcomes of this study presented this scaffold as a functional structure to be used in treating bone defects and reconstructing damaged bone.

Abstract

The main aim of the current study is to fabricate an osteocompatible, bioactive, porous, and degradable bone tissue engineering scaffold. For this purpose, bioactive glasses (BGs) were chosen due to their similarity to bone’s natural mineral composition, and the effect of replacing Ca ions with Sr on their properties were considered. First, strontium-containing BGs (Sr-BGs) were synthesized using the electrospinning technique and assembled by the sol–gel method, then they were incorporated into the alginate (Alg) matrix. Photographs of the scanning electron microscope (SEM) showed that the BG nanofibers have a diameter of 220 ± 36 nm, which was smaller than the precursor nanofibers (275 ± 66 nm). The scaffolds possess a porous internal microstructure (230–330 nm pore size) with interconnected pores. We demonstrated that the scaffolds could be degraded in the acetate sodium buffer and phosphate-buffered saline. The osteoactivity of the scaffolds was confirmed via visual inspection of the SEM illustrations after seven days of immersing them in the SBF solution. In vitro assessments disclosed that the produced Alg-based composites including Sr-BGs (Alg/Sr-BGs) are blood-compatible and biocompatible. Accumulating evidence shows that Alg/Sr-BG (5%, 10%, and 15%) hydrogels could be a promising scaffold for bone regeneration.

Functional biomaterials for tendon/ligament repair and regeneration

With an increase in life expectancy and the popularity of high-intensity exercise, the frequency of tendon and ligament injuries has also increased. Owing to the specificity of its tissue, the rapid restoration of injured tendons and ligaments is challenging for treatment. This review summarizes the latest progress in cells, biomaterials, active molecules and construction technology in treating tendon/ligament injuries. The characteristics of supports made of different materials and the development and application of different manufacturing methods are discussed. The development of natural polymers, synthetic polymers and composite materials has boosted the use of scaffolds. In addition, the development of electrospinning and hydrogel technology has diversified the production and treatment of materials. First, this article briefly introduces the structure, function and biological characteristics of tendons/ligaments. Then, it summarizes the advantages and disadvantages of different materials, such as natural polymer scaffolds, synthetic polymer scaffolds, composite scaffolds and extracellular matrix (ECM)-derived biological scaffolds, in the application of tendon/ligament regeneration. We then discuss the latest applications of electrospun fiber scaffolds and hydrogels in regeneration engineering. Finally, we discuss the current problems and future directions in the development of biomaterials for restoring damaged tendons and ligaments.

Physical, Chemical, and Biological Properties of Chitosan-Coated Alginate Microparticles Loaded with Porcine Interleukin-1β: A Potential Protein Adjuvant Delivery System

We previously developed chicken interleukin-1β (IL-1β) mutants as single-dose adjuvants that induce protective immunity when co-administered with an avian vaccine. However, livestock such as pigs may require a vaccine adjuvant delivery system that provides long-lasting protection to reduce the need for successive booster doses. Therefore, we developed chitosan-coated alginate microparticles as a carrier for bovine serum albumin (BSA) or porcine IL-1β (pIL-1β) and assessed their physical, chemical, and biological properties. Electrospraying of the BSA-loaded alginate microparticles (BSA/ALG MPs) resulted in an encapsulation efficiency of 50%, and those MPs were then coated with chitosan (BSA/ALG/CHI MPs). Optical and scanning electron microscopy, zeta potential analysis, and Fourier transform infrared spectroscopy were used to characterize these MPs. The BSA encapsulation parameters were applied to ALG/CHI MPs loaded with pIL-1β, which were not cytotoxic to porcine fibroblasts but had enhanced bio-activity over unencapsulated pIL-1β. The chitosan layer of the BSA/ALG/CHI MPs prevented burst release and facilitated sustained release of pIL-1β for at least 28 days. In conclusion, BSA/ALG/CHI MPs prepared as a carrier for pIL-1β may be used as an adjuvant for the formulation of pig vaccines.

Punicalagin-Loaded Alginate/Chitosan-Gallol Hydrogels for Efficient Wound Repair and Hemostasis

For recently devised wound-healing materials, a variety of acute application systems with sustainable therapeutic effects on wound sites have been suggested. For example, hydrogel-type healing agents with porous structures and high drug encapsulation efficiencies have been developed for wound repair. However, challenges remain about the poor mechanical and adhesive properties of hydrogels. Herein, we propose a punicalagin (PC)-containing wound-healing hydrogel in adhesive form that is mechanically stable and has sustainable wound-healing therapeutic efficiency. The APC hydrogel, composed of alginate (ALG), PC, and chitosan–gallol (CHI–G), exhibits significant mechanical and self-healing properties, thus indicating that PC increases cross-linking in ALG/CHI–G as macromolecule. The PC-containing mechanically enhanced hydrogel demonstrates high tissue adhesiveness. Sustainable PC release for 192 h, which indicates high therapeutic effect of the released PC, and great blood compatibility are evaluated based on rapid blood coagulation and minimal hemolysis. The cytocompatibility and wound-healing abilities of the PC-containing APC hydrogel are greater than those of the non-PC hydrogel, as verified by cell compatibility and wound scratch assays. These results indicate that a suitable concentration of PC-containing hydrogel with sustainable moisture condition and PC release may inspire further polyphenol-agent-containing hydrogels as wound-healing agents with structural stability and therapeutic efficiency.

Sodium Alginate/Chitosan Scaffolds for Cardiac Tissue Engineering: The Influence of Its Three-Dimensional Material Preparation and the Use of Gold Nanoparticles

Natural biopolymer scaffolds and conductive nanomaterials have been widely used in cardiac tissue engineering; however, there are still challenges in the scaffold fabrication, which include enhancing nutrient delivery, biocompatibility and properties that favor the growth, maturation and functionality of the generated tissue for therapeutic application. In the present work, different scaffolds prepared with sodium alginate and chitosan (alginate/chitosan) were fabricated with and without the addition of metal nanoparticles and how their fabrication affects cardiomyocyte growth was evaluated. The scaffolds (hydrogels) were dried by freeze drying using calcium gluconate as a crosslinking agent, and two types of metal nanoparticles were incorporated, gold (AuNp) and gold plus sodium alginate (AuNp+Alg). A physicochemical characterization of the scaffolds was carried out by swelling, degradation, permeability and infrared spectroscopy studies. The results show that the scaffolds obtained were highly porous (>90%) and hydrophilic, with swelling percentages of around 3000% and permeability of the order of 1 × 10−8 m2. In addition, the scaffolds proposed favored adhesion and spheroid formation, with cardiac markers expression such as tropomyosin, troponin I and cardiac myosin. The incorporation of AuNp+Alg increased cardiac protein expression and cell proliferation, thus demonstrating their potential use in cardiac tissue engineering.

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L⁻¹ according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl₂. Compared to 300 μmol L⁻¹ MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.

Liquid-type plasma-controlled in situ crosslinking of silk-alginate injectable gel displayed better bioactivities and mechanical properties

Silk is a promising biomaterial for injectable hydrogel, but its long-gelation time and cytotoxic crosslinking methods are the main obstacles for clinical application. Here, we purpose a new in situ crosslinking technique of silk-alginate (S-A) injectable hydrogel using liquid-type non-thermal atmospheric plasma (LTP) in vocal fold (VF) wound healing. We confirmed that LTP induces the secondary structure of silk in a dose-dependent manner, resulting in improved mechanical properties. Significantly increased crosslinking of silk was observed with reduced gelation time. Moreover, controlled release of nitrate, an LTP effectors, from LTP-treated S-A hydrogel was detected over 7 days. In vitro experiments regarding biocompatibility showed activation of fibroblasts beyond the non-cytotoxicity of LTP-treated S-A hydrogels. An in vivo animal model of VF injury was established in New Zealand White rabbits. Full-thickness injury was created on the VF followed by hydrogel injection. In histologic analyses, LTP-treated S-A hydrogels significantly reduced a scar formation and promoted favorable wound healing. Functional analysis using videokymography showed eventual viscoelastic recovery. The LTP not only changes the mechanical structures of a hydrogel, but also has sustained biochemical effects on the damaged tissue due to controlled release of LTP effectors, and that LTP-treated S-A hydrogel can be used to enhance wound healing after VF injury.

Viscoelastic and smart swelling disposition of Carboxymethylcellulose based hydrogels substantiated by Gemini surfactant and in-vitro encapsulation and controlled release of Quercetin

CMC-SA-12-E2-12 hydrogels were prepared from Carboxymethylcellulose (CMC), succinic acid (SA) (biocompatible cross-linker) and Ethane-1,2-diyl-bis(N, N-dimethyl-N-dodecylammoniumacetoxy) (referred as 12-E2-12) (0.0006, 0.0015, 0.003, 0.0045 mMoles) by thermal treatment with economical and easy solution polymerization strategy. The CMC-SA-12E2-12 hydrogels were characterized for mechanical and viscoelastic properties like self-healing, viscosity and modulus using rheological analysis. Further the structural, morphological and thermal properties were investigated by FTIR, SEM and TGA analysis. The investigation revealed significant modulation in mechanical, viscoelastic, self-healing and drug release behavior with the addition of 12-E2-12. The CMC-SA-12-E2-12 hydrogels were investigated for drug release studies in PBS 7.4 for 48 h using Quercetin dihydrate. The results showed sustained release behavior at optimised concentration values of surfactant. Release data fitted nicely to the Higuchi model and hence the release could be seen to be diffusion controlled phenomenon or Fickian diffusion. The biocompatibility of cross-linker and surfactant may potentially make the hydrogels suitable for drug delivery applications.

Designing a new alginate-fibrinogen biomaterial composite hydrogel for wound healing

Wound healing is a complex process and rapid healing necessitates a proper micro-environment. Therefore, design and fabrication of an efficacious wound dressing is an impressive innovation in the field of wound healing. The fabricated wound dressing in this scenario was designed using a combination of the appropriate coagulating and anti-bacterial materials like fibrinogen (as coagulating agent), nisin (as anti-bacterial agent), ethylenediaminetetraacetic acid (as anti-bacterial agent), and alginate (as wound healing agent). Biophysical characterization showed that the interaction of fibrinogen and alginate was associated with minor changes in the secondary structure of the protein. Conformational studies showed that the protein was structurally stable at 42 °C, is the maximum temperature of the infected wound. The properties of the hydrogel such as swelling, mechanical resistance, nisin release, antibacterial activity, cytotoxicity, gel porosity, and blood coagulation were assessed. The results showed a slow release for the nisin during 48 h. Antibacterial studies showed an inhibitory effect on the growth of Gram-negative and Gram-positive bacteria. The hydrogel was also capable to absorb a considerable amount of water and provide oxygenation as well as incorporation of the drug into its structure due to its sufficient porosity. Scanning electron microscopy showed pore sizes of about 14–198 µm in the hydrogel. Cell viability studies indicated high biocompatibility of the hydrogel. Blood coagulation test also confirmed the effectiveness of the synthesized hydrogel in accelerating the process of blood clot formation. In vivo studies showed higher rates of wound healing, re-epithelialization, and collagen deposition. According to the findings from in vitro as well as in vivo studies, the designed hydrogel can be considered as a novel attractive wound dressing after further prerequisite assessments.

Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications-Possibilities and Limits

Atomic force microscopy (AFM) is one of the microscopic techniques with the highest lateral resolution. It can usually be applied in air or even in liquids, enabling the investigation of a broader range of samples than scanning electron microscopy (SEM), which is mostly performed in vacuum. Since it works by following the sample surface based on the force between the scanning tip and the sample, interactions have to be taken into account, making the AFM of irregular samples complicated, but on the other hand it allows measurements of more physical parameters than pure topography. This is especially important for biopolymers and hydrogels used in tissue engineering and other biotechnological applications, where elastic properties, surface charges and other parameters influence mammalian cell adhesion and growth as well as many other effects. This review gives an overview of AFM modes relevant for the investigations of biopolymers and hydrogels and shows several examples of recent applications, focusing on the polysaccharides chitosan, alginate, carrageenan and different hydrogels, but depicting also a broader spectrum of materials on which different AFM measurements are reported in the literature.

Improving Antibacterial Efficiency of Curcumin in Magnetic Polymeric Nanocomposites

In recent years, resistance to chemical antibiotics, as well as their side effects, has caused a necessity to utilize natural substances and herbal components with antibacterial effects. Curcumin, the major substance of Curcuma longa’s rhizome, was used as an antibacterial agent since ancient times. This work aimed to formulate a novel nanocomposite for the delivery of curcumin to overcome orthodox drugs resistance against bacteria and improve its efficacy. To fabricate targeting nanocomposites, first, Fe3O4 nanoparticles were synthesized followed by coating the obtained nanoparticles using sodium alginate containing curcumin. A 2 by 3 factorial design was tailored to predict the optimum formulation of nanocomposites. Characterization of nanocomposites including particle size, polydispersity index (PDI), zeta potential, entrapment efficiency, and drug loading was performed. The optimum formulation was analyzed by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FT-IR), and in vitro release study at different pHs. Finally, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of samples against seven common bacteria were determined. Results showed that the optimized formulation contained 400 nm particles with the PDI and zeta potentials of 0.4 and − 58 mV, respectively. The optimized formulation with 70% entrapment efficiency reduced the MIC value 2 to 4 times in comparison with pure curcumin. Results also showed that polymer and drug concentrations can significantly affect entrapment efficiency. In conclusion, the current investigation demonstrated that this magnetic nanocomposite can be applied for the delivery of curcumin.

Graphical abstract

Microwave-Assisted Physically Cross-Linked Chitosan-Sodium Alginate Hydrogel Membrane Doped with Curcumin as a Novel Wound Healing Platform

This project purposes to develop chitosan and sodium alginate-based hydrogel membranes loaded with curcumin through microwave-based physical cross-linking technique and its evaluation for wound healing potential. For the purpose, curcumin-loaded chitosan and sodium alginate membranes were developed using microwave at fixed frequency of 2450 MHz, power 350 W for 60 s, and tested for their physicochemical attributes like swelling, erosion, surface morphology, drug content, and in vitro drug release. The membranes were also subjected to tensile strength and vibrational and thermal analysis followed by testing in vivo on animals. The results indicated that microwave treatment significantly enhanced the swelling ability, reduced the erosion, and ensured smooth surface texture with optimal drug content. The drug was released in a slow fashion releasing total of 41 ± 4.2% within 24-h period with a higher tensile strength of 16.4 ± 5.3 Mpa. The vibrational analysis results revealed significant fluidization of hydrophilic domains and defluidization of hydrophobic domains which translated into a significant rise in the melting temperature and corresponding enthalpy which were found to be 285.2 ± 3.2 °C and 4.89 ± 1.4 J/g. The in vivo testing revealed higher percent re-epithelialization (75 ± 2.3%) within 14 days of the treatment application in comparison to only gauze and other treatments applied, with higher extent of collagen deposition having well-defined epidermis and stratum corneum formation. The microwave-treated chitosan-sodium alginate hydrogel membranes loaded with curcumin may prove to be another alternative to treat skin injuries. Graphical Abstract.

Chitosan/Alginate Hydrogel Dressing Loaded FGF/VE-Cadherin to Accelerate Full-Thickness Skin Regeneration and More Normal Skin Repairs

The process of full-thickness skin regeneration is complex and has many parameters involved, which makes it difficult to use a single dressing to meet the various requirements of the complete regeneration at the same time. Therefore, developing hydrogel dressings with multifunction, including tunable rheological properties and aperture, hemostatic, antibacterial and super cytocompatibility, is a desirable candidate in wound healing. In this study, a series of complex hydrogels were developed via the hydrogen bond and covalent bond between chitosan (CS) and alginate (SA). These hydrogels exhibited suitable pore size and tunable rheological properties for cell adhesion. Chitosan endowed hemostatic, antibacterial properties and great cytocompatibility and thus solved two primary problems in the early stage of the wound healing process. Moreover, the sustained cytocompatibility of the hydrogels was further investigated after adding FGF and VE-cadherin via the co-culture of L929 and EC for 12 days. The confocal 3D fluorescent images showed that the cells were spherical and tended to form multicellular spheroids, which distributed in about 40-60 μm thick hydrogels. Furthermore, the hydrogel dressings significantly accelerate defected skin turn to normal skin with proper epithelial thickness and new blood vessels and hair follicles through the histological analysis of in vivo wound healing. The findings mentioned above demonstrated that the CS/SA hydrogels with growth factors have great potential as multifunctional hydrogel dressings for full-thickness skin regeneration incorporated with hemostatic, antibacterial, sustained cytocompatibility for 3D cell culture and normal skin repairing.

Genipin-crosslinked chitosan/alginate/alumina nanocomposite gels for 3D bioprinting

Immobilizing microorganisms inside 3D printed semi-permeable substrates can be desirable for biotechnological processes since it simplifies product separation and purification, reducing costs, and processing time. To this end, we developed a strategy for synthesizing a feedstock suitable for 3D bioprinting of mechanically rigid and insoluble materials with embedded living bacteria. The processing route is based on a highly particle-filled alumina/chitosan nanocomposite gel which is reinforced by (a) electrostatic interactions with alginate and (b) covalent binding between the chitosan molecules with the mild gelation agent genipin. To analyze network formation and material properties, we characterized the rheological properties and printability of the feedstock gel. Stability measurements showed that the genipin-crosslinked chitosan/alginate/alumina gels did not dissolve in PBS, NaOH, or HCl after 60 days of incubation. Alginate-containing gels also showed less swelling in water than gels without alginate. Furthermore, E. coli bacteria were embedded in the nanocomposites and we analyzed the influence of the individual bioink components as well as of the printing process on bacterial viability. Here, the addition of alginate was necessary to maintain the effective viability of the embedded bacteria, while samples without alginate showed no bacterial viability. The experimental results demonstrate the potential of this approach for producing macroscopic bioactive materials with complex 3D geometries as a platform for novel applications in bioprocessing.

Preparation of Teucrium polium extract-loaded chitosan-sodium lauryl sulfate beads and chitosan-alginate films for wound dressing application

This study aimed to formulate sodium lauryl sulfate cross-linked chitosan beads and sodium alginate-chitosan films for designing a dressing that would shorten the healing time of skin wounds. Teucrium polium extract-loaded chitosan-sodium lauryl sulfate beads (CH-SLS) and chitosan-alginate (CH-ALG) films were prepared and characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The swelling properties of the CH-SLS beads were also analyzed in a water solution. The obtained Teucrium polium extract-loaded CH-SLS beads and CH-ALG films (TBF) were further incorporated into the commercial adhesive dressing. This TBF wound dressing was then investigated for evaluation of its wound healing potential in the mice using the excision wound model. Healing was assessed by the macroscopic appearance and the rate of wound contraction during 8 days. On day 4, the TBF-treated wounds exhibited 98% reduction in the wound area when they were compared with healing ointment, elastic adhesive dressing, and untreated wounds which were exhibited 63%, 43%, and 32%, respectively. Furthermore, the application of TBF dressing reduced skin wound rank scores and increased the percentage of wounds contraction. These results demonstrate that TBF dressing improves considerably the healing rate and the macroscopic wound appearance at a short delay and this application may have therapeutic benefits in wound healing.

Bio-Zirconium Metal-Organic Framework Regenerable Bio-Beads for the Effective Removal of Organophosphates from Polluted Water

Organophosphate-based pesticides, such as diazinon, are among the most toxic organic contaminants to human and environment. Effective removal of diazinon from contaminated water sources is critical. Zirconium Metal−organic frameworks (Zr-MOFs) are promising candidates for the removal of organic contaminants from wastewater. Herein, we report the adequacy of a bio based Zr-MOF named MIP-202 for the removal of diazinon from water. On the other hand, the use of these materials in powder form is not workable, the development of scalable and economical processes and integrative of these materials onto beads is paramount for industrial processes. Hence, it was reported a scalable, bio aqueous solution-based preparation strategy for Bio Zr-MOF beads production. The composite material exposed identical reactivity under the same ambient parameters compared to powdered material in an aqueous solution. These results signify a critical procedure to an integrated strategy for organophosphates removal using bio-based MOFs, which demonstrates high potential for manufacturing applications such as continued removal of organophosphates from wastewater supplies.

In vitro Digestion and Swelling Kinetics of Thymoquinone-Loaded Pickering Emulsions Incorporated in Alginate-Chitosan Hydrogel Beads

The present work aimed to investigate the swelling behavior, in vitro digestion, and release of a hydrophobic bioactive compound, thymoquinone (TQ), loaded in Pickering emulsion incorporated in alginate-chitosan hydrogel beads using a simulated gastrointestinal model. In this study, oil-in-water Pickering emulsions of uniform micron droplet sizes were formulated using 20% red palm olein and 0.5% (w/v) cellulose nanocrystals-soy protein isolate (CNC/SPI) complex followed by encapsulation within beads. FT-IR was used to characterize the bonding between the alginate, chitosan, and Pickering emulsion. 2% (w/v) alginate-1% (w/v) chitosan hydrogel beads were found to be spherical with higher stability against structural deformation. The alginate-chitosan beads displayed excellent stability in simulated gastric fluid (SGF) with a low water uptake of ~19%. The hydrogel beads demonstrated a high swelling degree (85%) with a superior water uptake capacity of ~593% during intestinal digestion in simulated intestinal fluid (SIF). After exposure to SIF, the microstructure transformation was observed, causing erosion and degradation of alginate/chitosan wall materials. The release profile of TQ up to 83% was achieved in intestinal digestion, and the release behavior was dominated by diffusion via the bead swelling process. These results provided useful insight into the design of food-grade colloidal delivery systems using protein-polysaccharide complex-stabilized Pickering emulsions incorporated in alginate-chitosan hydrogel beads.

Facile fabrication of an erythropoietin-alginate/chitosan hydrogel and evaluation of its local therapeutic effects on spinal cord injury in rats

BACKGROUND AND OBJECTIVE

Spinal cord injury (SCI) is a major disabling disorder for which no effective treatment has yet been found. Regenerative incapability of neuronal cells as well as the secondary mechanisms of injury are the major reasons behind this clinical frustration. Thus, here we fabricated an erythropoietin-chitosan/alginate (EPO-CH/AL) hydrogel and investigated its local therapeutic effects on the apoptotic and inflammatory indices of SCI secondary injury.

METHODS

EPO-CH/AL hydrogels were fabricated by the ionic gelation method, and they were characterized using SEM and FTIR. In vitro drug release profile of EPO-CH/AL hydrogels was evaluated by UV-vis spectroscopy. Experimental SCI was inflicted in rats which were then treated with CH/AL hydrogels containing different doses of EPO (1000, 5000 and 10,000 IU/kg). The relative expression of Bax and Bcl2 (apoptosis index) and active and inactive forms of NF-κB (inflammation index) were assessed using western blot. Total serum levels of TNF-α were also assessed with ELISA, and histopathological and immunohistochemistry studies were carried out to check the overall changes in the injured tissues.

RESULTS

In vitro drug release test indicated that the EPO-CH/AL hydrogels had a sustained- and controlled-release profile for EPO under these conditions. All the fabricated hydrogels dramatically reduced the elevated inflammation and apoptosis indices of the SCI-inflicted rats (p ≤ 0.05). Nevertheless, only EPO-CH/AL hydrogel (1000 IU/kg EPO) significantly improved the tissue repair and histopathological appearance of the spinal cord at the sites of injury.

CONCLUSION

Based on our findings, EPO-CH/AL hydrogel (1000 IU/kg EPO) can effectively improve experimental SCI in rats via inhibiting apoptosis and inflammation. Further studies are warranted to elucidate the contributing role of the scaffold in the observed effects.

Fabrication and characterization of Chrysin - A plant polyphenol loaded alginate -chitosan composite for wound healing application

The present study explores the therapeutic efficacy of sodium alginate-chitosan scaffolds loaded with Chrysin (ALG-CS-CHY) for dermal wound management. Scaffolds were prepared by the vacuum freeze-drying method. The physiochemical characterization was done through Fourier Transform Infra-Red Spectroscopy (FTIR), which revealed the interactions between the scaffold's functional groups and the drug. Surface Electron microscopy (SEM) showed a porous architecture varying from 200-400 μm. X-ray Diffraction (XRD) showed an ionic interaction between ALG-CS leading to their excellent compatibility. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) results suggest increased ALG-CS scaffold's thermal stability. In-vitro biodegradation behavior demonstrated controlled degradation with lysozyme. The swelling ratio was highest in the first hour and decreased slowly with time, and the porosity analysis showed a high degree of porosity. The ALG-CS scaffold showed sustained drug availability and minimized re-application, which contributes to effective healing and treatment. The blood compatibility and whole blood clotting ability of the scaffold significantly improved after incorporating the drug. Calcein AM, Propidium iodide, was used for live and dead cell staining, which confirmed that fabricated ALG-CS-CHY scaffolds are biocompatible and facilitate cell growth and cell proliferation. In-vivo and in-vitro observations show that the experimental group treated using the ALG-CS-CHY reduces the period of re-epithelization, accelerated fibroblast cell migration, and contracted wound significantly (p < 0.001) compared to other groups. ALG-CS-CHY scaffolds also increased collagen deposition, hexosamine synthesis, accelerates angiogenesis, and recruiting immune cells at the site of a wound. These results suggest ALG-CS-CHY scaffold serves as an effective dressing for dermal wound management.

Development of bioactive sodium alginate/sulfonated polyether ether ketone/hydroxyapatite nanocomposites: Synthesis and in-vitro studies

Developing bioactive composites to fill bone cavities caused by disease, injury or surgery still remains a challenge. The aim of this research was to develop a new nanostructured sodium alginate/sulfonated polyether ether ketone/nano-hydroxyapatite (Alg/SPEEK/HA) biocomposite via a simple chemical precipitation strategy. Structural analysis was carried out using X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) was used to compare the HA content of the composites. The in-vitro bioactivity of the composites with different content of HA was investigated by immersing the specimens in the simulated body fluid (SBF) for 15 days. The presence of HA in the composite structure gave rise to the precipitation of an apatite layer on the surface, which was increased by increase in the content of HA. The formation of the HA layer on the composite surface was scrutinized via FESEM and EDX analysis. Transmission electron microscopy (TEM) images exhibited the presence of HA nanoparticles with less than 30 nm in size. The in-vitro cytotoxicity evaluation was also carried out using MG-63 cells via the MTT assay, which revealed that the cytocompatibility of all specimens was increased with raising the HA content. However, the higher concentration (100 μg/ml) of the composites displayed some toxicity against MG-63 cells. These findings, therefore, proposed that the achieved novel nanocomposites could be regarded as promising materials to serve as bone filler.

Chitosan-based blends for biomedical applications

Polysaccharides are the most abundant naturally available carbohydrate polymers; composed of monosaccharide units covalently connected together. Chitosan is the most widely used polysaccharides because of its exceptional biocompatibility, mucoadhesion, and chemical versatility. However, it suffers from a few drawbacks, e.g. poor mechanical properties and antibacterial activity for biomedical applications. Blending chitosan with natural or synthetic polymers may not merely improve its physicochemical and mechanical properties, but may also improve its bioactivity-induced properties. This review paper summarizes progress in chitosan blends with biodegradable polymers and polysaccharides and their biomedical applications. Blends of chitosan with alginate, starch, cellulose, pectin and dextran and their applications were particularly addressed. The critical and challenging aspects as well as the future ahead of the use of chitosan-based blends were eventually enlightened.