Alginate Solution Research Articles

Improving probiotic (Lactobacillus casei) viability by encapsulation in alginate-based microgels: Impact of polymeric and colloidal fillers

Biopolymer microgels (hydrogel beads) can be used to improve probiotic stability during food storage and gastrointestinal passage. In this study, the impact of including natural polymeric and colloidal fillers on the viability of Lactobacillus casei encapsulated in calcium alginate microgels was examined. The polymeric filler was polysaccharides isolated from Choerospondias axillaris fruit peel (CP) and the colloidal filler was oil-in-water emulsion stabilized by CP. Results showed that addition of CP or CP coated lipid droplets significantly increased the antioxidant activity but reduced the apparent viscosity of the alginate solutions. Encapsulation of the probiotics in pure calcium alginate microgels reduced their viability (≈0 log CFU g −1 after 24 h). The inclusion of the polymeric or colloidal fillers within the microgels eliminated this negative effect. Moreover, they enhanced probiotic viability under simulated gastrointestinal tract conditions (>7.0 log CFU g −1 ). The calcium alginate microgels containing CP had the highest probiotic viability (7.42 ± 0.08 log CFU g −1 ) after 20 days storage. Our results indicated that simple calcium alginate microgels are not effective at protecting Lactobacillus casei during storage or gastrointestinal passage. However, incorporation of suitable polymeric or colloidal fillers can significantly enhance their viability. • Microgels were formed by alginate and C. axillaris peel polysaccharides (CP). • Pure calcium alginate microgels encapsulation reduced probiotic viability. • Calcium alginate + CP microgels enhanced probiotic viability during storage. • Adding of CP or CP coated oil droplet improved probiotic gastrointestinal stability.

Alginate Gel Immobilization of Caenorhabditis elegans for Optical Calcium Imaging of Neurons.

A fascinating question in neuroscience is how sensory stimuli evoke calcium dynamics in neurons. Caenorhabditis elegans is one of the most suitable models for optically recording high-throughput calcium spikes at single-cell resolution. However, calcium imaging in C. elegans is challenging due to the difficulties associated with immobilizing the organism. Currently, methods for immobilizing worms include entrapment in a microfluidic channel, anesthesia, or adhesion to a glass slide. We have developed a new method to immobilize worms by trapping them in sodium alginate gel. The sodium alginate solution (5%), polymerized with divalent ions, effectively immobilizes worms in the gel. This technique is especially useful for imaging neuronal calcium dynamics during olfactory stimulation. The highly porous and transparent nature of alginate gel allows the optical recording of cellular calcium oscillations in neurons when briefly exposed to odor stimulation.

Enhanced growth and lipid productivity by living Chlorella sorokiniana immobilized in Ca-alginate beads

The bottleneck for the production of biofuels from microalgae consists on costly harvesting processes and low lipid production, immobilization technology could play a part on making the production of biofuels more feasible. The aim of this study was to evaluate the effect of alginate immobilization on the growth and lipid productivity of the microalgae Chlorella sorokiniana, so far, the main focus of immobilization technology has been its use for wastewater treatment and nutrient removal from effluents. The microalgae Chlorella sorokiniana was cultured in both free and immobilized forms under optimal autotrophic growth conditions. Microalgae were immobilized in calcium alginate beads generated by mixing algal cells with a sodium alginate solution, followed by extrusion into a CaCl2 solution. The results obtained in this study showed that the growth of the microalgae immobilized in alginate beads, was enhanced and achieved a dry cell weight 1.4-fold higher than that of a free cell culture, a higher light transmittance was also achieved in the alginate immobilized culture, and the lipid productivity was increased from 54.21 ± 2.48 mg l−1 d in the free cell culture to 82.22 ± 8.48 mg l−1 d in the immobilized culture. These results demonstrate the effectiveness of immobilization technology for promoting growth and lipid productivity in the microalgae Chlorella sorokiniana.

Effects of Au@Ag core-shell nanostructure with alginate coating on male reproductive system in mice.

Despite the widespread use of silver nanoparticles (NPs), these NPs can accumulate and have toxic effects on various organs. However, the effects of silver nanostructures (Ag-NS) with alginate coating on the male reproductive system have not been studied. Therefore, this study aimed to investigate the impacts of this NS on sperm function and testicular structure. After the synthesis and characterization of Ag-NS, the animals were divided into five groups (n=8), including one control group, two sham groups (received 1.5mg/kg/day alginate solution for 14 and 35 days), and two treatment groups (received Ag-NS at the same dose and time). Following injections, sperm parameters, apoptosis, and autophagy were analyzed by the TUNEL assay and measurement of the mRNA expression of Bax, Bcl-2, caspase-3, LC3, and Beclin-1. Fertilization rate was assessed by in vitro fertilization (IVF), and testicular structure was analyzed using the TUNEL assay and hematoxylin and eosin (H&E) staining. The results showed that the NS was rod-shaped, had a size of about 60nm, and could reduce sperm function and fertility. Gene expression results demonstrated an increase in the apoptotic markers and a decrease in autophagy markers, indicating apoptotic cell death. Moreover, Ag-NS invaded testicular tissues, especially in the chronic phase (35 days), resulting in tissue alteration and epithelium disintegration. The results suggest that sperm parameters and fertility were affected. In addition, NS has negative influences on testicular tissues, causing infertility in men exposed to these NS.

Prodrug-loaded semiconducting polymer hydrogels for deep-tissue sono-immunotherapy of orthotopic glioblastoma.

Although immunotherapy has achieved great success in the treatment of a variety of tumors, its efficacy for glioblastoma (GBM) is still limited. Both the immunosuppressive tumor microenvironment (TME) and poor penetration of immunotherapeutic agents into tumors contributed to the poor anti-glioma immunity. Herein, we develop an injectable prodrug-loaded hydrogel delivery system with sono-activatable properties for sonodynamic therapy (SDT)-triggered immunomodulation for GBM treatment. The prodrug alginate hydrogels (APN), which contain semiconducting polymer nanoparticles (SPNs) and the NLG919 prodrug linked by singlet oxygen (1O2)-cleavable linkers, are in situ formed via coordination of alginate solution with Ca2+ in the TME. SPNs serve as sonosensitizers to produce 1O2 upon ultrasound (US) irradiation for SDT. The generated 1O2 not only induce immunogenic cell death, but also break 1O2-cleavable linkers to precisely activate the NLG919 prodrug. Antitumor immunity is significantly amplified due to the reversal of immunosuppression mediated by indolamine 2,3-dioxygenase-dependent tryptophan metabolism. This smart prodrug hydrogel platform potently inhibits tumor growth in orthotopic glioma-bearing mice. Collectively, this work provides a sono-activatable hydrogel platform for precise sono-immunotherapy against GBM.

Novel Electrospun Polycaprolactone/Calcium Alginate Scaffolds for Skin Tissue Engineering

After decades of research, fully functional skin regeneration is still a challenge. Skin is a multilayered complex organ exhibiting a cascading healing process affected by various mechanisms. Specifically, nutrients, oxygen, and biochemical signals can lead to specific cell behavior, ultimately conducive to the formation of high-quality tissue. This biomolecular exchange can be tuned through scaffold engineering, one of the leading fields in skin substitutes and equivalents. The principal objective of this investigation was the design, fabrication, and evaluation of a new class of three-dimensional fibrous scaffolds consisting of poly(ε-caprolactone) (PCL)/calcium alginate (CA), with the goal to induce keratinocyte differentiation through the action of calcium leaching. Scaffolds fabricated by electrospinning using a PCL/sodium alginate solution were treated by immersion in a calcium chloride solution to replace alginate-linked sodium ions by calcium ions. This treatment not only provided ion replacement, but also induced fiber crosslinking. The scaffold morphology was examined by scanning electron microscopy and systematically assessed by measurements of the pore size and the diameter, alignment, and crosslinking of the fibers. The hydrophilicity of the scaffolds was quantified by contact angle measurements and was correlated to the augmentation of cell attachment in the presence of CA. The in vitro performance of the scaffolds was investigated by seeding and staining fibroblasts and keratinocytes and using differentiation markers to detect the evolution of basal, spinous, and granular keratinocytes. The results of this study illuminate the potential of the PCL/CA scaffolds for tissue engineering and suggest that calcium leaching out from the scaffolds might have contributed to the development of a desirable biological environment for the attachment, proliferation, and differentiation of the main skin cells (i.e., fibroblasts and keratinocytes).

Understanding the microfluidic generation of double emulsion droplets with alginate shell

The monodisperse double emulsions obtained by microfluidic method can serve as ideal templates for preparing core-shell alginate microcapsules, which have attracted much attention in biological applications, such as drug delivery systems and cell encapsulation, tissue engineering. However, the formation behavior and dynamic analysis of double emulsion with an alginate shell is still unclear due to the complex rheological behavior of alginate solutions. Herein, we employ a dual-coaxial microfluidic device to generate the high-quality double emulsion droplets with alginate shell, focusing on the effects of the fluid properties of alginate solution in the middle phase (viscosity, μm) and the fluid flow rate on the droplet formation mechanism. As the viscosity of the middle fluid (μm) increased, the size of compound droplets (D2) increased and the size of inner droplets (D1) decreased, and the break-up regimes occurred a dripping-to-jetting transition when μm = 160 mPa s. The number of encapsulated inner droplets can be predicted and precisely controlled by regulating the generation frequency of inner (f1) and outer droplets (f2). The breakup dynamics of the alginate thread are also analyzed by using the volume-of-fluid/continuum-surface-force (VOF/CSF) method. The results show that the pressure and velocity in the neck of pinch-off is lower in the jetting than that in the dripping regime. This study will provide useful guidance for the rational design and controllable preparation of core-shell alginate microcapsules.

Effect of Cross-linking Time on Sodium Alginate Based Blend Films as a Supporter of Bordeaux Mixture

Blend films based on sodium alginate (SA) are synthesized and the use of these films as a supporter for Bordeaux mixture to adhere the crops for longer time and sustained release of active ingredient were studied. An aqueous solution of Sodium alginate was prepared and the obtained solution was added to bordeaux mixture of fixed compositions. Alginate solution is cross-linked by the multivalent cations present in bordeaux mixture and forms films. Blends based on sodium alginate with gelatin(SAGN) and sodium alginate with guar gum(SAGM) were synthesised. The thickening and cross linking action of these films were controlled by varying the cross linking time. The films were dried at 50oC in an oven and kept in different buffer solutions for swelling studies. From the swelling data, rate and kinetics of swelling were studied and swelling parameters were tabulated. The swelling parameters showed that the various bordeaux mixture cross-linked films were stable and they can absorb sufficient quantity of water and may prevent leaching out of active ingredients on rough weathers. Also the cross-linked polymer film may serve in increasing life and sustained release of active ingredients. Keywords: Blends, Bordeaux mixture, ionic cross linking, pH sensitivity, sustained release

Magnetic chitosan hydrogel beads as adsorbent for copper removal from aqueous solution

Magnetic chitosan hydrogel beads (MCHB) were synthesized by blending chitosan and magnetite (Fe3O4) in sodium alginate solution. The MCHB was used to remove Cu (II) metal ions in an aqueous solution. The performance of MCHB to remove Cu (II) ions was evaluated experimentally at different parameters (the initial pH of the solution, contact time, and various magnetite ratios of the hydrogel beads) in the batch adsorption set-up. This study indicated that MCHB managed to remove Cu (II) ions by adsorption at pH 5 at 24 h of contact time. The hydrogel beads of MCHB-0.5 (C:M:A ratio by weight of 1:0.5:2) show the highest Cu (II) ions removal efficiency of 56.51%. The addition of magnetite at the minimal ratio does not hinder the adsorption of Cu (II) ions onto MCHB. The magnetite in the beads also eases the separation of the hydrogel beads from the solution by an external magnet after treatment.

Alginate based polymeric systems for drug delivery, antibacterial/microbial, and wound dressing applications

Alginates are anionic, hydrophilic polysaccharides that are derived from brown seaweeds and bacteria. The chemical structure contains β-D-mannuronic acid (M) and α-L-guluronic acid (G) and G and M residue segmentation is responsible for the property like gelation and viscosity. The inherent properties like biocompatibility, biodegradability, nontoxicity, high mechanical strength, abundance, and high adsorption capacity have made the alginate-based polymeric systems a promising material in biomedical applications such as drug delivery (controlled/sustained release and tumor therapy), tissue engineering, wound healing, cell encapsulation, and biosensing, etc. Distinctive forms of alginate-based polymeric systems/materials like foams, hydrogels, aerogels, nanocomposites, microspheres, scaffolds, and sponges are being widely explored in biomedical fields. The present review summarizes the sources, extraction/purification methods, properties, and different forms of alginate-based advanced polymeric systems, and their utilization in drug delivery, antibacterial/microbial, and wound dressing applications are thoroughly summarized. The reviewed research work reveals that the alginate-based polymeric systems could be a better candidate for a few of the selected biomedical applications. Moreover, it also reveals that the alginate polymeric systems such as hydrogels, scaffolds, and microspheres are potential candidates in real-time applications when compared to other reported materials. Mainly, alginate polymeric systems available commercially for wound dressing and other applications are still under exploration. In addition, future scopes are employed to highlight existing limitations and solutions of alginates and alginate-based advanced polymeric systems. • Alginates beneficial as potential polymeric system in biomedical applications • Various forms of alginates are comprehensively elucidated • Improved surface properties and important applications are systematically reviewed • Properties can be tuned by combining with other efficient synthetic and natural materials as future advanced polymeric systems

Synthetic seeds technology of Salvia officinalis as a method for short-term storage and in vitro propagation of valuable genotypes

Summary Introduction: The technological advancements in the production of synthetic seeds are critical for the preservation of valuable genotypes of many herbal plants, including Salvia officinalis – sage. Objective: The aim of this study was the production, storage and conversion of artificial sage seeds. The technology of synthetic seeds is placing explants capable of regeneration into plants in a protective casing. Methods: Apical and axillary buds were encapsulated with 1.2% sodium alginate solution, and then dripped in 200 mM CaCl2 solution. Artificial seeds were stored at 4°C for 30 days and then converted on MS medium containing 0.3 mg/l of BAP. Results: The synthetic seeds technology made it possible to obtain a high level of seeds conversion into plants using apical buds (85.0%), and slightly lower in the case of side buds (62.5%). Conclusion: The fully developed technology of synthetic seeds made it possible to obtain a high level of plant viability, which may prove useful for the storage of valuable genotypes of sage.

Mechanical, Barrier, Antioxidant and Antimicrobial Properties of Alginate Films: Effect of Seaweed Powder and Plasma-Activated Water

The incorporation of natural fillers such as seaweed may potentially enhance the properties of biopolymer films. In this study, we investigated the effect of seaweed powder as a bio-filler in alginate-based films at different concentrations (10, 30, and 50%, w/w alginate) and particle sizes (100 and 200 μm) on the mechanical, barrier, antioxidant, and antimicrobial properties of alginate which are essential for food packaging applications. Initially, mechanical properties of the alginate films prepared at different temperatures were evaluated to find the optimal temperature for preparing alginate solution. The addition of seaweed powder did not have any positive effect on the mechanical properties of the alginate films. However, the barrier (water vapor transmission rate) and antioxidant properties were improved with the addition of seaweed filler regardless of concentration. In addition, selected films were prepared in plasma-activated water (PAW). The mechanical properties (tensile strength, but not elongation at break) of the films prepared with PAW improved compared to the films prepared in distilled water, while a significant decrease was observed when incorporated with the seaweed filler. The films prepared in PAW also showed improved barrier properties compared to those prepared in distilled water. The antimicrobial activity of the alginate-seaweed film-forming solution was in general more pronounced when prepared with PAW and stored at 10 °C, particularly at the highest concentration of the film-forming solution (83.3% v/v). A more pronounced inhibitory effect was observed on the Gram-positive S. aureus than on the Gram-negative E. coli, which has been attributed to the different composition and structure of the respective cell walls. This study has demonstrated the potential of seaweed filler in combination with PAW towards enhanced functionality and bioactivity of alginate films for potential food packaging applications.

Green flame-retardant coatings based on iron alginate for polyester fabrics: Thermal stability, flame retardancy and mechanical properties

Polyester (PET) fabrics are widely used in our daily life, but they burn and drip quickly when they encounter flames, and the dripping can cause secondary damage to human bodies. In this study, flame-retardant finishing of PET fabrics was performed by preparing alginate coatings modified with Fe3+. A simple dip-coating technique was used and sodium alginate solution was employed to submerge PET fabrics, after that the coatings were complexed with Fe3+ to endow the flame retardancy of PET fabrics. The micromorphology, mechanical properties, thermal stability, flame retardancy, and burning behaviors of the coated PET fabrics were analyzed. Coated PET fabrics had a limiting oxygen index value of 29%. The vertical flame test illustrated that PET/Iron alginate-2 exhibited excellent self-extinguishing behaviors, no drips appeared. The peak heat release rate of PET/Iron alginate-2 was reduced by 70.3%. In the warp directions, compared with the control, the tensile strength of coated PET textiles increased dramatically. In a word, it is a green method to improve the flame retardancy and anti-dripping of PET fabrics.

Bacterial Cellulose Composites with Polysaccharides Filled with Nanosized Cerium Oxide: Characterization and Cytocompatibility Assessment.

A new biocompatible nanocomposite film material for cell engineering and other biomedical applications has been prepared. It is based on the composition of natural polysaccharides filled with cerium oxide nanoparticles (CeONPs). The preparative procedure consists of successive impregnations of pressed bacterial cellulose (BC) with a sodium alginate (ALG) solution containing nanoparticles of citrate-stabilized cerium oxide and a chitosan (CS) solution. The presence of CeONPs in the polysaccharide composite matrix and the interaction of the nanoparticles with the polymer, confirmed by IR spectroscopy, change the network architecture of the composite. This leads to noticeable changes in a number of properties of the material in comparison with those of the matrix's polysaccharide composition, viz., an increase in mechanical stiffness, a decrease in the degree of planar orientation of BC macrochains, an increase in hydrophilicity, and the shift of the processes of thermo-oxidative destruction of the material to a low-temperature region. The latter effect is considered to be caused by the redox activity of cerium oxide (reversible transitions between the states Ce4+ and Ce3+) in thermally stimulated processes in the nanocomposite films. In the equilibrium swollen state, the material retains a mechanical strength at the level of ~2 MPa. The results of in vitro tests (cultivation of multipotent mesenchymal stem cells) have demonstrated the good biocompatibility of the BC-ALG(CeONP)-CS film as cell proliferation scaffolds.

Effect of Composite Chitosan/Sodium Alginate Gel Coatings on the Quality of Fresh-Cut Purple-Flesh Sweet Potato.

In this study, single-layer coating using chitosan (Ch) and sodium alginate (SA) solutions and their gel coating (ChCSA) formed by layer-by-layer (LbL) electrostatic deposition using calcium chloride (C) as a cross linking agent were prepared to improve storage qualities and shelf-life of fresh-cut purple-flesh sweet potatoes (PFSP). The preservative effects of single-layer coating in comparison with LbL on the quality parameters of fresh-cut PFSP, including color change, weight loss, firmness, microbial analysis, CO2 production, pH, solid content, total anthocyanin content (TAC), and total phenolic content (TPC) were evaluated during 16 days of storage at 5 °C. Uncoated samples were applicable as a control. The result established the effectiveness of coating in reducing microbial proliferation (~2 times), color changes (~3 times), and weight loss (~4 times) with negligible firmness losses after the storage period. In addition, TAC and TPC were better retained in the coated samples than in the uncoated samples. In contrast, quality deterioration was observed in the uncoated fresh cuts, which progressed with storage time. Relatively, gel-coating ChCSA showed superior effects in preserving the quality of fresh-cut PFSP and could be suggested as a commercial method for preserving fresh-cut purple-flesh sweet potato and other similar roots.

Rheological Properties of Film-Forming Dispersions of Selected Biopolymers Used for Packaging Films or Food Coating

Film-forming solutions based on four types of biopolymers were prepared and their rheological properties were determined. High methylated apple pectin and sodium alginate were used at the concentrations 1%, 1.5%, and 2%, whereas soy protein isolate and pork gelatin were obtained at 4%, 8%, and 12%. The parameters determining the production of the appropriate type of packaging film or edible coating are the setting time on the substrate, regardless of its type, and the gelation temperature, which were analyzed in the study by determination of flow curves and rheological parameters of prepared dispersions. The Newtonian model was used to describe the flow curves of the gelatin and sodium alginate solutions, while the Ostwald–de Waele model was used to describe the flow curves of the soy protein isolate and high methylated apple pectin solutions. The apparent viscosity of all solutions increased with increasing biopolymer concentrations, from 0.0042 to 0.0061 Pa·s and from 0.0187 to 0.0884 Pa·s for high-methylated apple pectin and sodium alginate, respectively; whereas, for a protein-based solution the viscosity increase was from 0.024 to 0.100 Pa·s and from 0.0018 to 0.0056 Pa·s for soy and gelatin, respectively. Modulus of elasticity curves appeared only at the highest concentrations, which means that the formation of the continuous structure of film or coating occurs by different mechanisms depending on the biopolymer type and its amount dispersed in aqueous solutions.

Enzymes Encapsulated within Alginate Hydrogels: Bioelectrocatalysis and Electrochemiluminescence Applications.

A simple procedure to incorporate enzymes (horseradish peroxidase, HRP, and lactate oxidase, LOx) within alginate hydrogels is reported with electrochemiluminescence (ECL) used to detect the enzymatic reactions with the corresponding substrates. First, HRP and LOx were successfully immobilized into CaCO3 microspheres, followed by the electrostatic layer-by-layer deposition of a nanoshell onto the microspheres, and finally by their dispersion into alginate solution. The as-prepared dispersion was drop cast onto the glassy carbon electrodes and cross-linked by the external and internal gelation methods using Ca2+ cations. The enzymes encapsulated within the alginate hydrogels were characterized using cyclic voltammetry and kinetic studies performed using ECL. The results showed that the enzymatic activity was significantly maintained as a result of the immobilization, with values of the apparent Michaelis-Menten constants estimated as 7.71 ± 0.62 and 8.41 ± 0.43 μM, for HRP and LOx, respectively. The proposed biosensors showed good stability and repeatability with an estimated limit of detection of 5.38 ± 0.05 and 0.50 ± 0.03 μM for hydrogen peroxide and lactic acid, respectively. The as-prepared enzymes encapsulated within the alginate hydrogels showed good stability up to 28 days from their preparation. The sensitivity and selectivity of the enzymes encapsulated within the alginate hydrogels were tested in real matrices (HRP, hydrogen peroxide, in contact lens solution; LOx, lactic acid in artificial sweat) showing the sensitivity of the ECL detection methods for the detection of hydrogen peroxide and lactic acid in real samples.

Effect of Dietary Fiber on the Level of Free Hypoglycemic Agents in Vitro.

We studied the effect of dietary fibers (DFs) on the levels of free hypoglycemic agents in vitro, i.e., glimepiride and the biguanides buformin and metformin. The levels of free buformin and free metformin were not affected by mixtures of DFs, i.e., cellulose, chitosan, pectin (PE), and glucomannan (GM), in fluids of pH 1.2 and 6.8 (similar to the pH of the stomach and intestines, respectively). However, the free biguanide level was significantly reduced by mixing with PE or sodium alginate (AL), in water. The free glimepiride level was reduced in the mixture of AL, PE, and GM (in a solution with a pH of 6.8). The changes in aqueous AL solution pH seemed to reflect the free metformin levels. Therefore, the effects of DFs on free drug levels were dependent on drug type, hypoglycemic agent, and mixing solution. In this study, the oral regimen concentrations of the drug and DFs were used. Based on these results, it is important to consider the interactions between hypoglycemic agents and DFs.

Efficiency of accelerated electron beam sterilization of a hydrogel for 3D cultivation of mesenchymal multipotent cells

Background. Hydrogels are promising for use in tissue engineering for the restoration and regeneration of various tissues, since they are able to perform the functions of bulk scaffolds, providing the formation of 3D cell structures. Population of such scaffolds with autologous or heterogeneous mesenchymal multipotent stromal cells in vitro makes it possible to localize these cells in the area of target tissues after implantation in a patient. One of the difficult tasks is the choice of the method and mode of sterilization of the hydrogel, which does not change its properties.Aim. Study of the effectiveness of hydrogel sterilization by an accelerated electron beam in various modes, changes in the structure and biocompatibility of the scaffold, to assess the prospects for its use for medical purposes, including as a platform for mesenchymal stromal cells.Materials and methods. We used a hydrogel based on 4 % solutions of sodium alginate and sodium salt of carboxymethyl cellulose, cross-linked with calcium chloride, which was developed, obtained and provided for our research by the team of the Research and Educational Center for Biomedical Engineering of the National University of Science and Technology “MISIS”. Hydrogel samples loaded with Escherichia coli, Lactobacillus acidophilus, Saccharomyces cerevisiae were subjected to electron beam treatment in the range of 5–100 kGy. After electron beam treatment of hydrogel, the presence of living microorganisms and its structure were evaluated by IR-Fourier spectroscopy, as well as the phenotype and formation of 3D structures by mesenchymal multipotent cells.Results. It was found that the treatment of hydrogels with an electron beam at a mode of 25 kGy ensures the death of microorganisms, but does not destroy the structure of the hydrogel and does not inhibit the ability to form capillary-like structures by mesenchymal multipotent cells.Conclusion. Treatment with an accelerated electron beam at a 25 kGy can be used to sterilize hydrogels to obtain bulk scaffolds for cell engineering implants.

Prodrug and Glucose Oxidase Coloaded Photodynamic Hydrogels for Combinational Therapy of Melanoma.

With the advantages of high safety and selectivity, photodynamic therapy (PDT) has been widely used for cancer treatments, while the anticancer efficacy is often limited because of its relying on oxygen concentrations. Therefore, sole PDT fails to achieve the desired therapeutic effect for hypoxic tumors. To address this issue, we herein report the construction of prodrug and glucose oxidase (GOx) coloaded alginate (ALG) hydrogels for PDT-combined chemotherapy of melanoma. The hydrogels are in situ formed in tumor sites after injection of ALG solution containing semiconducting polymer nanoparticles, hypoxia-responsive prodrug tirapazamine (TPZ), and GOx, which is based on chelation of ALG by endogenous Ca2+. Due to the presence of semiconducting polymer nanoparticles acting as photosensitizers, the hydrogels mediate PDT to produce singlet oxygen (1O2) for directly killing tumor cells, in which oxygen is consumed to create a more hypoxic tumor microenvironment. Moreover, the loaded GOx within hydrogels can deplete oxygen to further aggravate tumor hypoxia. As such, TPZ is effectively activated by hypoxia to cause cancer cell death via chemotherapy. Thus, the hydrogels with laser irradiation achieve a combinational action of PDT with chemotherapy to almost completely eradicate tumors, leading to a much higher therapeutic efficacy relative to sole PDT. This study will provide a promising injectable hydrogel platform for effective treatments of cancer.