Nanoremediation of tilapia fish culture using iron oxide nanoparticles biosynthesized by Bacillus subtilis and immobilized in a free-floating macroporous cryogel.

BACKGROUND AND AIM: Contamination from increased anthropogenic activities poses a threat to human health as well as the ecosystem. To develop a nanotechnological approach to improve aqua fisheries, we synthesized magnetic hematite nanoparticle-based gel and evaluated its efficacy in a cadmium-polluted closed system to decontaminate water and improve tilapia fish health. METHODS: Green iron oxide nanoparticles were biosynthesized by the metabolite of bacillus subtilis and incorporated into polyvinyl alcohol to construct a hydrogel by cryogelation. KEY FINDINGS: The cryogel had interconnected macropores with diameters widely ranging between 20 and 200 µm and could be free-floating in water. When applied in cadmium-polluted tilapia culture, this nanogel reduced turbidity and ammonia in the aquarium, adsorbed cadmium from the water with a larger quantity on the gel's outer surface than in its center., and reduced cadmium concentration in tilapia's liver, gills, and muscles. Application of this nano-based cryogel reduced the toxic effects of cadmium on tilapia fish. It maintained hepatic and renal cell nuclear integrity as determined by comet assay. This nano-treatment also reversed the cadmium-induced elevations of plasma lipids, glucose, stress marker cortisol, the hepatic enzymes AST and ALT, and the kidney function marker urea, and improved the lymphocytopenia and other hematological functions in tilapia fish intoxicated by cadmium.

Agarose Cryogels Loaded with Polydopamine Microspheres for Sustainable Wound Care with Enhanced Hemostatic and Antioxidant Properties.

Excessive bleeding presents a grave risk to life, especially in scenarios involving deep wounds such as those inflicted by gunshots and accidental stabs. Despite advancements in wound care management, existing commercial hemostatic agents have limitations, necessitating the development of enhanced solutions. In this study, we developed cryogels using agarose and polydopamine microspheres as a hemostatic dressing to effectively manage profuse bleeding. The resulting cryogels demonstrated impressive attributes, such as high absorption capacity (>4000%), shape recovery ability, antioxidant properties, and excellent biocompatibility in mammalian cell lines. Particularly noteworthy was the rapid blood clotting observed in vitro, with the agarose/PDA cryogels achieving complete clotting within just 90 s. Subsequent validation in the rat trauma model further underscored their hemostatic efficacy, with clotting times of 40 and 53 s recorded in tail amputation and liver puncture models, respectively. The porous structure and hydrophilicity of the cryogels facilitated superior blood absorption and retention, while the amine groups of polydopamine played a pivotal role in enhancing blood clotting activity. This study represents a significant step forward in utilizing agarose/polydopamine cryogels as advanced materials for hemostatic wound dressings, promising an impactful contribution to wound therapy.

Antimicrobial activity and nanoremediation of heavy metals using biosynthesized CS/GO/ZnO nanocomposite by Bacillus subtilis ATCC 6633 alone or immobilized in a macroporous cryogel.

BACKGROUND: The world society is still suffering greatly from waterborne infections, with developing countries bearing most of the morbidity and death burden, especially concerning young children. Moreover, microbial resistance is one of the most prevalent global problems that extends the need for self-medication and the healing period, or it may be linked to treatment failure that results in further hospitalization, higher healthcare expenses, and higher mortality rates. Thus, innovative synthesis of new antimicrobial materials is required to preserve the environment and enhance human health. RESULTS: The present study highlighted a simple and cost-effective approach to biosynthesize a chitosan/graphene oxide/zinc oxide nanocomposite (CS/GO/ZnO) alone and immobilized in a macroporous cryogel as a new antimicrobial agent. Bacillus subtilis ATCC 6633 was used as a safe and efficient bio-nano-factory during biosynthesis. The formation of CS/GO/ZnO was confirmed and characterized using different analyses including ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), selective area diffraction pattern (SADP), Zeta analyses, scanning electron microscope (SEM) and transmission electron microscopy (TEM). GO combined with ZnO NPs successfully and displayed an adsorption peak at 358 nm. The XRD results showed the crystalline composition of the loaded ZnO NPs on GO sheets. FTIR spectrum confirmed the presence of proteins during the synthesis which act as stabilizing and capping agents. The nanocomposite has a high negative surface charge (-32.8 ± 5.7 mV) which increases its stability. SEM and TEM showing the size of biosynthesized ZnO-NPs was in the range of 40-50 nm. The CS/GO/ZnO alone or immobilized in cryogel revealed good antimicrobial activities against B. cereus ATCC 14,579, Escherichia coli ATCC 25,922, and Candida albicans ATCC 10,231 in a dose-dependent manner. The CS/GO/ZnO cryogel revealed higher antimicrobial activity than GO/ZnO nanocomposite and standard antibiotics (amoxicillin and miconazole) with inhibition zones averages of 24.33 ± 0.12, 15.67 ± 0.03, and 17.5 ± 0.49 mm, respectively. The MIC values of the prepared nanocomposite against B. cereus, E. coli, and C. albicans were 80, 80, and 90 µg/ml compared to standard drugs (90, 120 and 150 µg/ml, respectively). According to the TEM ultrastructure studies of nanocomposite-treated microbes, treated cells had severe deformities and morphological alterations compared to the untreated cells including cell wall distortion, the separation between the cell wall and plasma membrane, vacuoles formation moreover complete cell lyses were also noted. In the cytotoxicity test of CS/GO/ZnO alone and its cryogel, there was a significant reduction (p˂0.05) in cell viability of WI-38 normal lung cell line after the concentration of 209 and 164 µg/ml, respectively. It showed the low toxic effect of the nanocomposite and its cryogel on the WI-38 line which implies its safety. In addition, water treatment with the CS/GO/ZnO cryogel decreased turbidity (0.58 NTU), total coliform (2 CFU/100 ml), fecal coliform (1 CFU/100 ml), fecal Streptococcus (2 CFU/100 ml), and heterotrophic plate counts (53 CFU/1 ml) not only in comparison with the chlorine-treated samples (1.69 NTU, 4 CFU/100 ml, 6 CFU/100 ml, 57 CFU/100 ml, and 140 CFU/1 ml, respectively) but also with the raw water samples (6.9 NTU, 10800 CFU/100 ml, 660 CFU/100 ml, 800 CFU/100 ml, and 4400 CFU/1 ml, respectively). Moreover, cryogel significantly decreased the concentration of different heavy metals, especially cobalt compared to chlorine (0.004 ppm, 0.002 ppm, and 0.001 ppm for raw water, chlorine-treated, and cryogel-treated groups, respectively) which helped in the reduction of their toxic effects. CONCLUSION: This study provides an effective, promising, safe, and alternative nanocomposite to treat different human and animal pathogenic microbes that might be used in different environmental, industrial, and medical applications.

Recombinant Keratin-Chitosan Cryogel Decorated with Gallic Acid-Reduced Silver Nanoparticles for Wound Healing.

Background: Wound healing is a complex physiological process that can be roughly divided into four stages: hemostasis, inflammation, proliferation, and remodeling. Conventional wound dressings often fail to meet the diverse needs of these healing stages due to their limited functionality. Cryogels, however, possess several attractive properties, such as large, interconnected pores, good mechanical strength, and ease of modification, making them suitable for developing advanced dressings with multiple functions. In this study, we developed a multifunctional cryogel dressing, with biocompatible polysaccharides as the main component, designed to provide a breathable, moist, and antibacterial microenvironment for chronic infected wounds, thereby promoting wound healing. Methods: Recombinant keratin 31 (RK31) was combined with chitosan (CS) to produce a CS/RK31 cryogel, referred to as CK. Gallic acid-reduced silver nanoparticles (GA/Ag NPs) were incorporated as the active antibacterial component to create the CS/K31@GA/Ag cryogel, known as CKGA. The cryogel was characterized using scanning electron microscopy (SEM) and a universal testing machine, and its biocompatibility was assessed in vitro. The dynamic hemostatic performance of the cryogel was evaluated with a rat tail amputation bleeding model. Additionally, the antibacterial effects of the cryogel against Staphylococcus aureus and Escherichia coli were tested using agar diffusion assays and turbidimetry. The antioxidant capacity of the CKGA cryogel was also measured in vitro. Finally, the cryogel's ability to promote wound healing was tested in an SD rat model of infected wounds. Results: Characterization results showed that the CKGA cryogel features an interpenetrating porous network structure and exhibits excellent mechanical properties, with a swelling rate of up to 1800%. Both in vitro and in vivo experiments confirmed that the cryogel has good biocompatibility, effectively absorbs exudates, and rapidly stops bleeding. The addition of GA/Ag NPs provided significant antibacterial effects, achieving an inhibition rate of over 99.9% against both S. aureus and E. coli. Furthermore, CKGA cryogels demonstrated a strong scavenging capacity for ROS in a dose-dependent manner. Studies using the SD rat infected wound model showed that the cryogel effectively inhibited bacterial proliferation on wound surfaces, reduced local tissue inflammation, and promoted the healing of infected wounds. Conclusion: The multifunctional cryogel, with its rapid hemostatic, antibacterial, and antioxidant properties, as well as its ability to promote cell proliferation, could be widely used as a wound dressing for the healing of bacterial infections.

Cryogel microcarriers loaded with glial cell line-derived neurotrophic factor enhance the engraftment of primary dopaminergic neurons in a rat model of Parkinson's disease.

Objective.Cryogel microcarriers made of poly(ethylene glycol) diacrylate and 3-sulfopropyl acrylate have the potential to act as delivery vehicles for long-term retention of neurotrophic factors (NTFs) in the brain. In addition, they can potentially enhance stem cell-derived dopaminergic (DAergic) cell replacement strategies for Parkinson's disease (PD), by addressing the limitations of variable survival and poor differentiation of the transplanted precursors due to neurotrophic deprivation post-transplantation in the brain. In this context, to develop a proof-of-concept, the aim of this study was to determine the efficacy of glial cell line-derived NTF (GDNF)-loaded cryogel microcarriers by assessing their impact on the survival of, and reinnervation by, primary DAergic grafts after intra-striatal delivery in Parkinsonian rat brains.Approach.Rat embryonic day 14 ventral midbrain cells were transplanted into the 6-hydroxydopamine-lesioned striatum either alone, or with GDNF, or with unloaded cryogel microcarriers, or with GDNF-loaded cryogel microcarriers.Post-mortem, GDNF and tyrosine hydroxylase immunostaining were used to identify retention of the delivered GDNF within the implanted cryogel microcarriers, and to identify the transplanted DAergic neuronal cell bodies and fibres in the brains, respectively.Main results.We found an intact presence of GDNF-stained cryogel microcarriers in graft sites, indicating their ability for long-term retention of the delivered GDNF up to 4 weeks in the brain. This resulted in an enhanced survival (1.9-fold) of, and striatal reinnervation (density & volume) by, the grafted DAergic neurons, in addition to an enhanced sprouting of fibres within graft sites.Significance.This data provides an important proof-of-principle for the beneficial effects of neurotrophin-loaded cryogel microcarriers on engraftment of cells in the context of cell replacement therapy in PD. For clinical translation, further studies will be needed to assess the impact of cryogel microcarriers on the survival and differentiation of stem cell-derived DAergic precursors in Parkinsonian rat brains.

Tailoring the structural and physicochemical properties of rice straw cellulose-based cryogels by cell-mediated polyhydroxyalkanoate deposition.

This study presents a novel biotechnological approach for creating water vapor-resistant cryogels with improved integrity. Rice straw cellulose was transformed into nanofibrils through TEMPO-mediated oxidation and high-pressure homogenization. The resulting cryogels remained firm even when immersed in aqueous media, whose pores were used by live cell to deposit polyhydroxyalkanoate (PHA) particles inside them. This novel method allowed the compatibilization of PHA within the cellulosic fibers. As a consequence, the water sorption capacity was decreased by up to 6 times having just 4 % of PHA compared to untreated cryogels, preserving the cryogel density and elasticity. Additionally, this technique can be adapted to various bacterial strains and PHA types, allowing for further optimization. It was demonstrated that the amount and type of PHA (medium chain length and small chain length-PHA) used affects the properties for the cryogels, especially the water vapor sorption behavior and the compressive strength. Compared to traditional coating methods, this cell-mediated approach not only allows to distribute PHA on the surface of the cryogel, but also ensures polymer penetration throughout the cryogel due to bacterial self-movement. This study opens doors for creating cryogels with tunable water vapor sorption and other additional functionalities through the use of specialized PHA variants.

A thermal cross-linking approach to developing a reinforced elastic chitosan cryogel for hemostatic management of heavy bleeding.

Uncontrolled hemorrhage stands as the primary cause of potentially preventable deaths following traumatic injuries in both civilian and military populations. Addressing this critical medical need requires the development of a hemostatic material with rapid hemostatic performance and biosafety. This work describes the engineering of a chitosan-based cryogel construct using thermo-assisted cross-linking with α-ketoglutaric acid after freeze-drying. The resulting cryogel exhibited a highly interconnected macro-porous structure with low thermal conductivity, exceptional mechanical properties, and great fluid absorption capacity. Notably, assessments using rabbit whole blood in vitro, as well as rat liver volume defect and femoral artery injury models simulating severe bleeding, showed the remarkable hemostatic performance of the chitosan cryogel. Among the cryogel variants with different chitosan molecular weights, the 150 kDa one demonstrated superior hemostatic efficacy, reducing blood loss and hemostasis time by approximately 73 % and 63 % in the hepatic model, and by around 60 % and 68 %, in the femoral artery model. Additionally, comprehensive in vitro and in vivo evaluations underscored the good biocompatibility of the chitosan cryogel. Taken together, these results strongly indicate that the designed chitosan cryogel configuration holds significant potential as a safe and rapid hemostatic material for managing severe hemorrhage.

Implementation of a Macroporous Polyhydroxyethylmethacrylate Cryogel-Based Mini-Bioreactor System to Improve Monoclonal Antibody Production.

BACKGROUND: Monoclonal antibodies (mAbs) are pioneers in the diagnosis and treatment of many diseases, such as cancer, asthma, poisoning, viral infections, etc. As the market value of mAbs increases in the biopharma industry, the demand for high quantities is met by upscaled production using bioreactor systems. Thus, disposable, porous matrices called cryogels have gained the primary focus for adherent support in the proliferation of hybridoma cells. METHODS: In this study, a gelatin-immobilized polyhydroxyethylmethacrylate-based cryogel material (disc-shaped, 9 mL bed volume) was synthesized, and a mini-bioreactor set up developed for culturing hybridoma cells to produce mAbs continuously. The hybridoma clone, 1B4A2D5, secreting anti-human serum albumin monoclonal antibodies, was immobilized in the cryogel matrix (2 discs, 18 mL bed volume). RESULTS: The hybridoma cells were attached to the matrix within 12 h after inoculation, and the cells were in the lag phase for seven days, where they were secreted mAb into the circulation medium. During the initial exponential phase, the glucose consumption, lactic acid production, and mAb production were 3.36 mM/day, 3.67 mM/day, and 55.61 µg/mL/day, respectively. The medium was refreshed whenever the glucose in the media went below 50% of the initial glucose concentration. The cryogenic reactor was run continuously for 25 days, and the mAb concentration reached a maximum on the 17th day at 310.59 µg/mL. CONCLUSION: The cumulative amount of mAbs produced in 25 days of running was 246 µg/mL, 7.7 times higher than the mAbs produced from T-flask batch cultivation. These results demonstrate that the developed polyhydroxyethylmethacrylate-based cryogel reactor can be used efficiently for continuous mAb production.

Specific DNA aptamer-immobilized cryogel membranes as novel bioaffinity supports and their potential for the purification of activated protein C.

Activated protein C (APC), a serine protease produced from zymogen protein C (PC), is the key enzyme of the protein C pathway. APC has anticoagulant, anti-inflammatory, and cytoprotective features. APC has recently been shown to significantly reduce coagulation as well as mortality in patients with severe sepsis. Herein, we aimed to develop an affinity support material that allows the purification of plasma APC for the first time. In this research, a novel APC-specific DNA aptamer-based poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA/DNA-Apt)) macroporous cryogel membrane at different molar ratios was prepared using affinity binding method and their potential for purification and identification of APC was investigated. The DNA aptamer-immobilized cryogels were characterized to examine their structural and morphological properties. The effect of pH, initial concentration, temperature, ionic strength difference, and flow rate changes was examined. Selectivity studies were performed in the presence of APC and competitive proteins, and cryogel support materials were shown to have a very high affinity for APC. Adsorption capacity was found to be 89.02 mg/g. Finally, NaCl revealed efficiency for APC desorption and the reuse of cryogels was successfully tested for ten cycles.

Synthesis and characterization of Fe(III)-doped beta-cyclodextrin-grafted chitosan cryogel beads for adsorption of diclofenac in aqueous solutions: Adsorption experiments and deep-learning modeling.

Diclofenac (DCF) is frequently detected in aquatic environments, emphasizing the critical need for its efficient removal globally. Here, we present the synthesis of Fe(III)-doped ß-CD-grafted chitosan (Fe/ß-CD@CS) cryogel beads designed for adsorbing DCF in aqueous solutions. The beads exhibited an average size of 2.94 ± 0.66 mm and a point of zero charge of 8.03. Adsorption experiments demonstrated that the Langmuir kinetic model provided the most accurate description of the kinetic data, while the Redlich-Peterson isotherm offered the best fit for the equilibrium data. The beads showcased a theoretical maximum adsorption capacity of 712.3 mg/g for DCF, with the adsorption process being identified as exothermic. DCF adsorption on the beads was attributed to hydrogen bonding, metal cation-π interactions, and electrostatic interactions. Reusability tests exhibited that the beads could be regenerated using 0.1 M NaOH. To perform deep learning modeling, adsorption experiments (n = 17), designed utilizing central composite design (CCD), were conducted in duplicate. The CCD framework incorporated input variables such as initial DCF concentration, adsorbent dosage, and solution pH, while the output variable was the DCF removal rate. Utilizing the adsorption data, an artificial neural network (ANN) model was constructed with a topology of 3: 7:10:1, featuring 3 input variables, 7 neurons in the first hidden layer, 10 neurons in the second layer, and 1 output variable. Employing the ANN model data, 3-D response surface plots were generated to elucidate the relationship between input variables and DCF removal rate. Additional adsorption tests were conducted to evaluate the developed ANN model, affirming its reliable predictability for the DCF removal rate. Analysis of the relative importance of the input variables revealed the following order of importance: solution pH (100 %) > adsorbent dosage (75.2 %) > initial DCF concentration (57.7 %).

Characterization of gelatin-oxidized riclin cryogels and their applications as reusable ice cubes in shrimp preservation.

Traditional ice is usually employed to preserve food freshness and extend shelf life. However, ice cannot bear repeated freeze - thaw cycles during the transportation and retailing process, resulting in microbial cross-contamination and spoilage of foods. Herein, succinoglycan riclin was oxidated (RO) and crosslinked with gelatin (Ge), the Ge-RO cryogels were prepared via Schiff base reaction and three freeze - thaw cycles. The Ge-RO cryogels showed improved storage modulus (G') and thermal stability compared with pure gelatin hydrogel. The polymer framework of Ge-RO gels exhibited stable properties against ice crystals destructions during nine freeze - thaw treatments. During the storage and repeated freeze - thaw treatments of shrimps, Ge-RO cryogels exhibited a remarkable preservation effect on shrimps, and their freshness was evaluated using an electronic nose technique equipped with ten sensors. The results demonstrated that the shrimp muscle preserved in ice generated off-odors and resulted in high sensor responses. The sensor responses were reduced sharply of shrimps preserved in cryogels. Moreover, 1H NMR-based metabolomics analysis revealed that shrimps in Ge-RO cryogels group reversed the metabolic perturbations compared with the traditional ice group, the metabolic pathways were related to energy metabolism, nucleotide metabolism, and amino acid metabolism, which provide new clues to the freshness of shrimps. Furthermore, RO exhibited superior antimicrobial activity against E. coli and S. aureus microorganisms. Thus, the crosslinked cryogels are potentially applicable to food preservation, offering sustainable and reusable solutions against traditional ice.

Copper-MOF and tannic acid-empowered composite cryogel as a skin substitute for accelerated deep wound healing.

The effective management of deep skin wounds remains a significant healthcare challenge that often deteriorates with bacterial infection, oxidative stress, tissue necrosis, and excessive production of wound exudate. Current medical approaches, including traditional wound dressing materials, cannot effectively address these issues. There is a great need to engineer advanced and multifunctional wound dressings to address this multifaceted problem effectively. Herein, a rationally designed composite cryogel composed of a Copper Metal-Organic Framework (Cu-MOF), tannic acid (TA), polyvinyl alcohol (PVA), and zein protein has been developed by freeze-thaw technique. Cryogels display a remarkable swelling capacity attributed to their interconnected microporous morphology. Moreover, dynamic mechanical behaviour with the characteristics of potent antimicrobial, antioxidant, and biodegradation makes it a desirable wound dressing material. It was further confirmed that the material is highly biocompatible and can release TA and copper ions in a controlled manner. In-vivo skin irritation in a rat model demonstrated that composite cryogel did not provoke any irritation/inflammation when applied to the skin of a healthy recipient. In a deep wound model, the composite cryogel significantly accelerates the wound healing rate. These findings highlight the multifunctional nature of composite cryogels and their promising potential for clinical applications as advanced wound dressings.

Fabrication and characterization of calcium peroxide and berberine loaded cryogels for enhanced wound healing.

Wound healing represents a complex biological process crucial for tissue repair and regeneration. In recent years, biomaterial-based scaffolds loaded with bioactive compounds have emerged as promising therapeutic strategies to accelerate wound healing. In this study, we investigated the properties and wound healing effects of cryogels loaded with calcium peroxide (CP) and berberine (BB). The cryogels were synthesized through a cryogenic freezing technique and displayed pore diameters of 83 ± 39 µm, with porosity exceeding 90%. Following 20 days of degradation, the percentage of remaining weight for GPC and GPC-CP-BB cryogels was determined to be 12.42 ± 2.45% and 10.78 ± 2.08%, respectively. Moreover, the swelling ratios after 3 minutes for GPC and GPC-CP-BB were found to be 22.10 ± 0.05 and 21.00 ± 0.07, respectively. In vitro investigations demonstrated the cytocompatibility of the cryogels, with sufficient adhesion and proliferation of fibroblast (NIH-3T3) cells observed on the scaffolds, along with their hemocompatibility. Furthermore, the cryogels exhibited sustained release kinetics of both calcium peroxide and berberine, ensuring prolonged therapeutic effects at the wound site. In vivo assessment using a rat model of full-thickness skin wounds demonstrated accelerated wound closure rates in animals treated with the GPC-CP-BB scaffold compared to controls. Histological analysis revealed enhanced granulation tissue formation, re-epithelialization, and collagen deposition in the GPC-CP-BB group. Overall, our findings suggest that the scaffold loaded with CP and BB holds great promise as a therapeutic approach for promoting wound healing. Its multifaceted properties offer a multifunctional platform for localized delivery of therapeutic agents while providing mechanical support and maintaining a favorable microenvironment for tissue regeneration.

Synthesis and characterization of polysaccharide-cryogel and its application to the electrochemical detection of DNA.

The main goal of our study is to demonstrate the applicability of the PPy-cryogel-modified electrodes for electrochemical detection of DNA. First, a polysaccharide-based cryogel was synthesized. This cryogel was then used as a template for chemical polypyrrole synthesis. This prepared polysaccharide-based conductive cryogel was used for electrochemical biosensing on DNA. Carrageenan (CG) and sodium alginate (SA) polysaccharides, which stand out as biocompatible materials, were used in cryogel synthesis. Electron transfer was accelerated by polypyrrole (PPy) synthesized in cryogel networks. A 2B pencil graphite electrode with a diameter of 2.00 mm was used as a working electrode. The prepared polysaccharide solution was dropped onto a working electrode as a support material to improve the immobilization capacity of biomolecules and frozen to complete the cryogelation step. PPy synthesis was performed on the electrodes whose cryogelation process was completed. In addition, the structures of cryogels synthesized on the electrode surface were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Surface characterization of the modified electrodes was performed by energy-dispersive X-ray spectroscopy (EDX) analysis. Electrochemical determination of fish sperm DNA (fsDNA) was performed using a PPy-cryogel-modified electrode. The use of a porous 3D cryogel intermediate material enhanced the signal by providing a large surface area for the synthesis of PPy and increasing the biomolecule immobilization capacity. The detection limit was 0.98 µg mL-1 in the fsDNA concentration range 2.5-20 µg mL-1. The sensitivity of the DNA biosensor was estimated to 14.8 µA mM-1 cm-2. The stability of the biosensor under certain storage conditions was examined and observed to remain 66.95% up to 45 days.

Macroporous PEG-Alginate Hybrid Double-Network Cryogels with Tunable Degradation Rates Prepared via Radical-Free Cross-Linking for Cartilage Tissue Engineering.

Trauma or repeated damage to joints can result in focal cartilage defects, significantly elevating the risk of osteoarthritis. Damaged cartilage has an inherently limited self-healing capacity and remains an urgent unmet clinical need. Consequently, there is growing interest in biodegradable hydrogels as potential scaffolds for the repair or reconstruction of cartilage defects. Here, we developed a biodegradable and macroporous hybrid double-network (DN) cryogel by combining two independently cross-linked networks of multiarm polyethylene glycol (PEG) acrylate and alginate.Hybrid DN cryogels are formed using highly biocompatible click reactions for the PEG network and ionic bonding for the alginate network. By judicious selection of various structurally similar cross-linkers to form the PEG network, we can generate hybrid DN cryogels with customizable degradation kinetics. The resulting PEG-alginate hybrid DN cryogels have an interconnected macroporous structure, high mechanical strength, and rapid swelling kinetics. The interconnected macropores in the cryogels support efficient mesenchymal stem cell infiltration at a high density. Finally, we demonstrate that PEG-alginate hybrid DN cryogels allow sustained release of chondrogenic growth factors and support chondrogenic differentiation of mouse mesenchymal stem cells. This study provides a novel method to generate macroporous hybrid DN cryogels with customizable degradation rates and a potential scaffold for cartilage tissue engineering.

Arginine-loaded globular BSAMA/fibrous GelMA biohybrid cryogels with multifunctional features and enhanced healing for soft gingival tissue regeneration.

Mucogingival surgery has been widely used in soft gingival tissue augmentation in which autografts are predominantly employed. However, the autografts face grand challenges, such as scarcity of palatal donor tissue and postoperative discomfort. Therefore, development of alternative soft tissue substitutes has been an imperative need. Here, we engineered an interconnected porous bovine serum albumin methacryloyl (BSAMA: B, as a drug carrier and antioxidant)/gelatin methacryloyl (GelMA: G, as a biocompatible collagen-like component)-based cryogel with L-Arginine (Arg) loaded as an angiogenic molecule, which could serve as a promising gingival tissue biohybrid scaffold. BG@Arg cryogels featured macroporous architecture, biodegradation, sponge-like properties, suturability, and sustained Arg release. Moreover, BG@Arg cryogels promoted vessel formation and collagen deposition which play an important role in tissue regeneration. Most interestingly, BG@Arg cryogels were found to enhance antioxidant effects. Finally, the therapeutic effect of BG@Arg on promoting tissue regeneration was confirmed in rat full-thickness skin and oral gingival defect models. In vivo results revealed that BG@Arg2 could promote better angiogenesis, more collagen production, and better modulation of inflammation, as compared to a commercial collagen membrane. These advantages might render BG@Arg cryogels a promising alternative to commercial collagen membrane products and possibly autografts for soft gingival tissue regeneration.

Cryogel with Modular and Clickable Building Blocks: Toward the Ultimate Ideal Macroporous Medium for Bacterial Separation.

The lack of practical platforms for bacterial separation remains a hindrance to the detection of bacteria in complex samples. Herein, a composite cryogel was synthesized by using clickable building blocks and boronic acid for bacterial separation. Macroporous cryogels were synthesized by cryo-gelation polymerization using 2-hydroxyethyl methacrylate and allyl glycidyl ether. The interconnected macroporous architecture enabled high interfering substance tolerance. Nanohybrid nanoparticles were prepared via surface-initiated atom transfer radical polymerization and immobilized onto cryogel by click reaction. Alkyne-tagged boronic acid was conjugated to the composite for specific bacteria binding. The physical and chemical characteristics of the composite cryogel were analyzed systematically. Benefitting from the synergistic, multiple binding sites provided by the silica-assisted polymer, the composite cryogel exhibited excellent affinity toward S. aureus and Salmonella spp. with capacities of 91.6 × 107 CFU/g and 241.3 × 107 CFU/g in 0.01 M PBS (pH 8.0), respectively. Bacterial binding can be tuned by variations in pH and temperature and the addition of monosaccharides. The composite was employed to separate S. aureus and Salmonella spp. from spiked tap water, 40% cow milk, and sea cucumber enzymatic hydrolysate, which resulted in high bacteria separation and demonstrated remarkable potential in bacteria separation from food samples.

MXene reinforced microporous bacterial cellulose/sodium alginate dual crosslinked cryogel for bone tissue engineering.

The entangled assembly of bacterial cellulose (BC) nanofibers does not provide a three-dimensional (3D) macroporous structure for cellular infiltration thus hindering its use as a scaffold for bone tissue engineering. In addition, it is difficult to achieve uniform dispersion of bioactive agents in entangled BC nanofibers. To address this, the BC nanofibers were integrated with MXene, a two-dimensional nanomaterial known for its electrical signaling and mechanical strength, along with sodium alginate to form cryogel. The cryogel was fabricated using a cross-linking to enhance its mechanical properties, pores for cellular infilteration. MXene incorporation not only increased water absorption (852%-1446%) and retention (692%-973%) ability but also significantly improved the compressive stress (0.85 MPa-1.43 MPa) and modulus (0.22 MPa-1.17 MPa) confirming successful MXene reinforcement in cryogel. Biological evaluation revealed that the optimum concentration of MXene increased the cell proliferation and the osteogenic role of fabricated scaffolds was also confirmed through osteogenic gene expressions. The macropores in reconstructed MXene-BC-based cryogel provided ample space for cellular proliferation. The osteogenic role of the scaffold was examined through various gene expressions. The Quantitative polymerase chain reaction revealed that MXene-loaded scaffolds especially in low concentration, had an obvious osteogenic effect hence concluding that BC can not only be reconstructed into the desired form but osteogenic property can be induced. These findings can open a new way of reconstructing BC into a more optimal structure to overcome its structural limitations and retain its natural bioactivities.

Antimicrobial starch-based cryogels and hydrogels for dual-active food packaging applications.

The present study reports on the valorisation of starch waste biomass to produce dual-active cryogels and hydrogels able to adsorb water and deliver antimicrobial substances for fresh food packaging applications. Starch hydrogels were prepared by oxidation with sodium metaperiodate in water and mild conditions, while cryogels were obtained by freeze-drying process. To explore the role of starch composition on the final properties of materials, two starches differing in amylose/amylopectin ratio, were evaluated. The prepared materials were microstructurally and morphologically characterized by FTIR and NMR spectroscopy (1D, 2D, and DOSY experiments), and SEM microscopy. To provide the materials with active properties, they were loaded with antimicrobial molecules by absorption, or by crosslinking via Schiff-base reaction. All materials demonstrated high water absorption capacity and ability to deliver volatile molecules, including diacetyl and complex mixtures like mint essential oil. The release profiles of the adsorbed molecules were determined through quantitative NMR spectroscopy over time. The antibacterial activity was successfully demonstrated against Gram-positive bacterial strains for unloaded cryogels and hydrogels, and after loading with diacetyl and essential oil. The developed materials can be regarded as part of active pads for food packaging applications capable to control moisture inside the package and inhibit microbial contamination.

Binary fabrication of decellularized lung extracellular matrix hybridgels for in vitro chronic obstructive pulmonary disease modeling.

Limited treatments and a lack of appropriate animal models have spurred the study of scaffolds to mimic lung disease in vitro. Decellularized human lung and its application in extracellular matrix (ECM) hydrogels has advanced the development of these lung ECM models. Controlling the biochemical and mechanical properties of decellularized ECM hydrogels continues to be of interest due to inherent discrepancies of hydrogels when compared to their source tissue. To optimize the physiologic relevance of ECM hydrogel lung models without sacrificing the native composition we engineered a binary fabrication system to produce a Hybridgel composed of an ECM hydrogel reinforced with an ECM cryogel. Further, we compared the effect of ECM-altering disease on the properties of the gels using elastin poor Chronic Obstructive Pulmonary Disease (COPD) vs non-diseased (ND) human lung source tissue. Nanoindentation confirmed the significant loss of elasticity in hydrogels compared to that of ND human lung and further demonstrated the recovery of elastic moduli in ECM cryogels and Hybridgels. These findings were supported by similar observations in diseased tissue and gels. Successful cell encapsulation, distribution, cytotoxicity, and infiltration were observed and characterized via confocal microscopy. Cells were uniformly distributed throughout the Hybridgel and capable of survival for 7 days. Cell-laden ECM hybridgels were found to have elasticity similar to that of ND human lung. Compositional investigation into diseased and ND gels indicated the conservation of disease-specific elastin to collagen ratios. In brief, we have engineered a composited ECM hybridgel for the 3D study of cell-matrix interactions of varying lung disease states that optimizes the application of decellularized lung ECM materials to more closely mimic the human lung while conserving the compositional bioactivity of the native ECM. STATEMENT OF SIGNIFICANCE: The lack of an appropriate disease model for the study of chronic lung diseases continues to severely inhibit the advancement of treatments and preventions of these otherwise fatal illnesses due to the inability to recapture the biocomplexity of pathologic cell-ECM interactions. Engineering biomaterials that utilize decellularized lungs offers an opportunity to deconstruct, understand, and rebuild models that highlight and investigate how disease specific characteristics of the extracellular environment are involved in driving disease progression. We have advanced this space by designing a binary fabrication system for a ECM Hybridgel that retains properties from its source material required to observe native matrix interactions. This design simulates a 3D lung environment that is both mechanically elastic and compositionally relevant when derived from non-diseased tissue and pathologically diminished both mechanically and compositionally when derived from COPD tissue. Here we describe the ECM hybridgel as a model for the study of cell-ECM interactions involved in COPD.