Formation of calcium alginate gel capsules: Influence of sodium alginate and CaCl2 concentration on gelation kinetics

Follicle mural granulosa cells encapsulated in sodium alginate gel improve developmental competence of porcine oocytes of in vitro maturation

The maturation of oocytes has an important impact on the subsequent development of the embryo. However, during the in vitro maturation (IVM) of oocytes, oocytes are separated from the follicular environment, resulting in a low maturation rate of oocytes in vitro. In order to improve maturation rate of IVM of porcine oocytes, this study was conducted to investigate using sodium alginate (SA) to encapsulate porcine mural granulosa cells (MGs) to develop an SA three-dimensional (3D) co-culture system for IVM of porcine oocytes. And, gene expression, reactive oxygen species (ROS), ATP level, mitochondrial membrane potential, parthenogenetic activation development results of cultured oocytes, and as well as ROS and glutathione (GSH) levels in cumulus granulosa cells (CGs) were detected. Our results showed that the maturation rate of the SA 3D co-culture group was 85.41 %, that of the negative control (NC) group was 79.24 %, and that of the MGs co-culture group was 81.62 %. In SA 3D co-culture group, mitochondrial membrane potential level of oocytes was 1.6, ROS level was 19 and the ATP level was 1.7. While in NC group, mitochondrial membrane potential level of oocytes was 1.2, the ROS level was 52, and the ATP level was 0.4. The ROS level in the CGs of SA 3D co-culture group decreased by 1.5 times, and the glutathione content increased by 2.3 times. In the SA 3D co-culture group, GDF9 gene expression level was 2.0, and BMP15 gene expression level was 1.2. While in NC group, GDF9 gene expression level was 0.7, and BMP15 gene expression level was 0.6. The blastocyst rate in the SA 3D co-culture group was 41.4 %, and that in the NC group was 36.6 %. In conclusion, encapsulating MGs in SA gel and co-culturing them with porcine oocytes in 3D during IVM can improve the developmental potential of oocytes. This result will provide an important reference for improving the methods of in vitro maturation of oocytes.

3D Bioprinting of Cultivated Meat Followed by the Development of a Fine-Tuned YOLO Model for the Detection and Counting of Lipoblasts, Fibroblasts, and Myogenic Cells

BACKGROUND

Cultured meat holds significant potential as a pivotal solution for producing safe, sustainable, and high-quality protein to meet the growing demands of the global population. However, scaling this technology requires innovative bioengineering approaches integrated with software methods to assess the growth of cell cultures. This study aims to develop a technology for 3D printing a hybrid meat product and subsequently design a finely tuned You Only Look Once (YOLO) model for detecting and counting lipoblasts, fibroblasts, and myogenic cells.

METHODS

Cultures of multipotent mesenchymal stem cells (MMSCs) and fibroblasts were obtained from the domestic rabbit Oryctolagus cuniculus domesticus. Standard protocols were employed to induce adipogenic and myogenic differentiation from MMSCs. Fibroblasts were isolated from skin biopsy samples. The 3D printing process utilized bioinks. The engineering approach involved the development of a unique print head integrated into a 3D printer. Confocal and transmission electron microscopy of the cells within the construct was performed. A dataset of digital images of lipoblasts, myogenic cells, and fibroblasts was created. Four models based on the YOLOv8-seg architecture were trained on annotated images, implemented in the Telegram bot.

RESULTS

Stable cultures of lipoblasts, myogenic cells, and fibroblasts were obtained. 3D-printed tissue constructs composed of rabbit cells, sodium alginate, and sunflower protein were successfully fabricated. A unique print head for a 3D printer was assembled. Confocal microscopy confirmed cell viability within the tissue construct. Ultrastructural analysis revealed dense intercellular contacts and high metabolic activity. The resulting product replicated the organoleptic and structural properties of natural meat. In the IT segment, the single-class model trained on lipoblasts achieved metrics of recall 85%, precision 77%, and mean Average Precision at IoU threshold 0.50 (mAP50) 79%, which improved in the multiclass model to recall 92%, precision 92%, and mAP50 81%. The IT solution was implemented in a Telegram bot capable of detecting and counting different cell types.

CONCLUSIONS

A 3D tissue construct was achieved. Detailed microscopic analysis demonstrated cell viability and high metabolic activity within the polymerized alginate hydrogel. The engineered tissue product presents a potential alternative to natural meat. Additionally, the trained neural network models, implemented in a Telegram bot, proved effective in monitoring culture growth and identifying cell types in digital images across three cell cultures. As a result, we developed four YOLOv8 models and demonstrated that the multiclass model outperforms the single-class model. However, all models exhibited reduced accuracy in high-density cultures, where overlapping cells led to undercounting.

FRESH 3D printing of zoledronic acid-loaded chitosan/alginate/hydroxyapatite composite thermosensitive hydrogel for promoting bone regeneration

The aim of this study was to develop a composite thermosensitive hydrogel for bone regeneration applications. This hydrogel consisted of chitosan, alginate and hydroxyapatite, and was loaded with zoledronic acid as a model drug. The feasibility of three-dimensional (3D) printing of the thermosensitive hydrogel using the extrusion based technique was investigated. The 3D printing technique called Freeform Reversible Embedded Suspended Hydrogel (FRESH) printing was employed for this purpose. To characterize the composite hydrogels, several tests were conducted. The gelation time, rheological properties, and in vitro drug release were analyzed. Additionally, the cell viability test on human osteosarcoma MG-63 cells for the composite hydrogel was assessed using an MTT assay. The results of the study showed that the zoledronic acid-loaded composite thermosensitive hydrogel was successfully printed using the FRESH 3D printing technique which was not possible otherwise i.e., by using traditional 3D printing techniques. Further examination of the printed constructs using a Scanning Electron Microscope revealed the presence of porous and layered structures. The gelation times of the composite thermosensitive hydrogel was determined to be 10 and 20 min, respectively for scaffolds with and without HA, indicating the successful formation of the gel within a reasonable time to the FRESH technique. The flow behavior of the hydrogel was found to be pseudoplastic, following a non-Newtonian flow pattern with Farrow's constant (N) values of 1.708 and 1.853 for scaffolds with and without hydroxyapatite, respectively. In terms of drug release, scaffolds prepared with and without hydroxyapatite reached nearly 100% of zoledronic acid release in 360 h and 48 h, respectively. The cell viability test on human osteosarcoma MG-63 cells using MTT assay has shown increased cell viability % in the case of composite hydrogel, indicating biocompatibility of the scaffold. Overall, this study successfully developed a composite thermosensitive hydrogel loaded with zoledronic acid for bone regeneration applications and was 3D printed using the FRESH 3D printing technique. The results of this study provide valuable insights into the potential use of this composite hydrogel for future biomedical applications.

Advanced alginate-based nanofiber aerogels: A synthetic matrix for high-efficiency lysozyme adsorption and controlled release

The development of materials with high lysozyme adsorption is critical for drug delivery and skin wound applications, as it enhances antibacterial properties, stability, and controlled release of therapeutic agents, thereby improving treatment efficacy and safety. Alginate-based nanofiber scaffolds, featuring high surface area and multiple adsorption sites, can efficiently absorb lysozyme and regulate its release through tunable pore channels, offering a promising approach to chronic wound management. In this study, we fabricated poly (vinyl alcohol-co-ethylene) (EVOH) nanofiber-based sodium alginate (ENSA) aerogels using a simple two-step crosslinking procedure. The resulting aerogels, with controllable porosity formed via high-pressure spraying techniques (aerogel film) and molding (aerogel sponge), were evaluated for their high-loading capacity and controllable release of lysozyme. The aerogel film exhibited a remarkable lysozyme adsorption capacity of 1965 ± 36 mg/g, while the aerogel sponge sustained lysozyme release over 14 days. Analysis of the drug-release mechanism through four kinetic models revealed two distinct processes: cation exchange and matrix diffusion. The aerogel's pore structure influenced the diffusion processes, enabling tailored drug release profiles. Additionally, the ENSA aerogels demonstrated good mechanical properties, non-cytotoxicity, and potent antibacterial activity, positioning them as promising materials for skin wound dressings.

Preparation of Controlled Multicompartmental Gel Microcarriers Based on Aqueous Two-Phase Emulsions for 3D Partitioned Cell Coculture In Vitro

A facile method was proposed for preparing controllable multicompartment gel microcarriers using an aqueous two-phase emulsion system. By leveraging the density difference between the upper polyethylene glycol solution and the lower dextran-calcium chloride (CaCl2) solution in the collection solution and the high viscosity of the lower solution, controllable fusion of core-shell droplets made by coextrusion devices was achieved at the water/water (w/w) interface to fabricate microcarriers with separated core compartments. By adjusting the sodium alginate concentration, collected solution composition, and number of fused liquid droplets, the pore size, shape, and number of compartments could be controlled. Caco-2 and HepG2 cells were encapsulated in different compartments to establish gut-liver coculture models, exhibiting higher viability and proliferation compared to monoculture models. Notably, significant differences in cytokine expression and functional proteins were observed between the coculture and monoculture models. This method provides new possibilities for preparing complex and functional three-dimensional coculture materials.

Preparation and assessment of alginate-microencapsulated Trichoderma harzianum for controlling Sclerotinia sclerotiorum and Rhizoctonia solani on tomato

This study aimed to develop microencapsulation technology using alginate to improve the viability and performance of Trichoderma harzianum. The method of ionic gelation was used to prepare the microparticles, and the efficiency of encapsulation was estimated to be 99%. The average size of the prepared microspheres was 2600 μm (wet) and 1000 μm (dry). Scanning electron microscopy revealed that the microspheres were approximately spherical. Fourier transform infrared spectrophotometer analysis indicated an interaction between T. harzianum and the microspheres. The results of temperature resistance and light stability against ultraviolet radiation emphasized the positive impact of microencapsulation in improving the viability and resistance of T. harzianum compared to the non-microencapsulated state. The disease percentage of Rhizoctonia solani and Sclerotinia sclerotiorum in plants treated with microencapsulated T. harzianum microcapsules was 8.88 % and 20 % respectively, but in the control group was 73.33 % (p ≤ 0.05).

Development of cultivable alginate fibers for an ideal cell-cultivated meat scaffold and production of hybrid cultured meat

Slaughtering animals for meat pose several challenges, including environmental pollution and ethical concerns. Scaffold-based cell-cultivated meat has been proposed as a solution to these problems, however, the utilization of animal-derived materials for scaffolding or the high cost of production remains a significant challenge. Alginate is an ideal material for cell-cultivated meat scaffolds but has poor cell adhesion properties. To address this issue, we achieved 82 % cell adhesion coverage by controlling the specific structure generated during the ionic crosslinking process of alginate. Post 11 days of culture; we evaluated cell adhesion, differentiation, and aligned cell networks. The cell growth increased by 12.7 % compared to the initial seeding concentration. Finally, we created hybrid cell-cultivated meat by combining single-cell protein from mycelium and cell-cultivated meat. This is non-animal based, edible, cost-effective, and has a desirable texture by blending cell-cultivated meat with a meat analogue. In summary, the creation of improved alginate fibers can effectively tackle various obstacles encountered in the manufacturing of cell-cultivated meat. This includes enhancing cell adhesion, reducing costs, and streamlining the production procedure.

Recent update on alginate based promising transdermal drug delivery systems

Alongside oral delivery of therapeutics, transdermal delivery systems have gained increased patient acceptability over past few decades. With increasing popularity, novel techniques were employed for transdermal drug targeting which involves microneedle patches, transdermal films and hydrogel based formulations. Hydrogel forming ability along with other rheological behaviour makes natural polysaccharides an attractive option for transdermal use. Being a marine originated anionic polysaccharide, alginates are widely used in pharmaceutical, cosmetics and food industries. Alginate possesses excellent biodegradability, biocompatibility and mucoadhesive properties. Owing to many favourable properties required for transdermal drug delivery systems (TDDS), the application of alginates are increasing in recent times. This review summarizes the source and properties of alginate along with several transdermal delivery techniques including the application of alginate for respective transdermal systems.

Orthogonal Gelations to Synthesize Core-Shell Hydrogels Loaded with Nanoemulsion-Templated Drug Nanoparticles for Versatile Oral Drug Delivery

Hydrophobic active pharmaceutical ingredients (APIs) are ubiquitous in the drug development pipeline, but their poor bioavailability often prevents their translation into drug products. Industrial processes to formulate hydrophobic APIs are expensive, difficult to optimize, and not flexible enough to incorporate customizable drug release profiles into drug products. Here, a novel, dual-responsive gelation process that exploits orthogonal thermo-responsive and ion-responsive gelations is introduced. This one-step "dual gelation" synthesizes core-shell (methylcellulose-alginate) hydrogel particles and encapsulates drug-laden nanoemulsions in the hydrogel matrices. In situ crystallization templates drug nanocrystals inside the polymeric core, while a kinetically stable amorphous solid dispersion is templated in the shell. Drug release is explored as a function of particle geometry, and programmable release is demonstrated for various therapeutic applications including delayed pulsatile release and sequential release of a model fixed-dose combination drug product of ibuprofen and fenofibrate. Independent control over drug loading between the shell and the core is demonstrated. This formulation approach is shown to be a flexible process to develop drug products with biocompatible materials, facile synthesis, and precise drug release performance. This work suggests and applies a novel method to leverage orthogonal gel chemistries to generate functional core-shell hydrogel particles.

Novel Zinc/Silver Ions-Loaded Alginate/Chitosan Microparticles Antifungal Activity against Botrytis cinerea

Addressing the growing need for environmentally friendly fungicides in agriculture, this study explored the potential of biopolymer microparticles loaded with metal ions as a novel approach to combat fungal pathogens. Novel alginate microspheres and chitosan/alginate microcapsules loaded with zinc or with zinc and silver ions were prepared and characterized (microparticle size, morphology, topography, encapsulation efficiency, loading capacity, and swelling behavior). Investigation of molecular interactions in microparticles using FTIR-ATR spectroscopy exhibited complex interactions between all constituents. Fitting to the simple Korsmeyer-Peppas empirical model revealed the rate-controlling mechanism of metal ions release from microparticles is Fickian diffusion. Lower values of the release constant k imply a slower release rate of Zn2+ or Ag+ ions from microcapsules compared to that of microspheres. The antimicrobial potential of the new formulations against the fungus Botrytis cinerea was evaluated. When subjected to tests against the fungus, microspheres exhibited superior antifungal activity especially those loaded with both zinc and silver ions, reducing fungal growth up to 98.9% and altering the hyphal structures. Due to the slower release of metal ions, the microcapsule formulations seem suitable for plant protection throughout the growing season. The results showed the potential of these novel microparticles as powerful fungicides in agriculture.

Phosphatidylserine-functionalized liposomes-in-microgels for delivering genistein to effectively treat ulcerative colitis

Ulcerative colitis (UC) is an inflammatory disease involving ulcers in the colon and rectum. The conventional treatments for UC still have many limitations, such as non-specific release, adverse effects and low absorption, resulting in the poor bioavailability of therapeutic agents. To address these challenges, targeting delivery systems are required to specifically deliver drugs to the colonic site with controlled release. Herein, we present a novel microgel oral delivery system, loaded with liposome nanoparticles (Li NPs) containing a natural anti-inflammatory compound genistein (Gen) into alginate microgels, thereby achieving the targeted release of Gen in the colonic region and ameliorating UC symptoms. Initially, Gen was loaded into phosphatidylserine (PS)-functionalized Li NPs to form Gen@Li NPs with an average size of 245.9 ± 9.6 nm. In vitro assessments confirmed that Gen@Li NPs efficiently targeted macrophages and facilitated the internalization of Gen into cells. To prevent rapid degradation in the harsh gastrointestinal tract, Gen@Li NPs were further encapsulated into alginate microgels through electric spraying technology, forming Gen@Li microgels. In vivo distribution tests demonstrated that Gen@Li microgels possessed long-term retention in the colon and gradual release characteristics compared to Gen@Li NPs. Furthermore, in vivo experiments confirmed that Gen@Li microgels significantly alleviated UC symptoms in mice induced by dextran sulfate sodium salt (DSS) mainly through reducing the expression levels of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and promoting colonic mucosal barrier repair through upregulation of mucosal protein expression. This study shed light on the potential of utilizing oral administration of natural compounds for UC treatment.

Polysaccharide/Silica Microcapsules Prepared via Ionic Gelation Combined with Spray Drying: Application in the Release of Hydrophilic Substances and Catalysis

Polysaccharide/silica hybrid microcapsules were prepared using ionic gelation followed by spray-drying. Chitosan and alginate were used as biopolymer matrices, and in situ prepared silica was used as a structuring additive. The prepared microparticles were used in two very different applications: the encapsulation of hydrophilic molecules, and as a support for palladium nanoparticles used as catalysts for a model organic reaction, namely the reduction of p-nitrophenol by sodium borhydride. In the first application, erioglaucine disodium salt, taken as a model hydrophilic substance, was encapsulated in situ during the preparation of the microparticles. The results indicate that the presence of silica nanostructures, integrated within the polymer matrix, affect the morphology and the stability of the particles, retarding the release of the encapsulated substance. In the second application, chloropalladate was complexed on the surface of chitosan microparticles, and palladium(II) was subsequently reduced to palladium(0) to obtain heterogeneous catalysts with an excellent performance.

Experimental Advances in the Real-Time Recording of Cross-Linking Alginate In Situ Gelation: A Review

Alginate-based hydrogels are promising smart materials widely employed in the food, bioengineering, and energy sectors. The development and optimization of their production require a thorough knowledge of gelation. In recent years, advanced experimental procedures have been developed for real-time cross-linking alginate reaction monitoring. Novel methods, such as customized rheometric setups, enable the recording of mechanical properties and morphological changes during hydrogel formation. These innovative techniques provide important insights into the gelation stages, the reaction rate, the diffusion of cross-linker to polymer chains, and the homogeneity of the gelling structures. Based on real-time experimental data, kinetic models are developed to enhance comprehension of the reaction mechanism and, eventually, to predict the gelation progress. The aim is to enable better control of the characterization of both the complex gelation and the propagated structures. This review aspires to present a comprehensive overview and evaluation of the breakthrough innovations of the real-time in situ recording of cross-linking alginate hydrogels and bead formation. A detailed analysis of the pioneering experimental developments provides a deep comprehension of the alginate gelation, including the parameters controlling the reaction.

Bacteria-Polymer Composite Material for Glycerol Valorization

Bacterial immobilization is regarded as an enabling technology to improve the stability and reusability of biocatalysts. Natural polymers are often used as immobilization matrices but present certain drawbacks, such as biocatalyst leakage and loss of physical integrity upon utilization in bioprocesses. Herein, we prepared a hybrid polymeric matrix that included silica nanoparticles for the unprecedented immobilization of the industrially relevant Gluconobacter frateurii (Gfr). This biocatalyst can valorize glycerol, an abundant by-product of the biodiesel industry, into glyceric acid (GA) and dihydroxyacetone (DHA). Different concentrations of siliceous nanosized materials, such as biomimetic Si nanoparticles (SiNps) and montmorillonite (MT), were added to alginate. These hybrid materials were significantly more resistant by texture analysis and presented a more compact structure as seen by scanning electron microscopy. The preparation including 4% alginate with 4% SiNps proved to be the most resistant material, with a homogeneous distribution of the biocatalyst in the beads as seen by confocal microscopy using a fluorescent mutant of Gfr. It produced the highest amounts of GA and DHA and could be reused for up to eight consecutive 24 h reactions with no loss of physical integrity and negligible bacterial leakage. Overall, our results indicate a new approach to generating biocatalysts using hybrid biopolymer supports.

Recent advances of three-dimensional bioprinting technology in hepato-pancreato-biliary cancer models

Hepato-pancreato-biliary (HPB) cancer is a serious category of cancer including tumors originating in the liver, pancreas, gallbladder and biliary ducts. It is limited by two-dimensional (2D) cell culture models for studying its complicated tumor microenvironment including diverse contents and dynamic nature. Recently developed three-dimensional (3D) bioprinting is a state-of-the-art technology for fabrication of biological constructs through layer-by-layer deposition of bioinks in a spatially defined manner, which is computer-aided and designed to generate viable 3D constructs. 3D bioprinting has the potential to more closely recapitulate the tumor microenvironment, dynamic and complex cell-cell and cell-matrix interactions compared to the current methods, which benefits from its precise definition of positioning of various cell types and perfusing network in a high-throughput manner. In this review, we introduce and compare multiple types of 3D bioprinting methodologies for HPB cancer and other digestive tumors. We discuss the progress and application of 3D bioprinting in HPB and gastrointestinal cancers, focusing on tumor model manufacturing. We also highlight the current challenges regarding clinical translation of 3D bioprinting and bioinks in the field of digestive tumor research. Finally, we suggest valuable perspectives for this advanced technology, including combination of 3D bioprinting with microfluidics and application of 3D bioprinting in the field of tumor immunology.

Temporary hydraulic barriers using organic gel for enhanced aquifer remediation during groundwater flushing: Bench-scale experiments

This study presents the use of organic gel-forming material for the construction of hydraulic barriers in aquifer, which can be easily removed after use. Experiments on the performance of the temporary hydraulic barrier during NAPL removal (aquifer flushing) were also conducted. An aqueous solution of sodium alginate was injected into the horizontally oriented, 2-dimensional flow chamber packed with sand, followed by gelation using a calcium solution. The alginate gel formed in the porous media produced a circular shape barrier (24 cm diameter, 1.3 cm thickness) that was successfully removed using sodium bicarbonate solution (1.0 M) in 72 h, whereas the gel was stable for 7 days during simulated groundwater flushing at the same flow rate as the sodium bicarbonate solution. When circular hydraulic barriers (12 cm diameter each, 14 cm apart) were set on either side of the NAPL (n-hexane and PCE mixture)-contaminated zone, the increased water flux during water flushing resulted in significantly increased PCE removal by almost 108%. When a surfactant solution (sodium dodecyl sulfate, 0.037%) was applied, the influenced groundwater flow controlled by hydraulic barriers on the NAPL removal was amplified by 196% removal.

Fabrication of Encapsulated Gemini Surfactants

(1) Background: Encapsulation of surfactants is an innovative approach that allows not only protection of the active substance, but also its controlled and gradual release. This is primarily used to protect metallic surfaces against corrosion or to create biologically active surfaces. Gemini surfactants are known for their excellent anticorrosion, antimicrobial and surface properties; (2) Methods: In this study, we present an efficient methods of preparation of encapsulated gemini surfactants in form of alginate and gelatin capsules; (3) Results: The analysis of infrared spectra and images of the scanning electron microscope confirm the effectiveness of encapsulation; (4) Conclusions: Gemini surfactants in encapsulated form are promising candidates for corrosion inhibitors and antimicrobials with the possibility of protecting the active substance against environmental factors and the possibility of controlled outflow.

Effect of nanoemulsion-loaded hybrid biopolymeric hydrogel beads on the release kinetics, antioxidant potential and antibacterial activity of encapsulated curcumin

Nanoemulsion encapsulated in the hydrogel beads are important entrants for loading hydrophobic active ingredients for enhancing their bioavailability and biological activities relevant in the pharmaceutical, food and cosmetic industries. Herein, we report the formulation of curcumin-loaded nanoemulsion encapsulated in ionotropic hybrid hydrogel beads of alginate, chitosan, gelatin and polyethylene oxide for effective delivery of curcumin. The release behaviour in simulated gastric and intestinal fluids (SGF and SIF) at 37 °C showed faster release in SGF which could be explained on the basis of mesh size, the extent of hydration and the complexation of the curcumin with the Ca2+ ions present within the hydrogel network. The free radical scavenging and antibacterial activities of the released curcumin in SGF were significantly greater than in SIF. This study shows promises of such hybrid systems, ignored so far, for proper encapsulation, protection and delivery of curcumin for the development of functional foods and pharmaceutics. The high structural stability of these nanoemulsion carriers and their effective delivery of curcumin provide a novel and tailored formulation out of existing polymers with plethora of advantages for oral drug delivery. Moreover, this study opens new door for different possibilities to improve the physicochemical characteristics and delivery of bioactive molecules like curcumin.

Cellulose-deconstruction potential of nano-biocatalytic systems: A strategic drive from designing to sustainable applications of immobilized cellulases

Nanostructured materials along with an added value of polymers-based support carriers have gained high interest and considered ideal for enzyme immobilization. The recently emerged nanoscience interface in the form of nanostructured materials combined with immobilized-enzyme-based bio-catalysis has now become research and development frontiers in advance and applied bio-catalysis engineering. With the involvement of nanoscience, various polymers have been thoroughly developed and exploited to nanostructured engineer constructs as ideal support carriers/matrices. Such nanotechnologically engineered support carriers/matrix possesses unique structural, physicochemical, and functional attributes which equilibrate principal factors and strengthen the biocatalysts efficacy for multipurpose applications. In addition, nano-supported catalysts are potential alternatives that can outstrip several limitations of conventional biocatalysts, such as reduced catalytic efficacy and turnover, low mass transfer efficiency, instability during the reaction, and most importantly, partial, or complete inhibition/deactivation. In this context, engineering robust and highly efficient biocatalysts is an industrially relevant prerequisite. This review comprehensively covered various biopolymers and nanostructured materials, including silica, hybrid nanoflower, nanotubes or nanofibers, nanomembranes, graphene oxide nanoparticles, metal-oxide frameworks, and magnetic nanoparticles as robust matrices for cellulase immobilization. The work is further enriched by spotlighting applied and industrially relevant considerations of nano-immobilized cellulases. For instance, owing to the cellulose-deconstruction features of nano-immobilized cellulases, the applications like lignocellulosic biomass conversion into industrially useful products or biofuels, improved paper sheet density and pulp beat in paper and pulp industry, fruit juice clarification in food industry are evident examples of cellulases, thereof are discussed in this work.

Impact of heterogeneously crosslinked calcium alginate networks on the encapsulation of β-carotene-loaded beads

This study investigated the impact of heterogeneity of crosslinking on a range of physical and mechanical properties of calcium alginate networks formed via external gelation with 0.25-2% sodium alginate and 2.5 and 5% CaCl₂. Crosslinking in films with 1-2% alginate was highly heterogeneous, as indicated by their lower calcium content (35-7 mg Ca·g alginate^-1) and apparent solubility (5-6%). Overall, films with 1-2% alginate showed higher resistance (tensile strength = 51-147 MPa) but lower elasticity (Elastic Modulus = 2136-10,079 MPa) than other samples more homogeneous in nature (0.5% alginate, Elastic Modulus = 1918 MPa). Beads with 0.5% alginate prevented the degradation of β-carotene 1.5 times more efficiently than 1% beads (5% CaCl₂) at any of the storage temperatures studied. Therefore, it was postulated that calcium alginate networks crosslinked to a greater extent and in a more homogeneous manner showed better mechanical performance and barrier properties for encapsulation applications.

Effect of Different Physical Cross-Linkers on Drug Release from Hydrogel Layers Coated on Magnetically Steerable 3D-Printed Microdevices

In the last few decades, the introduction of microrobotics has drastically changed the way medicine will be approached in the future. The development of untethered steerable microdevices able to operate in vivo inside the human body allows a high localization of the therapeutical action, thus limiting invasiveness and possible medical complications. This approach results are particularly useful in drug delivery, where it is highly beneficial to administer the drug of choice exclusively to the target organ to avoid overdosage and side effects. In this context, drug releasing layers can be loaded on magnetically moveable platforms that can be guided toward the target organ to perform highly targeted release. In the present paper, we evaluate the possible application of alginate hydrogel layers on moveable platforms manufactured by coupling additive manufacturing with wet metallization. Such alginate layers are reticulated using three different physical crosslinkers: Ca, Zn or Mn. Their effect on drug release kinetics and on device functionality is evaluated. In the case of alginate reticulated using Mn, the strongly pH dependent behavior of the resulting hydrogel is evaluated as a possible way to introduce a triggered release functionality on the devices.

W/O/W double emulsion-loaded alginate capsules containing Lactobacillus plantarum and lipophilic sea buckthorn (Hippophae rhamnoides L.) pomace extract in different phases

In this study, double emulsion containing L. plantarum F1 cells and prebiotic mannitol in the inner water phase, lipophilic sea buckthorn pomace extract as an antioxidant in the oil phase, and alginate in the outer water phase showed high encapsulation yield (82.19%), good cell survival rate (76.99%) and low chemical degradation of the oil (peroxide value - 3.8 meq O₂/kg fat) after 42 days of storage. Gelation of the outer water phase enhanced the viability of L. plantarum F1 cells both during storage and under gastrointestinal conditions due to strong physical barrier formation. Encapsulated L. plantarum F1 viability throughout the 30-day storage period decreased to the value meeting the minimum required dose for probiotics. In vitro digestion of the loaded alginate capsules showed high survival rate of encapsulated cells under gastric conditions and significant reduction at the end of the duodenal phase of digestion.

Mechanical properties of starch-filled alginate gel particles

The aim of this work was to investigate the mechanical behaviour of alginate-based composite particles. Alginate gel beads with entrapped starch were used as the replicates of storage cells of plant tissue. Beads were formulated using different ratios of both ingredients and were produced using two methods, resulting in particles in the macro- and micro-scale size range. Compression tests revealed an effect of bead size on mechanical properties and a dominant role of the alginate on the material properties. Starch was successfully encapsulated as native granules in the beads and once encompassed, it suffered restricted swelling, up to 45 % of its original size, after undergoing heating. Force versus displacement data were fitted to both an empirical and the Hertz model and Young's modulus was found to increase only with heated starch inclusions. Microscopy was deemed crucial for the interpretation of mechanical measurements.

Pickering emulsion-embedded hierarchical solid-liquid hydrogel spheres for static and flow photocatalysis

Pickering emulsion-based photocatalysis is considered to be a promising system due to its large active surface area and water/oil spatial separation capability for enrichment of substrates and products. In this work, a novel hierarchical structure composed of calcium alginate gel sphere wrapped ionic liquid-in-water Pickering emulsion with TiO₂ in the water phase, which are stabilized by graphene oxide, is prepared via a facile one-step emulsion gelation method. Such subtle combination of Pickering emulsion, hydrogel and TiO₂ with a multi-stage solid-liquid assemblage structure shows enhanced degradation activity of 2-naphthol into small molecular alkanes under simulated solar irradiation. The photodegradation activity is attributed to the ionic liquid as adsorption medium for 2-naphthol, and the high-efficient charge separation at graphene oxide/TiO₂ interface superior to that of pure TiO₂. More importantly, the as-prepared millimeter-sized assembled gel spheres can be directly used as the column filler to construct continuous flow photocatalytic system, maintaining the promising performance in removing pollutants from water with ~100% remove ability of 2-naphthol on stream. A charge transfer mechanism of the photocatalyst is proposed, i.e. photogenerated charges are separated in TiO₂/graphene oxide p-n heterostructure at the interface of Pickering emulsion droplets.

Recent advancements in cardiovascular bioprinting and bioprinted cardiac constructs

Three-dimensionally bioprinted cardiac constructs with biomimetic bioink helps to create native-equivalent cardiac tissues to treat patients with myocardial infarction.

Patient-Specific Bone Particles Bioprinting for Bone Tissue Engineering

Although bioinks with both high printability and shape fidelity while maintaining high cell viability are developed, the biofunctionality of the resulting bioprinted construct is often overlooked. To address this, a methacrylated gelatin (GelMA)-based bioink biofunctionalized with bone particles (BPs) is developed as a personalized treatment strategy for bone regeneration. The bioink consists of incorporating BPs of various sizes (0-500 µm) in GelMA at various concentrations (ranging from 5 to 15% w/v). The printability of the bioink is systematically investigated and it is demonstrated that a 15% w/v BP-loading results in high print quality for 10% and 12.5% GelMA concentrations. Rheological evaluation reveals a strong shear thinning behavior essential for printing and a high gel strength in bioink with 15% w/v 0-500 µm BPs for both GelMA concentrations. In addition, the printability of the bioink and the metabolic activity of the resulting scaffolds are dependent on both the concentration of hydrogel and size of the BPs. Importantly, the cells initially contained in the BPs are able to migrate and colonize the bioprinted scaffold while maintaining their capacity to express early osteogenic markers. This study demonstrates the feasibility of bioprinted viable BPs and may have some potential for chairside clinical translation.

Patient-Friendly, Olfactory-Targeted, Stimuli-Responsive Hydrogels for Cerebral Degenerative Disorders Ensured > 400% Brain Targeting Efficiency in Rats

Non-invasive brain therapy for chronic neurological disorders is in high demand. Vinpocetine (VIN) tablets for cerebrovascular degenerative disorders ensued < 7% oral bioavailability. The olfactory pathway (providing direct brain access) can improve VIN pharmacokinetic/pharmacodynamic profile. In this context, VIN hydrogels based on temperature-, pH-, and ion-triggered gelation in physiological milieu were formulated. Poloxamer-chitosan (PLX-CS) and carbopol-HPMC-alginate (CP-HPMC-SA) systems were optimized for appropriate gelation time, temperature, and pH. PLX-CS-hydrogels exhibited strong mucoadhesion for > 8 h, while CP-HPMC-SA hydrogels were mucoadhesive in simulated nasal fluid, owing to pH and ion-activated gelation. Along with prolonged mucosal residence, hydrogels confirmed sustained VIN release (> 24 h), especially from CP-HPMC-SA hydrogels. As proof of concept, brain exposure of intranasal VIN hydrogels was investigated in rats versus VIN-IV bolus. PLX-CS provided 146% increase in AUC_0-30 and 3-fold maximum brain concentration (BC_max) relative to IV bolus. BC_max was reached after 4 h versus 1 h (IV bolus). CP-HPMC-SA hydrogel showed superior brain targeting efficiency (460%) and brain direct transport percentage (78.23%). VIN plasma pharmacokinetics confirmed 45-60% reduction in AUC_plasma versus IV bolus, while PC_max of CP-HPMC-SA and PLX-CS represented 17 and 28% that of IV bolus, respectively. Olfactory-targeted hydrogels grant effective, sustainable VIN brain level with minimal systemic exposure, thus, assuring lower dose, dose frequency, side effects, and per se better patient compliance.

Time matters for macroscopic membranes formed by alginate and cationic β-sheet peptides

Hierarchically ordered planar and spherical membranes (sacs) were constructed using amphiphilic and cationic β-sheet peptides that spontaneously assembled together with negatively charged alginate solution. The system was found to form either a fully developed membrane structure with three distinct regions including characteristic perpendicular fibers or a non-fully developed contact layer lacking these standing fibers, depending on the peptide age, membrane geometry and membrane incubation time. The morphological differences were found to strongly depend on fairly-long incubation time frames that influenced both the peptide's intrinsic alignment and the reaction-diffusion process taking place at the interface. A three-stage mechanism was suggested and key parameters affecting the development process were identified. Stability tests in biologically relevant buffers confirmed the suitability of these membranes for bio applications.

Custom-made rheological setup for in situ real-time fast alginate-Ca2+ gelation

There is a growing interest in the in situ gelation of the alginate-Ca²⁺ system due to its remarkable applications. In this work, we record and evaluate the fast gelation kinetics of alginate-Ca²⁺ using a custom-made rheometric setup. This enables us to inject CaCl₂ into the alginate while we perform the rheological measurements. We successfully measure the in situ gelation reaction from the early stages. As the alginate concentration is increased up to 3 wt.%, we observe a systematic increase of the elastic modulus, G'. Similarly, higher concentrations and injected volumes of CaCl₂ increase the magnitude and initial growth rate of G'. At longer times, the growth rate of G' is lower. It decreases further very slowly, indicating that the chemical reaction requires quite a considerable amount of time to be completed. Finally, from the rheometric data, we estimate the average rates of the elastic modulus during the initial and quasi-steady-state stages.

The highly-stable immobilization of enzymes on a waste mycelium carrier

Mycelium is an abundant waste from the fermentation industry, and the environmental problems associated with its required disposal seriously limited the development of fermentation industry. In China, millions of tons of various kinds of mycelium residues were produced each year. Research into providing added-value to mycelium, while avoiding its disposal, is hence of paramount importance. Mycelium can be used as carrier for enzymes, while the enzyme immobilization moreover improves their stability and lifetime performance. Carrier recycling, the natural degradation and disposal of artificial polymer carriers are critical issues in immobilization. This research investigated its use to manufacture a highly-stable immobilized enzyme. An acid pretreatment was employed to enhance the adsorption ability of mycelium, and its adsorption ability was compared with other carriers. Under the optimal conditions, a core-shell immobilized enzyme with porous structure was obtained. The stability and the recycle results of the evaluation indicated the excellent performance of the immobilized enzyme. The mycelium recycling was also investigated to verify the practicability. All the results indicated that the use of a mycelium-based carrier was a promising strategy for the reutilization of the fermentation waste, and this technique provides an alternative way to reduce the total amount of the waste mycelium. Meanwhile, the stability and reusability performance of the mycelium-based immobilization could also decrease the influence of the disposal of the solid waste from denatured enzymes to the environment.

Nanoemulsion-Loaded Capsules for Controlled Delivery of Lipophilic Active Ingredients

Nanoemulsions have become ideal candidates for loading hydrophobic active ingredients and enhancing their bioavailability in the pharmaceutical, food, and cosmetic industries. However, the lack of versatile carrier platforms for nanoemulsions hinders advanced control over their release behavior. In this work, a method is developed to encapsulate nanoemulsions in alginate capsules for the controlled delivery of lipophilic active ingredients. Functional nanoemulsions loaded with active ingredients and calcium ions are first prepared, followed by encapsulation inside alginate shells. The intrinsically high viscosity of the nanoemulsions ensures the formation of spherical capsules and high encapsulation efficiency during the synthesis. Moreover, a facile approach is developed to measure the nanoemulsion release profile from capsules through UV-vis measurement without an additional extraction step. A quantitative analysis of the release profiles shows that the capsule systems possess a tunable, delayed-burst release. The encapsulation methodology is generalized to other active ingredients, oil phases, nanodroplet sizes, and chemically crosslinked inner hydrogel cores. Overall, the capsule systems provide promising platforms for various functional nanoemulsion formulations.

Yield Stress Enhancement of a Ternary Colloidal Suspension via the Addition of Minute Amounts of Sodium Alginate to the Interparticle Capillary Bridges

Capillary suspensions are ternary solid-liquid-liquid systems produced via the addition of a small amount of secondary fluid to the bulk fluid that contained the dispersed solid particles. The secondary fluid could exert strong capillary forces between the particles and dramatically change the rheological properties of the suspension. So far, research has focused on capillary suspensions that consist of additive-free fluids, whereas capillary suspensions with additives, particularly those of large molecular weight that are highly relevant for industrial purposes, have been relatively less studied. In this study, we performed a systematic analysis of the properties of capillary suspensions that consist of paraffin oil (bulk phase), water (secondary phase), and α-Al₂O₃ microparticles (particle phase), in which the aqueous secondary phase contained an important eco-friendly polymeric binder, sodium alginate (SA). It was determined that the yield stress of the suspension increased significantly with the increase in the SA content in the aqueous secondary phase, which was attributed to the synergistic effect of the capillary force and hydrogen bonding force that may be related to the increase in the number of capillary bridges. The amounts of SA used to induce a significant change in the yield stress in this study were very small (<0.02% of the total sample volume). The addition of Ca²⁺ ions to the SA-containing secondary phase further increased the yield stress with possible gelation of the SA chains-in the presence of excess Ca²⁺ ions, however, the yield stress decreased because of the microscopic phase separation that occurred in the aqueous secondary phase. The microstructures of the sintered porous materials that were produced by using capillary suspensions as precursors were qualitatively well correlated to the rheological behavior of the precursor suspensions, suggesting a new method for the subtle control of the microstructures of porous materials using the addition of minute amounts of polymeric additives.

Technologies and Formulation Design of Polysaccharide-Based Hydrogels for Drug Delivery

Polysaccharide-based hydrogel particles (PbHPs) are very promising carriers aiming to control and target the release of drugs with different physico-chemical properties. Such delivery systems can offer benefits through the proper encapsulation of many drugs (non-steroidal and steroidal anti-inflammatory drugs, antibiotics, etc) ensuring their proper release and targeting. This review discusses the different phases involved in the production of PbHPs in pharmaceutical technology, such as droplet formation (SOL phase), sol-gel transition of the droplets (GEL phase) and drying, as well as the different methods available for droplet production with a special focus on prilling technique. In addition, an overview of the various droplet gelation methods with particular emphasis on ionic cross-linking of several polysaccharides enabling the formation of particles with inner highly porous network or nanofibrillar structure is given. Moreover, a detailed survey of the different inner texture, in xerogels, cryogels or aerogels, each with specific arrangement and properties, which can be obtained with different drying methods, is presented. Various case studies are reported to highlight the most appropriate application of such systems in pharmaceutical field. We also describe the challenges to be faced for the breakthrough towards clinic studies and, finally, the market, focusing on the useful approach of safety-by-design (SbD).