Gellan gum-based delivery systems of therapeutic agents and cells

Recent advances in gellan gum production and modification for enhanced applicability in food printing and bioactive delivery applications

The importance of Gellan gum has been increasing gradually and its unique characteristics are suitable for various advanced food technologies. This review outlines recent developments in gellan gum production, modification, and newer applications focusing on food printing and bioactive delivery applications, in the last three years. The yield and production condition of gellan gum is a major factor that affects the cost and its applications. Moreover, modified Gellan gum has been shown to have superior characteristics and functionality as compared to native one. The viscosifying, thermosensitive, gelling etc. characteristics of gellan gum makes it an crucial ingredient in case of preparation of 3D printing ink. Further, gellan gum is also found to be important wall material in case of bioactive delivery application through encapsulation. Optimized methods of production, sustainable feedstock, and stress conditions are critical for the desired functionality and yield of the Gellan gum.

Challenges and opportunities in bioprocessing of gellan gum: A review

Gellan gum (GG) - the microbial exopolysaccharide is increasingly being adopted into drug development, tissue engineering, and food and pharmaceutical products. In spite of the commercial importance and expanding application horizon of GG, little attention has been directed toward the exploration of novel microbial cultures, development of advanced screening protocols, strain engineering, and robust upstream or downstream processes. This comprehensive review not only attempts to summarize the existing knowledge pool on GG bioprocess but also critically assesses their inherent challenges. The process optimization design augmented with advanced machine learning modeling tools, widely adopted in other microbial bioprocesses, should be extended to GG. The unification of mechanistic insight into data-driven modeling would help to formulate optimal feeding and process control strategies.

Formulation and characterization of ionically crosslinked gellan gum hydrogels using trilysine at low temperatures for antibody delivery

Research of the nontraditional polysaccharide gellan gum (GG) is a growing space for the development of novel drug delivery systems due to its tunable physic-mechanical properties, biocompatibility, and stability in a wide range of environments. Unfortunately, high temperature crosslinking is often required, representing a limiting factor for the incorporation of thermosensitive therapeutic agents. Here, we demonstrated that GG can be crosslinked at a low temperature (38 °C) using a simple fabrication process that utilizes trilysine as an alternative to traditional mono- or divalent ion crosslinkers. While elevated temperature mixing is still required to form a clear GG solution, crosslinking of 0.5 - 1 % GG (w/v) in the presence of trilysine (0.03 % - 0.05 % w/v) was achieved at 38 °C resulting in hydrogels with suitable working formulations to facilitate syringe loading. Low injection forces (< 20 N), and biocompatibility was evaluated with normal human dermal fibroblast (cell viability > 90 %). Frequency sweep showed a transition from purely liquid-like behavior to gel-like behavior with increased trilysine concentration. A temperature dependent behavior was lost with higher trilysine concentrations, indicating stable hydrogel formation. NMR results suggest that trilysine participates in gelation via both ionic interactions between the primary amines of trilysine and the carboxylate residues of glucuronic acid and hydrogen bonding. Released studies showed that GG hydrogels can entrap and provide sustained release of IgG in relation to the crosslinker, and antibody concentration used, with a burst release within the first 24 h (∼80 % cumulative released) followed by a sustained released for up to 5 days. Overall, findings demonstrate a promising nontoxic injectable hydrogel that requires lower crosslinking temperatures, is simple to manufacture and serves as a carrier of thermosensitive therapeutic agents.

Recent advances on biomedical applications of gellan gum: A review

Gellan gum (GG) has attracted considerable attention as a versatile biopolymer with numerous potential biological applications, especially in the fields of tissue engineering, wound healing, and cargo delivery. Due to its distinctive characteristics like biocompatibility, biodegradability, nontoxicity, and gel-forming ability, GG is well-suited for these applications. This review focuses on recent research on GG-based hydrogels and biocomposites and their biomedical applications. It discusses the incorporation of GG into hydrogels for controlled drug release, its role in promoting wound healing processes, and its potential in tissue engineering for various tissues including bone, retina, cartilage, vascular, adipose, and cardiac tissue. It provides an in-depth analysis of the latest findings and advancements in these areas, making it a valuable resource for researchers and professionals in these fields.

Enhanced probiotic viability in innovative double-network emulsion gels: Synergistic effects of the whey protein concentrate-xanthan gum complex and κ-carrageenan

In this study, the whey protein concentrate and xanthan gum complex obtained by specific pH treatment, along with κ-carrageenan (KC), were used to encapsulate Lactobacillus acidophilus JYLA-191 in an emulsion gel system. The effects of crosslinking and KC concentration on the visual characteristics, stability, mechanical properties, and formation mechanism of emulsion gels were investigated. The results of optical imaging, particle size distribution, and rheology exhibited that with the addition of crosslinking agents, denser and more homogeneous emulsion gels were formed, along with a relative decrease in the droplet size and a gradual increase in viscosity. Especially when the concentration of citric acid (CA) was 0.09 wt%, KC was 0.8 wt%, and K+ was present in the system, the double-network emulsion gel was stable at high temperatures and in freezing environments, and the swelling ratio was the lowest (9.41%). Gastrointestinal tract digestive treatments and pasteurization revealed that the probiotics encapsulated in the double-network emulsion gel had a higher survival rate, which was attributed to the synergistic cross-linking of CA and K+ biopolymers to construct the emulsion gels. Overall, this study highlights the potential of emulsion gels to maintain probiotic vitality and provides valuable insights for developing inventive functional foods.

Nanocrystalline cellulose as a reinforcing agent for poly (vinyl alcohol)/ gellan-gum-based composite film for moxifloxacin ocular delivery

Nanocrystalline cellulose (NCC) is a star material in drug delivery applications due to its good biocompatibility, large specific surface area, high tensile strength (TS), and high hydrophilicity. Poly(Vinyl Alcohol)/Gellan-gum-based innovative composite film has been prepared using nanocrystalline cellulose (PVA/GG/NCC) as a strengthening agent for ocular delivery of moxifloxacin (MOX) via solvent casting method. Impedance analysis was studied using the capacitive sensing technique for examining new capacitance nature of the nanocomposite MOX film. Antimicrobial properties of films were evaluated using Pseudomonas aeruginosa and Staphylococcus aureus as gram-negative and gram-positive bacteria respectively by disc diffusion technique. XRD revealed the characteristic peak of NCC and the amorphous form of the drug. Sustained in vitro release and enhanced corneal permeation of drug were noticed in the presence of NCC. Polymer matrix enhanced the mechanical properties (tensile strength 22.05 to 28.41 MPa) and impedance behavior (resistance 59.23 to 213.23 Ω) in the film due to the presence of NCC rather than its absence (16.78 MPa and 39.03 Ω respectively). Occurrence of NCC brought about good antimicrobial behavior (both gram-positive and gram-negative) of the film. NCC incorporated poly(vinyl alcohol)/gellan-gum-based composite film exhibited increased mechanical properties and impedance behavior for improved ocular delivery of moxifloxacin.

Exploring gellan gum-based hydrogels for regenerating human embryonic stem cells in age-related macular degeneration therapy: A literature review

Age-related macular degeneration (AMD) is a progressive ocular disease marked by the deterioration of retinal photoreceptor cells, leading to central vision decline, predominantly affecting the elderly population worldwide. Current treatment modalities, such as anti-VEGF agents, laser therapy, and photodynamic therapy, aim to manage the condition, with emerging strategies like stem cell replacement therapy showing promise. However, challenges like immune rejection and cell survival hinder the efficacy of stem cell interventions. Regenerative medicine faces obstacles in maximizing stem cell potential due to limitations in mimicking the dynamic cues of the extracellular matrix (ECM) crucial for guiding stem cell behaviour. Innovative biomaterials like gellan gum hydrogels offer tailored microenvironments conducive to enhancing stem cell culture efficacy and tissue regeneration. Gellan gum-based hydrogels, renowned for biocompatibility and customizable mechanical properties, provide crucial support for cell viability, differentiation, and controlled release of therapeutic factors, making them an ideal platform for culturing human embryonic stem cells (hESCs). These hydrogels mimic native tissue mechanics, promoting optimal hESC differentiation while minimizing immune responses and facilitating localized delivery. This review explores the potential of Gellan Gum-Based Hydrogels in regenerative AMD therapy, emphasizing their role in enhancing hESC regeneration and addressing current status, treatment limitations, and future directions.

Gellan Gum as a Unique Microbial Polysaccharide: Its Characteristics, Synthesis, and Current Application Trends

Gellan gum (GG) is a linear, negatively charged exopolysaccharide that is biodegradable and non-toxic. When metallic ions are present, a hard and transparent gel is produced, which remains stable at a low pH. It exhibits high water solubility, can be easily bio-fabricated, demonstrates excellent film/hydrogel formation, is biodegradable, and shows biocompatibility. These characteristics render GG a suitable option for use in food, biomedical, and cosmetic fields. Thus, this review paper offers a concise summary of microbial polysaccharides. Moreover, an in-depth investigation of trends in different facets of GG, such as biosynthesis, chemical composition, and physical and chemical properties, is emphasized. In addition, this paper highlights the process of extracting and purifying GG. Furthermore, an in-depth discussion of the advantages and disadvantages of GG concerning other polysaccharides is presented. Moreover, the utilization of GG across different industries, such as food, medicine, pharmaceuticals, cosmetics, etc., is thoroughly examined and will greatly benefit individuals involved in this field who are seeking fresh opportunities for innovative projects in the future.

Advances in tissue engineering of gellan gum-based hydrogels

Gellan Gum (GG) is a large, naturally occurring, linear polysaccharide with a similar structure and biological properties to the extracellular matrix. It's appropriate as a matrix material for the development of different composite materials due to its biocompatibility, biodegradability, and injectability. Hydrogels made from GG have found various applications in the field of Tissue Engineering (TE) in recent years after being mixed with a variety of other organic and inorganic components. These composites are considered multifunctional developing biomaterials because of their impressive mechanical capabilities, biocompatibility, low cytotoxicity, etc. This review focuses on the emerging advances of GG-based hydrogels in TE, providing an overview of the applications of different types of GG-based composite materials in bone TE, cartilage TE, nervous TE, retina TE, and other fields. Moreover, the investigations of GG-based hydrogels as bioink components for 3D bioprinting in TE will be elucidated. This review offers general guidance for the development of biomaterials related to GG, as well as ideas for future clinical diagnosis and treatment.

Polysaccharide nanocomposites in wastewater treatment: A review

In modern times, wastewater treatment is vital due to increased water contamination arising from pollutants such as nutrients, pathogens, heavy metals, and pharmaceutical residues. Polysaccharides (PSAs) are natural, renewable, and non-toxic biopolymers used in wastewater treatment in the field of gas separation, liquid filtration, adsorption processes, pervaporation, and proton exchange membranes. Since addition of nanoparticles to PSAs improves their sustainability and strength, nanocomposite PSAs has gained significant attention for wastewater treatment in the past decade. This review presents a comprehensive analysis of PSA-based nanocomposites used for efficient wastewater treatment, focusing on adsorption, photocatalysis, and membrane-based methods. It also discusses potential future applications, challenges, and opportunities in adsorption, filtration, and photocatalysis. Recently, PSAs have shown promise as adsorbents in biological-based systems, effectively removing heavy metals that could hinder microbial activity. Cellulose-mediated adsorbents have successfully removed various pollutants from wastewater, including heavy metals, dyes, oil, organic solvents, pesticides, and pharmaceutical residues. Thus, PSA nanocomposites would support biological processes in wastewater treatment plants. A major concern is the discharge of antibiotic wastes from pharmaceutical industries, posing significant environmental and health risks. PSA-mediated bio-adsorbents, like clay polymeric nanocomposite hydrogel beads, efficiently remove antibiotics from wastewater, ensuring water quality and ecosystem balance. The successful use of PSA-mediated bio-adsorbents in wastewater treatment depends on ongoing research to optimize their application and evaluate their potential environmental impacts. Implementing these eco-friendly adsorbents on a large scale holds great promise in significantly reducing water pollution, safeguarding ecosystems, and protecting human health.

Mastering textural control in multi-polysaccharide gels: Effect of κ-carrageenan, konjac glucomannan, locust bean gum, low-acyl gellan gum, and sodium alginate

To comprehend the intricate interplay of five common food polysaccharides, κ-Carrageenan (KC), konjac glucomannan (KGM), locust bean gum (LBG), low-acyl gellan gum (LAG), and sodium alginate (SA), within composite polysaccharide gels, widely employed for textural modulation and flavor enhancement. This study systematically modulates the quantities of these five polysaccharides to yield six distinct multi-polysaccharide gels. The unique impact of each polysaccharide on the overall quality of composite gels were studied by thermostability, microstructure, water-holding capacity (WHC), texture, and sensory attributes. The findings unequivocally manifest the phenomenon of thermoreversible gelation in all composite gels, except for the KC-devoid sample, which displayed an inability to solidify. Notably, KGM, LBG, and LAG emerged as pivotal enhancers of the network structure in these composite gels, while SA was identified as a promotor of layered structure, resulting in a reduction of surface hardness. Leveraging principal component analysis (PCA) to analyzed 14 critical evaluation parameters of the five multi-polysaccharide gels, revealing the order as follows: KC > KGM > SA > LAG > LBG. These findings would imparts valuable insights into the pragmatic utilization of multi-polysaccharide gels for the development of food products (e.g. Bobo balls in milk tea) with tailored textural and sensory attributes.

Hydrogels in Ophthalmology: Novel Strategies for Overcoming Therapeutic Challenges

The human eye's intricate anatomical and physiological design necessitates tailored approaches for managing ocular diseases. Recent advancements in ophthalmology underscore the potential of hydrogels as a versatile therapeutic tool, owing to their biocompatibility, adaptability, and customizability. This review offers an exploration of hydrogel applications in ophthalmology over the past five years. Emphasis is placed on their role in optimized drug delivery for the posterior segment and advancements in intraocular lens technology. Hydrogels demonstrate the capacity for targeted, controlled, and sustained drug release in the posterior segment of the eye, potentially minimizing invasive interventions and enhancing patient outcomes. Furthermore, in intraocular lens domains, hydrogels showcase potential in post-operative drug delivery, disease sensing, and improved biocompatibility. However, while their promise is immense, most hydrogel-based studies remain preclinical, necessitating rigorous clinical evaluations. Patient-specific factors, potential complications, and the current nascent stage of research should inform their clinical application. In essence, the incorporation of hydrogels into ocular therapeutics represents a seminal convergence of material science and medicine, heralding advancements in patient-centric care within ophthalmology.

Antibacterial Broad-Spectrum Dendritic/Gellan Gum Hybrid Hydrogels with Rapid Shape-Forming and Self-Healing for Wound Healing Application

Treating wound infections is a difficult task ever since pathogenic bacteria started to develop resistance to common antibiotics. The present study develops hybrid hydrogels based on the formation of a polyelectrolyte complex between the anionic charges of dopamine-functionalized Gellan Gum (GG-DA) and the cationic moieties of the TMP-G2-alanine dendrimer. The hydrogels thus obtained can be doubly crosslinked with CaCl2 , obtaining solid hydrogels. Or, by oxidizing dopamine to GG-DA, possibly causing further interactions such as Schiff Base and Michael addition to take place, hydrogels called injectables can be obtained. The latter have shear-thinning and self-healing properties (efficiency up to 100%). Human dermal fibroblasts (HDF), human epidermal keratinocytes (HaCaT), and mouse monocyte cells (RAW 264.7), after incubation with hydrogels, in most cases show cell viability up to 100%. Hydrogels exhibit adhesive behavior on various substrates, including porcine skin. At the same time, the dendrimer serves to crosslink the hydrogels and endows them with excellent broad-spectrum microbial eradication activity within four hours, evaluated using Staphylococcus aureus 2569 and Escherichia coli 178. Using the same GG-DA/TMP-G2-alanine ratios hybrid hydrogels with tunable properties and potential for wound dressing applications can be produced.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

The energetic and physical concept of gold nanorod-dependent fluorescence in cancer treatment and development of new photonic compounds|review

The optical features of gold nanorods (GNR) may be precisely controlled by manipulating their size, shape, and aspect ratio. This review explores the impact of these parameters on the optical tuning of (GNR). By altering the experimental conditions, like the addition of silver ions during the seed-mediated growth process, the aspect ratio of (GNR) may be regulated. The shape is trans from spherical to rod-like structures resulting in noticeable changes in the nanoparticles surface plasmons resonance (SPR) bands. The longitudinal SPR band, associated with electron oscillations along the long axis, exhibits a pronounced red shift into the (NIR) region as the aspect ratio increases. In contrast, the transverse SPR band remains relate unchanged. Using computational methods like the discrete dipole approximation (DDA) allows for analyzing absorption, scattering, and total extinction features of gold (G) nanoparticles. Studies have shown that increasing the aspect ratio enhances the scattering efficiency, indicating a higher scattering quantum yield (QY). These findings highlight the importance of size, shape, and aspect ratio in controlling the optical features of (GNR) providing valuable insights for various uses in nanophotonics and plasmonic-dependent fluorescence in cancer treatment and developing new photonic compound NRs.

3D Printing of Collagen Scaffold with Enhanced Resolution in a Citrate-Modulated Gellan Gum Microgel Bath

3D printing in a microgel-based supporting bath enables the construction of complex structures with soft and watery biomaterials but the low print resolution is usually an obstacle to its practical application in tissue engineering. Herein, high-resolution printing of a 3D collagen organ scaffold is realized by using an engineered Gellan gum (GG) microgel bath containing trisodium citrate (TSC). The introduction of TSC into the bath system not only mitigates the aggregation of GG microgels, leading to a more homogeneous bath morphology but also suppresses the diffusion of the collagen ink in the bath due to the dehydration effect of TSC, both of which contribute to the improvement of print resolution. 3D collagen organ structures such as hand, ear, and heart are successfully constructed with high shape fidelity in the developed bath. After printing, the GG and TSC can be easily removed by washing with water, and the obtained collagen product exhibits good cell affinity in a tissue scaffold application. This work offers an easy-to-operate strategy for developing a microgel bath for high-resolution printing of collagen, providing an alternative path to in vitro 3D organ construction.

Electrospun PVA Fibers for Drug Delivery: A Review

Innovation in biomedical science is always a field of interest for researchers. Drug delivery, being one of the key areas of biomedical science, has gained considerable significance. The utilization of simple yet effective techniques such as electrospinning has undergone significant development in the field of drug delivery. Various polymers such as PEG (polyethylene glycol), PLGA (Poly(lactic-co-glycolic acid)), PLA(Polylactic acid), and PCA (poly(methacrylate citric acid)) have been utilized to prepare electrospinning-based drug delivery systems (DDSs). Polyvinyl alcohol (PVA) has recently gained attention because of its biocompatibility, biodegradability, non-toxicity, and ideal mechanical properties as these are the key factors in developing DDSs. Moreover, it has shown promising results in developing DDSs individually and when combined with natural and synthetic polymers such as chitosan and polycaprolactone (PCL). Considering the outstanding properties of PVA, the aim of this review paper was therefore to summarize these recent advances by highlighting the potential of electrospun PVA for drug delivery systems.

Microbial exopolysaccharides in the biomedical and pharmaceutical industries

The most significant and renewable class of polymeric materials are extracellular exopolysaccharides (EPSs) produced by microorganisms. Because of their diverse chemical and structural makeup, EPSs play a variety of functions in a variety of industries, including the agricultural industry, dairy industry, biofilms, cosmetics, and others, demonstrating their biotechnological significance. EPSs are typically utilized in high-value applications, and current research has focused heavily on them because of their biocompatibility, biodegradability, and compatibility with both people and the environment. Due to their high production costs, only a few microbial EPSs have been commercially successful. The emergence of financial barriers and the growing significance of microbial EPSs in industrial and medical biotechnology has increased interest in exopolysaccharides. Since exopolysaccharides can be altered in a variety of ways, their use is expected to increase across a wide range of industries in the coming years. This review introduces some significant EPSs and their composites while concentrating on their biomedical uses.

Polysaccharides, proteins, and their complex as microencapsulation carriers for delivery of probiotics: A review on carrier types and encapsulation techniques

Probiotics provide several benefits for humans, including restoring the balance of gut bacteria, boosting the immune system, and aiding in the management of certain conditions such as irritable bowel syndrome and lactose intolerance. However, the viability of probiotics may undergo a significant reduction during food storage and gastrointestinal transit, potentially hindering the realization of their health benefits. Microencapsulation techniques have been recognized as an effective way to improve the stability of probiotics during processing and storage and allow for their localization and slow release in intestine. Although, numerous techniques have been employed for the encapsulation of probiotics, the encapsulation techniques itself and carrier types are the main factors affecting the encapsulate effect. This work summarizes the applications of commonly used polysaccharides (alginate, starch, and chitosan), proteins (whey protein isolate, soy protein isolate, and zein) and its complex as the probiotics encapsulation materials; evaluates the evolutions in microencapsulation technologies and coating materials for probiotics, discusses their benefits and limitations, and provides directions for future research to improve targeted release of beneficial additives as well as microencapsulation techniques. This study provides a comprehensive reference for current knowledge pertaining to microencapsulation in probiotics processing and suggestions for best practices gleaned from the literature.

Carbohydrate polymer-based nanocomposites for breast cancer treatment

Breast cancer is known as the most common invasive malignancy in women with the highest mortality rate worldwide. This concerning disease may be presented in situ (relatively easier treatment) or be invasive, especially invasive ductal carcinoma which is highly worrisome nowadays. Among several strategies used in breast cancer treatment, nanotechnology-based targeted therapy is currently being investigated, as it depicts advanced technological features able of preventing drugs' side effects on normal cells while effectively acting on tumor cells. In this context, carbohydrate polymer-based nanocomposites have gained particular interest among the biomedical community for breast cancer therapy applications due to their advantage features, including abundance in nature, biocompatibility, straightforward fabrication methods, and good physicochemical properties. In this review, the physicochemical properties and biological activities of carbohydrate polymers and their derivate nanocomposites were discussed. Then, various methods for the fabrication of carbohydrate polymer-based nanocomposites as well as their application in breast cancer therapy and future perspectives were discussed.

Progress and opportunities in Gellan gum-based materials: A review of preparation, characterization and emerging applications

Gellan gum, a microbial exopolysaccharide, is biodegradable and has potential to fill several key roles in many fields from food to pharmacy, biomedicine and tissue engineering. In order to improve the physicochemical and biological properties of gellan gum, some researchers take advantage of numerous hydroxyl groups and the free carboxyl present in each repeating unit. As a result, design and development of gellan-based materials have advanced significantly. The goal of this review is to provide a summary of the most recent, high-quality research trends that have used gellan gum as a polymeric component in the design of numerous cutting-edge materials with applications in various fields.

A novel method for making cell blocks with higher cellular yield

INTRODUCTION

Cytopathology is an important part of pathology that is used to diagnose disease on the cellular level. The application of the cell block (CB) technique plays a vital role in cytological diagnosis, as blocks and slides can be further used for special stains, immunohistochemistry (IHC), and molecular pathological analysis. Several methods for making CBs have been reported, but their procedures and cellular yield are still deemed unsatisfactory. In this article, we used gellan gum (GG) as an adjuvant for CBs, which resulted in higher cellular yield with simpler procedures.

METHODS

CBs were prepared by using GG, copper sulfate, plasma/thrombin, or pregelatinized starch methods. The procedures of each of these four methods were then compared. CB sections were stained with hematoxylin and eosin (H&E), and the background and morphological features seen by H&E staining were compared. A preliminary IHC and fluorescence in situ hybridization (FISH) study was performed using cytology specimens from eleven and five cases, respectively. The expression of immunocomplex by IHC and the molecular signals detected by FISH were compared in CB sections made by the four methods and a section derived from the biopsy specimen block from the same patient. Feulgen staining, Alcian blue staining, and Masson trichrome staining were performed on the CB sections from 3 cases of pleural fluid. The cellular yield of CB sections from 83 cases according to the four methods was compared using NDP analysis software.

RESULTS

The results demonstrated that sections derived from CBs made with GG had a clear background and good morphological features by H&E staining. The expression of immunocomplex by IHC and the molecular signals of FISH detection in the sections from CBs made by GG were accurately located just as those in biopsy sections from the same patient. The DNA, acidic mucus, and fibrin could be clearly identified through special stains in the CB sections. The procedures involved in the GG method were easily controllable and the coagulated gel increased the ease by which the CB was embedded and sectioned. Specifically, sections from CBs made by the GG method contained higher cellular yield because cells could be concentrated on the bottom of the gel after centrifugation.

CONCLUSION

This novel method for making CBs is a practical, simple method that can result in higher cellular yield. This method is therefore worth promoting in clinical applications.

Partial sulfation of gellan gum produces cytocompatible, body temperature-responsive hydrogels

Gellan gum (GG) is a biodegradable polysaccharide and forms thermosensitive hydrogels by a helix-mediated mechanism. Unfortunately, the wide use of GG in tissue engineering has been restricted due to its dramatically higher gelation temperature than normal body temperature. Here, we show that partial sulfation of GG affords a cytocompatible body temperature-responsive hydrogel with an interesting thermoreversibility at 42 °C. The partial sulfation of GG was confirmed by FTIR, EDX and elemental analyses. The sulfated GGs (SGGs) had a higher swelling ratio and degradation in PBS compared to the neat GG. Based on the results of rheometry analysis, the SGG with a degree of sulfation of 0.27 (H3 sample) showed a gelation temperature close to the physiological temperature. In addition, the drop in mechanical properties of SGGs was compensated by a further calcium-mediated ionic crosslinking, where Young's modulus of H3 increased from 10.6 ± 1.9 kPa up to 38.4 ± 5.5 kPa. Finally, we showed that the partial sulfation reaction of GG is a simple and mild strategy to modify chemical structure of GG, and to produce a cytocompatible, body temperature-responsive hydrogel compared to other modifying reactions such as oxidation reaction.

Research progress of water-in-oil emulsion gelated with internal aqueous phase: gel factors, gel mechanism, application fields, and future direction of development

The W/O emulsion is a promising system. Its special structure can keep the sensory properties of fat while reducing the fat content. Improving the stability and physical properties of W/O emulsions is generally oriented toward outer oil-phase modified oil gels and inner water-phase modified inner hydrogels. In this paper, the research progress of internal aqueous gel was reviewed, and some gel factors suitable for internal aqueous gel and the gel mechanism of main gel factors were discussed. The advantages of this internal aqueous gel emulsion system allow its use in the field of fat substitutes and encapsulating substances. Finally, some shortcomings and possible research directions in the future were proposed, which would provide a theoretical basis for the further development of internal water-phase gelled W/O emulsion in the future.

Injectable Hydrogel Based on Gellan Gum/Silk Sericin for Application as a Retinal Pigment Epithelium Cell Carrier

The damage to retinal pigment epithelium (RPE) cells can lead to vision loss and permanent blindness. Therefore, an effective therapeutic strategy has emerged to replace damaged cells through RPE cell delivery. In this study, we fabricated injectable gellan gum (GG)/silk sericin (SS) hydrogels as a cell carrier by blending GG and SS. To determine the appropriate concentration of SS for human RPE ARPE-19, 0, 0.05, 0.1, and 0.5% (w/v) of SS solution were blended in 1% (w/v) GG solution (GG/SS 0%, GG/SS 0.05%, GG/SS 0.1%, and GG/SS 0.5%, respectively). The physical and chemical properties were measured through Fourier-transform infrared spectroscopy, scanning electron microscopy, mass swelling, and weight loss. Also, viscosity, injection force, and compressive tests were used to evaluate mechanical characteristics. Cell proliferation and differentiation of ARPE-19 were evaluated using quantitative dsDNA analysis and real-time polymerase chain reaction, respectively. The addition of SS gave GG/SS hydrogels a compressive strength similar to that of natural RPE tissue, which may well support the growth of RPE and enhance cell proliferation and differentiation. In particular, the GG/SS 0.5% hydrogel showed the most similar compressive strength (about 10 kPa) and exhibited the highest gene expression related to ARPE-19 cell proliferation. These results indicate that GG/SS 0.5% hydrogels can be a promising biomaterial for cell delivery in retina tissue engineering.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H₂O₂ neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Gellan Gum in Wound Dressing Scaffolds

Several factors, such as bacterial infections, underlying conditions, malnutrition, obesity, ageing, and smoking are the most common issues that cause a delayed process of wound healing. Developing wound dressings that promote an accelerated wound healing process and skin regeneration is crucial. The properties of wound dressings that make them suitable for the acceleration of the wound healing process include good antibacterial efficacy, excellent biocompatibility, and non-toxicity, the ability to provide a moist environment, stimulating cell migration and adhesion, and providing gaseous permeation. Biopolymers have demonstrated features appropriate for the development of effective wound dressing scaffolds. Gellan gum is one of the biopolymers that has attracted great attention in biomedical applications. The wound dressing materials fabricated from gellan gum possess outstanding properties when compared to traditional dressings, such as good biocompatibility, biodegradability, non-toxicity, renewability, and stable nature. This biopolymer has been broadly employed for the development of wound dressing scaffolds in different forms. This review discusses the physicochemical and biological properties of gellan gum-based scaffolds in the management of wounds.

Exploiting Polymeric Films as a Multipurpose Drug Delivery System: a Review

Polymeric films are drug delivery systems that maintain contact with the delivery tissue and sustain a controlled release of therapeutic molecules. These systems allow a longer time of drug contact with the target site in the case of topical treatments and allow the controlled administration of drugs. They can be manufactured by various methods such as solvent casting, hot melt extrusion, electrospinning, and 3D bioprinting. Furthermore, they can employ various polymers, for example PVP, PVA, cellulose derivatives, chitosan, gelling gum, pectin, and alginate. Its versatility is also applicable to different routes of administration, as it can be administered to the skin, oral mucosa, vaginal canal, and eyeballs. All these factors allow numerous combinations to obtain a better treatment. This review focuses on exploring some possible ways to develop them and some particularities and advantages/disadvantages in each case. It also aims to show the versatility of these systems and the advantages and disadvantages in each case, as they bring the opportunity to develop different medicines to facilitate therapies for the most diverse purposes .

In vivo efficacy of verteporfin loaded gold nanorods for combined photothermal/photodynamic colon cancer therapy

The high incidence of cancer recurrences and the frequent occurrence of multidrug resistance often stem from a poorly selective and inefficient antineoplastic therapy, responsible for the onset of undesired side effects as well. A combination of minimal-invasive approaches could thus be a useful strategy to surmount these shortcomings, achieving a safe and solid cancer therapy. Herein, a multi-therapeutic nanotool was designed by merging the photothermal properties of gold nanorods (AuNRs) with the photodynamic activity of the photosensitizer verteporfin. AuNRs were coated with the natural materials lipoic acid and gellan gum (AuNRs_LA,GG) and subsequently loaded with verteporfin (AuNRs_LA,GG/Vert) producing stable colloidal dispersions. AuNRs_LA,GG/Vert were characterized in terms of stability, size and morphology. The hyperthermia exhibited after NIR excitation (810 nm) was also evaluated to highlight the effect on increasing the drug released profile in intra-tumoral mimicking media, as well as cytotoxicity on human colon cancer cell line (HCT116). In vivo studies on HCT116 murine xenograft models were carried out to prove the ability of AuNRs_LA,GG to arrest the tumor growth via NIR laser-triggered hyperthermia. Furthermore, the complete xenograft depletion was demonstrated upon AuNRs_LA,GG/Vert administration by combined photothermal (PTT) and photodynamic (PDT) effects.

Emerging Bioactive Agent Delivery-Based Regenerative Therapies for Lower Genitourinary Tissues

Injury to lower genitourinary (GU) tissues, which may result in either infertility and/or organ dysfunctions, threatens the overall health of humans. Bioactive agent-based regenerative therapy is a promising therapeutic method. However, strategies for spatiotemporal delivery of bioactive agents with optimal stability, activity, and tunable delivery for effective sustained disease management are still in need and present challenges. In this review, we present the advancements of the pivotal components in delivery systems, including biomedical innovations, system fabrication methods, and loading strategies, which may improve the performance of delivery systems for better regenerative effects. We also review the most recent developments in the application of these technologies, and the potential for delivery-based regenerative therapies to treat lower GU injuries. Recent progress suggests that the use of advanced strategies have not only made it possible to develop better and more diverse functionalities, but also more precise, and smarter bioactive agent delivery systems for regenerative therapy. Their application in lower GU injury treatment has achieved certain effects in both patients with lower genitourinary injuries and/or in model animals. The continuous evolution of biomaterials and therapeutic agents, advances in three-dimensional printing, as well as emerging techniques all show a promising future for the treatment of lower GU-related disorders and dysfunctions.

Pickering emulsion hydrogel based on alginate-gellan gum with carboxymethyl chitosan as a pH-responsive controlled release delivery system

Pickering emulsion hydrogels (PEHs) were developed as a pH-responsive, controlled-release delivery system to address the limitations of Pickering emulsions in some harsh processing or gastrointestinal conditions. Specifically, the PEHs were fabricated based on alginate and various concentrations of gellan gum (GG) with carboxymethyl chitosan (CMCS) matrix. The encapsulation efficiency (EE), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results proved the successful encapsulation. Furthermore, the hydrogels remained stable in the presence of destabilizing ions (Na⁺ or phosphate ions) and high osmotic pressure mediums. The texture profile analysis (TPA) characteristics and Young's modulus of the 0.8 % GG (w/v) PEHs were superior to the others. The PEHs prevented the emulsions from being released at pH 2.0, while the emulsions were entirely released at pH 7.4 in vitro, with the rate of release controlled by CMCS and the degree by GG concentration. This work facilitates the delivery of Pickering emulsions with excellent stability and pH-responsive controlled release for hydrophobic actives in food applications.

Arctiin-reinforced antioxidant microcarrier antagonizes osteoarthritis progression

Loss of extracellular matrix (ECM) of cartilage due to oxidative stress injury is one of the main characteristics of osteoarthritis (OA). As a bioactive molecule derived from the traditional Chinese Burdock, arctiin exerts robust antioxidant properties to modulate redox balance. However, the potential therapeutic effects of arctiin on OA and the underlying mechanisms involved are still unknown. Based on the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) tool, Burdock-extracted small molecule arctiin was identified as a potential anti-arthritic component. In vitro, treatment using arctiin rescued the interleukin (IL)-1β-induced activation of proteinases and promoted the cartilage ECM synthesis in human chondrocytes. In vivo, intraperitoneal injection of arctiin ameliorated cartilage erosion and encountered subchondral bone sclerosis in the post-traumatic OA mice. Transcriptome sequencing uncovered that arctiin-enhanced cartilage matrix deposition was associated with restricted oxidative stress. Mechanistically, inhibition of nuclear factor erythroid 2-related factor 2 (NRF2) abolished arctiin-mediated anti-oxidative and anti-arthritic functions. To further broaden the application prospects, a gellan gum (GG)-based bioactive gel (GG-CD@ARC) encapsulated with arctiin was made to achieve long-term and sustained drug release. Intra-articular injection of GG-CD@ARC counteracted cartilage degeneration in the severe (12 weeks) OA mice model. These findings indicate that arctiin may be a promising anti-arthritic agent. Furthermore, GG-modified bioactive glue loaded with arctiin provides a unique strategy for treating moderate to severe OA.

Development of an antibiotics delivery system for topical treatment of the neglected tropical disease Buruli ulcer

Skin infection by Mycobacterium ulcerans causes Buruli ulcer (BU) disease, a serious condition that significantly impact patient' health and quality of life and can be very difficult to treat. Treatment of BU is based on daily systemic administration of antibiotics for at least 8 weeks and presents drawbacks associated with the mode and duration of drug administration and potential side effects. Thus, new therapeutic strategies are needed to improve the efficacy and modality of BU therapeutics, resulting in a more convenient and safer antibiotic regimen. Hence, we developed a dual delivery system based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) microparticles and a gellan gum (GG) hydrogel for delivery of rifampicin (RIF) and streptomycin (STR), two antibiotics used for BU treatment. RIF was successfully loaded into PHBV microparticles, with an encapsulation efficiency of 43%, that also revealed a mean size of 10 µm, spherical form and rough topography. These microparticles were further embedded in a GG hydrogel containing STR. The resultant hydrogel showed a porous microstructure that conferred a high water retention capability (superior to 2000%) and a controlled release of both antibiotics. Also, biological studies revealed antibacterial activity against M. ulcerans, and a good cytocompatibility in a fibroblast cell line. Thus, the proposed drug delivery system can constitute a potential topical approach for treatment of skin ulcers caused by BU disease.

Selection of natural biomaterials for micro-tissue and organ-on-chip models

The desired organ in micro-tissue models of organ-on-a-chip (OoC) devices dictates the optimum biomaterials, divided into natural and synthetic biomaterials. They can resemble biological tissues' biological functions and architectures by constructing bioactivity of macromolecules, cells, nanoparticles, and other biological agents. The inclusion of such components in OoCs allows them having biological processes, such as basic biorecognition, enzymatic cleavage, and regulated drug release. In this report, we review natural-based biomaterials that are used in OoCs and their main characteristics. We address the preparation, modification, and characterization methods of natural-based biomaterials and summarize recent reports on their applications in the design and fabrication of micro-tissue models. This article will help bioengineers select the proper biomaterials based on developing new technologies to meet clinical expectations and improve patient outcomes fusing disease modeling.

Correlating Rheological Properties of a Gellan Gum-Based Bioink: A Study of the Impact of Cell Density

Here, for the production of a bioink-based gellan gum, an amino derivative of this polysaccharide was mixed with a mono-functionalized aldehyde polyethyleneglycol in order to improve viscoelastic macroscopic properties and the potential processability by means of bioprinting techniques as confirmed by the printing tests. The dynamic Schiff base linkage between amino and aldehyde groups temporally modulates the rheological properties and allows a reduction of the applied pressure during extrusion followed by the recovery of gellan gum strength. Rheological properties, often related to printing resolution, were extensively investigated confirming pseudoplastic behavior and thermotropic and ionotropic responses. The success of bioprinting is related to different parameters. Among them, cell density must be carefully selected, and in order to quantify their role on printability, murine preostoblastic cells (MC3T3-E1) and human colon tumor cells (HCT-116) were chosen as cell line models. Here, we investigated the effect of their density on the bioink’s rheological properties, showing a more significant difference between cell densities for MC3T3-E1 compared to HCT-116. The results suggest the necessity of not neglecting this aspect and carrying out preliminary studies to choose the best cell densities to have the maximum viability and consequently to set the printing parameters.

Fabrication Methods and Form Factors of Gellan Gum-Based Materials for Drug Delivery and Anti-Cancer Applications

Despite the success of cancer therapeutics, off target cell toxicity prevails as one of the main challenges of cancer treatment. Exploration of drug delivery methods is a growing field of research, which involves a variety of materials and processing techniques. A natural polymer, gellan gum presents physicochemical properties that enable drug loading for sustained release in a broad range of environmental conditions and anatomical locations. Gellan gum is an anionic exopolysaccharide, produced via fermentation by Sphingomonas elodea, which gels in the presence of cations. Additionally, it is biocompatible and nontoxic. Multiple physical and chemical gelation processes have been reported for the use of gellan gum in drug delivery applications to produced varying form factors, including hydrogels, nanohydrogels, beads, films, or patches, with tunable mechanical and physicochemical properties. The resulting formulations have shown promising outcomes for drug delivery including improving drug bioavailability, drug solubility, and drug release over time, without compromising biocompatibility or the introduction of adverse effects. This review presents studies in which gellan gum has been processed to enable the delivery of antibiotics, antiallergens, anti-inflammatory, or antifungal molecules with a special focus on drugs for anticancer applications.

Composite Hydrogels of Alkyl Functionalized Gellan Gum Derivative and Hydroxyapatite/Tricalcium Phosphate Nanoparticles as Injectable Scaffolds for bone Regeneration

An alkyl functionalized gellan gum derivative is here used to produce hydrogels containing hydroxyapatite and tricalcium phosphate nanoparticles as injectable nanostructured scaffolds for bone regeneration. The amphiphilic nature of the polysaccharide derivative along with its thermotropic behavior and ionotropic crosslinking features make possible to produce injectable bone mimetic scaffolds that can be used to release viable cells and osteoinductive biomolecules. The influence of different nanoparticles concentration on the rheological and physicochemical properties of the injectable systems is studied. It is found that the presence of inorganic nanoparticles reinforces the 3D hydrated polymeric networks without influencing their injectability but improving the physicochemical properties of ionotropic crosslinked hydrogels produced with two different curing media. Preliminary cytocompatibility tests performed with murine preosteoblast cells revealed that gellan gum based hydrogels can safely encapsulate viable cells. Loading and release experiments for dexamethasone and stromal cell-derived factor-1 demonstrate the drug delivery features of the obtained injectable systems.

The Fabrication of a Gellan Gum-Based Hydrogel Loaded With Magnesium Ions for the Synergistic Promotion of Skin Wound Healing

To accelerate serious skin burn wound healing in a convenient manner, an interpenetrating network of hydrogel consisting of gellan gum and polyacrylamide was synthesized by chemical crosslinking and Mg2+ ion immersion techniques. The prepared Mg2+@PAM/GG hydrogel was characterized by morphology, water vapor loss, swelling ratio, rheological properties, tensile mechanical, biocompatibility, and flow cytometry study. The results show that Mg2+@PAM/GG hydrogel's mechanical strength could be enhanced by the dual network structure and physical crosslinking agent Mg2+ ions. In addition, the tension strength of Mg2+@PAM/GG hydrogel is obviously increased from 86 to 392 kPa, the elongation at break increased from 84 to 231%, and crosslinking density N increased from 4.3 to 7.2 mol/m3 compared with pure GG hydrogel. The cumulative release curve of Mg2+ ions shows that the multiple release mechanism of Mg2+ ions belong to non-Fick's diffusion. Meanwhile, in vitro experiments show that Mg2+@PAM/GG double network hydrogel has favorable proliferation and an NF-κB pathway inhibition property for fibroblast cells. Finally, the healing effect of the Mg2+@PAM/GG was evaluated in a rat full-thickness burn model. The animal study demonstrates that Mg2+@PAM/GG could accelerate the healing efficiency in case of the sustained-released Mg2+ ions in wound beds. Considering this excellent performance, this convenient prepared hydrogel has great potential as a commercial application for skin full-thickness burn healing materials.

Physicochemical and Rheological Characterization of Different Low Molecular Weight Gellan Gum Products and Derived Ionotropic Crosslinked Hydrogels

A series of four different low molecular weight gellan gum products was obtained by alkaline hydrolysis with the aim to investigate the impact of the molecular weight on the rheological properties of the polysaccharide aqueous dispersions and on the physicochemical characteristics of derived ionotropic crosslinked hydrogels. In particular, thermo-rheological analysis was conducted on aqueous dispersions to study the influence of molecular weight on the thermogelation properties typical of the native polysaccharide while strain sweep experiments were conducted to establish if aqueous dispersion shows a viscoelastic behavior. The effect of different Ca2+ on the rheological properties of hydrogels were studied. Furthermore, ionotropic crosslinked hydrogels were analyzed in terms of morphology on the dried state and swelling behavior, while their viscoelastic properties were studied by means of rheological analysis conducted in frequency sweep regime after different time points of incubation in phosphate buffer at pH 7.4. Release experiments conducted using fluorescein isothiocyanate labelled dextran as a model diffusion agent and was performed to investigate the possibility of using the low molecular weight GG-derived hydrogels as an active molecule-releasing device. Finally, the cytocompatibility of hydrolysis products was investigated, as well as the capacity of hydrogels to encapsulate viable MC3T3-E1 preosteoblastic cells.

In vivo and in vitro Evaluation of in situ Gel Formulation of Pemirolast Potassium in Allergic Conjunctivitis

Background

To establish a novel delivery system of pemirolast potassium-loaded gellan gum in situ gel in allergic conjunctivitis therapy.

Methods

The prepared in situ gels were studied in the following aspects: in vitro gelation, in vitro release, stability, viscosity measurement, in vivo tear kinetics and pharmacodynamics.

Results

In this study, the results showed that the viscosity of the in situ gels significantly increased when the preparation was in contact with simulated tear fluid and it also exhibited good stability in a period of three months. In vitro release showed that the release of pemirolast potassium from in situ gels had a good sustained release ability. No ocular damage or abnormal clinical signs to the cornea, iris, or conjunctivae were visible. Consistent with the in vitro studies, pemirolast potassium in situ gels were highly efficient in suppressing the inflammatory symptoms and improving the ocular bioavailability.

Conclusion

Pemirolast potassium ocular in situ gels are safe and promising therapeutic alternatives to the existing medications for allergic conjunctivitis therapy.

Does polysaccharide quaternization improve biological activity?

The natural polysaccharides, due to their structural diversity, commonly present very distinct solubility and physical chemical properties and additionally have intrinsic biological activities that, gene-rally, reveal themselves in a light way. The chemical modification of the molecular structure can improve these parameters. In this review, original articles that approached the quaternization of polysaccharides for purposes of biological application were selected, without limitation of year of publication, in the databases Scopus, Web of Science and PubMed. The results obtained from the bibliographic survey indicate that the increase in positive charges caused by quaternization improves the interaction between modified polysaccharides and structures that have negative charges on their surface, such as the cell wall of microorganisms and some cells in the human body, such as the DNA. This greater interaction is reflected as an increase in the biological activity of all polysaccharides broached in this study. Another important data obtained was the fact that the chemical changes did not affect or irrelevantly affect the toxicity of almost all of the polysaccharides that were quaternized. Therefore, polysaccharide quaternization is a safe and effective way to obtain improvements in the biological behavior of these macromolecules.