Applications of alginate microspheres in therapeutics delivery and cell culture: Past, present and future

Delivery vehicles for light-mediated drug delivery: microspheres, microbots, and nanoparticles: a review

This review delves into the evolving landscape of mediated drug delivery, focusing on the versatility of a variety of drug delivery vehicles such as microspheres, microbots, and nanoparticles (NPs). The review also expounds on the critical components and mechanisms for light-mediated drug delivery, including photosensitizers and light sources such as visible light detectable by the human eye, ultraviolet (UV) light, shorter wavelengths than visible light, and near-infra-red (NIR) light, which has longer wavelength than visible light. This longer wavelength has been implemented in drug delivery for its ability to penetrate deeper tissues and highlighted for its role in precise and controlled drug release. Furthermore, this review discusses the significance of these drug delivery vehicles towards a spectrum of diverse applications spanning gene therapy, cancer treatment, diagnostics, and microsurgery, and the materials used in the fabrication of these vehicles encompassing polymers, ceramics, and lipids. Moreover, the review analyses the challenges and limitations of such drug delivery vehicles as areas of improvement to provide researchers with valuable insights for addressing current obstacles in the progression of drug delivery. Overall, this review underscores the potential of light-mediated drug delivery to revolutionise healthcare and personalised medicine, providing precise, targeted, and effective therapeutic interventions.

Advance of the application of seaweed polysaccharides on antitumor drug delivery systems

In recent years, the morbidity and death rate of patients with tumors have been continuously increasing. How to administer radiotherapy, chemotherapy, and other methods for reducing damage to normal tissue cells and accurately targeting the tumor is one of the key issues in solving the problem of cancer. Using nanocarriers is a feasible approach into targeted control on the release of medicine to increase patient compliance. Nowadays, many researchers are gradually focusing on the application of drug delivery systems with natural ingredients as carriers in tumor therapy. At the same time, natural active ingredients may have better biocompatibility and fewer side effects. Especially, a variety of polysaccharides from algae has exhibited antitumor activity, providing greater possibilities for their use as drug delivery carriers. To facilitate the advancement and clinical translation of algae-derived polysaccharides in medical applications, we summarized the structural features of a range of polysaccharides extracted from macroalgae, their physical properties suitable for use as carriers, and the ways they are utilized in delivering medicines in oncology therapy (particularly in combination with novel oncology therapies, such as immunotherapy and photothermal therapy).

Collagen-based micro/nanogel delivery systems: Manufacturing, release mechanisms, and biomedical applications

ABSTRACT

Collagen-based materials, renowned for their biocompatibility and minimal immunogenicity, serve as exemplary substrates in a myriad of biomedical applications. Collagen-based micro/nanogels, in particular, are valued for their increased surface area, tunable degradation rates, and ability to facilitate targeted drug delivery, making them instrumental in advanced therapeutics and tissue engineering endeavors. Although extensive reviews on micro/nanogels exist, they tend to cover a wide range of biomaterials and lack a specific focus on collagen-based materials. The current review offers an in-depth look into the manufacturing technologies, drug release mechanisms, and biomedical applications of collagen-based micro/nanogels to address this gap. First, we provide an overview of the synthetic strategies that allow the precise control of the size, shape, and mechanical strength of these collagen-based micro/nanogels by controlling the degree of cross-linking of the materials. These properties are crucial for their performance in biomedical applications. We then highlight the environmental responsiveness of these collagen-based micro/nanogels, particularly their sensitivity to enzymes and pH, which enables controlled drug release under various pathological conditions. The discussion then expands to include their applications in cancer therapy, antimicrobial treatments, bone tissue repair, and imaging diagnosis, emphasizing their versatility and potential in these critical areas. The challenges and future perspectives of collagen-based micro/nanogels in the field are discussed at the end of the review, with an emphasis on the translation to clinical practice. This comprehensive review serves as a valuable resource for researchers, clinicians, and scientists alike, providing insights into the current state and future directions of collagen-based micro/nanogel research and development.

Sodium alginate microspheres loaded with Quercetin/Mg nanoparticles as novel drug delivery systems for osteoarthritis therapy

BACKGROUND

Osteoarthritis (OA) is the most prevalent arthritic disease characterized by cartilage degradation and low-grade inflammation, for which there remains a lack of efficacious therapeutic interventions. Notably, mitigating the impact of oxidative stress (OS) and inflammatory factors could help alleviate or hinder the advancement of OA. Given the benefits of both quercetin (Que) and Magnesium ion (Mg2+) in OA treatment, coupled with the structural properties of Que, we have innovatively developed the Que-Mg2+ nanoparticles (NPs), aiming to deliver both Que and Mg2+ simultaneously and achieve enhanced therapeutic outcomes for OA. Moreover, to avoid the adverse reactions linked to frequent injections, sodium alginate (SA) microspheres encapsulating Que-Mg2+ NPs (Que-Mg@SA) were designed to treat the H2O2-induced OA cell model.

METHODS

Que-Mg@SA microspheres were synthesized using the ionotropic gelation technique, with calcium chloride acting as the cross-linking agent. Comprehensive characterization of the Que-Mg@SA was conducted through transmission electron microscope (TEM), dynamic light scattering (DLS), optical microscope, and scanning electron microscope (SEM), which provided detailed insights into their size, zeta potential, morphology, and micromorphology. Additionally, the microsphere swelling rate and Que release were evaluated. The biocompatibility of Que-Mg@SA microspheres, along with their impact on chondrocyte viability, were detected through CCK-8 assay and live/dead cell staining. Furthermore, the antioxidant and anti-inflammatory properties of Que-Mg@SA were evaluated by examining the ROS scavenging ability and pro-inflammatory factors levels, respectively. Finally, the regulatory influence of Que-Mg@SA microspheres on extracellular matrix (ECM) metabolism in OA was assessed by immunofluorescence staining and Western blot.

RESULTS

Characterization results revealed that Que-Mg NPs exhibit nanoscale diameter, exceptional stability, and good dispersibility, while Que-Mg@SA possesses high entrapment efficiency (EE%) and loading efficiency (LE%), pronounced hygroscopic properties, and sustained drug-release capabilities. Additionally, in vitro cellular assays revealed that the biocompatible Que-Mg@SA microspheres significantly restored chondrocyte viability, scavenged H2O2-induced excessive ROS, reduced the levels of inflammatory cytokines, upregulated cartilage anabolic gene expression, downregulated cartilage catabolic protease gene expression, and maintained the metabolic balance of cartilage tissue.

CONCLUSION

The functionalized Que-Mg@SA microspheres developed in our study hold great promise as a drug delivery system for OA and potentially other biomedical applications.

CLINICAL TRIAL NUMBER

Not applicable.

MRI monitoring of USPIO-labeled BMSCs combined with alginate scaffold for cartilage defect repair

Objective

This study aimed to evaluate the effectiveness of bone marrow mesenchymal stem cells (BMSCs) combined with sodium alginate scaffolds in repairing knee cartilage defects in New Zealand rabbits. Additionally, it assessed the potential of functional magnetic resonance imaging (fMRI) for non-invasive monitoring of the dynamic repair process.

Methods

Rabbits were randomly divided into four groups: Group A (control), Group B (sodium alginate scaffold), Group C (BMSCs-sodium alginate scaffold), and Group D (USPIO-labeled BMSCs-sodium alginate scaffold). A cartilage defect model was created, and the respective materials were implanted into the defect regions. T2 mapping MRI was performed at weeks 1, 2, and 4 post-surgery to evaluate the repair process, followed by histological analysis to confirm the outcomes.

Results

BMSCs significantly promoted cartilage defect repair and accelerated the degradation of sodium alginate scaffolds. Macroscopic and histological evaluations revealed repair tissue formation in Groups C and D by week 1, with most defect regions filled with new cartilage by week 4. T2 mapping analysis showed a gradual decline in T2 values in Group B, a more pronounced decrease in Group C, and consistently lower T2 values in Group D compared to Group C, with a slow upward trend over time.

Conclusion

This study demonstrated that BMSCs exhibit significant regenerative potential for cartilage defect repair. USPIO labeling enables non-invasive, dynamic monitoring of the repair process without adverse effects on cell viability or differentiation. These findings provide experimental evidence supporting the application of BMSCs combined with magnetic labeling technology in cartilage regeneration.

Chitosan-alginate microcapsules: A strategy for improving stability and antibacterial potential of bovine Lactoferrin

Lactoferrin, a multifunctional glycoprotein with significant biological properties, presents significant potential for the prevention and treatment of infectious diseases. However, the effectiveness of oral Lactoferrin is limited by its susceptibility to degradation in harsh stomach conditions, reducing its bioavailability and therapeutic efficacy. To address this challenge, this study employs Chitosan/Alginate microparticles to enhance Lactoferrin stability and antibacterial activity. Microparticles were synthesized through external ionic gelation and thoroughly characterized. Chitosan/Alginate microparticles were significantly smaller than Alginate microparticles, with a high loading efficiency of 93.65 %. Fourier transform infrared (FT-IR) spectroscopy confirmed the successful incorporation of Lactoferrin. Release studies demonstrated minimal Lactoferrin release in simulated gastric fluid, while a controlled release was observed in simulated intestinal fluid. Notably encapsulated Lactoferrin retained its structural integrity after exposure to simulated gastrointestinal conditions. Antibacterial assay against Escherichia coli showed that Chitosan/Alginate microcapsules maintain Lactoferrin antibacterial activity after its passage through simulated gastrointestinal conditions. Furthermore, FT-IR spectroscopy and zeta-potential analysis provided novel insights into the mechanism of Lactoferrin's interaction with bacterial LPS, highlighting its ability to destabilize bacterial membrane of this Escherichia coli strain. These findings underscore the Chitosan/Alginate system as a promising strategy for enhancing the therapeutic potential of Lactoferrin.

Multifunctional hydrogel targeting senescence to accelerate diabetic wound healing through promoting angiogenesis

Diabetic wound healing remains a significant clinical challenge because of hyperglycaemia-induced cellular senescence, impaired angiogenesis, and chronic inflammation. To address these issues, we developed a multifunctional hydrogel (GelMA/PNS/Alg@IGF-1) that integrates gelatine methacryloyl (GelMA), Panax notoginseng saponins (PNS), and sodium alginate microspheres encapsulating insulin-like growth factor-1 (IGF-1). This hydrogel was engineered to achieve gradient and sustained release of bioactive agents to target senescence and promote vascular repair. In vitro studies demonstrated that the hydrogel significantly reduced oxidative stress, suppressed senescence markers and senescence-associated secretory phenotypes, and restored endothelial cell function under high-glucose conditions by inhibiting NF-κB pathway activation. Transcriptomic analysis revealed the modulation of pathways linked to inflammation, apoptosis, and angiogenesis. This hydrogel accelerated diabetic wound closure in a rat model in vivo and enhanced collagen deposition, granulation tissue formation, and neovascularization. Furthermore, the hydrogel mitigated oxidative stress and cellular senescence and promoted tissue remodelling. The synergistic effects of PNS and IGF-1 within the hydrogel established a pro-regenerative microenvironment to address both pathological ageing and vascular dysfunction. These findings highlight GelMA/PNS/Alg@IGF-1 as a promising therapeutic platform for diabetic wound management, as this material offers dual anti-senescence and proangiogenic efficacy to overcome the complexities of chronic wound healing.

Seaweed in the Diet as a Source of Bioactive Metabolites and a Potential Natural Immunity Booster: A Comprehensive Review

Seaweed plays an essential role in the survival of marine life, provides habitats and helps in nutrient recycling. It is rich in valuable nutritious compounds such as pigments, proteins, polysaccharides, minerals, vitamins, omega-rich oils, secondary metabolites, fibers and sterols. Pigments like fucoxanthin and astaxanthin and polysaccharides like laminarin, fucoidan, galactan and ulvan possess immune-modulatory and immune-enhancing properties. Moreover, they show antioxidative, antidiabetic, anticancer, anti-inflammatory, antiproliferative, anti-obesity, antimicrobial, anticoagulation and anti-aging properties and can prevent diseases such as Alzheimer's and Parkinson's and cardiovascular diseases. Though seaweed is frequently consumed by Eastern Asian countries like China, Japan, and Korea and has gained the attention of Western countries in recent years due to its nutritional properties, its consumption on a global scale is very limited because of a lack of awareness. Thus, to incorporate seaweed into the global diet and to make it familiar as a functional food, issues such as large-scale cultivation, processing, consumer acceptance and the development of seaweed-based food products need to be addressed. This review is intended to give a brief overview of the present status of seaweed, its nutritional value and its bioactive metabolites as functional foods for human health and diseases owing to its immunity-boosting potential. Further, seaweed as a source of sustainable food and its prospects along with its issues are discussed in this review.

Delivery of Probiotic-Loaded Microcapsules in the Gastrointestinal Tract: A Review

Probiotics are live microorganisms that inhabit the gastrointestinal tract and confer health benefits to consumers. However, a sufficient number of viable probiotic cells must be delivered to the specific site of interest in the gastrointestinal tract to exert these benefits. Enhanced viability and tolerance to sublethal gastrointestinal stress can be achieved using appropriate coating materials and food matrices for orally consumed probiotics. The release mechanism and interaction of probiotic microcapsules with the gastrointestinal tract have been minimally explored in the literature to date. To the authors' knowledge, no review has been published to discuss the nature of release and the challenges in the targeted delivery of probiotics. This review addresses gastrointestinal-related complications in the formulation of targeted delivery and controlled release of probiotic strains. It investigates the impacts of environmental stresses during the transition stage and delivery to the target region in the gastrointestinal tract. The influence of factors such as pH levels, enzymatic degradation, and redox conditions on the release mechanisms of probiotics is presented. Finally, the available methods to evaluate the efficiency of a probiotic delivery system, including in vitro and in vivo, are reviewed and assessed. The paper concludes with a discussion highlighting the emerging technologies in the field and emphasising key areas in need of future study.

Marine-Derived Polysaccharide Hydrogels as Delivery Platforms for Natural Bioactive Compounds

Marine polysaccharide hydrogels have emerged as an innovative platform for regulating the in vivo release of natural bioactive compounds for medical purposes. These hydrogels, which have exceptional biocompatibility, biodegradability, and high water absorption capacity, create effective matrices for encapsulating different bioactive molecules. In addition, by modifying the physical and chemical properties of marine hydrogels, including cross-linking density, swelling behavior, and response to external stimuli like pH, temperature, or ionic strength, the release profile of encapsulated bioactive compounds is strictly regulated, thus maximizing therapeutic efficacy and minimizing side effects. Finally, by using naturally sourced polysaccharides in hydrogel formulations, sustainability is promoted by reducing dependence on synthetic polymers, meeting the growing demand for eco-friendly materials. This review analyzes the interaction between marine polysaccharide hydrogels and encapsulating compounds and offers examples of how bioactive molecules can be encapsulated, released, and stabilized.

Hydrogel-Assisted Robust Supraparticles Evolved from Droplet Evaporation

Supraparticles, formed through the self-assembly of nanoparticles, are promising contenders in catalysis, sensing, and drug delivery due to their exceptional specific surface area and porosity. However, their mechanical resilience, especially in dimensions spanning micrometers and beyond, is challenged by the inherently weak interactions among their constituent building blocks, significantly constraining their broad applicability. Here, we have exploited a robust supraparticle fabrication strategy by integrating hydrogel components into the assembly system and evaporating on the superamphiphobic surface. The resultant SiO2/SA (sodium alginate) supraparticles, achieved by evaporating a 15% volume fraction dispersion of SiO2 nanoparticles containing 18.46 mg/mL of sodium alginate and subsequently cross-linking with Ca2+, demonstrate mechanical robustness with a fracture force of 6.04 N, representing a mechanical strength enhancement of 60 times higher than that prior to the incorporation of the hydrogel component. The supraparticles maintain their original morphology after 30 min of ultrasonic treatment (200 W), demonstrating mechanical stability. This method exhibits generalizability, enabling the customization of supraparticles with various building blocks and hydrogel backbone materials. Based on such a methodology, we have synthesized enzyme-carrying supraparticles, further expanding the potential applications in intricate cascade reactions. The encapsulated glucose oxidase and horseradish peroxidase maintained their inherent reactivity, and such hydrogel-assisted robust supraparticles exhibited exceptional performance in accurate glucose assays, indicating great practical application in biocatalysis.

Current status and future developments of biopolymer microspheres in the field of pharmaceutical preparation

Polymer composite microspheres offer several advantages including highly designable structural properties, adjustable micro-nano particle size distribution, easy surface modification, large specific surface area, and high stability. These features make them valuable in various fields such as medicine, sensing, optics, and display technologies, with significant applications in clinical diagnostics, pathological imaging, and drug delivery in the medical field. Currently, microspheres are primarily used in biomedical research as long-acting controlled-release agents and targeted delivery systems, and are widely applied in bone tissue repair, cancer treatment, and wound healing. Different types of polymer microspheres offer distinct advantages and application prospects. Efforts are ongoing to transition successful experimental research to industrial production by expanding various fabrication technologies. This article provides an overview of materials used in microsphere manufacturing, different fabrication methods, modification techniques to enhance their properties and applications, and discusses the role of microspheres in drug delivery engineering.

Injectable calcium phosphate cement integrated with BMSCs-encapsulated microcapsules for bone tissue regeneration

Injectable calcium phosphate cement (CPC) offers significant benefits for the minimally invasive repair of irregular bone defects. However, the main limitations of CPC, including its deficiency in osteogenic properties and insufficient large porosity, require further investigation and resolution. In this study, alginate-chitosan-alginate (ACA) microcapsules were used to encapsulate and deliver rat bone mesenchymal stem cells (rBMSCs) into CPC paste, while a porous CPC scaffold was established to support cell growth. Our results demonstrated that the ACA cell microcapsules effectively protect the cells and facilitate their transport into the CPC paste, thereby enhancing cell viability post-implantation. Additionally, the ACA + CPC extracts were found to stimulate osteogenic differentiation of rBMSCs. Furthermore, results from a rat cranial parietal bone defect model showed that ACA microcapsules containing exogenous rBMSCs initially improved thein situosteogenic potential of CPC within bone defects, providing multiple sites for bone growth. Over time, the osteogenic potential of the exogenous cells diminishes, yet the pores created by the microcapsules persist in supporting ongoing bone formation by recruiting endogenous cells to the osteogenic sites. In conclusion, the utilization of ACA loaded stem cell microcapsules satisfactorily facilitate osteogenesis and degradation of CPC, making it a promising scaffold for bone defect transplantation.

Fabrication of hydrogel mini-capsules as carrier systems

Conventional drug administration often results in systemic action, thus needing high dosages and leading to potentially pronounced side effects. Targeted delivery, employing carriers like nanoparticles, aims to release drugs at a target site, but only a small fraction of nanoparticles actually reaches it. Microrobots have been proposed to overcome this issue since they can be guided to hard-to-reach sites and locally deliver payloads. To enhance their functionality, we propose microrobots made as deformable capsules with hydrogel shells and aqueous cores, having the potential added advantages of biocompatibility, permeability, and stimulus-responsiveness. Endowing microrobots with deformability could allow them to navigate inside capillaries and cross barriers to finally reach the target site. In this study, we present a cost-effective method for fabricating core-shell structures without the use of organic solvents, surfactants, or extreme pH conditions unlike other techniques (e.g. Layer by Layer). The process begins with the dripping of a mixture of hydrogels, agarose and alginate, into a solution to gelate the drops into beads. After they are loaded with calcium ions at different concentrations, they are immersed in an alginate solution to form the shell. Finally, the beads are heated to let the agarose melt and diffuse out, leaving a liquid core. By varying the concentration of calcium ions, we obtain shells of different thicknesses. To estimate it, we have developed a method using the colour intensity from microscope images. This allowed us to observe that lowering the calcium ions concentration below a threshold does not lead to the formation of continuous shells. For higher concentrations, although the core may remain partially gelled, continuous shells successfully form. Therefore, our fabrication process could find applications in drug delivery, encapsulation systems, and microrobotics.

Gelatin-Based Polymers Can Be Processed to Highly Resilient Biocompatible Porous Hydrogel Scaffolds for Soft Tissue Regeneration Applications

Tissue regeneration relies on the mechanical properties of the surrounding environment, and it has already been shown that mechanostimulation is highly dependent on the stiffness of the native biological tissue. The main advantage of injectable hydrogels in medical applications is their ability to be delivered through minimally invasive techniques. Natural polymer-based hydrogels have been widely used in biomedical applications, due to their high biocompatibility, low immunogenicity, and similarity to soft tissues. However, the crucial combination of low stiffness with high resilience has not been achieved for natural polymers. The current study focuses on the development of novel gelatin-based injectable hydrogels for soft tissue regeneration applications, elucidating the effects of the formulation parameters on the resilience, microstructure, biocompatibility, and mechanical properties. Non-foamed hydrogels demonstrated resilience of at least 95%, while porous hydrogels maintained resilience above 90%, allowing them to withstand mechanical stresses and dynamic conditions within the body. The adjustable modulus of these hydrogels provides the necessary flexibility to mimic the mechanical properties of soft and very soft tissues, without compromising resilience. Environmental Scanning Electron Microscopy (ESEM) observations of the porous hydrogels indicated round interconnected pore structures, desired for cell migration and nutrient flow. Biocompatibility tests on fibroblasts and pre-adipocytes confirmed high biocompatibility, both directly and indirectly. In summary, structuring these new hydrogels for achieving adjustable stiffness, along with the excellent resilience and biocompatibility, is expected to enable this new technology to fit various soft tissue regeneration applications.

Bioactive polymers: A comprehensive review on bone grafting biomaterials

The application of bone grafting materials in bone tissue engineering is paramount for treating severe bone defects. In this comprehensive review, we explore the significance and novelty of utilizing bioactive polymers as grafts for successful bone repair. Unlike metals and ceramics, polymers offer inherent biodegradability and biocompatibility, mimicking the native extracellular matrix of bone. While these polymeric micro-nano materials may face challenges such as mechanical strength, various fabrication techniques are available to overcome these shortcomings. Our study not only investigates diverse biopolymeric materials but also illuminates innovative fabrication methods, highlighting their importance in advancing bone tissue engineering.

Biomedical potentials of alginate via physical, chemical, and biological modifications

Alginate is a linear polysaccharide with a modifiable structure and abundant functional groups, offers immense potential for tailoring diverse alginate-based materials to meet the demands of biomedical applications. Given the advancements in modification techniques, it is significant to analyze and summarize the modification of alginate by physical, chemical and biological methods. These approaches provide plentiful information on the preparation, characterization and application of alginate-based materials. Physical modification generally involves blending and physical crosslinking, while chemical modification relies on chemical reactions, mainly including acylation, sulfation, phosphorylation, carbodiimide coupling, nucleophilic substitution, graft copolymerization, terminal modification, and degradation. Chemical modified alginate contains chemically crosslinked alginate, grafted alginate and oligo-alginate. Biological modification associated with various enzymes to realize the hydrolysis or grafting. These diverse modifications hold great promise in fully harnessing the potential of alginate for its burgeoning biomedical applications in the future. In summary, this review provides a comprehensive discussion and summary of different modification methods applied to improve the properties of alginate while expanding its biomedical potentials.

Multi-Colored Aqueous Ink for Rewritable Paper

As sustainable and eco-friendly replacements to conventional paper, rewritable paper is a very attractive alternative for communication, information circulation, and storage. Development is made for rewritable paper using chromogenic materials that change its color in presence of external stimuli. However, the new techniques have faced several major challenges including feasible operational method, eco-friendly approach. Herein, a simple, convenient, and eco-friendly strategy is described for the preparation of rewritable paper substrate, and multi colored ink for efficient use in writing, painting or printing purpose. In addition, writing with "invisible ink" on the rewritable paper can be realized for potential anti-counterfeiting application. The written, painted, or printed information on the paper substrate can be easily erased using an aqueous solution. Thus, the original paper can be retrieved and the paper substrate can be reused multiple times. Besides, the written or printed information can be retained for a prolonged time at ambient conditions. Overall, this approach shows the rewritable paper as a prototype of multicolor writing/painting application, offering a sustainable solution for reducing paper waste and promoting environmental stewardship.

The Immune System-A Double-Edged Sword for Adenovirus-Based Therapies

Pathogenic adenovirus (Ad) infections are widespread but typically mild and transient, except in the immunocompromised. As vectors for gene therapy, vaccine, and oncology applications, Ad-based platforms offer advantages, including ease of genetic manipulation, scale of production, and well-established safety profiles, making them attractive tools for therapeutic development. However, the immune system often poses a significant challenge that must be overcome for adenovirus-based therapies to be truly efficacious. Both pre-existing anti-Ad immunity in the population as well as the rapid development of an immune response against engineered adenoviral vectors can have detrimental effects on the downstream impact of an adenovirus-based therapeutic. This review focuses on the different challenges posed, including pre-existing natural immunity and anti-vector immunity induced by a therapeutic, in the context of innate and adaptive immune responses. We summarise different approaches developed with the aim of tackling these problems, as well as their outcomes and potential future applications.

Development of a tobramycin-loaded calcium alginate microsphere/chitosan composite sponge with antibacterial effects as a wound dressing

Traditional dressings exhibit several disadvantages, as they frequently lead to bacterial infections, cause severe tissue adhesion and perform a relatively single function. Therefore, in this study, a composite sponge dressing with antibacterial properties and excellent physicochemical properties was developed. Six groups of tobramycin-loaded calcium alginate microspheres were prepared by changing the amount of tobramycin added, and the optimal group was selected. Then, seven groups of tobramycin-loaded calcium alginate microsphere/chitosan composite sponges were fabricated via a solvent blending process and a freeze-drying method. The surface morphology, physicochemical properties,in vitrodegradation properties,in vitrodrug release properties, antibacterial properties and cytotoxicity of the composite sponges were examined. Group 3.0 contained the best microspheres with the largest drug loading capacity, good swelling performance and cumulative drug release rate, obvious and sustained antibacterial activity, and good cytocompatibility. The tobramycin-loaded calcium alginate microsphere/chitosan composite sponges exhibited three-dimensional porous structures, and their porosity, swelling rate, water absorption and water retention rates and water vapor transmission rate met the standards needed for an ideal dressing. The comprehensive performance of the sponge was best when 20 mg of drug-loaded microspheres was added (i.e. group 20). The cumulative drug release rate of the sponge was 29.67 ± 4.14% at 7 d, the diameters of the inhibition zones against the three bacteria were greater than 15 mm, and L929 cell proliferation was promoted. These results demonstrated that the tobramycin-loaded calcium alginate microsphere/chitosan composite sponge with 20 mg of tobramycin-loaded microspheres shows promise as a dressing for infected wounds.

Development of an alginate-chitosan biopolymer composite with dECM bioink additive for organ-on-a-chip articular cartilage

In vitro use of articular cartilage on an organ-on-a-chip (OOAC) via microfluidics is challenging owing to the dense extracellular matrix (ECM) composed of numerous protein moieties and few chondrocytes, which has limited proliferation potential and microscale translation. Hence, this study proposes a novel approach for using a combination of biopolymers and decellularised ECM (dECM) as a bioink additive in the development of scalable OOAC using a microfluidic platform. The bioink was tested with native chondrocytes and mesenchymal stem cell-induced chondrocytes using biopolymers of alginate and chitosan composite hydrogels. Two-dimensional (2D) and three-dimensional (3D) biomimetic tissue construction approaches have been used to characterise the morphology and cellular marker expression (by histology and confocal laser scanning microscopy), viability (cell viability dye using flow cytometry), and genotypic expression of ECM-specific markers (by quantitative PCR). The results demonstrated that the bioink had a significant impact on the increase in phenotypic and genotypic expression, with a statistical significance level of p < 0.05 according to Student's t-test. The use of a cell-laden biopolymer as a bioink optimised the niche conditions for obtaining hyaline-type cartilage under culture conditions, paving the way for testing mechano-responsive properties and translating these findings to a cartilage-on-a-chip microfluidics system.

Clinical research progress of callisperes® of drug-loaded microsphere arterial chemoembolisation in the treatment of solid tumors

The incidence and mortality of cancer is ever-increasing, which poses a significant challengesto human health and a substantial economic burden to patients. At present, chemotherapy is still a primary treatment for various cancers. However, chemotherapy kills tumors but also induces the related side effects, whichadversely impacting patient quality of life and exacerbating suffering. Therefore, there is an urgent need for new and effective treatments that can control tumor growth while reducing the side effects for patients. Arterial chemoembolization has been attracted much attentionwhich attributed to the advantage of ability to embolize tumor vessels to block blood and nutrition supplies. Thus, to achieve local tumor control, it has become an effective means of local tumor control and has been widely used in clinical practice. Despite its efficacy, conventional arterial chemoembolization techniques, limited by embolization materials, have been associated with incomplete embolization and suboptimal drug delivery outcomes. Gradually, researchers have shifted their attention to a new type of embolic material called CalliSperes® drug-eluting embolic bead (DEB). DEB can not only load high doses of drugs, but also has strong sustained drug release ability and good biocompatibility. The integration of DEBs with traditional arterial chemoembolization (DEB-TACE) promises targeted vascular embolization, mitigated tumor ischemia and hypoxia, and direct intravascular chemotherapy delivery. It can prevent cancer cell differentiation and accelerate their death, meanwhile, directly injecting chemotherapy drugs into the target blood vessels reduced the blood concentration of the whole body, thus reduced the toxic and side effects of chemotherapy. Furthermore, DEB-TACE's sustained drug release capability elevates local drug concentrations at the tumor site, amplifying its antitumor efficacy. Therefore, DEB-TACE has become a hot spot in clinical research worldwide. This review introduces the pathogenesis of solid tumors, the background of research and biological characteristics of DEB, and the action mechanism of DEB-TACE, as well as its clinical research in various solid tumors and future prospects. This review aims to provide new ideas for the treatment of DEB-TACE in various solid tumors.

Optimizing Process Parameters for Controlled Drug Delivery: A Quality by Design (QbD) Approach in Naltrexone Microspheres

The formulation of microspheres involves a complex manufacturing process with multiple steps. Identifying the appropriate process parameters to achieve the desired quality attributes poses a significant challenge. This study aims to optimize the critical process parameters (CPPs) involved in the preparation of naltrexone microspheres using a Quality by Design (QbD) methodology. Additionally, the research aims to assess the drug release profiles of these microspheres under both in vivo and in vitro conditions. Critical process parameters (CPPs) and critical quality attributes (CQAs) were identified, and a Box-Behnken design was utilized to delineate the design space, ensuring alignment with the desired Quality Target Product Profile (QTPP). The investigated CPPs comprised polymer concentration, aqueous phase ratio to organic phase ratio, and quench volume. The microspheres were fabricated using the oil-in-water emulsion solvent extraction technique. Analysis revealed that increased polymer concentration was correlated with decreased particle size, reduced quench volume resulted in decreased burst release, and a heightened aqueous phase ratio to organic phase ratio improved drug entrapment. Upon analyzing the results, an optimal formulation was determined. In conclusion, the study conducted in vivo drug release testing on both the commercially available innovator product and the optimized test product utilizing an animal model. The integration of in vitro dissolution data with in vivo assessments presents a holistic understanding of drug release dynamics. The QbD approach-based optimization of CPPs furnishes informed guidance for the development of generic pharmaceutical formulations.

Microencapsulate Probiotics (MP) Promote Growth Performance and Inhibit Inflammatory Response in Broilers Challenged with Salmonella typhimurium

Antibiotic-resistant bacteria are prevalent in husbandry around the world due to the abuse of antibiotic growth promoters (AGPs); therefore, it is necessary to find alternatives to AGPs in animal feed. Among all the candidates, probiotics are promising alternatives to AGPs against Salmonella infection. The anti-Salmonella effects of three probiotic strains, namely, Lactobacillus crispatus 7-4, Lactobacillus johnsonii 3-1, and Pediococcus acidilactici 20-1, have been demonstrated in our previous study. In this study, we further obtained the alginate beads containing compound probiotics, namely, microencapsulate probiotics (MP), and evaluated its regulatory effect on the health of broilers. We incubated free and microencapsulate probiotics in simulated gastric and intestinal juice for 2 h, and the results showed that compared to free probiotics, encapsulation increased tolerance of compound probiotics in the simulated gastrointestinal condition. We observed that the application of probiotics, especially MP, conferred protective effects against Salmonella typhimurium (S.Tm) infection in broilers. Compared to the S.Tm group, the MP could promote the growth performance (p < 0.05) and reduce the S.Tm load in intestine and liver (p < 0.05). In detail, MP pretreatment could modulate the cecal microflora and upregulate the relative abundance of Lactobacillus and Enterobacteriaceae. Besides, MP could reduce the inflammation injury of the intestine and liver, reduce the pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) expression, and induce of anti-inflammatory cytokine (IL-10) expression. Furthermore, MP could inhibit NLRP3 pathway in ileum, thereby attenuating S.Tm-induced inflammation. In conclusion, MP could be a new feeding supplementation strategy to substitute AGPs in poultry feeding.

Recent Advances in Alginate-Based Hydrogels for Cell Transplantation Applications

With its exceptional biocompatibility, alginate emerged as a highly promising biomaterial for a large range of applications in regenerative medicine. Whether in the form of microparticles, injectable hydrogels, rigid scaffolds, or bioinks, alginate provides a versatile platform for encapsulating cells and fostering an optimal environment to enhance cell viability. This review aims to highlight recent studies utilizing alginate in diverse formulations for cell transplantation, offering insights into its efficacy in treating various diseases and injuries within the field of regenerative medicine.

Evolution of Hybrid Hydrogels: Next-Generation Biomaterials for Drug Delivery and Tissue Engineering

Hydrogels, being hydrophilic polymer networks capable of absorbing and retaining aqueous fluids, hold significant promise in biomedical applications owing to their high water content, permeability, and structural similarity to the extracellular matrix. Recent chemical advancements have bolstered their versatility, facilitating the integration of the molecules guiding cellular activities and enabling their controlled activation under time constraints. However, conventional synthetic hydrogels suffer from inherent weaknesses such as heterogeneity and network imperfections, which adversely affect their mechanical properties, diffusion rates, and biological activity. In response to these challenges, hybrid hydrogels have emerged, aiming to enhance their strength, drug release efficiency, and therapeutic effectiveness. These hybrid hydrogels, featuring improved formulations, are tailored for controlled drug release and tissue regeneration across both soft and hard tissues. The scientific community has increasingly recognized the versatile characteristics of hybrid hydrogels, particularly in the biomedical sector. This comprehensive review delves into recent advancements in hybrid hydrogel systems, covering the diverse types, modification strategies, and the integration of nano/microstructures. The discussion includes innovative fabrication techniques such as click reactions, 3D printing, and photopatterning alongside the elucidation of the release mechanisms of bioactive molecules. By addressing challenges, the review underscores diverse biomedical applications and envisages a promising future for hybrid hydrogels across various domains in the biomedical field.

Smart/stimuli-responsive chitosan/gelatin and other polymeric macromolecules natural hydrogels vs. synthetic hydrogels systems for brain tissue engineering: A state-of-the-art review

Currently, there are no viable curative treatments that can enhance the central nervous system's (CNS) recovery from trauma or illness. Bioengineered injectable smart/stimuli-responsive hydrogels (SSRHs) that mirror the intricacy of the CNS milieu and architecture have been suggested as a way to get around these restrictions in combination with medication and cell therapy. Additionally, the right biophysical and pharmacological stimuli are required to boost meaningful CNS regeneration. Recent research has focused heavily on developing SSRHs as cutting-edge delivery systems that can direct the regeneration of brain tissue. In the present article, we have discussed the pathology of brain injuries, and the applicable strategies employed to regenerate the brain tissues. Moreover, the most promising SSRHs for neural tissue engineering (TE) including alginate (Alg.), hyaluronic acid (HA), chitosan (CH), gelatin, and collagen are used in natural polymer-based hydrogels and thoroughly discussed in this review. The ability of these hydrogels to distribute bioactive substances or cells in response to internal and external stimuli is highlighted with particular attention. In addition, this article provides a summary of the most cutting-edge techniques for CNS recovery employing SSRHs for several neurodegenerative diseases.

Alginate microspheres encapsulating hox transcript antisense RNA siRNA regulate the Hedgehog-Gli1 pathway to alleviate epidermal growth factor receptor tyrosine kinase inhibitors resistance

The long non-coding RNA HOTAIR and the Hedgehog-Gli1 signaling pathway are closely associated with tumor occurrence and drug resistance in various cancers. However, their specific roles in the development of EGFR-TKIs resistance in non-small cell carcinoma remain unclear. To address the issue of EGFR-TKIs resistance, this study utilized the electrospray method to prepare sodium alginate microspheres encapsulating HOTAIR siRNA (SA/HOTAIR siRNA) and investigated its effects on RNA interference (RNAi) in the gefitinib-resistant cell line PC9/GR. Furthermore, the study explored whether HOTAIR could modulate EGFR-TKIs resistance through the Hedgehog-GLi1 signaling pathway. The experimental results showed that sodium alginate (SA) microspheres demonstrated excellent biocompatibility with high encapsulation efficiency and drug-loading capacity, effectively enhancing the silencing efficiency of siRNA. HOTAIR siRNA significantly inhibited the proliferation, migration, and invasion abilities of PC9/GR cells while promoting apoptosis. Additionally, HOTAIR siRNA effectively suppressed tumor growth and downregulated the Hedgehog-GLi1 pathway and anti-apoptotic proteins, which were confirmed in animal experiments. Moreover, SA/HOTAIR siRNA exhibited superior inhibition of cellular and tumor functions compared to using HOTAIR siRNA alone. Clinical research findings indicated that monitoring the expression level of HOTAIR in the serum and urine samples of NSCLC patients before and after receiving EGFR-TKIs treatment can predict the efficacy of EGFR-TKIs to a certain extent. This study provided evidence that HOTAIR siRNA effectively mitigated the development of acquired resistance to EGFR-TKIs by inhibiting the Hedgehog-GLi1 pathway. Furthermore, it introduced a reliable and long-lasting drug delivery system for combating acquired resistance to EGFR-TKIs.

Nanoclay-Modified Hyaluronic Acid Microspheres for Bone Induction by Sustained rhBMP-2 Delivery

Microspheres (MSs) are ideal candidates as biological scaffolds loading with growth factors or cells for bone tissue engineering to repair irregular alveolar bone defects by minimally invasive injection. However, the high initial burst release of growth factor and low cell attachment limit the application of microspheres. The modification of microspheres often needs expensive experiments facility or complex chemical reactions, which is difficult to achieve and may bring other problems. In this study, a sol-grade nanoclay, laponite XLS is used to modify the surface of MSs to enhance its affinity to either positively or negatively charged proteins and cells without changing the interior structure of the MSs. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used as a representation of growth factor to check the osteoinduction ability of laponite XLS-modified MSs. By modification, the protein sustained release, cell loading, and osteoinduction ability of MSs are improved. Modified by 1% laponite XLS, the MSs can not only promote osteogenic differentiation of MC3T3-E1 cells by themselves, but also enhance the effect of the rhBMP-2 below the effective dose. Collectively, the study provides an easy and viable method to modify the biological behavior of microspheres for bone tissue regeneration.

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

3D Coculture between Cancer Cells and Macrophages: From Conception to Experimentation

A tumor is a complex cluster with many types of cells in the microenvironment that help it grow. Macrophages, immune cells whose main role is to maintain body homeostasis, represent in the majority of cancers the most important cell population. In this context, they are called tumor-associated macrophages (TAMs) because of their phenotype, which contributes to tumor growth. In order to limit the use of animals, there is a real demand for the creation of in vitro models able to represent more specifically the complexity of the tumor microenvironment (TME) in order to characterize it and evaluate new treatments. However, the two-dimensional (2D) culture, which has been used for a long time, has shown many limitations, especially in terms of tumor representation. The three-dimensional (3D) models, developed over the last 20 years, have made it possible to get closer to what happens in vivo in terms of phenotypic and functional characteristics. Due to their architectural similarity to in vivo tissues, they provide a more physiologically relevant in vitro system. Most recently, it is the development of 3D coculture models in which two or three cell lines are cultured together that has allowed a better representation of TME with cell-cell interactions. Unfortunately, there is no clear direction for the design of these models at this time. In this Review on the coculture between cancer cells and TAMs, an in-depth analysis is performed to answer multiple questions on the conception of these models: Which models to use, and with which material and cancer lineage? Which monocyte or macrophage lines should be added to the coculture? And how can these models be exploited?

Alginate biopolymeric structures: Versatile carriers for bioactive compounds in functional foods and nutraceutical formulations: A review

Alginate-based biopolymer products have gained attention for protecting and delivering bioactive components in nutraceuticals and functional foods. These naturally abundant anionic, unbranched, and linear copolymers are also produced commercially by microorganisms. Alone or in combination with other copolymers, they efficiently transport bioactive molecules in food and nutraceutical products. This review aims to provide an in-depth understanding of alginate-based products and structures, emphasizing their role in delivering functional molecules in various formulations and delivery systems. These include edible coatings/films, gels/emulsions, beads/droplets, microspheres/particles, and engineered nanostructures where alginates have been used potentially. By exploring these applications, readers gain insights into the benefits of these products. Because, alginate-based biopolymer products have shown promise in delivering bioactive compounds like vitamin C, vitamin D3, curcumin, β-carotene, resveratrol, folic acid, gliadins, caffeic acid, betanin, limonoids, quercetin, several polyphenols and essential oils, etc., which are chief contributors to treating specific/overall nutritional and chronic metabolic disorders. So, this review summarizes the potential of alginate-based structures/products in various forms for delivering a wide range of functional food ingredients and nutraceutical components that offer promising perspectives for future investigations.

Design and fabrication of a vaccine candidate based on rOmpA from Klebsiella pneumoniae encapsulated in silk fibroin-sodium alginate nanoparticles against pneumonia infection

The present study describes the design and fabrication of a novel vaccine candidate based on the outer membrane protein A (rOmpA) from Klebsiella pneumoniae (K. pneumoniae) encapsulated in silk fibroin-sodium alginate nanoparticles (SF-SANPs) against K. pneumoniae-mediated pneumonia. The physicochemical properties, toxicity, release profile, and in vivo potency of SF-SANPs encapsulated with rOmpA were evaluated. The spherical nano vaccine was created with an average particle size of 160 nm and an encapsulation efficiency of 80 %. Antigen release from SF-SANPs was 40 % after 22 days release assay. The SF-SANPs showed a zeta potential of -24.8 mV and had no toxic effect on the L929 cells in vitro. It was found that SF-SANPs in the vaccine formulation promoted systemic and mucosal antibodies and also stimulated cytokine responses, inducing both humoral (Th2) and cellular (Th1) immune responses, with a Th1-polarized response. The vaccine candidate was effective in protecting the mice lung against experimental pneumonia and reducing inflammation. These findings suggest that the rOmpA-based vaccine encapsulated in SF-SANPs could be a promising strategy for preventing pneumonia caused by K. pneumoniae.

The Effect of Chitosan/Alginate/Graphene Oxide Nanocomposites on Proliferation of Mouse Spermatogonial Stem Cells

Male survivors of childhood cancer have been known to be afflicted with azoospermia. To combat this, the isolation and purification of spermatogonial stem cells (SSCs) are crucial. Implementing scaffolds that emulate the extracellular matrix environment is vital for promoting the regeneration and proliferation of SSCs. This research aimed to evaluate the efficiency of nanocomposite scaffolds based on alginate, chitosan, and graphene oxide (GO) in facilitating SSCs proliferation. To analyze the cytotoxicity of the scaffolds, an MTT assay was conducted at 1, 3, and 7 days, and the sample containing 30 µg/mL of GO (ALGCS/GO30) exhibited the most favorable results, indicating its optimal performance. The identity of the cells was confirmed using flow cytometry with C-Kit and GFRα1 markers. The scaffolds were subjected to various analyses to characterize their properties. FTIR was employed to assess the chemical structure, XRD to examine crystallinity, and SEM to visualize the morphology of the scaffolds. To evaluate the proliferation of SSCs, qRT-PCR was used. The study's results demonstrated that the ALGCS/GO30 nanocomposite scaffold exhibited biocompatibility and facilitated the attachment and proliferation of SSCs. Notably, the scaffold displayed a significant increase in proliferation markers compared to the control group, indicating its ability to support SSC growth. The expression level of the PLZF protein was assessed using the Immunocytochemistry method. The observations confirmed the qRT-PCR results, which indicated that the nanocomposite scaffolds had higher levels of PLZF protein expression than scaffolds without GO. The biocompatible ALGCS/GO30 is a promising alternative for promoting SSC proliferation in in vitro applications.

The effects of Lactobacillus reuteri microcapsules on radiation-induced brain injury by regulating the gut microenvironment

A radiation-induced brain injury (RIBI) is a major adverse event following radiotherapy of malignant tumors. RIBI would affect cognitive function, leading to a series of complications and even death. However, the pathogenesis of RIBI is still unclear, and it still lacks specific therapeutic drugs. The gut-brain bidirectional communication may be mediated by various microbiota and metabolites in the gastrointestinal tract. Probiotics are closely related to physiological health. The theory of the gut-brain axis provides us with a new idea to improve the gut microenvironment by supplementing probiotics against RIBI. Here, Lactobacillus reuteri microcapsules (LMCs) were prepared, which were predominantly irregular spheres with a rough surface under a scanning electron microscope and a narrow size distribution ranging from 20 to 700 μm. The transmission electron microscopy images showed that the structure of microcapsules containing Lactobacillus reuteri (L. reuteri) was a core and shell structure. The survival of L. reuteri in microcapsules was significantly more than that of free L. reuteri in the simulated stomach environment of pH 1.2. 16S rDNA sequencing showed that LMCs observably increased the relative abundance of Lactobacillus in RIBI mice. More importantly, compared with the RIBI model mice, the behavior of RIBI mice treated with LMCs was significantly improved. In addition, LMCs greatly alleviated the pathological damage of the hippocampus and intestines in the mice after irradiation and reduced the level of TNF-α and IL-6 in vivo. Generally, LMCs are a promising oral preparation, which provide new ideas and methods for the treatment of RIBI.

Characteristics and release of isoniazid from inhalable alginate/carrageenan microspheres

Aim: Inhalable microspheres made of polymers as a targeted drug delivery system have been developed to overcome the limitation of current treatments in Tuberculosis. Materials & methods: Isoniazid inhalable microspheres were created using a gelation ionotropic method with sodium alginate, carrageenan and calcium chloride in four different formulations. Result: The particle morphology has smooth surfaces and round spherical shapes with sizes below 5 μm; good flowability. The drug loading and entrapment efficiency values ranged from 1.69 to 2.75% and 62.44 to 85.30%, respectively. The microspheres drug release followed the Korsmeyer-Peppas model, indicating Fickian diffusion. Conclusion: Isoniazid inhalable microspheres achieved as targeted lung delivery for tuberculosis treatment.

A review on chitosan and alginate-based microcapsules: Mechanism and applications in drug delivery systems

Natural polymers, like chitosan and alginate have potential of appearance, as well as the changes and handling necessary to make it acceptable vehicle for the controlled release of medicines and biomolecules. Microcapsules are characterized as micrometer-sized particulate that can be employed to store chemicals within them. In the present review, we have discussed various advantages, components of microcapsules, release mechanisms, preparation methods, and their applications in drug delivery systems. The preparation methods exhibited strong encapsulation effectiveness and may be used in a wide range of pharmaceutical and biomedical applications. The major advantages of using the microencapsulation technique are, sustained and controlled delivery of drugs, drug targeting, improvement of shelf life, stabilization, immobilization of enzymes and microorganisms. As new biomaterials are developed for the body, they are better suited to the development of pharmaceutical systems than traditional pharmaceuticals because they are more reliable, biocompatible, biodegradable, and nontoxic. Furthermore, the designed microcapsules had been capable of shielding the essential components from hostile environments. More advanced techniques could be developed in the future to facilitate the formulation and applications of microcapsules and working with the pharmaceutical and medical industries.

Biopolymer-Based Nanosystems: Potential Novel Carriers for Kidney Drug Delivery

Kidney disease has become a serious public health problem throughout the world, and its treatment and management constitute a huge global economic burden. Currently, the main clinical treatments are not sufficient to cure kidney diseases. During its development, nanotechnology has shown unprecedented potential for application to kidney diseases. However, nanotechnology has disadvantages such as high cost and poor bioavailability. In contrast, biopolymers are not only widely available but also highly bioavailable. Therefore, biopolymer-based nanosystems offer new promising solutions for the treatment of kidney diseases. This paper reviews the biopolymer-based nanosystems that have been used for renal diseases and describes strategies for the specific, targeted delivery of drugs to the kidney as well as the physicochemical properties of the nanoparticles that affect the targeting success.

Structural and mechanical analysis on mannuronate-rich alginate gels and xerogels beads based on Calcium, Copper and Zinc as crosslinkers

Beads based on a mannuronate(M)-rich alginate (86 % M units) were prepared by adding the polysaccharide solution to a crosslinking bath containing different concentrations (0.5, 2 and 10 wt%) of XCl2 where X = Ca, Cu or Zn. Primarily focus was on Zn, due to its antioxidant, anti-inflammatory and anti-microbial capabilities. The beads were characterized by Field-Emission Scanning Electron Microscopy (FESEM), Fourier-Transform Infra-Red spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Small-Angle X-ray Scattering (SAXS) and compression tests. The crosslinking agent significantly influenced the properties of the resulting beads. Specifically, Ca-based beads exhibited a smoother surface, while Cu- and Zn-based beads appeared rougher. Interestingly, Zn-based beads displayed a core-shell structure. Young moduli ranged from 3500 and 7000 MPa, with the highest values observed for Zn-beads. SAXS investigation at 0.5 wt% XCl2 suggested increase in the densely packed domains amount in the order: Ca < Cu < Zn. Extended X-ray Absorption Fine Structure (EXAFS) showed that the coordination number was 4.3 ± 0.4 for Cu, and 4.0 ± 0.2 and 1.1 ± 0.1 for Zn in 0.5 wt% XCl2 alginate xerogels, in agreement with reported Density Functional Calculations on Cu2+- and Zn2+-MM complexes. The results from FT-IR, compositional analysis and EXAFS collectively suggested a bridging coordination for these systems.

Antiproliferative and Apoptotic Effects of Olive Leaf Extract Microcapsules on MCF-7 and A549 Cancer Cells

Alginate microcapsules are a talented means for the delivery of broad curative biomacromolecules. In this study, we immobilized olive leaf extract (OLE) by calcium alginate (CA) and chitosan-coated CA (CCA) and characterized the OLE-loaded CA and CCA. The cytotoxic effect, the cell cycle arrest, and the apoptotic effect of OLE and its microcapsules were investigated against breast adenocarcinoma (MCF-7) and lung carcinoma (A549). As a result, the loading capacity of OLE-CA and OLE-CCA was found to be 80 and 99%, respectively, in optimal conditions. Also, OLE-CA and OLE-CCA were characterized by unique FTIR peaks and morphological display relative to the empty CCA microcapsules. The cytotoxicity analysis showed that the IC50 values of OLE-CA and OLE-CCA were determined to be 312 and 0.94 μg mL-1 against A549, respectively, whereas these were found to be 865.4 and 425.5 μg mL-1 for MCF-7 cells. On the other hand, the OLE microcapsules did not possess in any concentration of cytotoxic influence on the BEAS 2B healthy cell line. Also, the exposure of OLE-CCA to MCF-7 and A549 resulted in the arrest of more MCF-7 and A549 cells at the G0/G1 phase compared to the OLE. A549 and MCF-7 cells were predominantly found in the late apoptosis phase and necrosis phase, respectively. Optical microscopy images confirmed that OLE microcapsules were more effective against MCF-7 and A549 than free OLE. The present work suggested that the OLE microcapsules might be administered as nutrition supplements for cancer therapy.

CpG ODN/Mangiferin Dual Delivery through Calcium Alginate Hydrogels Inhibits Immune-Mediated Osteoclastogenesis and Promotes Alveolar Bone Regeneration in Mice

The immune system plays an important role in the skeletal system during bone repair and regeneration. The controlled release of biological factors from the immune system could facilitate and optimize the bone remodeling process through the regulation of the activities of bone cells. This study aimed to determine the effect of the controlled delivery of immunomodulatory biologicals on bone regeneration. Immunostimulatory cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODN) and glucosylxanthone Mangiferin (MAG)-embedded microbeads were incubated with P. gingivalis-challenged splenocytes, or co-cultured with RAW264.7 cells. The effect of CpG ODN/MAG-containing microbeads on bone regeneration was then tested in vivo in a mouse alveolar bone defect model. The results demonstrated that MAG significantly antagonized P. gingivalis proliferation and reduced the live/dead cell ratio. After the addition of CpG ODN + MAG microbeads, anti-inflammatory cytokines IL-10 and IL-4 were upregulated on day 2 but not day 4, whereas pro-inflammatory cytokine IL-1β responses showed no difference at both timepoints. RANKL production by splenocytes and TRAP+ cell formation of RAW264.7 cells were inhibited by the addition of CpG ODN + MAG microbeads. Alveolar bony defects, filled with CpG ODN + MAG microbeads, showed significantly increased new bone after 4 weeks. In summary, this study evaluated a new hydrogel-based regimen for the local delivery and controlled release of biologicals to repair and regenerate alveolar bony defects. The combined CpG ODN + MAG treatment may promote alveolar bone regeneration through the anti-microbial/anti-inflammatory effects and the inhibition of RANKL-mediated osteoclastogenesis.

Alginate-based drug carrier systems to target inflammatory bowel disease: A review

Inflammatory bowel disease (IBD) is an inflammatory disorder that affects the gastrointestinal tract. IBD has become an increasingly common condition in both developed and developing nations over the last few decades, owing to a variety of factors like a rising population and diets packed with processed and junk foods. While the root pathophysiology of IBD is unknown, treatments are focused on medications aimed to mitigate symptoms. Alginate (AG), a marine-derived polysaccharide, is extensively studied for its biocompatibility, pH sensitivity, and crosslinking nature. This polymer is thoroughly researched in drug delivery systems for IBD treatment, as it is naturally available, non-toxic, cost effective, and can be easily and safely cross-linked with other polymers to form an interconnected network, which helps in controlling the release of drugs over an extended period. There are various types of drug delivery systems developed from AG to deliver therapeutic agents; among them, nanotechnology-based systems and hydrogels are popular due to their ability to facilitate targeted drug delivery, reduce dosage, and increase the therapeutic efficiency. AG-based carrier systems are not only used for the sustained release of drug, but also used in the delivery of siRNA, interleukins, and stem cells for site directed drug delivery and tissue regenerating ability respectively. This review is focussed on pathogenesis and currently studied medications for IBD, AG-based drug delivery systems and their properties for the alleviation of IBD. Moreover, future challenges are also be discoursed to improve the research of AG in the field of biopharmaceuticals and drug delivery.

Alginate-Based 3D A549 Cell Culture Model to Study Paracoccidioides Infection

A three-dimensional (3D) lung aggregate model based on sodium alginate scaffolds was developed to study the interactions between Paracoccidioides brasiliensis (Pb) and lung epithelial cells. The suitability of the 3D aggregate as an infection model was examined using cell viability (cytotoxicity), metabolic activity, and proliferation assays. Several studies exemplify the similarity between 3D cell cultures and living organisms, which can generate complementary data due to the greater complexity observed in these designed models, compared to 2D cell cultures. A 3D cell culture system of human A549 lung cell line plus sodium alginate was used to create the scaffolds that were infected with Pb18. Our results showed low cytotoxicity, evidence of increased cell density (indicative of cell proliferation), and the maintenance of cell viability for seven days. The confocal analysis revealed viable yeast within the 3D scaffold, as demonstrated in the solid BHI Agar medium cultivation. Moreover, when ECM proteins were added to the alginate scaffolds, the number of retrieved fungi was significantly higher. Our results highlight that this 3D model may be promising for in vitro studies of host-pathogen interactions.

Artificial ovaries constructed from biodegradable chitin-based hydrogels with the ability to restore ovarian endocrine function and alleviate osteoporosis in ovariectomized mice

BACKGROUND

Artificial ovary (AO) is an alternative approach to provide physiological hormone to post-menopausal women. The therapeutic effects of AO constructed using alginate (ALG) hydrogels are limited by their low angiogenic potential, rigidity, and non-degradability. To address these limitations, biodegradable chitin-based (CTP) hydrogels that promote cell proliferation and vascularization were synthesized, as supportive matrix.

METHODS

In vitro, follicles isolated from 10-12-days-old mice were cultured in 2D, ALG hydrogels, and CTP hydrogels. After 12 days of culture, follicle growth, steroid hormone levels, oocyte meiotic competence, and expression of folliculogenesis-related genes were monitored. Additionally, follicles isolated from 10-12-days-old mice were encapsulated in CTP and ALG hydrogels and transplanted into the peritoneal pockets of ovariectomised (OVX) mice. After transplantation, steroid hormone levels, body weight, rectal temperature, and visceral fat of the mice were monitored every two weeks. At 6 and 10 weeks after transplantation, the uterus, vagina, and femur were collected for histological examination.

RESULTS

The follicles developed normally in CTP hydrogels under in vitro culture conditions. Additionally, follicular diametre and survival rate, oestrogen production, and expression of folliculogenesis-related genes were significantly higher than those in ALG hydrogels. After one week of transplantation, the numbers of CD34-positive vessels and Ki-67-positive cells in CTP hydrogels were significantly higher than those in ALG hydrogels (P < 0.05), and the follicle recovery rate was significantly higher in CTP hydrogels (28%) than in ALG hydrogels (17.2%) (P < 0.05). After two weeks of transplantation, OVX mice implanted with CTP grafts exhibited normal steroid hormone levels, which were maintained until week eight. After 10 weeks of transplantation, CTP grafts effectively ameliorated bone loss and atrophy of the reproductive organs, as well as prevented the increase in body weight and rectal temperature in OVX mice, which were superior to those elicited by ALG grafts.

CONCLUSIONS

Our study is the first to demonstrate that CTP hydrogels support follicles longer than ALG hydrogels in vitro and in vivo. The results highlight the clinical potential of AO constructed using CTP hydrogels in the treatment of menopausal symptoms.

Optimization strategies of mesenchymal stem cell-based therapy for acute kidney injury

Considering the high prevalence and the lack of targeted pharmacological management of acute kidney injury (AKI), the search for new therapeutic approaches for it is in urgent demand. Mesenchymal stem cells (MSCs) have been increasingly recognized as a promising candidate for the treatment of AKI. However, clinical translation of MSCs-based therapies is hindered due to the poor retention and survival rates as well as the impaired paracrine ability of MSCs post-delivery. To address these issues, a series of strategies including local administration, three-dimensional culture, and preconditioning have been applied. Owing to the emergence and development of these novel biotechnologies, the effectiveness of MSCs in experimental AKI models is greatly improved. Here, we summarize the different approaches suggested to optimize the efficacy of MSCs therapy, aiming at promoting the therapeutic effects of MSCs on AKI patients.

Application of Biomedical Microspheres in Wound Healing

Tissue injury, one of the most common traumatic injuries in daily life, easily leads to secondary wound infections. To promote wound healing and reduce scarring, various kinds of wound dressings, such as gauze, bandages, sponges, patches, and microspheres, have been developed for wound healing. Among them, microsphere-based tissue dressings have attracted increasing attention due to the advantage of easy to fabricate, excellent physicochemical performance and superior drug release ability. In this review, we first introduced the common methods for microspheres preparation, such as emulsification-solvent method, electrospray method, microfluidic technology as well as phase separation methods. Next, we summarized the common biomaterials for the fabrication of the microspheres including natural polymers and synthetic polymers. Then, we presented the application of the various microspheres from different processing methods in wound healing and other applications. Finally, we analyzed the limitations and discussed the future development direction of microspheres in the future.

k-Carrageenan/sericin-based multiparticulate systems: A novel gastro-resistant polymer matrix for indomethacin delivery

This study aimed to develop a natural and multiparticulate carrier of k-carrageenan (k-Car) and sericin (Ser) for encapsulation of indomethacin (IND) in order to minimize gastrointestinal effects caused by immediate-release. Increasing the amount of IND in the formulations subtly reduced the entrapment efficiency (EE) and drug loading (DL) due to matrix saturation. Sericin was essential to improve EE and DL when compared to pure k-Car (EE > 90 % and DL > 47 %) with suitable particle sizes (1.3461 ± 0.1891-1.7213 ± 0.1586 mm). The incorporation and integrity of IND in the particles were confirmed by analytical techniques of HPLC, XRD, FTIR, and SEM. Additionally, the k-Car/Ser matrix was pH-responsive with low IND release at pH 1.2 and extended-release at pH 6.8. The Weibull model had an adequate fit to the experimental data with R²aju 0.950.99 and AIC 82.4-24.9, with curves in parabolic profile (b < 1) and indicative of a controlled drug-release mechanism by diffusion. Besides, k-Car/Ser/IND and placebo were not cytotoxic (cell viability > 85 % at 150-600 μM) for the Caco-2 cell line. Therefore, the polymeric matrix is gastro-resistant, stable, and biocompatible to carry indomethacin and deliver it to the intestinal environment.

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Recent progressions in biomedical and pharmaceutical applications of chitosan nanoparticles: A comprehensive review

Nowadays, the most common approaches in the prognosis, diagnosis, and treatment of diseases are along with undeniable limitations. Thus, the ever-increasing need for using biocompatible natural materials and novel practical modalities is required. Applying biomaterials, such as chitosan nanoparticles (CS NPs: FDA-approved long-chain polymer of N-acetyl-glucosamine and D-glucosamine for some pharmaceutical applications), can serve as an appropriate alternative to overcome these limitations. Recently, the biomedical applications of CS NPs have extensively been investigated. These NPs and their derivatives can not only prepare through different physical and chemical approaches but also modify with various molecules and bioactive materials. The potential properties of CS NPs, such as biocompatibility, biodegradability, serum stability, solubility, non-immunogenicity, anti-inflammatory properties, appropriate pharmacokinetics and pharmacodynamics, and so forth, have made them excellent candidates for biomedical applications. Therefore, CS NPs have efficiently applied for various biomedical applications, like regenerative medicine and tissue engineering, biosensors for the detection of microorganisms, and drug delivery systems (DDS) for the suppression of diseases. These NPs possess a high level of biosafety. In summary, CS NPs have the potential ability for biomedical and clinical applications, and it would be remarkably beneficial to develop new generations of CS-based material for the future of medicine.