Alginate-Based Bio-Composites and Their Potential Applications

Diverse Approaches in Wet-Spun Alginate Filament Production from the Textile Industry Perspective: From Process Optimization to Composite Filament Production

Alginate, categorized as a natural-based biodegradable polymer, stands out for its inherently exclusive properties. Although this unique polymer is widely processed using film, coating, and membrane technologies for different usage areas, textile applications are still limited. This study aims to compile promising approaches that will pave the way for the use of wet-spun alginate filaments in textile applications. In this regard, this study provides information about the molecular structure of alginate, the gel formation mechanism, and cross-linking using different techniques. Our literature review categorizes parameters affecting the mechanical properties of wet-spun alginate filaments, such as the effect of ion source and spinning dope concentration, needle diameter, temperature, and coagulants. Following this, a detailed and comprehensive literature review of the various approaches, such as use of additives, preparation of blended filaments, and grafted nanocrystal addition, developed by researchers to produce composite alginate filaments is presented. Additionally, studies concerning the use of different cations in the coagulation phase are reported. Moreover, studies about the functionalism of wet-spun alginate filaments have been offered.

Hydrogels in Cutaneous Wound Healing: Insights into Characterization, Properties, Formulation and Therapeutic Potential

Hydrogels are polymeric materials that possess a set of characteristics meeting various requirements of an ideal wound dressing, making them promising for wound care. These features include, among others, the ability to absorb and retain large amounts of water and the capacity to closely mimic native structures, such as the extracellular matrix, facilitating various cellular processes like proliferation and differentiation. The polymers used in hydrogel formulations exhibit a broad spectrum of properties, allowing them to be classified into two main categories: natural polymers like collagen and chitosan, and synthetic polymers such as polyurethane and polyethylene glycol. This review offers a comprehensive overview and critical analysis of the key polymers that can constitute hydrogels, beginning with a brief contextualization of the polymers. It delves into their function, origin, and chemical structure, highlighting key sources of extraction and obtaining. Additionally, this review encompasses the main intrinsic properties of these polymers and their roles in the wound healing process, accompanied, whenever available, by explanations of the underlying mechanisms of action. It also addresses limitations and describes some studies on the effectiveness of isolated polymers in promoting skin regeneration and wound healing. Subsequently, we briefly discuss some application strategies of hydrogels derived from their intrinsic potential to promote the wound healing process. This can be achieved due to their role in the stimulation of angiogenesis, for example, or through the incorporation of substances like growth factors or drugs, such as antimicrobials, imparting new properties to the hydrogels. In addition to substance incorporation, the potential of hydrogels is also related to their ability to serve as a three-dimensional matrix for cell culture, whether it involves loading cells into the hydrogel or recruiting cells to the wound site, where they proliferate on the scaffold to form new tissue. The latter strategy presupposes the incorporation of biosensors into the hydrogel for real-time monitoring of wound conditions, such as temperature and pH. Future prospects are then ultimately addressed. As far as we are aware, this manuscript represents the first comprehensive approach that brings together and critically analyzes fundamental aspects of both natural and synthetic polymers constituting hydrogels in the context of cutaneous wound healing. It will serve as a foundational point for future studies, aiming to contribute to the development of an effective and environmentally friendly dressing for wounds.

Photochromic biomaterials: Synthesis and fluorescence properties of spiroxanthenes-grafted alginate derivatives

Herein, we reported a general and green synthetic strategy for photochromic functional alginate derivatives grafting with isoindolinone spiroxanthenes. Under mild condition, diverse 2-aminoalkyl isoindolinone spiroxanthene derivatives have been prepared from organic photochromic isobenzofuranone spiroxanthenes (including rhodamine B, rhodamine 6G and fluorescein), and grafted on alginate chains through amidation reaction using diamine as a linkage with water as a green solvent at room temperature. The photochromic properties of the fluorophores-modified polymers and the effect of pH value have been explored. Under acid conditions, the spiroisoindolinone rings of alginate derivatives are opened resulting in showing absorption bands and fluorescence with orange to green emission, while the alginate derivatives turned to colourless under basic conditions which is reversibly. In addition to biodegradability and biocompatibility, the polymers exhibit good film-forming properties simultaneously. The films and fibers produced from the alginate derivatives also project good fluorescence properties.

Blood Coagulation Activities of Cotton-Alginate-Copper Composites

Alginate-based materials have gained significant attention in the medical industry due to their biochemical properties. In this article, we aimed to synthesize Cotton-Alginate-Copper Composite Materials (COT-Alg(-)Cu(2+)). The main purpose of this study was to assess the biochemical properties of new composites in the area of blood plasma coagulation processes, including activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). This study also involved in vitro antimicrobial activity evaluation of materials against representative colonies of Gram-positive and Gram-negative bacteria and antifungal susceptibility tests. The materials were prepared by immersing cotton fibers in an aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the fibers with Cu(II) ions to yield antimicrobial activity. The results showed that the obtained cotton-alginate-copper composites were promising materials to be used in biomedical applications, e.g., wound dressing.

Antioxidant, Anti-Inflammatory Effects and Ability to Stimulate Wound Healing of a Common-Plantain Extract in Alginate Gel Formulations

Our study aimed to investigate the biological effects of a common-plantain (Plantago major L.) extract, encapsulated in alginate, on dermal human fibroblast cultures in vitro, in view of its potential use as a wound healing adjuvant therapy. Common-plantain extracts were obtained by infusion and ultrasound extraction, and their total polyphenolic content and antioxidant capacity were determined by spectrophotometry. The best extract, which was obtained by infusion, was further encapsulated in sodium alginate in two different formulations. Fourier Transform Infrared Spectroscopy (FTIR) was used to demonstrate the existing interactions in the obtained common-plantain extract in the alginate formulations. The encapsulation efficiency was evaluated based on the total polyphenol content. These alginate gel formulations were further used in vitro to determine their biocompatibility and antioxidant and anti-inflammatory effects by spectrophotometry and ELISA, as well as their ability to stimulate fibroblast migration (scratch test assay) at different time points. In addition, the collagen 1 and 3 levels were determined by Western blot analysis. The data showed that the microencapsulated plantain extract formulations induced an antioxidant, anti-inflammatory effect, enhanced collagen production and increased wound closure in the first 8 h of their application. These results are encouraging for the use of this alginate plantain extract formulation as an adjuvant for skin wound healing.

Material matters: exploring the interplay between natural biomaterials and host immune system

Biomaterials are widely used for various medical purposes, for instance, implants, tissue engineering, medical devices, and drug delivery systems. Natural biomaterials can be obtained from proteins, carbohydrates, and cell-specific sources. However, when these biomaterials are introduced into the body, they trigger an immune response which may lead to rejection and failure of the implanted device or tissue. The immune system recognizes natural biomaterials as foreign substances and triggers the activation of several immune cells, for instance, macrophages, dendritic cells, and T cells. These cells release pro-inflammatory cytokines and chemokines, which recruit other immune cells to the implantation site. The activation of the immune system can lead to an inflammatory response, which can be beneficial or detrimental, depending on the type of natural biomaterial and the extent of the immune response. These biomaterials can also influence the immune response by modulating the behavior of immune cells. For example, biomaterials with specific surface properties, such as charge and hydrophobicity, can affect the activation and differentiation of immune cells. Additionally, biomaterials can be engineered to release immunomodulatory factors, such as anti-inflammatory cytokines, to promote a tolerogenic immune response. In conclusion, the interaction between biomaterials and the body's immune system is an intricate procedure with potential consequences for the effectiveness of therapeutics and medical devices. A better understanding of this interplay can help to design biomaterials that promote favorable immune responses and minimize adverse reactions.

Effect of Polydopamine and Curcumin on Physicochemical and Mechanical Properties of Polymeric Blends

In this study, we prepared composites made from polyvinyl alcohol (PVA), sodium alginate (SA), curcumin (Cur), and polydopamine (PD). The film-forming properties of the composites were researched for potential wound-healing applications. The structures of the polymer blends and composites were studied by FTIR spectroscopy and microscopic observations (AFM and SEM). The mechanical properties were measured using a Zwick Roell testing machine. It was observed that the formation of a polymeric film based on the blend of polyvinyl alcohol and sodium alginate led to the generation of pores. The presence of curcumin in the composite resulted in the alteration of the blend properties. After solvent evaporation, the polymeric blend of PVA, SA, and curcumin formed a stable polymeric film, but the film showed poor mechanical properties. The addition of polydopamine led to an improvement in the mechanical strength of the film and an increase in its surface roughness. A polymeric film of sodium alginate presented the highest surface roughness value among all the studied specimens (66.6 nm), whereas polyvinyl alcohol showed the lowest value (1.60 nm). The roughness of the composites made of PVA/SA/Cur and PVA/SA/Cur/PD showed a value of about 25 nm. Sodium alginate showed the highest values of Young's modulus (4.10 GPa), stress (32.73 N), and tensile strength (98.48 MPa). The addition of PD to PVA/SA/Cur led to an improvement in the mechanical properties. Improved mechanical properties and appropriate surface roughness may suggest that prepared blends can be used for the preparation of wound-healing materials.

A Critical Review on Classified Excipient Sodium-Alginate-Based Hydrogels: Modification, Characterization, and Application in Soft Tissue Engineering

Alginates are polysaccharides that are produced naturally and can be isolated from brown sea algae and bacteria. Sodium alginate (SA) is utilized extensively in the field of biological soft tissue repair and regeneration owing to its low cost, high biological compatibility, and quick and moderate crosslinking. In addition to their high printability, SA hydrogels have found growing popularity in tissue engineering, particularly due to the advent of 3D bioprinting. There is a developing curiosity in tissue engineering with SA-based composite hydrogels and their potential for further improvement in terms of material modification, the molding process, and their application. This has resulted in numerous productive outcomes. The use of 3D scaffolds for growing cells and tissues in tissue engineering and 3D cell culture is an innovative technique for developing in vitro culture models that mimic the in vivo environment. Especially compared to in vivo models, in vitro models were more ethical and cost-effective, and they stimulate tissue growth. This article discusses the use of sodium alginate (SA) in tissue engineering, focusing on SA modification techniques and providing a comparative examination of the properties of several SA-based hydrogels. This review also covers hydrogel preparation techniques, and a catalogue of patents covering different hydrogel formulations is also discussed. Finally, SA-based hydrogel applications and future research areas concerning SA-based hydrogels in tissue engineering were examined.

The Antibacterial Activities and Characterizations of Biosynthesized Zinc Oxide Nanoparticles, and Their Coated with Alginate Derived from Fucus vesiculosus

Zinc oxide nanoparticles have many advantages for nano-biotechnologists due to their intense biomedical applications. ZnO-NPs are used as antibacterial agents, which influence bacterial cells through the rupture of the cell membrane and the generation of reactive free radicals. Alginate is a polysaccharide of natural origin due to its excellent properties that are used in various biomedical applications. Brown algae are good sources of alginate and are used as a reducing agent in the synthesis of nanoparticles. This study aims to synthesize ZnO-NPs by using brown alga Fucus vesiculosus (Fu/ZnO-NPs) and also to extract alginate from the same alga, which is used in coating the ZnO-NPs (Fu/ZnO-Alg-NCMs). The characterizations of Fu/ZnO-NPs and Fu/ZnO-Alg-NCMs were determined by FTIR, TEM, XRD, and zeta potential. The antibacterial activities were applied against multidrug resistance bacteria of both gram-positive and negative. The results obtained in FT-TR showed there are some shifts in the peak positions of Fu/ZnO-NPs and Fu/ZnO-Alg-NCMs. The peak at 1655 cm^-1, which assigned amide I-III, is present in both Fu/ZnO-NPs and Fu-Alg-ZnO-NCMs; this band is responsible for bio-reductions and stabilization of both nanoparticles. The TEM images proved the Fu/ZnO-NPs have rod shapes with sizes ranging from 12.68 to 17.66 and are aggregated, but Fu/ZnO/Alg-NCMs are spherical in shape with sizes ranging from 12.13 to 19.77. XRD-cleared Fu/ZnO-NPs have nine sharp peaks that are considered good crystalline, but Fu/ZnO-Alg-NCMs have four broad and sharp peaks that are considered semi-crystalline. Both Fu/ZnO-NPs and Fu/ZnO-Alg-NCMs have negative charges (-1.74 and -3.56, respectively). Fu/ZnO-NPs have more antibacterial activities than Fu/ZnO/Alg-NCMs in all tested multidrug-resistant bacterial strains. Fu/ZnO/Alg-NCMs had no effect on Acinetobacter KY856930, Staphylococcus epidermidis, and Enterobacter aerogenes, whereas there was an apparent effect of ZnO-NPs against the same strains.

Alginate-Based Biomaterials in Tissue Engineering and Regenerative Medicine

Today, with the salient advancements of modern and smart technologies related to tissue engineering and regenerative medicine (TE-RM), the use of sustainable and biodegradable materials with biocompatibility and cost-effective advantages have been investigated more than before. Alginate as a naturally occurring anionic polymer can be obtained from brown seaweed to develop a wide variety of composites for TE, drug delivery, wound healing, and cancer therapy. This sustainable and renewable biomaterial displays several fascinating properties such as high biocompatibility, low toxicity, cost-effectiveness, and mild gelation by inserting divalent cations (e.g., Ca2+). In this context, challenges still exist in relation to the low solubility and high viscosity of high-molecular weight alginate, high density of intra- and inter-molecular hydrogen bonding, polyelectrolyte nature of the aqueous solution, and a lack of suitable organic solvents. Herein, TE-RM applications of alginate-based materials are deliberated, focusing on current trends, important challenges, and future prospects.

Alginate Ag/AgCl Nanoparticles Composite Films for Wound Dressings with Antibiofilm and Antimicrobial Activities

Recently, silver-based nanoparticles have been proposed as components of wound dressings due to their antimicrobial activity. Unfortunately, they are cytotoxic for keratinocytes and fibroblasts, and this limits their use. Less consideration has been given to the use of AgCl nanoparticles in wound dressings. In this paper, a sustainable preparation of alginate AgCl nanoparticles composite films by simultaneous alginate gelation and AgCl nanoparticle formation in the presence of CaCl₂ solution is proposed with the aim of obtaining films with antimicrobial and antibiofilm activities and low cytotoxicity. First, AgNO₃ alginate films were prepared, and then, gelation and nanoparticle formation were induced by film immersion in CaCl₂ solution. Films characterization revealed the presence of both AgCl and metallic silver nanoparticles, which resulted as quite homogeneously distributed, and good hydration properties. Finally, films were tested for their antimicrobial and antibiofilm activities against Staphylococcus epidermidis (ATCC 12228), Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 15692), and the yeast Candida albicans. Composite films showed antibacterial and antibiofilm activities against the tested bacteria and resulted as less active towards Candida albicans. Film cytotoxicity was investigated towards human dermis fibroblasts (HuDe) and human skin keratinocytes (NCTC2544). Composite films showed low cytotoxicity, especially towards fibroblasts. Thus, the proposed sustainable approach allows to obtain composite films of Ag/AgCl alginate nanoparticles capable of preventing the onset of infections without showing high cytotoxicity for tissue cells.

Ultrasound-assisted extraction of alginic acid from Sargassum angustifolium harvested from Persian Gulf shores using response surface methodology

In this study, the extraction and characterization of alginic acid, the most abundant compound among brown algae were investigated. The used algae were Sargassum angustifolium from the family of brown algae native to the coasts of the Persian Gulf. The effect of temperature, time, algae mass to solvent volume ratio, and ultrasonic power on the extraction yield and ratio of monomers (M/G) was investigated using the central composite design method. Moreover, the effect of the mentioned parameters on the poly dispersity index and cytotoxic effects against breast cancer cells were also investigated. The maximum obtained extraction yield was 46 %, which was higher than those reported for algae in tropical climates. This shows the effectiveness of ultrasound in facilitating the extraction process. In addition, the minimum monomer ratio was 0.45, the minimum poly dispersity index was 2.5 and the maximum cytotoxicity for using the extract on breast cancer cell line (MCF-7) was 20.3 % (with alginic acid concentration of 250 micrograms per milliliter).

Progress of Electrospun Nanofibrous Carriers for Modifications to Drug Release Profiles

Electrospinning is an advanced technology for the preparation of drug-carrying nanofibers that has demonstrated great advantages in the biomedical field. Electrospun nanofiber membranes are widely used in the field of drug administration due to their advantages such as their large specific surface area and similarity to the extracellular matrix. Different electrospinning technologies can be used to prepare nanofibers of different structures, such as those with a monolithic structure, a core-shell structure, a Janus structure, or a porous structure. It is also possible to prepare nanofibers with different controlled-release functions, such as sustained release, delayed release, biphasic release, and targeted release. This paper elaborates on the preparation of drug-loaded nanofibers using various electrospinning technologies and concludes the mechanisms behind the controlled release of drugs.