Agarose/κ-carrageenan-based hydrogel film enriched with natural plant extracts for the treatment of cutaneous wounds

Advances in agar-based composites: A comprehensive review

This review article explores the developments and applications in agar-based composites (ABCs), emphasizing various constituents such as metals, clay/ceramic, graphene, and polymers across diversified fields like wastewater treatment, drug delivery, food packaging, the energy sector, biomedical engineering, bioplastics, agriculture, and cosmetics. The focus is on agar as a sustainable and versatile biodegradable polysaccharide, highlighting research that has advanced the technology of ABCs. A bibliometric analysis is conducted using the Web of Science database, covering publications from January 2020 to March 2024, processed through VOSviewer Software Version 1.6.2. This analysis assesses evolving trends and scopes in the literature, visualizing co-words and themes that underscore the growing importance and potential of ABCs in various applications. This review paper contributes by showcasing the existing state-of-the-art knowledge and motivating further development in this promising field.

Developmental prospects of carrageenan-based wound dressing films: Unveiling techno-functional properties and freeze-drying technology for the development of absorbent films - A review

This review explores the intricate wound healing process, emphasizing the critical role of dressing material selection, particularly for chronic wounds with high exudate levels. The aim is to tailor biodegradable dressings for comprehensive healing, focusing on maximizing moisture retention, a vital element for adequate recovery. Researchers are designing advanced wound dressings that enhance techno-functional and bioactive properties, minimizing healing time and ensuring cost-effective care. The study delves into wound dressing materials, highlighting carrageenan biocomposites superior attributes and potential in advancing wound care. Carrageenan's versatility in various biomedical applications demonstrates its potential for tissue repair, bone regeneration, and drug delivery. Ongoing research explores synergistic effects by combining carrageenan with other novel materials, aiming for complete biocompatibility. As innovative solutions emerge, carrageenan-based wound-healing medical devices are poised for global accessibility, addressing challenges associated with the complex wound-healing process. The exceptional physico-mechanical properties of carrageenan make it well-suited for highly exudating wounds, offering a promising avenue to revolutionize wound care through freeze-drying techniques. This thorough approach to evaluating the wound healing effectiveness of carrageenan-based films, particularly emphasizing the development potential of lyophilized films, has the potential to significantly improve the quality of life for patients receiving wound healing treatments.

Highly Compressible, Superabsorbent, and Biocompatible Hybrid Cryogel Constructs Comprising Functionalized Chitosan and St. John's Wort Extract

Biobased porous hydrogels enriched with phytocompounds-rich herbal extracts have aroused great interest in recent years, especially in healthcare. In this study, new macroporous hybrid cryogel constructs comprising thiourea-containing chitosan (CSTU) derivative and a Hypericum perforatum L. extract (HYPE), commonly known as St John's wort, were prepared by a facile one-pot ice-templating strategy. Benefiting from the strong interactions between the functional groups of the CSTU matrix and those of polyphenols in HYPE, the hybrid cryogels possess excellent liquid absorption capacity, mechanical resilience, antioxidant performance, and a broad spectrum of antibacterial activity simultaneously. Thus, owing to their design, the hybrid constructs exhibit an interconnected porous architecture with the ability to absorb over 33 and 136 times their dry weight, respectively, when contacted with a phosphate buffer solution (pH 7.4) and an acidic aqueous solution (pH 2). These cryogel constructs have extremely high compressive strengths ranging from 839 to 1045 kPa and withstand elevated strains of over 70% without developing fractures. Moreover, the water-swollen hybrid cryogels with the highest HYPE content revealed a complete and instant shape recovery after uniaxial compression. The incorporation of HYPE into CSTU cryogels enabled substantial improvement in scavenging reactive oxygen species and an expanded antibacterial spectrum toward multiple pathogens, including Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungi (Candida albicans). Cell viability experiments demonstrated the cytocompatibility of the 3D cryogel constructs, which did not induce changes in the fibroblast morphology. This work showcases a simple and effective strategy to immobilize HYPE extracts on CSTU 3D networks, allowing the development of novel multifunctional platforms with promising potential in hemostasis, wound dressing, and dermal regeneration scaffolds.

Exploring carrageenan: From seaweed to biomedicine-A comprehensive review

Biomaterials are pivotal in the realms of tissue engineering, regenerative medicine, and drug delivery and serve as fundamental building blocks. Within this dynamic landscape, polymeric biomaterials emerge as the frontrunners, offering unparalleled versatility across physical, chemical, and biological domains. Natural polymers, in particular, captivate attention for their inherent bioactivity. Among these, carrageenan (CRG), extracted from red seaweeds, stands out as a naturally occurring polysaccharide with immense potential in various biomedical applications. CRG boasts a unique array of properties, encompassing antiviral, antibacterial, immunomodulatory, antihyperlipidemic, antioxidant, and antitumor attributes, positioning it as an attractive choice for cutting-edge research in drug delivery, wound healing, and tissue regeneration. This comprehensive review encapsulates the multifaceted properties of CRG, shedding light on the chemical modifications that it undergoes. Additionally, it spotlights pioneering research that harnesses the potential of CRG to craft scaffolds and drug delivery systems, offering high efficacy in the realms of tissue repair and disease intervention. In essence, this review celebrates the remarkable versatility of CRG and its transformative role in advancing biomedical solutions.

Hydrothermal processing of Sarcopeltis skottsbergii and study of the potential of its carrageenan for tissue engineering

The red macroalga Sarcopeltis skottsbergii was subjected to hydrothermal processing to maximize the solubilization and recovery of carrageenan. Once isolated by ethanol precipitation, the carrageenan was further chemically (oligosaccharides composition), and structurally (TGA/DTG, DSC, HPSEC, FTIR-ATR, 1H NMR, SEM, etc.) characterized, as well as employed as source for the synthesis of hydrogels. The rheological properties of the carrageenan showed promising results as biopolymer for food applications due to the high molecular weight (500 kDa) presenting higher cell viability than 70 %. The evaluation of immune activation using ELISA test reflected a lower inflammatory response for concentrations of 0.025 % of carrageenan. Conversely, the cell viability of the synthesized hydrogels did not surpass 50 %. This work represents a considerable step forward to obtain a biopolymer from natural sources and a thorough study of their chemical, structural and biological properties.

Immunomodulatory zymosan/ι-carrageenan/ agarose hydrogel for targeting M2 to M1 macrophages (antitumoral)

Several studies have been performed on the immunomodulatory effects of yeast β-(1,3) glucan, but there is no proper evaluation of the thermal and immunomodulating properties of zymosan (ZM). Thermogravimetry analysis indicated a 54% weight loss of ZM at 270 °C. Circular dichroism showed absorption peaks in the region of 250 to 400 nm, suggesting a helical coil β-sheet configuration. XRD showed a broad peak at 2θ of 20.38°, indicating the crystalline nature, and the size was found to be 23 nm. ZM is biocompatible and showed no toxicity against L929 and RAW 264.7 cell lines (cell viability > 90%). Immunomodulatory studies with PCR showed upregulation of M1 genes in human differentiated THP-1 macrophage cell lines, which were responsible for antitumor properties. The uptake of ZM particles inside the differentiated THP-1 macrophages and Raw 264.7 cells was confirmed (Video clip). ZM particle uptake via Dectin-1 was identified by competitive receptor blocking. Seaweed derived carrageenan/ZM/agarose hydrogel was successfully prepared (@5 : 5 wt%) and was seen to support the growth of L929 cells (1 × 105 cells per mL) and have a higher swelling (≈250-280%). This study indicates that ZM-based hydrogel could be a potential drug carrier (Rifampicin and Levofloxacin) for targeting tumour-associated macrophages (M2).

Bringing innovative wound care polymer materials to the market: Challenges, developments, and new trends

The development of innovative products for treating acute and chronic wounds has become a significant topic in healthcare, resulting in numerous products and innovations over time. The growing number of patients with comorbidities and chronic diseases, which may significantly alter, delay, or inhibit normal wound healing, has introduced considerable new challenges into the wound management scenario. Researchers in academia have quickly identified promising solutions, and many advanced wound healing materials have recently been designed; however, their successful translation to the market remains highly complex and unlikely without the contribution of industry experts. This review article condenses the main aspects of wound healing applications that will serve as a practical guide for researchers working in academia and industry devoted to designing, evaluating, validating, and translating polymer wound care materials to the market. The article highlights the current challenges in wound management, describes the state-of-the-art products already on the market and trending polymer materials, describes the regulation pathways for approval, discusses current wound healing models, and offers a perspective on new technologies that could soon reach consumers. We envision that this comprehensive review will significantly contribute to highlighting the importance of networking and exchanges between academia and healthcare companies. Only through the joint of these two actors, where innovation, manufacturing, regulatory insights, and financial resources act in harmony, can wound care products be developed efficiently to reach patients quickly and affordably.

Marine polysaccharides, proteins, lipids, and silica for drug delivery systems: A review

Marine environments represent an incredible source of biopolymers with potential biomedical applications. Recently, drug delivery studies have received great attention for the increasing need to improve site specificity, therapeutic value, and bioavailability, reducing off-target effects. Marine polymers, such as alginate, carrageenan, collagen, chitosan, and silica, have reported unique biochemical features, allowing an efficient binding with drugs, and a controlled release to the target tissue, also obtainable through "green processes". In the present review, we i) analysed the last ten years of scientific peer-reviewed literature; ii) divided the articles based on the achieved experimental phases, tagged as chemistry, drug release, and drug delivery, and iii) compared the best performances among marine polymers extracted from micro- and macro-organisms. Many reviews describe drug carriers from marine organisms, focusing on a single biopolymer or a chemical class. Our study is a groundbreaking literature collection, representing the first thorough investigation of all marine biopolymers described. Most articles report experimental results on the chemical characterisation of marine biopolymers and their in vitro behaviour as drug carriers, although development processes and commercial applications are still in the early stages. Hence, the next efforts should be focused on the sustainable production of marine polymers and final product development.

Polysaccharide based transdermal patches for chronic wound healing: Recent advances and clinical perspective

Polysaccharides form a major class of natural polymers with diverse applications in biomedical science and tissue engineering. One of the key thrust areas for polysaccharide materials is skin tissue engineering and regeneration, whose market is estimated to reach around 31 billion USD globally by 2030, with a compounded annual growth rate of 10.46 %. Out of this, chronic wound healing and management is a major concern, especially for underdeveloped and developing nations, mainly due to poor access to medical interventions for such societies. Polysaccharide materials have shown promising results and clinical potential in recent decades with regard to chronic wound healing. Their low cost, ease of fabrication, biodegradability, and ability to form hydrogels make them ideal candidates for managing and healing such difficult-to-heal wounds. The present review presents a summary of the recently explored polysaccharide-based transdermal patches for managing and healing chronic wounds. Their efficacy and potency of healing both as active and passive wound dressings are evaluated in several in-vitro and in-vivo models. Finally, their clinical performances and future challenges are summarized to draw a road map towards their role in advanced wound care.

Research progress of colon-targeted oral hydrogel system based on natural polysaccharides

The quality of life is significantly impacted by colon-related diseases. There have been a lot of interest in the oral colon-specific drug delivery system (OCDDS) as a potential carrier to decrease systemic side effects and protect drugs from degradation in the upper gastrointestinal tract (GIT). Hydrogels are effective oral colon-targeted drug delivery carriers due to their high biodegradability, substantial drug loading, and great biocompatibility. Natural polysaccharides give the hydrogel system unique structure and function to effectively respond to the complex environment of the GIT and deliver drugs to the colon. In this paper, the physiological factors of colonic drug delivery and the pathological characteristics of common colonic diseases are summarized, and the latest advances in the design, preparation and characterization of natural polysaccharide hydrogels are reviewed, which are expected to provide new references for colon-targeted oral hydrogel systems using natural polysaccharides as raw materials.

Pullulan/Poly(vinyl alcohol) Hydrogels Loaded with Calendula officinalis Extract: Design and In Vitro Evaluation for Wound Healing Applications

The therapeutic efficiency of plant extracts has been limited by their poor pharmaceutical availability. Hydrogels have promising potential to be applied as wound dressings due to their high capacity to absorb exudates and their enhanced performance in loading and releasing plant extracts. In this work, pullulan/poly (vinyl alcohol) (P/PVA) hydrogels were first prepared using an eco-friendly method based on both a covalent and physical cross-linking approach. Then, the hydrogels were loaded with the hydroalcoholic extract of Calendula officinalis by a simple post-loading immersion method. Different loading capacities were investigated in terms of the physico-chemical properties, chemical composition, mechanical properties, and water absorption. The hydrogels exhibited high loading efficiency due to the hydrogen bonding interactions between polymer and extract. The water retention capacity as well as the mechanical properties decreased with the increase in the extract amount in hydrogel. However, higher amounts of extract in the hydrogel improved the bioadhesiveness. The release of extract from hydrogels was controlled by the Fickian diffusion mechanism. Extract-loaded hydrogels expressed high antioxidant activity, reaching 70% DPPH radical scavenging after 15 min immersion in buffer solution at pH 5.5. Additionally, loaded hydrogels showed a high antibacterial activity against Gram-positive and Gram-negative bacteria and were non-cytotoxic against HDFa cells.

κ-Carrageenan-essential oil loaded composite biomaterial film facilitates mechanosensing and tissue regenerative wound healing

Polysaccharides κ-carrageenan (κ-Car) have become a predominant source in developing bioactive materials. We aimed to develop biopolymer composite materials of κ-Car with coriander essential oil (CEO) (κ-Car-CEO) films for fibroblast-associated wound healing. Initially, we loaded the CEO in to κ-Car and CEO through homogenization and ultrasonication to fabricate composite film bioactive materials. After performing morphological and chemical characterizations, we validated the developed material functionalities in both in vitro and in vivo models. The chemical and morphological analysis with physical structure, swelling ratio, encapsulation efficiency, CEO release, and water barrier properties of films examined and showed the structural interaction of κ-Car and CEO-loaded into the polymer network. Furthermore, the bioactive applications of CEO release showed initial burst release followed by controlled release from the κ-Car composite film with fibroblast (L929) cell adhesive capabilities and mechanosensing. Our results proved that the CEO-loaded into the κ-Car film impacts cell adhesion, F-actin organization, and collagen synthesis, followed by in vitro mechanosensing activation, further promoting wound healing in vivo. Our innovative perspectives of active polysaccharide (κ-Car)-based CEO functional film materials could potentially accomplish regenerative medicine.

New Hydrogels Based on Agarose/Phytagel and Peptides

Short aromatic peptide derivatives, i.e., peptides or amino acids modified with aromatic groups, such as 9-fluorenylmethoxycarbonyl (Fmoc), can self-assemble into extracellular matrix-like hydrogels due to their nanofibrillar architecture. Among different types of amino acids, lysine (Lys) and glycine (Gly) are involved in multiple physiological processes, being key factors in the proper growth of cells, carnitine production, and collagen formation. The authors have previously successfully presented the possibility of obtaining supramolecular gels based on Fmoc-Lys-Fmoc and short peptides such as Fmoc-Gly-Gly-Gly in order to use them as a substrate for cell cultures. This paper investigates how the introduction of a gelling polymer can influence the properties of the network as well as the compatibility of the resulting materials with different cell types. A series of hydrogel compositions consisting of combinations of Fmoc-Lys-Fmoc and Fmoc-Gly-Gly-Gly with Agarose and Phytagel are thus obtained. All compositions form structured gels as shown by rheological studies and scanning electron microscopy. Fourier transform infrared spectroscopy analysis evidences the formation of H-bonds between the polysaccharides and amino acids or short peptides. Moreover, all gels exhibit good cell viability on fibroblasts as demonstrated by a live-dead staining test and good in vivo biocompatibility, which highlights the great potential of these biomaterials for biomedical applications.

Designing Deferoxamine-Loaded Flaxseed Gum and Carrageenan-Based Controlled Release Biocomposite Hydrogel Films for Wound Healing

In this study, biocomposite hydrogel films made from flaxseed gum (FSG)/kappa carrageenan (CGN) were fabricated, using potassium chloride as a crosslinker and glycerol as a plasticizer. The composite films were loaded with deferoxamine (DFX), an iron chelator that promotes neovascularization and angiogenesis for the healing of wounds. The properties of the biocomposite hydrogel films, including swelling, solubility, water vapor transmission rate, tensile strength, elongation at break, and Young’s modulus studies, were tested. The films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). In addition, drug release studies in PBS at pH 7.2 were investigated. In vivo analysis was performed by assessing the wound contraction in a full-thickness excisional wound rat model. Hematoxylin & eosin (H & E) and Masson’s trichome staining were performed to evaluate the effect of the films on wound healing progress. The visual and micro-morphological analysis revealed the homogenous structure of the films; however, the elongation at break property decreased within the crosslinked film but increased for the drug-loaded film. The FTIR analysis confirmed the crosslinking due to potassium chloride. A superior resistance towards thermal degradation was confirmed by TGA for the crosslinked and drug-loaded films. Drug release from the optimum film was sustained for up to 24 h. In vivo testing demonstrated 100% wound contraction for the drug-loaded film group compared to 72% for the pure drug solution group. In light of the obtained results, the higher potential of the optimized biocomposite hydrogel film for wound healing applications was corroborated.

Biocompatible and antibacterial Flammulina velutipes-based natural hybrid cryogel to treat noncompressible hemorrhages and skin defects

Hemorrhage, infection, and frequent replacement of dressings bring great clinical challenges to wound healing. In this work, Flammulina velutipes extract (FV) and hydroxyethyl cellulose (HEC) were chemically cross-linked and freeze-dried to obtain novel HFV cryogels (named HFVn, with n = 10, 40, or 70 corresponding to the weight percentage of the FV content), which were constructed for wound hemostasis and full-thickness skin defect repair. Systematic characterization experiments were performed to assess the morphology, mechanical properties, hydrophilic properties, and degradation rate of the cryogels. The results indicated that HFV70 showed a loose interconnected-porous structure and exhibited the highest porosity (95%) and water uptake ratio (over 2,500%) with a desirable degradation rate and shape memory properties. In vitro cell culture and hemocompatibility experiments indicated that HFV70 showed improved cytocompatibility and hemocompatibility. It can effectively mimic the extracellular matrix microenvironment and support the adhesion and proliferation of L929 cells, and its hemolysis rate in vitro was less than 5%. Moreover, HFV70 effectively induced tube formation in HUVEC cells in vitro. The results of the bacteriostatic annulus confirmed that HFV70 significantly inhibited the growth of Gram-negative E. coli and Gram-positive S. aureus. In addition, HFV70 showed ideal antioxidant properties, with the DPPH scavenging rate in vitro reaching 74.55%. In vivo rat liver hemostasis experiments confirmed that HFV70 showed rapid and effective hemostasis, with effects comparable to those of commercial gelatin sponges. Furthermore, when applied to the repair of full-thickness skin defects in a rat model, HFV70 significantly promoted tissue regeneration. Histological analysis further confirmed the improved pro-angiogenic and anti-inflammatory activity of HFV70 in vivo. Collectively, our results demonstrated the potential of HFV70 in the treatment of full-thickness skin defects and rapid hemostasis.

Assessment of the Anti-Inflammatory, Antibacterial and Anti-Aging Properties and Possible Use on the Skin of Hydrogels Containing Epilobium angustifolium L. Extracts

Epilobium angustifolium L. is an ethnomedicinal plant known as a medicinal plant in many regions of the world, among others, in various skin diseases. Despite the great interest in this plant, there are still few reports of biological activity of ready-made dermatological or cosmetical preparations containing the E. angustifolium extracts. The antioxidant, anti-ageing, anti-inflammatory, antibacterial properties and toxicity, wound healing, and skin permeation of topical hydrogels containing E. angustifolium extracts (HEas) was assessed. First, the plant extracts were prepared using three solvents: 70% (v/v) ethanol, 70% (v/v) isopropanol and water, next by preparing hydrogels witch by dry extracts (HEa-EtOH), (HEa-iPrOH) and (HEa-WA), respectively. Finally, the content of selected phenolic acids in the HEas was evaluated by high-performance liquid chromatography (HPLC). All the HEas were characterized by high antioxidant activity. The most increased antibacterial activity was observed for a strain of Streptococcus pneumoniae ATCC 49619, Escherichia coli, Enterococcus faecalis ATCC 29212, Enterococcus faecium, Sarcina lutea ATCC 9341 and Bacillus pseudomycoides, while the strains of Streptococcus epidermidis, Bacillus subtilis, and Staphylococcus aureus were the least sensitive. All the HEas showed a reduction in the activity of lipoxygenase enzymes, proteases, and inhibition of protein denaturation. The HEa-EtOH and HEa-iPrOH also enhanced the wound healing activity of HDF cells. Additionally, in vitro penetration studies were performed using the Franz diffusion cells. These studies showed that the active ingredients contained in E. angustifolium penetrate through human skin and accumulate in it. Furthermore, the hydrogels containing E. angustifolium extracts showed a broad spectrum of activity. Therefore, they can be considered as an interesting alternative for dermatologic and cosmetic preparations.

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

Hydrogels are three-dimensional crosslinked hydrophilic polymer networks with great potential in drug delivery, tissue engineering, wound dressing, agrochemicals application, food packaging, and cosmetics. However, conventional synthetic polymer hydrogels may be hazardous and have poor biocompatibility and biodegradability. Algal polysaccharides are abundant natural products with biocompatible and biodegradable properties. Polysaccharides and their derivatives also possess unique features such as physicochemical properties, hydrophilicity, mechanical strength, and tunable functionality. As such, algal polysaccharides have been widely exploited as building blocks in the fabrication of polysaccharide-based hydrogels through physical and/or chemical crosslinking. In this review, we discuss the extraction and characterization of polysaccharides derived from algae. This review focuses on recent advances in synthesis and applications of algal polysaccharides-based hydrogels. Additionally, we discuss the techno-economic analyses of chitosan and acrylic acid-based hydrogels, drawing attention to the importance of such analyses for hydrogels. Finally, the future prospects of algal polysaccharides-based hydrogels are outlined.

An Overview on the Recent Advances in the Treatment of Infected Wounds: Antibacterial Wound Dressings

A wound can be surgical, cuts from an operation or due to accident and trauma. The infected wound, as a result of bacteria growth within the damaged skin, interrupts the natural wound healing process and significantly impacts the quality of life. Wound dressing is an important segment of the skincare industry with its economic burden estimated at $ 20.4 billion (in 2021) in the global market. The results of recent clinical trials suggest that the use of modern dressings can be the easiest, most accessible, and most cost-effective way to treat chronic wounds and, hence, holds significant promise. With the sheer number of dressings in the market, the selection of correct dressing is confusing for clinicians and healthcare workers. The aim of this research was to review widely used types of antibacterial wound dressings, as well as emerging products, for their efficiency and mode of action. In this review, we focus on introducing antibiotics and antibacterial nanoparticles as two important and clinically widely used categories of antibacterial agents. The perspectives and challenges for paving the way for future research in this field are also discussed. This article is protected by copyright. All rights reserved.

Carboxylated-xyloglucan and peptide amphiphile co-assembly in wound healing

Hydrogel wound dressings can play critical roles in wound healing protecting the wound from trauma or contamination and providing an ideal environment to support the growth of endogenous cells and promote wound closure. This work presents a self-assembling hydrogel dressing that can assist the wound repair process mimicking the hierarchical structure of skin extracellular matrix. To this aim, the co-assembly behaviour of a carboxylated variant of xyloglucan (CXG) with a peptide amphiphile (PA-H3) has been investigated to generate hierarchical constructs with tuneable molecular composition, structure, and properties. Transmission electron microscopy and circular dichroism at a low concentration shows that CXG and PA-H3 co-assemble into nanofibres by hydrophobic and electrostatic interactions and further aggregate into nanofibre bundles and networks. At a higher concentration, CXG and PA-H3 yield hydrogels that have been characterized for their morphology by scanning electron microscopy and for the mechanical properties by small-amplitude oscillatory shear rheological measurements and compression tests at different CXG/PA-H3 ratios. A preliminary biological evaluation has been carried out both in vitro with HaCat cells and in vivo in a mouse model.

Semi-synthesis of hybrid ulvan-kappa-carrabiose polysaccharides and evaluation of their cytotoxic and anticoagulant effects

In this study we described the synthesis of a hybrid polysaccharide harboring moieties of ulvan and kappa-carrabiose. Alkylamines (1,3-diaminopropane and 1,6-diaminohexane) were selectively inserted into β-D-GlcAp and α-L-IdoAp units in the ulvan structure via an amide bond formation producing ulvan-amide derivatives F-DAP (N% = 1.77; M_w = 208 kg mol^-1) and F-DAH (N% = 1.77; M_w = 202 kg mol^-1), which were reacted with kappa-carrabiose via reductive amination to produce hybrid ulvan-kappa-carrabiose polysaccharides F-DAP-Kb (N% = 1.56; M_w = 206 kg mol^-1) and F-DAH-Kb (N% = 1.16; M_w = 200 kg mol^-1). All the ulvan derivatives were characterized by ¹H and ¹³C NMR spectroscopy and did not show cytotoxicity against human dermal fibroblasts (HDFa) at the concentrations of 25, 100, and 500 μg mL^-1, neither anticoagulant properties at the range of 10-150 μg mL^-1. Therefore, the ulvan-amide derivatives and the hybrid ulvan-kappa-carrabiose polysaccharides showed good biocompatibility in vitro, presenting as worthy candidates for tailoring scaffolds for biomedical applications.

Nanomaterials in Skin Regeneration and Rejuvenation

Skin is the external part of the human body; thus, it is exposed to outer stimuli leading to injuries and damage, due to being the tissue mostly affected by wounds and aging that compromise its protective function. The recent extension of the average lifespan raises the interest in products capable of counteracting skin related health conditions. However, the skin barrier is not easy to permeate and could be influenced by different factors. In the last decades an innovative pharmacotherapeutic approach has been possible thanks to the advent of nanomedicine. Nanodevices can represent an appropriate formulation to enhance the passive penetration, modulate drug solubility and increase the thermodynamic activity of drugs. Here, we summarize the recent nanotechnological approaches to maintain and replace skin homeostasis, with particular attention to nanomaterials applications on wound healing, regeneration and rejuvenation of skin tissue. The different nanomaterials as nanofibers, hydrogels, nanosuspensions, and nanoparticles are described and in particular we highlight their main chemical features that are useful in drug delivery and tissue regeneration.

Impact of the Type of Crosslinking Agents on the Properties of Modified Sodium Alginate/Poly(vinyl Alcohol) Hydrogels

Here, we report on studies on the influence of different crosslinking methods (ionic and chemical) on the physicochemical (swelling ability and degradation in simulated body fluids), structural (FT-IR spectra analysis) and morphological (SEM analysis) properties of SA/PVA hydrogels containing active substances of natural origin. First, an aqueous extract of Echinacea purpurea was prepared using a Soxhlet apparatus. Next, a series of modified SA/PVA-based hydrogels were obtained through the chemical crosslinking method using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) as a crosslinking agent and, additionally, the ionic reaction in the presence of a 5% w/v calcium chloride solution. The compositions of SA/PVA/E. purpurea-based hydrogels contained a polymer of natural origin-sodium alginate (SA, 1.5% solution)-and a synthetic polymer-poly(vinyl alcohol) (PVA, Mn = 72,000 g/mol, 10% solution)-in the ratio 2:1, and different amounts of the aqueous extract of E. purpurea-5, 10, 15 or 20% (v/v). Additionally, the release behavior of echinacoside from the polymeric matrix was evaluated in phosphate-buffered saline (PBS) at 37 °C. The results indicate that the type of the crosslinking method has a direct impact on the release profile. Consequently, it is possible to design a system that delivers an active substance in a way that depends on the application.

Effect of red seaweed sulfated galactans on initial steps of complement activation in vitro

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Red algal galactans can participate in cell surface biology involving complement system.

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Polysaccharides inhibit C3 binding to LPS with direct dependence on degree of sulfation.

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Degree of sulfation mattered in carrageenans capacity to reduce C4 binding to mannan.

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C4 binding to antibodies was activated in the presence of carrageenans.

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No relevant structural characteristics were observed in ameliorating C5 cleavage by plasmin.

The research described here presents data on the effect of galactans of red algae, carrageenans (λ/μ/ν-, κ-, κ/β-, and ι/κ-types), and agar on complement system activation in normal human serum. The experiments were based on well surfaces coated with triggering agents for binding initiating complement components —C3 and C4. The sulfated galactans inhibited C3 binding to lipopolysaccharide with direct dependence on the sulfation degree of polysaccharides. Sulfation degree was also important in carrageenans’ capacity to reduce C4 binding to mannan. However, C4 binding to antibodies was considerably activated by carrageenans, especially with 3,6-anhydrogalactose. The gelling carrageenans were able to block antigen binding centers of total serum IgM and with more intensity than non-gelling. No structural characteristics mattered in ameliorating C5 cleavage by plasmin in extrinsic protease complement activation, but λ/μ/ν- and κ/β-carrageenans almost completely inhibited C5 cleavage. Thus, galactans participated in cell surface biology by imitating surface glycans in inhibition of C3 binding and mannose binding lectin, but as to the tthe heclassical pathway these substances stimulated complement, probably due to their structure based on carrabiose.