Levan-based hydrogels for controlled release of Amphotericin B for dermal local antifungal therapy of Candidiasis

Advances in nanotechnology for improving the targeted delivery and activity of amphotericin B (2011-2023): a systematic review

Amphotericin B (AmB) is a broad-spectrum therapeutic and effective drug, but it has serious side effects of toxicity and solubility. Therefore, reducing its toxicity should be considered in therapeutic applications. Nanotechnology has paved the way to improve drug delivery systems and reduce toxicity. The present study, for the first time, comprehensively reviews the studies from 2011 to 2023 on reducing the in vitro toxicity of AmB. The findings showed that loading AmB with micellar structures, nanostructured lipid carriers, liposomes, emulsions, poly lactide-co-glycolide acid, chitosan, dendrimers, and other polymeric nanoparticles increases the biocompatibility and efficacy of the drug and significantly reduces toxicity. In addition, modified carbon nanoparticles (including graphene, carbon nanotubes, and carbon dots) with positively charged amine groups, PEI, and other components showed favorable drug delivery properties. Uncoated and coated magnetic nanoparticles and silver NPs-AmB composites had less cytotoxicity and more antifungal activity than free AmB. Citrate-reduced GNPs and lipoic acid-functionalized GNPs were also effective nanocarriers to reduce AmB cytotoxicity and improve anti-leishmania efficacy. In addition, zinc oxide-NPs and PEGylated zinc oxide-NPs showed favorable antifungal activity and negligible toxicity. According to a review study, carbon-based nanoparticles, metal nanoparticles, and especially polymer nanoparticles caused some reduction in the toxicity and improved solubility of AmB in water. Overall, considering the discussed nanocarriers, further research on the application of nanotechnology as a cost-effective candidate to improve the efficiency and reduce the cytotoxicity of AmB is recommended.

Fabrication of wound dressings: Herbal extract-loaded nanoliposomes embedded in fungal chitosan/polycaprolactone electrospun nanofibers for tissue regeneration

Wound healing is a complex process and one of the major therapeutic and economic subjects in the pharmaceutical area. In recent years, the fabrication of nano-sized wound dressing models has attracted great attention for tissue regeneration. Plant extracts loaded nanoparticles are environmentally friendly and non-toxic and the release of the bioactive substance will be controlled to the wound area. This study aims to fabricate wound dressing models that contain bioactive components for tissue regeneration. Fungal chitosan/polycaprolactone nanofiber was fabricated by electrospinning and it has been characterized. Plant extracts loaded nanoliposomes were prepared, characterized, and embedded in nanofiber structures. The effectiveness of wound dressing models for tissue regeneration was evaluated by in vitro and in vivo studies. It was observed that all wound dressing models positively affect the cell viability of human dermal fibroblast cells. It was determined that plant extracts loaded nanoparticles embedded in nanofibers increased in cell viability than nanoparticles that were non-embedded in nanofiber structures. Histological analysis showed that plant extract-loaded nanoliposomes embedded in chitosan/PCL nanofibers were used for tissue regeneration. The most effective nanofibers were determined as Wd-ClNL nanofibers. RESEARCH HIGHLIGHTS: Hypericum perforatum L. and Cistus laurifolius L. were prepared by modified ultrasonic extraction method. Fungal chitosan/polycaprolactone nanofiber was fabricated by electrospinning and it has been characterized. Plant extract-loaded nanoliposomes were prepared, and characterized. They were embedded in chitosan/polycaprolactone nanofiber. Effects of the wound dressing model were analyzed by in vitro and in vivo assays for tissue regeneration.

Fabrication and characterization of new levan@CBD biocomposite sponges as potential materials in natural, non-toxic wound dressing applications

Wound healing is a complex process; therefore, new dressings are frequently required to facilitate it. In this study, porous bacterial levan-based sponges containing cannabis oil (Lev@CBDs) were prepared and fully characterized. The sponges exhibited a suitable swelling ratio, proper water vapor transmission rate, sufficient thermal stability, desired mechanical properties, and good antioxidant and anti-inflammatory properties. The obtained Lev@CBD materials were evaluated in terms of their interaction with proteins, human serum albumin and fibrinogen, of which fibrinogen revealed the highest binding effect. Moreover, the obtained biomaterials exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, as well as being non-hemolytic material as indicated by hemolysis tests. Furthermore, the sponges were non-toxic and compatible with L929 mouse fibroblasts and HDF cells. Most significantly, the levan sponge with the highest content of cannabis oil, in comparison to others, retained its non-hemolytic, anti-inflammatory, and antimicrobial properties after prolonged storage in a climate chamber at a constant temperature and relative humidity. The designed sponges have conclusively proven their beneficial physicochemical properties and, at the preliminary stage, biocompatibility as well, and therefore can be considered a promising material for wound dressings in future in vivo applications.

Elaboration of Nanostructured Levan-Based Colloid System as a Biological Alternative with Antimicrobial Activity for Applications in the Management of Pathogenic Microorganisms

Considering the documented health benefits of bacterial exopolysaccharides (EPSs), specifically of bacterial levan (BL), including its intrinsic antimicrobial activity against certain pathogenic species, the current study concentrated on the development of active pharmaceutical ingredients (APIs) in the form of colloid systems (CoSs) containing silver nanoparticles (AgNPs) employing in-house biosynthesized BL as a reducing and capping agent. The established protocol of fermentation conditions implicating two species of lactic acid bacteria (LAB), i.e., Streptococcus salivarius K12 and Leuconostoc mesenteroides DSM 20343, ensured a yield of up to 25.7 and 13.7 g L-1 of BL within 72 h, respectively. An analytical approach accomplished by Fourier-transform infrared (FT-IR) spectroscopy allowed for the verification of structural features attributed to biosynthesized BL. Furthermore, scanning electron microscopy (SEM) revealed the crystalline morphology of biosynthesized BL with a smooth and glossy surface and highly porous structure. Molecular weight (Mw) estimated by multi-detector size-exclusion chromatography (SEC) indicated that BL biosynthesized using S. salivarius K12 has an impressively high Mw, corresponding to 15.435 × 104 kilodaltons (kDa). In turn, BL isolated from L. mesenteroides DSM 20343 was found to have an Mw of only 26.6 kDa. Polydispersity index estimation (PD = Mw/Mn) of produced BL displayed a monodispersed molecule isolated from S. salivarius K12, corresponding to 1.08, while this was 2.17 for L. mesenteroides DSM 20343 isolate. The presence of fructose as the main backbone and, to a lesser extent, glucose and galactose as side chain molecules in EPS hydrolysates was supported by HPLC-RID detection. In producing CoS-BL@AgNPs within green biosynthesis, the presence of nanostructured objects with a size distribution from 12.67 ± 5.56 nm to 46.97 ± 20.23 was confirmed by SEM and energy-dispersive X-ray spectroscopy (EDX). The prominent inhibitory potency of elaborated CoS-BL@AgNPs against both reference test cultures, i.e., Pseudomonas aeruginosa, Escherichia coli, Enterobacter aerogenes, and Staphylococcus aureus and those of clinical origin with multi-drug resistance (MDR), was confirmed by disc and well diffusion tests and supported by the values of the minimum inhibitory and bactericidal concentrations. CoS-BL@AgNPs can be treated as APIs suitable for designing new antimicrobial agents and modifying therapies in controlling MDR pathogens.

Properties of Active Levan-Bitter Vetch Protein Films for Potential Use in Food Packaging Applications

ζ-potential and Z-average were determined on film-forming solutions of bitter vetch-levan-based films prepared at different ratios in the absence and presence of glycerol as a plasticizer. The casting method was used to obtain manageable films. The results revealed that levan increases the elongation at break of bitter vetch protein films and reduces the tensile strength. The optimal result was obtained through the film that was prepared with the ratio of 50% bitter vetch proteins and 50% levan, in terms of mechanical properties. The surfaces of the prepared films appeared to be more compact and smooth. On increasing the glycerol concentration in the bitter vetch protein-levan films, the oxygen and water vapor permeability increased compared to the control (P < 0.05). Based on the overall results, the reinforcement of bitter vetch proteins with levan at a ratio of 1:1 represents optimal film properties in the presence of a low concentration of glycerol. The proposed film is suggested as an innovative packaging system for beef meat to preserve its quality over time.

Recent Developments and Applications of Microbial Levan, A Versatile Polysaccharide-Based Biopolymer

Polysaccharides are essential components with diverse functions in living organisms and find widespread applications in various industries. They serve as food additives, stabilizers, thickeners, and fat substitutes in the food industry, while also contributing to dietary fiber for improved digestion and gut health. Plant-based polysaccharides are utilized in paper, textiles, wound dressings, biodegradable packaging, and tissue regeneration. Polysaccharides play a crucial role in medicine, pharmacy, and cosmetology, as well as in the production of biofuels and biomaterials. Among microbial biopolymers, microbial levan, a fructose polysaccharide, holds significant promise due to its high productivity and chemical diversity. Levan exhibits a wide range of properties, including film-forming ability, biodegradability, non-toxicity, self-aggregation, encapsulation, controlled release capacity, water retention, immunomodulatory and prebiotic activity, antimicrobial and anticancer activity, as well as high biocompatibility. These exceptional properties position levan as an attractive candidate for nature-based materials in food production, modern cosmetology, medicine, and pharmacy. Advancing the understanding of microbial polymers and reducing production costs is crucial to the future development of these fields. By further exploring the potential of microbial biopolymers, particularly levan, we can unlock new opportunities for sustainable materials and innovative applications that benefit various industries and contribute to advancements in healthcare, environmental conservation, and biotechnology.

Exploring the potential of Halomonas levan and its derivatives as active ingredients in cosmeceutical and skin regenerating formulations

Demand on natural products that contain biological ingredients mimicking growth factors and cytokines made natural polysaccharides popular in pharmaceutical and cosmetic industries. Levan is the β-(2-6) linked, nontoxic, biocompatible, water-soluble, film former fructan polymer that has diverse applications in pharmacy and cosmeceutical industries with its moisturizing, whitening, anti-irritant, anti-aging and slimming activities. Driven by the limited reports on few structurally similar levan polymers, this study presents the first systematic investigation on the effects of structurally different extremophilic Halomonas levan polysaccharides on human skin epidermis cells. In-vitro experiments with microbially produced linear Halomonas levan (HL), its hydrolyzed, (hHL) and sulfonated (ShHL) derivatives as well as enzymatically produced branched levan (EL) revealed increased keratinocyte and fibroblast proliferation (113-118 %), improved skin barrier function through induced expressions of involucrin (2.0 and 6.43 fold changes for HL and EL) and filaggrin (1.74 and 3.89 fold changes for hHL and ShHL) genes and increased type I collagen (2.63 for ShHL) and hyaluronan synthase 3 (1.41 for HL) gene expressions together with fast wound healing ability within 24 h (100 %, HL) on 2D wound models clearly showed that HL and its derivatives have high potential to be used as natural active ingredients in cosmeceutical and skin regenerating formulations.

Synthesis of Cationic Quaternized Nanolevan Derivative for Small Molecule and Nucleic Acid Delivery

Levan is a biopolymer composed of fructose chains covalently linked by β−2,6 glycosidic linkages. This polymer self−assembles into a nanoparticle of uniform size, making it useful for a wide range of applications. Also, levan exhibits various biological activities such as antioxidants, anti-inflammatory, and anti-tumor, that make this polymer very attractive for biomedical application. In this study, levan synthesized from Erwinia tasmaniensis was chemically modified by glycidyl trimethylammonium chloride (GTMAC) to produce cationized nanolevan (QA-levan). The structure of the obtained GTMAC−modified levan was determined by FT-IR, 1H-NMR and elemental (CHN) analyzer. The size of the nanoparticle was calculated using the dynamic light scattering method (DLS). The formation of DNA/QA-levan polyplex was then investigated by gel electrophoresis. The modified levan was able to increase the solubility of quercetin and curcumin by 11-folds and 205-folds, respectively, compared to free compounds. Cytotoxicity of levan and QA−levan was also investigated in HEK293 cells. This finding suggests that GTMAC−modified levan should have a potential application for drug and nucleic acid delivery.

The impact of varying dextran oxidation levels on the inhibitory activity of a bacteriocin loaded injectable hydrogel

In the design of injectable antimicrobial dextran-alginate hydrogels, the impact of dextran oxidation and its subsequent changes in molecular weight and the incorporation of glycol chitosan on (i) gel mechanical strength and (ii) the inhibitory profile of an encapsulated bacteriocin, nisin A, are explored. As the degree of oxidation increases, the weight average molecular mass of the dextran decreases, resulting in a reduction in elastic modulus of the gels made. Upon encapsulation of the bacteriocin nisin into the gels, varying the dextran mass/oxidation level allowed the antimicrobial activity against S. aureus to be controlled. Gels made with a higher molecular weight (less oxidised) dextran show a higher initial degree of inhibition while those made with a lower molecular weight (more oxidised) dextran exhibit a more sustained inhibition. Incorporating glycol chitosan into gels composed of dextran with higher masses significantly increased their storage modulus and the gels' initial degree of inhibition.

Scaffolds in the microbial resistant era: Fabrication, materials, properties and tissue engineering applications

Due to microbial infections dramatically affect cell survival and increase the risk of implant failure, scaffolds produced with antimicrobial materials are now much more likely to be successful. Multidrug-resistant infections without suitable prevention strategies are increasing at an alarming rate. The ability of cells to organize, develop, differentiate, produce a functioning extracellular matrix (ECM) and create new functional tissue can all be controlled by careful control of the extracellular microenvironment. This review covers the present state of advanced strategies to develop scaffolds with antimicrobial properties for bone, oral tissue, skin, muscle, nerve, trachea, cardiac and other tissue engineering applications. The review focuses on the development of antimicrobial scaffolds against bacteria and fungi using a wide range of materials, including polymers, biopolymers, glass, ceramics and antimicrobials agents such as antibiotics, antiseptics, antimicrobial polymers, peptides, metals, carbon nanomaterials, combinatorial strategies, and includes discussions on the antimicrobial mechanisms involved in these antimicrobial approaches. The toxicological aspects of these advanced scaffolds are also analyzed to ensure future technological transfer to clinics. The main antimicrobial methods of characterizing scaffolds’ antimicrobial and antibiofilm properties are described. The production methods of these porous supports, such as electrospinning, phase separation, gas foaming, the porogen method, polymerization in solution, fiber mesh coating, self-assembly, membrane lamination, freeze drying, 3D printing and bioprinting, among others, are also included in this article. These important advances in antimicrobial materials-based scaffolds for regenerative medicine offer many new promising avenues to the material design and tissue-engineering communities.

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Antibacterial, antifungal and antibiofilm scaffolds.

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Antimicrobial scaffold fabrication techniques.

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Antimicrobial biomaterials for tissue engineering applications.

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Antimicrobial characterization methods of scaffolds.

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Bone, oral tissue, skin, muscle, nerve, trachea, cardiac, among other applications.

Development of Lipid Nanoparticles Containing Omega-3-Rich Extract of Microalga Nannochlorpsis gaditana

Microalgae are described as a new source of a wide range of bioactive compounds with health-promoting properties, such as omega-3 lipids. This biomass product is gaining attention mainly due to its potential to accumulate different compounds depending on the species and environment, and it has been commonly recognized as a valuable nutraceutical alternative to fish and krill oils. In this work, we obtained the extract of the microalga Nannochloropsis gaditana, selected on the basis of its content of eicosapentaenoic acid (EPA) and glycolipids, which were determined using GC-MS and high-performance liquid chromatography (HPLC), respectively. To develop an oral formulation for the delivery of the extract, we used a 2³ factorial design approach to obtain an optimal lipid nanoparticle formulation. The surfactant and solid lipid content were set as the independent variables, while the particle size, polydispersity index, and zeta potential were taken as the dependent variables of the design. To ensure the potential use of the optimum LN formulation to protect and modify the release of the loaded microalga extract, rheological and differential scanning calorimetry analyses were carried out. The developed formulations were found to be stable over 30 days, with an encapsulation efficiency over 60%.

Evaluation of Physically and/or Chemically Modified Chitosan Hydrogels for Proficient Release of Insoluble Nystatin in Simulated Fluids

To avoid fungal spreading in the bloodstream and internal organs, many research efforts concentrate on finding appropriate candidiasis treatment from the initial stage. This paper proposes chitosan-based physically or chemically cross-linked hydrogels aimed to provide sustained release of micronized nystatin (NYSm) antifungal drug, known for its large activity spectrum. Nystatin was demonstrated itself to provide hydrodynamic/mechanic stability to the chitosan hydrogel through hydrophobic interactions and H-bonds. For chemical cross-linking of the succinylated chitosan, a non-toxic diepoxy-functionalized siloxane compound was used. The chemical structure and composition of the hydrogels, also their morphology, were evidenced by infrared spectroscopy (FTIR), by energy dispersive X-ray (EDX) analysis and by scanning electron microscopy (SEM), respectively. The hydrogels presented mechanical properties which mimic those of the soft tissues (elastic moduli < 1 MPa), necessary to ensure matrix accommodation and bioadhesion. Maximum swelling capacities were reached by the hydrogels with higher succinic anhydride content at both pH 7.4 (429%) and pH 4.2 (471%), while higher amounts of nystatin released in the simulative immersion media (57% in acidic pH and 51% in pH 7.4) occurred from the physical cross-linked hydrogel. The release mechanism by non-swellable matrix diffusion and the susceptibility of three Candida strains make all the hydrogel formulations effective for NYSm local delivery and for combating fungal infections.

UV and Chemically Induced Halomonas smyrnensis Mutants for Enhanced Levan Productivity

Halomonas smyrnensis AAD6^T is a moderately halophilic bacterium proven to be a powerful biotechnological tool with its ability to accumulate valuable biopolymers such as levan and poly(3-hydroxybutyrate) (PHB). Levan is a fructose homopolymer with β-2,6 fructofuranosidic linkages on the polymer backbone, and its distinctive applications in various industries such as food, pharmaceutical, medical, and chemical have been well-defined. On the other hand, PHB is a promising raw material to produce biodegradable plastics. Although it was shown in our previous studies that H. smyrnensis AAD6^T exhibits one of the highest conversion yields of sucrose to levan reported to date, novel strategies are required to overcome high costs of levan production. In this study, we aimed at increasing levan productivity of H. smyrnensis AAD6^T cultures using random mutagenesis techniques combined (i.e., ethyl methanesulfate treatment and/or ultraviolet irradiation). After several consecutive treatments, mutant strains BAE2, BAE5 and BAE6 were selected as efficient levan producers, as BAE2 standing out as the most efficient one not only in sucrose utilization and levan production rates, but also in final PHB concentrations. The mutants' whole genome sequences were analysed to determine the mutations occurred. Several mutations in genes related to central carbon metabolism and osmoregulation were found. Our results suggest that random mutagenesis can be a facile and efficient strategy to enhance the performance of extremophiles in adverse conditions.

Synthesis and characterization of levan hydrogels and their use for resveratrol release

Considering the need for systematic studies on levan based hydrogels to widen their use in drug delivery systems and biomedical applications, this study is mainly focused on the synthesis and comprehensive characterization as well as drug release properties of hydrogels based on Halomonas levan (HL) and its chemical derivatives. For this, hydrolyzed and phosphonated HL derivatives were chemically synthesized and then cross-linked with 1,4-Butanediol diglycidyl ether (BDDE) and the obtained hydrogels were characterized in terms of their swelling, adhesivity, and rheological properties. Both native and phosphonated HL hydrogels retained their rigid gel like structure with increasing shear stress levels and tack test analysis showed superior adhesive properties of the phosphonated HL hydrogels. Moreover, hydrogels were loaded with resveratrol and entrapment and release studies as well as cell culture studies with human keratinocytes were performed. Biocompatible and adhesive features of the hydrogels confirmed their suitability for tissue engineering and drug delivery applications.

Resveratrol-Loaded Levan Nanoparticles Produced by Electrohydrodynamic Atomization Technique

Considering the significant advances in nanostructured systems in various biomedical applications and the escalating need for levan-based nanoparticles as delivery systems, this study aimed to fabricate levan nanoparticles by the electrohydrodynamic atomization (EHDA) technique. The hydrolyzed derivative of levan polysaccharide from Halomonas smyrnensis halophilic bacteria, hydrolyzed Halomonas levan (hHL), was used. Nanoparticles were obtained by optimizing the EHDA parameters and then they were characterized in terms of morphology, molecular interactions, drug release and cell culture studies. The optimized hHL and resveratrol (RS)-loaded hHL nanoparticles were monodisperse and had smooth surfaces. The particle diameter size of hHL nanoparticles was 82.06 ± 15.33 nm. Additionally, release of RS from the fabricated hHL nanoparticles at different pH conditions were found to follow the first-order release model and hHL with higher RS loading showed a more gradual release. In vitro biocompatibility assay with human dermal fibroblast cell lines was performed and cell behavior on coated surfaces was observed. Nanoparticles were found to be safe for healthy cells. Consequently, the fabricated hHL-based nanoparticle system may have potential use in drug delivery systems for wound healing and tissue engineering applications and surfaces could be coated with these electrosprayed particles to improve cellular interaction.

Macroporous zwitterionic composite cryogel based on chitosan oligosaccharide for antifungal application

Chitosan oligosaccharide (COS), a time-dependent antimicrobial carbohydrate, is found antifungal active with a short duration of action due to excessive solubility. We attempted to address this issue by employing a hydrogel as a COS carrier. In this research, macroporous zwitterionic composite cryogels composed of COS and poly(N-methacryl arginine) (PMarg) were fabricated, serving as long-term antifungal dressings. Firstly, Marg was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H and ¹³C nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS). Then, the COS/PMarg cryogels were prepared by redox initiation cryopolymerization. The macroporous morphology of the cryogels was confirmed by scanning electron microscope (SEM) with pore size varying from 20.86 to 50.87 μm. FTIR indicated that hydrogen bonding formed between COS and PMarg, and the interaction elevated thermal stability of the cryogels as evidenced by thermal-gravimetric analysis (TGA). Swelling capacity, mechanical properties, and COS release behavior of the COS/PMarg cryogels were investigated. With the release of COS, the antifouling activity of the cryogel increased. Antimicrobial tests indicated the COS/PMarg cryogel could effectively inhibit the proliferation of Candida albicans. It demonstrated that the macroporous zwitterionic COS/PMarg composite cryogel might be a potential antifungal dressing with sequential "sterilization-release" capacity.

Delivery strategies of amphotericin B for invasive fungal infections

Invasive fungal infections (IFIs) represent a growing public concern for clinicians to manage in many medical settings, with substantial associated morbidities and mortalities. Among many current therapeutic options for the treatment of IFIs, amphotericin B (AmB) is the most frequently used drug. AmB is considered as a first-line drug in the clinic that has strong antifungal activity and less resistance. In this review, we summarized the most promising research efforts on nanocarriers for AmB delivery and highlighted their efficacy and safety for treating IFIs. We have also discussed the mechanism of actions of AmB, rationale for treating IFIs, and recent advances in formulating AmB for clinical use. Finally, this review discusses some practical considerations and provides recommendations for future studies in applying AmB for combating IFIs.

Fabrication of amphotericin B-loaded electrospun core-shell nanofibers as a novel dressing for superficial mycoses and cutaneous leishmaniasis

Amphotericin B (AmB) is an antifungal and antiparasitic agent that is the main drug used for the treatment of mycoses infections and leishmaniasis. However, its high toxicity and side effects are the main difficulties attributed to its application. In this study, to minimize its harmful effects, AmB-loaded core-shell nanofibers were fabricated, using polyvinyl alcohol, chitosan, and AmB as the core, and polyethylene oxide and gelatin as the shell-forming components. The nanofibers were characterized, using scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, tensile test, drug release, and MTT assay. The results showed that the prepared nanofibers were smooth and had a core-shell structure with almost no cytotoxicity against fibroblast cells and the release study suggested that the core-shell structure decreased the burst release. The disk diffusion assay revealed that the nanofibrous mats at different AmB concentrations exhibited significant activity against all the eight evaluated fungal species with the inhibition zones of 1.4-2.6 cm. The flow cytometry assay also showed that the prepared nanofibrous mat significantly killed Leishmania major promastigotes up to 84%. The obtained results indicated that this AmB-loaded nanofibrous system could be a suitable candidate for a topical drug delivery system for the treatment of both superficial mycoses and cutaneous leishmaniasis.

A review of extracellular polysaccharides from extreme niches: An emerging natural source for the biotechnology. From the adverse to diverse!

Every year, new organisms that survive and colonize adverse environments are discovered and isolated. Those organisms, called extremophiles, are distributed throughout the world, both in aquatic and terrestrial environments, such as sulfurous marsh waters, hydrothermal springs, deep waters, volcanos, terrestrial hot springs, marine saltern, salt lakes, among others. According to the ecosystem inhabiting, extremophiles are categorized as thermophiles, psychrophiles, halophiles, acidophiles, alkalophilic, piezophiles, saccharophiles, metallophiles and polyextremophiles. They have developed chemical adaptation strategies that allow them to maintain their cellular integrity, altering physiology or improving repair capabilities; one of them is the biosynthesis of extracellular polysaccharides (EPS), which constitute a slime and hydrated matrix that keep the cells embedded, protecting from environmental stress (desiccation, salinity, temperature, radiation). EPS have gained interest; they are explored by their unique properties such as structural complexity, biodegradability, biological activities, and biocompatibility. Here, we present a review concerning the biosynthesis, characterization, and potential EPS applications produced by extremophile microorganisms, namely, thermophiles, halophiles, and psychrophiles. A bibliometric analysis was conducted, considering research articles published within the last two decades. Besides, an overview of the culture conditions used for extremophiles, the main properties and multiple potential applications of their EPS is also presented.

Bioactivity reinforced surface patch bound collagen-pectin hydrogel

In this report, we discuss the design of a novel collagen/pectin (CP) hybrid composite hydrogel (CPBG) containing in-situ mineralized bioactive glass (BG) particles to simulate an integrative 3D cell environment. Systematic analysis of the CP sol revealed collagen and pectin molecules interacted regardless of both possessing similar net negative charge through the mechanism of surface patch binding interaction. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed this associative interaction which resulted in the formation of a hybrid crosslinked network with the BG nanoparticles acting as pseudo crosslink junctions. Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX) and Transmission Electron Microscopy (TEM) results confirmed uniform mineralization of BG particles, and their synergetic interaction with the network. The in-vitro bioactivity tests on CPBG indicated the formation of bone-like hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) microcrystals on its surface after interaction with simulated body fluid. This hydrogel was loaded with a model antifungal drug amphotericin-B (AmB) and tested against Candida albicans. The AmB release kinetics from the hydrogel followed the Fickian mechanism and showed direct proportionality to gel swelling behavior. Rheological analysis revealed the viscoelastic compatibility of CPBG for the mechanical load bearing applications. Cell viability tests indicated appreciable compatibility of the hydrogel against U2OS and HaCaT cell lines. FDA/PI on the hydrogel portrayed preferential U2OS cell adhesion on hydrophobic hydroxyapatite layer compared to hydrophilic surfaces, thereby promising the regeneration of both soft and hard tissues.

Biomimetic Coatings Obtained by Combinatorial Laser Technologies

The modification of implant devices with biocompatible coatings has become necessary as a consequence of premature loosening of prosthesis. This is caused mainly by chronic inflammation or allergies that are triggered by implant wear, production of abrasion particles, and/or release of metallic ions from the implantable device surface. Specific to the implant tissue destination, it could require coatings with specific features in order to provide optimal osseointegration. Pulsed laser deposition (PLD) became a well-known physical vapor deposition technology that has been successfully applied to a large variety of biocompatible inorganic coatings for biomedical prosthetic applications. Matrix assisted pulsed laser evaporation (MAPLE) is a PLD-derived technology used for depositions of thin organic material coatings. In an attempt to surpass solvent related difficulties, when different solvents are used for blending various organic materials, combinatorial MAPLE was proposed to grow thin hybrid coatings, assembled in a gradient of composition. We review herein the evolution of the laser technological process and capabilities of growing thin bio-coatings with emphasis on blended or multilayered biomimetic combinations. These can be used either as implant surfaces with enhanced bioactivity for accelerating orthopedic integration and tissue regeneration or combinatorial bio-platforms for cancer research.