Antibacterial performance of bovine lactoferrin-fish gelatine electrospun membranes

Cross-linking electrospinning

Although electrospinning (e-spinning) has witnessed rapid development in recent years, it has also been criticized by environmentalists due to the use of organic solvents. Therefore, aqueous e-spinning (green e-spinning) is considered a more attractive technique. However, considering the poor water resistance and mechanical properties of electrospun (e-spun) nanofibers, cross-linking is a perfect solution. In this review, we systematically discuss the cross-linking e-spinning system for the first time, including cross-linking strategies (in situ, liquid immersion, vapor, and spray cross-linking), cross-linking mechanism (physical and chemical cross-linking) of e-spun nanofibers, and the various applications (e.g., tissue engineering, drug delivery, water treatment, food packaging, and sensors) of cross-linked e-spun nanofibers. Among them, we highlight several cross-linking methods, including UV light cross-linking, electron beam cross-linking, glutaraldehyde (and other commonly used cross-linking agents) chemical cross-linking, thermal cross-linking, and enzymatic cross-linking. Finally, we confirm the significance of cross-linking e-spinning and reveal the problems in the construction of this system.

Electrospinning and Electrospraying: Emerging Techniques for Probiotic Stabilization and Application

Probiotics are beneficial for human health. However, they are vulnerable to adverse effects during processing, storage, and passage through the gastrointestinal tract, thus reducing their viability. The exploration of strategies for probiotic stabilization is essential for application and function. Electrospinning and electrospraying, two electrohydrodynamic techniques with simple, mild, and versatile characteristics, have recently attracted increased interest for encapsulating and immobilizing probiotics to improve their survivability under harsh conditions and promoting high-viability delivery in the gastrointestinal tract. This review begins with a more detailed classification of electrospinning and electrospraying, especially dry electrospraying and wet electrospraying. The feasibility of electrospinning and electrospraying in the construction of probiotic carriers, as well as the efficacy of various formulations on the stabilization and colonic delivery of probiotics, are then discussed. Meanwhile, the current application of electrospun and electrosprayed probiotic formulations is introduced. Finally, the existing limitations and future opportunities for electrohydrodynamic techniques in probiotic stabilization are proposed and analyzed. This work comprehensively explains how electrospinning and electrospraying are used to stabilize probiotics, which may aid in their development in probiotic therapy and nutrition.

Characterization of the produced electrospun fish gelatin nanofiber containing fucoxanthin

This study aims to prepare fish gelatin nanofibers extracted from fish waste by using electrospinning method and its encapsulation with fucoxanthin extracted from macroalgae Sargassum angustifolium. Four concentrations of gelatin and two concentrations of fucoxanthin were used under different voltage for preparing the nanofibers. The optimal conditions for producing the nanofibers were considered as 30%, 10 cm, 12 kV, and 5% for fish gelatin concentration, distance, voltage, and fucoxanthin, respectively. The average thickness of nanofibers was estimated 198 ± 0.073 nm. The FTIR results confirmed the presence of functional groups between fucoxanthin and gelatin. The loading efficiency of fucoxanthin in nanofibers and the free radical scavenging of DPPH were calculated 91% and 62%, respectively. Further, these nanofibers showed the antibacterial properties against bacteria. Based on the results, the fish gelatin nanofibers containing fucoxanthin can be proposed as a suitable coating for using in the food packaging industry.

Ionic Liquids as Biocompatible Antibacterial Agents: A Case Study on Structure-Related Bioactivity on Escherichia coli

The potential of ionic liquids (ILs) to be used as antimicrobial agents for biomedical applications has been hindered by the fact that most of them are cytotoxic toward mammalian cells. Understanding the mechanism of bacterial and mammalian cellular damage of ILs is key to their safety design. In this work, we evaluate the antimicrobial activity and mode of action of several ILs with varying anions and cations toward the clinically relevant Gram-negative Escherichia coli. Langmuir monolayer technique was used to evaluate if the IL's mode of action was related to the bacterial cell membrane interaction for an effective E. coli killing. 1-Decyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [DMIM][TFSI] and trihexyltetradecyl phosphonium bis(trifluoromethylsulfonyl) imide [P_6,6,6,14][TFSI] were surface-active and induced bacterial cell lysis, through a membrane-disruption phenomenon on bacteria, in a mechanism that was clearly related to the long alkyl chains of the cation. 1-Ethyl-3-methylimidazolium hydrogen sulfate [EMIM][HSO₄] was highly antimicrobial toward E. coli and found suitable for biological applications since it was harmless to mammalian cells at most of the tested concentrations. The results suggest that the imidazolium cation of the ILs is mostly responsible not only for their antimicrobial activity but also for their cytotoxicity, and the inclusion of different anions may tailor the ILs' biocompatibility without losing the capacity to kill bacteria, as is the case of [EMIM][HSO₄]. Importantly, this IL was found to be highly antimicrobial even when incorporated in a polymeric matrix.

Natural Biomaterials from Biodiversity for Healthcare Applications

Natural biomaterials originating during the growth cycles of all living organisms have been used for many applications. They span from bioinert to bioactive materials including bioinspired ones. As they exhibit an increasing degree of sophistication, natural biomaterials have proven suitable to address the needs of the healthcare sector. Here the different natural healthcare biomaterials, their biodiversity sources, properties, and promising healthcare applications are reviewed. The variability of their properties as a result of considered species and their habitat is also discussed. Finally, some limitations of natural biomaterials are discussed and possible future developments are provided as more natural biomaterials are yet to be discovered and studied.

Electrospun Antibacterial Nanomaterials for Wound Dressings Applications

Chronic wounds are caused by bacterial infections and create major healthcare discomforts; to overcome this issue, wound dressings with antibacterial properties are to be utilized. The requirements of antibacterial wound dressings cannot be fulfilled by traditional wound dressing materials. Hence, to improve and accelerate the process of wound healing, an antibacterial wound dressing is to be designed. Electrospun nanofibers offer a promising solution to the management of wound healing, and numerous options are available to load antibacterial compounds onto the nanofiber webs. This review gives us an overview of some recent advances of electrospun antibacterial nanomaterials used in wound dressings. First, we provide a brief overview of the electrospinning process of nanofibers in wound healing and later discuss electrospun fibers that have incorporated various antimicrobial agents to be used in wound dressings. In addition, we highlight the latest research and patents related to electrospun nanofibers in wound dressing. This review also aims to concentrate on the importance of nanofibers for wound dressing applications and discuss functionalized antibacterial nanofibers in wound dressing.

Electrospinning Proteins for Wound Healing Purposes: Opportunities and Challenges

With the growth of the aging population worldwide, chronic wounds represent an increasing burden to healthcare systems. Wound healing is complex and not only affected by the patient's physiological conditions, but also by bacterial infections and inflammation, which delay wound closure and re-epithelialization. In recent years, there has been a growing interest for electrospun polymeric wound dressings with fiber diameters in the nano- and micrometer range. Such wound dressings display a number of properties, which support and accelerate wound healing. For instance, they provide physical and mechanical protection, exhibit a high surface area, allow gas exchange, are cytocompatible and biodegradable, resemble the structure of the native extracellular matrix, and deliver antibacterial agents locally into the wound. This review paper gives an overview on cytocompatible and biodegradable fibrous wound dressings obtained by electrospinning proteins and peptides of animal and plant origin in recent years. Focus is placed on the requirements for the fabrication of such drug delivery systems by electrospinning as well as their wound healing properties and therapeutic potential. Moreover, the incorporation of antimicrobial agents into the fibers or their attachment onto the fiber surface as well as their antimicrobial activity are discussed.

Effect of bacterial nanocellulose binding on the bactericidal activity of bovine lactoferrin

Bovine lactoferrin (bLF) has been extensively described as a wide spectrum antimicrobial protein. bLF bactericidal activity has been mainly attributed to two different mechanisms: environmental iron depletion and cell membrane destabilization. Due to its antimicrobial properties, bLF has been included in the formulation nutraceutical food products and edible active packages. This work comprises the experimental evidence of the requirement of bLF unrestricted mobility ("free bLF") to effectively perform its bactericidal action. To assess the unrestricted and restricted bLF activity, a nontoxic matrix of bacterial nanocellulose (BNC) was used as carrier, and as an anchoring scaffold, respectively. Therefore, BNC was functionalized with bLF through two different methodologies: (i) bLF was embedded within the three-dimensional structure of BNC and; (ii) bLF was covalently bounded to the nanofibrils of BNC. bLF efficiency was tested against two bacteria isolated from clinical specimens, Escherichia coli and Staphylococcus aureus. bLF concentration after covalent binding to BNC was two-fold higher in comparison to the embedding method. Nevertheless, only the embedded bLF exhibited a significant bactericidal activity, due to bLF ability to permeate the BNC matrix and execute its bactericidal action.

Spectroscopic and Molecular Modeling Investigation on the Interaction between Folic Acid and Bovine Lactoferrin from Encapsulation Perspectives

The impact of thermal treatment on the ability of lactoferrin (FL) to bind folic acid (FA) was investigated by employing fluorescence spectroscopy, molecular dynamics and docking tests. The structural and conformational particularities of LF upon heating at 80 °C and 100 °C were first estimated based on the intrinsic fluorescence changes in respect to the native protein. The emission spectra indicated gradual unfolding events accompanied by Trp exposure with increasing temperature. In agreement with the experimental results, molecular modeling investigations showed that the secondary and tertiary structure of LF are slightly affected by the thermal treatment. Some minor unfolding events related particularly to the α-helical regions of LF were observed when the temperature increased to 100 °C. The LF fluorescence quenching upon FA addition indicated that a static mechanism stands behind LF-FA complex formation. Regardless of the simulated temperature, the hydrogen bonds played an important role in regulating the interaction between the protein and ligand. FA binding to LF equilibrated at different temperatures occurred spontaneously, and all complexes displayed good thermodynamic stability. The obtained results support the suitability of LF as biocompatible material, for obtaining micro- and nanoparticles for delivery of dietary supplements or for enhancing the functionality of target delivery systems.

Delivery to the gut microbiota: A rapidly proliferating research field

The post genomic era has brought breakthroughs in our understanding of the complex and fascinating symbiosis we have with our co-evolving microbiota, and its dramatic impact on our physiology, physical and mental health, mood, interpersonal communication, and more. This fast "proliferating" knowledge, particularly related to the gut microbiota, is leading to the development of numerous technologies aimed to promote our health via prudent modulation of our gut microbiota. This review embarks on a journey through the gastrointestinal tract from a biomaterial science and engineering perspective, and focusses on the various state-of-the-art approaches proposed in research institutes and those already used in various industries and clinics, for delivery to the gut microbiota, with emphasis on the latest developments published within the last 5 years. Current and possible future trends are discussed. It seems that future development will progress toward more personalized solutions, combining high throughput diagnostic omic methods, and precision interventions.

Comparative assessment of the interface between poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and fish scales in composites: Preparation, characterization, and applications

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) composites containing fish scales (FSs) were prepared and used in the fabrication of three-dimensional printing filaments. Maleic anhydride (MA)-grafted polyhydroxyalkanoate (PHBV-g-MA) and FS were used to improve the compatibility of FS within a PHBV matrix. Mechanical and morphological characterization indicated that improved adhesion between FS and PHBV-g-MA enhanced the tensile strength of the composite compared with that of PHBV/FS. The PHBV-g-MA/FS composites were also more water-resistant than the PHBV/FS composites. Human foreskin fibroblasts (FBs) were seeded on two series of these composites to assess cytocompatibility. FB proliferation was greater on PHBV/FS composites than on PHBV-g-MA/FS composites. Cell-cycle assays with FBs on PHBV/FS and PHBV-g-MA/FS series composites were unaffected. Moreover, FS enhanced the antioxidant and antimicrobial properties of PHBV-g-MA/FS and PHBV/FS composites, demonstrating the potential of PHBV-g-MA/FS and PHBV/FS composites for biomedical material applications.

Hydrophobic Ethylcellulose/Gelatin Nanofibers Containing Zinc Oxide Nanoparticles for Antimicrobial Packaging

The ethylcellulose/gelatin solutions containing various concentrations of zinc oxide (ZnO) nanoparticles were electrospun, and the resultant nanofibers were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray photoelectron spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy, mechanical testing, water contact angle, and water stability. Results indicated that ZnO nanoparticles acting as fillers interacted with polymers, resulting in the enhanced surface hydrophobicity and water stability of nanofibers. The antibacterial assay showed a concentration-dependent effect of ZnO on the viabilities of Escherichia coli and Staphylococcus aureus. Notably, the antimicrobial efficiency of the 1.5 wt % ZnO-containing fibers against Staphylococcus aureus was 43.7% but increased to 62.5% after UV irradiation at 364 nm, possibly due to the significantly increased amounts of intracellular reactive oxygen species. These results suggested that the ZnO-containing nanofibers with excellent surface hydrophobicity, water stability, and antimicrobial activity exhibited potential uses in food packaging.

Encapsulation of Bioactive Compound in Electrospun Fibers and Its Potential Application

Electrospinning is a simple and versatile encapsulation technology. Since electrospinning does not involve severe conditions of temperature or pressure or the use of harsh chemicals, it has great potential for effectively entrapping and delivering bioactive compounds. Recently, electrospinning has been used in the food industry to encapsulate bioactive compounds into different biopolymers (carbohydrates and proteins), protecting them from adverse environmental conditions, maintaining the health-promoting properties, and achieving their controlled release. Electrospinning opens a new horizon in food technology with possible commercialization in the near future. This review summarizes the principles and the types of electrospinning processes. The electrospinning of biopolymers and their application in encapsulating of bioactive compounds are highlighted. The existing scope, limitations, and future prospects of electrospinning bioactive compounds are also presented.

Fabrication of an ultrafine fish gelatin nanofibrous web from an aqueous solution by electrospinning

Electrospinning of aqueous gelatin solution obtained from bovine or porcine sources has been difficult to achieve without additional facilities, such as a temperature control oven or heating cover. Gelatin from cold-water fish has low contents of proline (Pro) and hydroxyproline (Hyp) compared with mammalian-derived gelatin. For this reason, the fish-derived gelatin maintains a sol state without showing gelation behavior at room temperature. In the present study, we prepared an ultrafine fish gelatin nanofibrous web by electrospinning from aqueous solutions without any additive polymers or temperature control facilities. The concentration and viscosity of fish gelatin are the most important factor in determining the electrospinnability and fiber diameter. Electrospinning of aqueous fish gelatin has the highest nanofiber productivity compared to other organic solvent systems. Using glutaraldehyde vapor (GTA), the water stability was improved and substantial enhancement was achieved in the mechanical properties. Finally, the cytotoxicity of a fish gelatin nanofibrous scaffold was evaluated based on a cell proliferation study by culturing human dermal fibroblasts (HDFs) compared with a fish gelatin film and nanofibrous mat from mammalian gelatin. The result shows better initial cell attachment and proliferation compared with the fish gelatin film and no significant difference compared with mammalian-derived gelatin nanofibrous mat. We expect that electrospinning of aqueous fish gelatin could be an effective alternative mammalian gelatin source.