Impact of Biogenic and Chemogenic Selenium Nanoparticles on Model Eukaryotic Lipid Membranes

Microbial nanotechnology is an expanding research area devoted to producing biogenic metal and metalloid nanomaterials (NMs) using microorganisms. Often, biogenic NMs are explored as antimicrobial, anticancer, or antioxidant agents. Yet, most studies focus on their applications rather than the underlying mechanism of action or toxicity. Here, we evaluate the toxicity of our well-characterized biogenic selenium nanoparticles (bSeNPs) produced by the Stenotrophomonas maltophilia strain SeITE02 against the model yeast Saccharomyces cerevisiae comparing it with chemogenic SeNPs (cSeNPs). Knowing from previous studies that the biogenic extract contained bSeNPs in an organic material (OM) and supported here by Fourier transform infrared spectroscopy, we removed and incubated it with cSeNPs (cSeNPs_OM) to assess its influence on the toxicity of these formulations. Specifically, we focused on the first stages of the eukaryotic cell exposure to these samples─i.e., their interaction with the cell lipid membrane, which was mimicked by preparing vesicles from yeast polar lipid extract or phosphatidylcholine lipids. Fluidity changes derived from biogenic and chemogenic samples revealed that the bSeNP extract mediated the overall rigidification of lipid vesicles, while cSeNPs showed negligible effects. The OM and cSeNPs_OM induced similar modifications to the bSeNP extract, reiterating the need to consider the OM influence on the physical-chemical and biological properties of bSeNP extracts.

Recent Biomedical Approaches for Chitosan Based Materials as Drug Delivery Nanocarriers

In recent decades, drug delivery systems (DDSs) based on nanotechnology have been attracting substantial interest in the pharmaceutical field, especially those developed based on natural polymers such as chitosan, cellulose, starch, collagen, gelatin, alginate and elastin. Nanomaterials based on chitosan (CS) or chitosan derivatives are broadly investigated as promising nanocarriers due to their biodegradability, good biocompatibility, non-toxicity, low immunogenicity, great versatility and beneficial biological effects. CS, either alone or as composites, are suitable substrates in the fabrication of different types of products like hydrogels, membranes, beads, porous foams, nanoparticles, in-situ gel, microparticles, sponges and nanofibers/scaffolds. Currently, the CS based nanocarriers are intensely studied as controlled and targeted drug release systems for different drugs (anti-inflammatory, antibiotic, anticancer etc.) as well as for proteins/peptides, growth factors, vaccines, small DNA (DNAs) and short interfering RNA (siRNA). This review targets the latest biomedical approaches for CS based nanocarriers such as nanoparticles (NPs) nanofibers (NFs), nanogels (NGs) and chitosan coated liposomes (LPs) and their potential applications for medical and pharmaceutical fields. The advantages and challenges of reviewed CS based nanocarriers for different routes of administration (oral, transmucosal, pulmonary and transdermal) with reference to classical formulations are also emphasized.

Polysaccharide dual coating of yeast capsules for stabilization of anthocyanins

The dual coated yeast capsules for anthocyanin encapsulation and stabilization were fabricated. Anthocyanins were preloaded in hollow yeast capsules, and then the dual coating was performed by deposition of opposite charged polysaccharides using layer-by-layer technique. The combination of positively charged chitosan and negatively charged chondroitin sulfate was found to confer the yeast capsules with the highest encapsulation efficiency and retention rate of anthocyanins. Additionally, the coated yeast capsules featured high tolerance to environmental stresses (i.e., oxygen, ascorbic acid, and heat) and therefore effectively inhibited the degradation of anthocyanins. These stabilizing effects were related to the formation of high penetration barrier provided by the double layers of polysaccharides, as well as the enhanced hydrophobic microenvironment in the capsules. Further development of the polysaccharide-coated yeast capsules may hold promise for the controlled delivery of other water-soluble bioactive components.

Biopolymer-liposome hybrid systems for controlled delivery of bioactive compounds: Recent advances

Conventional liposomes still face many challenges associated with the poor physical and chemical stability, considerable loss of encapsulated cargo, lack of stimulus responsiveness, and rapid elimination from blood circulation. Integration of versatile functional biopolymers has emerged as an attractive strategy to overcome the limitation of usage of liposomes. This review comprehensively summarizes the most recent studies (2015-2020) and their challenges aiming at the exploration of biopolymer-liposome hybrid systems, including surface-modified liposomes, biopolymer-incorporated liposomes, guest-in-cyclodextrin-in-liposome, liposome-in-hydrogel, liposome-in-film, and liposome-in-nanofiber. The physicochemical principles and key technical information underlying the combined strategies for the fabrication of polymeric liposomes, the advantages and limitations of each of the systems, and the stabilization mechanisms are discussed through various case studies. Special emphasis is directed toward the synergistic efficiencies of biopolymers and phospholipid bilayers on encapsulation, protection, and controlled delivery of bioactives (e.g., vitamins, carotenoids, phenolics, peptides, and other health-related compounds) for the biomedical, pharmaceutical, cosmetic, and functional food applications. The major challenges, opportunities, and possible further developments for future studies are also highlighted.

Synthesis, Characterization, and Evaluation of Genistein-Loaded Zein/Carboxymethyl Chitosan Nanoparticles with Improved Water Dispersibility, Enhanced Antioxidant Activity, and Controlled Release Property

Genistein is one of major isoflavones derived from soybean products and it is believed to have beneficial effects on human health. However, its low water-solubility and poor oral bioavailability severely hamper its use as a functional food ingredient or for pharmaceutical industry. In this study, zein and zein/carboxymethyl chitosan (CMCS) nanoparticles were prepared to encapsulate genistein using a combined liquid-liquid phase separation method. The physicochemical properties of fabricated nanoparticles were characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that genistein encapsulated with zein nanoparticles significantly improved its water dispersibility, antioxidant activity in the aqueous phase, and photostability against UV light. Moreover, genistein encapsulated in zein nanoparticles showed a sustained release property. Furthermore, it was found that encapsulation efficiency of genistein was significantly enhanced after CMCS coating, and this effect was more pronounced after the complex nanoparticles cross-linked with calcium ions when compared with the use of zein as a single encapsulant. In addition, compared to zein nanoparticles without biopolymer coating, CMCS coating significantly enhanced the thermal and storage stability of the formed nanoparticles, and delayed the release of genistein. A schematic diagram of zein and zein/carboxymethyl chitosan (CMCS) nanoparticles formation mechanism for encapsulation of genistein was proposed. According to the results of the current study, it could be concluded that encapsulation of genistein in zein/CMCS nanoparticles is a promising approach to improve its water dispersibility, antioxidant activity, photostability against UV light and provide controlled release for food/pharmaceutical applications.

+Brettanomyces bruxellensis Displays Variable Susceptibility to Chitosan Treatment in Wine

Brettanomyces bruxellensis is the main spoilage microbial agent in red wines. The use of fungal chitosan has been authorized since 2009 as a curative treatment to eliminate this yeast in conventional wines and in 2018 in organic wines. As this species is known to exhibit great genetic and phenotypic diversity, we examined whether all the strains responded the same way to chitosan treatment. A collection of 53 strains of B. bruxellensis was used. In the conditions of the reference test, all were at least temporarily affected by the addition of chitosan to wine, with significant decrease of cultivable population. Some (41%) were very sensitive and no cultivable yeast was detected in wine or lees after 3 days of treatment, while others (13%) were tolerant and, after a slight drop in cultivability, resumed growth between 3 and 10 days and remained able to produce spoilage compounds. There were also many strains with intermediate behavior. The strain behavior was only partially linked to the strain genetic group. This behavior was little modulated by the physiological state of the strain or the dose of chitosan used (within the limits of the authorized doses). On the other hand, for a given strain, the sensitivity to chitosan treatment was modulated by the chitosan used and by the properties of the wine in which the treatment was carried out.

Coating of Nanolipid Structures by a Novel Simil-Microfluidic Technique: Experimental and Theoretical Approaches

Nanolipid vesicular structures are ideal candidates for the controlled release of various ingredients, from vitamins for nutraceutical purposes to chemoterapic drugs. To improve their stability, permeability, and some specific surface properties, such as mucoadhesiveness, these structures can require a process of surface engineering. The interaction of lipid vesicles with oppositely charged polyelectrolytes seems to be an interesting solution, especially when the negatively charged liposomes are complexed with the cationic chitosan. In this work, a novel simil-microfluidic technique was used to produce both chitosan-coated vesicles and a vegan alternative composed of cholesterol-free liposomes coated by Guar Hydroxypropyltrimonium Chloride (Guar-HC). The combination between the experimental approach, based on experimental observations in terms of Z-potential, and size evolutions, and the theoretical approach, based on concepts of saturation, was the methodology applied to define the best polycation concentration to fairly cover (vegan or not) liposomes without aggregation. The smart production of coated nanolipid structures was confirmed by characterizations of morphology, mucoadhesiveness, and stability.

Modification of Chitosan for the Generation of Functional Derivatives

Today, chitosan (CS) is probably considered as a biofunctional polysaccharide with the most notable growth and potential for applications in various fields. The progress in chitin chemistry and the need to replace additives and non-natural polymers with functional natural-based polymers have opened many new opportunities for CS and its derivatives. Thanks to the specific reactive groups of CS and easy chemical modifications, a wide range of physico-chemical and biological properties can be obtained from this ubiquitous polysaccharide that is composed of β-(1,4)-2-acetamido-2-deoxy-d-glucose repeating units. This review is presented to share insights into multiple native/modified CSs and chitooligosaccharides (COS) associated with their functional properties. An overview will be given on bioadhesive applications, antimicrobial activities, adsorption, and chelation in the wine industry, as well as developments in medical fields or biodegradability.

Combination of internal structuring and external coating in an oleogel-based delivery system for fish oil stabilization

In this study, we created oleogel-based formulations featuring varying degrees of beeswax for internal structure and whey protein isolate (WPI) as external coating to improve the oxidative stability of fish oil. Oleogel was characterized by rheological analysis to access gelation behavior, and morphology was visualized using electron microscopy. It was found that the WPI-coated oleogel displayed strong physical stability during storage. The oxidative assay demonstrated that WPI-coated oleogel had the best protection against fish oil oxidation under both thermal treatment and ultraviolet-C radiation. The oxidation of fish oil was inhibited by 2-3 fold, compared to its unencapsulated form. This stability was attributed to the modulation of beeswax and WPI on the micropolarity and microviscosity of the formulation, as evidenced by pyrene fluorescence measurement. Our approach combining internal structuring and external coating may contribute to the development of oleogel system for efficient delivery of lipophilic bioactive components.

Characterizations on the Stability and Release Properties of β-ionone Loaded Thermosensitive Liposomes (TSLs)

Liposomes with phase transition temperatures, T_m, near pathogenic site temperature are potential chemoprophylactic delivery vehicles. We prepared and characterized the thermal properties of liposomes composed of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and hydrogenated soy phosphatidylcholine (HSPC) incorporating β-ionone with T_m at 42 °C. Liposomes with β-ionone/lipid ratio (w/w) of 1:20 and 1:8 had the necessary stability and released most of the β-ionone. The molecular architecture surrounding T_m was studied by fluorescent probes, Raman spectroscopy, and differential scanning calorimeter (DSC). β-Ionone was found to be preferentially located in the deep regions of the lipid bilayer (toward the long chain alkyl of the lipid) at moderate loading. The results showed that β-ionone encapsulated liposomes have a superior release at higher loading amount. Increasing β-ionone leads to disorder in the liquid crystalline state and accelerates the release rate. These studies provide information on the membrane structural properties of β-ionone loaded liposomes that guide rational bioactive molecular delivery systems design for health products.

A chitosan-coated liposome encapsulating antibacterial peptide, Apep10: characterisation, triggered-release effects and antilisterial activity in thaw water of frozen chicken

Contamination of Listeria monocytogenes in food and their processing environment is a focus of attention in the food industry. To achieve the controlled release of antibacterial agents to a food processing environment contaminated by L. monocytogenes, chitosan-stabilised liposomes encapsulating Apep10 (GLARCLAGTL), an antibacterial peptide derived from boiled-dried anchovies, were prepared by utilising listeria toxins to activate the peptide release. Characteristics including the particle size, polydispersity index (PDI), encapsulation efficiency (EE), and morphology of the chitosan-coated Apep10 liposomes were investigated. The chitosan liposomes were more stable than their uncoated counterparts, which indicated that the coating of chitosan on the surface of the liposomes inhibited undesirable vesicle fusion and payload release during storage. However, once the chitosan-stabilised liposomes encountered L. monocytogenes, which secretes pore-forming toxins, the encapsulated antibacterial peptide was released and it exerted antimicrobial effects on the strain. The results of time-kill inhibition, scanning electron microscopy (SEM), crystal violet staining and confocal laser scanning microscopy (CLSM) images demonstrated that these liposomes have favourable antibacterial and anti-biofilm activities against L. monocytogenes in the thaw water of frozen chicken. This bacterial toxin-enabled release of the encapsulated antibacterial peptide from chitosan-coated liposomes provides an effective approach for the control of listerial contamination. This technique can be broadly applied to treat contamination by a variety of pathogens that secrete pore-forming toxins.

Polyelectrolyte microcapsules built on CaCO3 scaffolds for the integration, encapsulation, and controlled release of copigmented anthocyanins

The all-polysaccharide based polyelectrolyte microcapsules combining copigmentation for anthocyanin encapsulation and stabilization were fabricated. Copigmented complexes of chondroitin sulfate and anthocyanin were preloaded in CaCO₃ scaffold, and then microcapsules were created by coating the sacrificial CaCO₃ using layer-by-layer technique. It was observed that the preloading of copigmented complex affected the precipitation reaction of CaCO₃ and the subsequent entrapment of anthocyanin. With addition of anthocyanin from 0.125 to 0.75 mg, copigmentation can significantly increase the encapsulation efficiency of anthocyanin in CaCO₃, whereas such effect was not obvious at higher loadings. The leakage of anthocyanin during CaCO₃ core dissolution and storage was also inhibited by two polysaccharide layers coupled with copigmentation, which may be related to the formation of interconnecting networks. Additionally, a higher anthocyanin antioxidant activity was provided by carbohydrate matrix. These findings may allow for the encapsulation of large amounts of water-soluble components; particularly natural colorant by copigmented complex-polyelectrolyte structures.