Preparation of keratin-based microcapsules for encapsulation of hydrophilic molecules

Development and Evaluation of Microencapsulated Oregano Essential Oil as an Alternative Treatment for Candida albicans Infections

Vulvovaginal candidiasis (VVC) is characterized as a very common fungal infection that significantly affects women's health worldwide. Essential oils (EOs) are currently being evaluated as an alternative therapy. The development of efficient techniques such as micro- or nanoencapsulation for protecting and controlling release is essential to overcome the limitations of EO applications. Therefore, the aim of this study was to develop and characterize oregano EO-loaded keratin microparticles (OEO-KMPs) as a potential treatment for VVC. OEO-KMPs were produced using high-intensity ultrasonic cycles and characterized in terms of morphological and physicochemical parameters. In vitro evaluation included assessing the toxicity of the OEO-KMPs and their effect against Candida albicans using microdilution and agar diffusion, while the activity against biofilm was quantified using colony forming units (CFU). The efficacy of the OEO-KMPs in an in vivo VVC mouse model was also studied. Female BALB/c mice were intravaginally infected with C. albicans, 24 h postinfection animals were treated intravaginally with 15 μL of OEO-KMPs and 24 h later vaginal fluid was analyzed for C. albicans and Lactobacillus growth (CFU mL-1). The results showed the stability of the OEO-KMPs over time, with high encapsulation efficiency and controlled release. This nanoparticle size facilitated penetration and completely inhibited the planktonic growth of C. albicans. In addition, an in vitro application of 2.5% of the OEO-KMPs eradicated mature C. albicans biofilms while preserving Lactobacillus species. In in vivo, a single intravaginal application of OEO-KMPs induced a reduction in C. albicans growth, while maintaining Lactobacillus species. In conclusion, this therapeutic approach with OEO-KMPs is promising as a potential alternative or complementary therapy for VVC while preserving vaginal microflora.

Advances in protein-based microcapsules and their applications: A review

Due to their excellent emulsification, biocompatibility, and biological activity, proteins are widely used as microcapsule wall materials for encapsulating drugs, natural bioactive substances, essential oils, probiotics, etc. In this review, we summarize the protein-based microcapsules, discussing the types of proteins utilized in microcapsule wall materials, the preparation process, and the main factors that influence their properties. Additionally, we conclude with examples of the vital role of protein-based microcapsules in advancing the food industry from primary processing to deep processing and their potential applications in the biomedical, chemical, and textile industries. However, the low stability and controllability of protein wall materials lead to degraded performance and quality of microcapsules. Protein complexes with polysaccharides or modifications to proteins are often used to improve the thermal instability, pH sensitivity, encapsulation efficiency and antioxidant capacity of microcapsules. In addition, factors such as wall material composition, wall material ratio, the ratio of core to wall material, pH, and preparation method all play critical roles in the preparation and performance of microcapsules. The application area and scope of protein-based microcapsules can be further expanded by optimizing the preparation process and studying the microcapsule release mechanism and control strategy.

Preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics

Most of the functional substances in food are absorbed in the small intestine, but before entering the small intestine, the strong acid and enzymes in the stomach limit the amount that can reach the small intestine. Therefore, in this paper, to develop a delivery system for functional food ingredients, maintain the biological activity of the ingredients, and deliver them to the target digestive organs, preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics were reviewed. Embedding unstable food active ingredients in starch-based nano-microcapsules can give the core material excellent stability and certain functional effects. Starch-based wall materials refer to a type of natural polymer material that uses starch or its derivatives to coat fat-soluble components with its hydrophobic cavities. The preparation methods of starch-based wall materials mainly include spray drying, extrusion, freeze drying, ultra-high pressure, coagulation, fluidized bed coating, molecular inclusion, chemical, and enzymic methods. The controlled release of functional food can be achieved by preparing starch-based nano-microcapsules to encapsulate the active agents. It has been reported that that compared with traditional embedding agents such as gelatin, acacia gum, and xanthan gum, starch-based functional food nano-microcapsule delivery system had many good properties, including improving antioxidant capacity, bioavailability, probiotics, and concealing bad flavors. From this review, we can learn which method should be chosen to prepare starch-based functional food nano-microcapsule delivery system and understand the mechanism of controlled release.

Sonoproduction of nanobiomaterials - A critical review

Ultrasound (US) demonstrates remarkable potential in synthesising nanomaterials, particularly nanobiomaterials targeted towards biomedical applications. This review briefly introduces existing top-down and bottom-up approaches for nanomaterials synthesis and their corresponding synthesis mechanisms, followed by the expounding of US-driven nanomaterials synthesis. Subsequently, the pros and cons of sono-nanotechnology and its advances in the synthesis of nanobiomaterials are drawn based on recent works. US-synthesised nanobiomaterials have improved properties and performance over conventional synthesis methods and most essentially eliminate the need for harsh and expensive chemicals. The sonoproduction of different classes and types of nanobiomaterials such as metal and superparamagnetic nanoparticles (NPs), lipid- and carbohydrate-based NPs, protein microspheres, microgels and other nanocomposites are broadly categorised based on the physical and/or chemical effects induced by US. This review ends on a good note and recognises US-driven synthesis as a pragmatic solution to satisfy the growing demand for nanobiomaterials, nonetheless some technical challenges are highlighted.

Keratin-Chitosan Microcapsules via Membrane Emulsification and Interfacial Complexation

The continuous fabrication via membrane emulsification of stable microcapsules using renewable, biodegradable biopolymer wall materials keratin and chitosan is reported here for the first time. Microcapsule formation was based on opposite charge interactions between keratin and chitosan, which formed polyelectrolyte complexes when solutions were mixed at pH 5.5. Interfacial complexation was induced by transfer of keratin-stabilized primary emulsion droplets to chitosan solution, where the deposition of chitosan around droplets formed a core-shell structure. Capsule formation was demonstrated both in batch and continuous systems, with the latter showing a productivity up to 4.5 million capsules per minute. Keratin-chitosan microcapsules (in the 30-120 μm range) released less encapsulated nile red than the keratin-only emulsion, whereas microcapsules cross-linked with glutaraldehyde were stable for at least 6 months, and a greater amount of cross-linker was associated with enhanced dye release under the application of force due to increased shell brittleness. In light of recent bans involving microplastics in cosmetics, applications may be found in skin-pH formulas for the protection of oils or oil-soluble compounds, with a possible mechanical rupture release mechanism (e.g., rubbing on skin).

Designing Natural Polymer-Based Capsules and Spheres for Biomedical Applications-A Review

Natural polymers, such as polysaccharides and polypeptides, are potential candidates to serve as carriers of biomedical cargo. Natural polymer-based carriers, having a core-shell structural configuration, offer ample scope for introducing multifunctional capabilities and enable the simultaneous encapsulation of cargo materials of different physical and chemical properties for their targeted delivery and sustained and stimuli-responsive release. On the other hand, carriers with a porous matrix structure offer larger surface area and lower density, in order to serve as potential platforms for cell culture and tissue regeneration. This review explores the designing of micro- and nano-metric core-shell capsules and porous spheres, based on various functions. Synthesis approaches, mechanisms of formation, general- and function-specific characteristics, challenges, and future perspectives are discussed. Recent advances in protein-based carriers with a porous matrix structure and different core-shell configurations are also presented in detail.

Closing the Loop with Keratin-Rich Fibrous Materials

One of the agro-industry's side streams that is widely met is the-keratin rich fibrous material that is becoming a waste product without valorization. Its management as a waste is costly, as the incineration of this type of waste constitutes high environmental concern. Considering these facts, the keratin-rich waste can be considered as a treasure for the producers interested in the valorization of such slowly-biodegradable by-products. As keratin is a protein that needs harsh conditions for its degradation, and that in most of the cases its constitutive amino acids are destroyed, we review new extraction methods that are eco-friendly and cost-effective. The chemical and enzymatic extractions of keratin are compared and the optimization of the extraction conditions at the lab scale is considered. In this study, there are also considered the potential applications of the extracted keratin as well as the reuse of the by-products obtained during the extraction processes.

Photocatalytic Properties of Core-Shell Structured Wool-TiO2 Hybrid Composite Powders

In this study, a special core–shell structured wool-TiO2 (WT) hybrid composite powder also having TiO2 nanoparticles incorporated inside cortical cells was reported. The wool pallets were pulverized from wool fibers using vibration-assisted ball milling technique and the WT powders having mesopores and macropores were produced in hydrothermal process. Experimental results indicated that the infiltrated TiO2 nanoparticles were amorphous structure, while the coated TiO2 nanoparticles were anatase phase structure. The crystallized TiO2 nanoparticles were grafted with wool pallets by the N−Ti4+/S−Ti4+/O−Ti4+ bonds. The BET surface area was measured as 153.5 m2/g and the particle sizes were in the 600–3600 nm and 4000–6500 nm ranges. The main reactive radical species of the WT powders were holes, and •O2−, 1O2, and •OH were also involved in the photodegradation of MB dye under visible light irradiation. The experimental parameters for photodegradation of MB dye solution were optimized as follows: 0.25 g/L of WT powders was added in 40 mL of 3 mg/L MB dye solution containing 50 mL/L H2O2, which resulted in the increases of COD value of degraded MB dye solution up to 916.9 mg/L at 120 min. The WT powders could be used for repeatedly photodegradation of both anionic and cationic dyes.

Sonochemical fabrication of reduction-responsive magnetic starch-based microcapsules

In this work, a novel, biocompatible, non-immunogenic and reductive-responsive magnetic starch-based microcapsules (RMSMCs) were designed and fabricated successfully via a facile sonochemical method for targeted delivery and triggered release of hydrophobic drugs. TEM image indicated that oleic acid (OA) modified Fe₃O₄ nanoparticles (OA-Fe₃O₄ NPs) were encapsulated into RMSMCs. The obtained RMSMCs were endowed with magnetism for drug targeted delivery because that the superparamagnetic OA-Fe₃O₄ NPs were encapsulated into RMSMCs. Moreover, Coumarin 6 (C6), a green fluorescent dye, was used as a model hydrophobic drug and loaded into RMSMCs. As drug carriers, the obtained spherical RMSMCs with the average size of 2 μm presented excellent reductive-responsive release ability for hydrophobic drugs. Accordingly, the obtained RMSMCs would be promising carriers for targeted delivery and triggered release of hydrophobic drugs in biomedical applications.

Sonochemistry-Assembled Stimuli-Responsive Polymer Microcapsules for Drug Delivery

Stimuli-responsive polymer microcapsules (PMs) fabricated by the sonochemical method have emerged for developing useful drug delivery systems, and the latest developments are mainly focusing on the synthetic strategies and properties such as structure, size, stability, loading capacity, drug delivery, and release. There, the primary attribution of sonochemistry is to offer a simple and practical approach for the preparation of PMs. Structure, size, stability, and properties of PMs are designed mainly according to synthetic materials, implementation schemes, or specific demands. Numerous functionalities of PMs based on different stimuli are demonstrated: targeting motion in a magnetic field or adhering to the living cells with sensitive sites through molecular recognition, and stimuli-triggered release including enzymatic catalysis, chemical reaction as well as physical or mechanical process. The current review discusses the basic principles and mechanisms of stimuli effects, and describes the progress in the application such as targeted drug systems and controlled drug systems, and also gives an outlook on the future challenges and opportunities for drug delivery and theranostics.