Preparation of pH-Responsive Dual-Compartmental Microcapsules via Pickering Emulsion and Their Application in Multifunctional Textiles

Lignin microcapsules prepared on the basis of flexible skeleton with high foliar retention and UV shielding properties

Lignin-based microcapsules are extremely attractive for their biodegradability and photolysis resistance. However, the water-soluble all-lignin shells were unsatisfactory in terms of rainfall and foliar retention, and lacked the test of agricultural production practices. Herein, a novel microcapsule based on a flexible skeleton formed by interfacial polymerization and absorbed with lignin particles (LPMCs) was prepared in this study. Further analysis demonstrated that the shell was formed by cross-linking the two materials in layers and showed excellent flexibility and photolysis resistance. The pesticide loaded LPMCs showed about 98.68 % and 73.00 % improvement in scour resistance and photolysis resistance, respectively, as compared to the bare active ingredient. The foliar retention performance of LPMCs was tested in peanut plantations during the rainy season. LPMCs loaded with pyraclostrobin (Pyr) and tebuconazole (Teb) exhibited the best foliar disease control and optimum plant architecture, resulting in an increase in yield of about 5.36 %. LPMCs have a promising application prospect in the efficient pesticide utilization, by controlling its deformation, adhesion and release, an effective strategy for controlling diseases and managing plant growth was developed.

Production and investigation of Pickering emulsion stabilised by casein-Qodume Shirazi (Alyssum homolocarpum) seed gum complex particles: gastrointestinal digestion

Recently, there has been growing research interests in designing Pickering emulsions. In this work, Alyssum homolocarpum seed gum (AHSG) and casein protein (CP) nanoparticles (NPs) fabricated as Pickering stabilizers. AHSG (0.0, 0.05, 0.10, and 0.15% (w/w))-CP (2% (w/w)) nanoparticles were fabricated and their properties were investigated (mean diameter, morphology, zeta potential, Fourier transform infra-red, and contact angle). Formation and stability of Pickering emulsion (Pes) stabilized by AHSG-CP NPs were monitored by mean diameter, rheological properties, and in vitro digestion. AHSG-CP Nps exhibited a small size (107.75 ± 0.42-201.52 ± 0.70 nm) and had wettability between 64.94 ± 3.44° and 70.92 ± 7.64°. The stability of PEs was greatly improved by 0.05AHSG-CP NPs, even after 30 days of storage, centrifugation, and in vitro digestion, owing to the reinforcement of particle structure at the oil/water interfaces.This study demonstrates that 0.05% (w/w) AHSG-CP NP showed the highest stability during storage and against gastrointestinal digestion which showed its suitability as a fat reducer emulsion structure.

Preparation of robust silicone superhydrophobic and antibacterial textiles using the Pickering emulsion method

This study aimed to prepare textiles with superhydrophobic and antibacterial properties using the Pickering emulsion impregnation method. Cellulose nanocrystals were synergistically employed with dimethyloctadecyl[3-(trimethoxysilyl)-propyl] ammonium chloride as the solid surfactant, and hydrogenated (PHMS) and hydroxyl (MSDS) polysiloxane were used as the oil phase for emulsification. The emulsions were mixed and diluted in specific proportions, and the superhydrophobic and antibacterial textiles were prepared through fabric impregnation-drying strategies. The study optimised factors such as emulsion ratio and surfactant dosage. Results demonstrated that the nanoscale rough structure prepared using Pickering emulsion exhibited remarkable superhydrophobicity with contact and rolling angles of 163.1° ± 0.5° and 7.2° ± 0.2°, respectively. This effect was achieved when the ratio of PHMS emulsion to MSDS emulsion was maintained at 1:2 and the surfactant dosage was set at 2 %. The superhydrophobicity of textiles was maintained even after three washing cycles and 50 abrasion cycles, demonstrating excellent mechanical durability. The developed textiles also exhibited excellent oil/water separation ability, reliable recyclability and stability. Moreover, they demonstrated excellent self-cleaning and antibacterial capabilities. Thus, these valuable functionalities hold the potential to considerably improve the practical feasibility of superhydrophobic textiles in various application scenarios.

Novel antimicrobial and self-healing dental resin to combat secondary caries and restoration fracture

OBJECTIVE

Dental resin composites have been the most popular materials for repairing tooth decay in recent years. However, secondary caries and bulk fracture are the major hurdles that affect the lifetime of dental resin composites. This current study synthesized a novel antimicrobial and self-healing dental resin containing nanoparticle-modified self-healing microcapsules to combat secondary caries and restoration fracture.

METHODS

Multifunctional dental resins containing 0-20% nanoparticle-modified self-healing microcapsules were prepared. The water contact angle, antimicrobial properties, mechanical properties, cell toxicity, and self-healing capability of the dental resins were tested.

RESULTS

A novel multifunctional dental resin was synthesized. When the microcapsule mass fraction was 10%, the resin presented a strong bacteriostasis rate (80.3%) and excellent self-healing efficiency (66.1%), while the hydrophilicity, mechanical properties, and cell toxicity were not affected.

SIGNIFICANCE

The novel antimicrobial self-healing dental resin is a promising candidate for use in clinical practice, which provides a simple and highly efficient strategy to combat secondary caries and restoration fracture. This novel dental resin also gives the inspiration to prolong the service life of dental restorations.

Temperature-Sensitive Fragrance Microcapsules with Double Capsule Walls: A Study on Preparation and Sustained Release Mechanism

Microcapsules are small particles that can effectively protect a core material from degradation. Microcapsules with double capsule walls can improve stability and reduce breakage due to the fact that the physical and chemical properties of double-walled materials can complement each other, thus enhancing the quality and applicability of a microcapsule. Microcapsules can achieve controlled release of core materials by using a temperature-sensitive wall material. In this research, gelatin was used as the inner wall material for these double-walled microcapsules. The outer wall material was a composite material prepared by the reaction of a hydroxyl group in gum arabic with an amino group in N-isopropylacrylamide (NIPAM) in the presence of N, N'-methylene bisacrylamide (BIS), while lavender fragrance oil served as the core material. A complex coalescence method was used for the preparation of microcapsules with double capsule walls. The effects of different proportions of gum arabic to NIPAM on the core loading, microcapsule yield and thermal stability of microcapsules were studied in detail. Additionally, the stability of these fragrance microcapsules with double capsule walls in different solvents and pH values was evaluated. The sustained release properties and mechanism of cotton fabrics treated with prepared fragrance microcapsules were investigated. The results show that the microcapsules prepared with a 10:1 ratio of NIPAM to gum arabic have good temperature responsiveness. Therefore, clothing treated with microcapsules with temperature-sensitive wall materials can ensure that the human body has a fresh and pleasant smell in the case of perspiring in summer.

Gastrointestinal pH-Sensitive Pickering Emulsions Stabilized by Zein Nanoparticles Coated with Bioactive Glycyrrhizic Acid for Improving Oral Bioaccessibility of Curcumin

Pickering emulsions have received considerable attention for their stability and functionality. Environmentally responsive Pickering emulsions could be used as vehicles for oral administration. However, challenges still exist, such as nonbiocompatibility of emulsifier and mismatched response behavior in the gastrointestinal environment. In this study, a strategy was proposed that bioactive saponin glycyrrhizic acid (GA) was used as a pH-responsive substance to functionalize zein nanoparticles, and tannic acid (TA) was used as a primer for cross-linking GA and zein nanoparticles. The Pickering emulsions fabricated by zein/TA/GA nanoparticles (ZTGs) exhibited excellent stability at acid conditions while slowly demulsifying at neutral conditions, which can be further used as an intestine-targeted delivery system. Curcumin was encapsulated into ZTG-stabilized Pickering emulsions, and the encapsulation efficiency results suggested that the presence of GA coating remarkably facilitated the encapsulation of curcumin. An in vitro digestion study suggested that ZTGs provided protection for emulsions from pepsin hydrolysis and exhibited higher free fatty acid release as well as higher bioaccessibility of curcumin during simulated intestine digestion. This study provides an effective strategy to prepare pH-responsive Pickering emulsions for improving the oral bioaccessibility of hydrophobic nutraceuticals.

Factors that affect Pickering emulsions stabilized by mesoporous hollow silica microspheres

HYPOTHESIS

Classical (solid particles stabilized) Pickering emulsions have been widely studied due to the irreversible adsorption of solid particles at the oil-water interface. Mesoporous hollow silica microspheres (MHSMs) are promising stabilizers for Pickering emulsion owing to its larger specific surface area and lower apparent density. However, this type of Pickering emulsion has not attracted enough attention. The stabilization mechanism of Pickering emulsion by MHSMs has not been studied in detail yet.

EXPERIMENTS

Herein, stable Pickering emulsions were prepared using only MHSMs as stabilizers. In order to investigate its stabilization mechanism, the effect factors of size, shell thickness, wettability and concentration of MHSMs, and oil/water ratio on the stability of Pickering emulsions were analyzed deeply.

FINDINGS

As a result, the stability of Pickering emulsion can be improved by MHSMs with smaller particle size and shell thickness. Also, MHSMs with the intermediate hydrophobicity and suitable oil/water ratio actually do favour for the stability of Pickering emulsion. As expected, the stability of Pickering emulsion can be enhanced by increasing the concentration of MHSMs in a certain range. The Pickering emulsions tend to achieve excellent stable state when the concentration of MHSMs is 1.25 mg/mL. All those results suggested that the stability of Pickering emulsions correlates directly to particle size, shell thickness, wettability and concentration of MHSMs, and oil/water ratio. This research paves a way for the fabrication of functional materials via Pickering emulsions.

Copper(I)-Iodide Clusters as Carriers for Regulating and Visualizing Release of Aroma Molecules

Achieving the controlled release of functional substances is indispensable in many aspects of life. Especially for the aroma molecules, their effective delivery of flavor and fragrance is challenging. Here, selected pyridines, as highly volatile odorants, were individually coordinated with copper(I) iodide (Cu^II) via a straightforward one-pot synthesis method, rapidly forming pure or even crystalline Cu^II cluster-based profragrances at room temperature. The obtained profragrances enabled the stable and high loading of volatile fragrances under ambient conditions and guaranteed their long-lasting release during heating. Furthermore, the intrinsic emission luminescence of these solid-state profragrances decayed along with the aroma release, which can serve as an additional indicator for monitoring the delivery process. This research sets a precedent for using Cu^II clusters as dual-purpose release agents and greatly expands their potential applications.

Stimulus responsive microcapsules and their aromatic applications

Fragrances and essential oils are promising for a wide range of applications due to their pleasant odors and diverse effects. However, direct addition to consumer products has the disadvantages of short retention time and easy deterioration of odor. At the same time, releasing a large amount of odor in a short time may be an unpleasant experience, which severely limits the practical application of aromatic substances. Microencapsulation perfectly solves these problems. Stimuli-responsive microcapsules, which combine environmental stimulation with microencapsulation, can not only effectively prevent the rapid decomposition and evaporation of aroma components, but also realize the "on-off" intelligent release of aroma substances to environmental changes, which have great promise in the field of fragrances. In this review, the application of stimuli-responsive microcapsules in fragrances is highlighted. Firstly, various encapsulation materials used to prepare stimuli-responsive aromatic microcapsules are described, mainly including some natural polymers, synthetic polymers, and inorganic materials. Subsequently, there is a detailed description of the common release mechanisms of stimuli-responsive aromatic microcapsules are described in detail. Finally, the application and future research directions are given for stimuli-responsive aromatic microcapsules in new textiles, food, paper, and leather.

Microencapsulation for Functional Textile Coatings with Emphasis on Biodegradability—A Systematic Review

The review provides an overview of research findings on microencapsulation for functional textile coatings. Methods for the preparation of microcapsules in textiles include in situ and interfacial polymerization, simple and complex coacervation, molecular inclusion and solvent evaporation from emulsions. Binders play a crucial role in coating formulations. Acrylic and polyurethane binders are commonly used in textile finishing, while organic acids and catalysts can be used for chemical grafting as crosslinkers between microcapsules and cotton fibres. Most of the conventional coating processes can be used for microcapsule-containing coatings, provided that the properties of the microcapsules are appropriate. There are standardised test methods available to evaluate the characteristics and washfastness of coated textiles. Among the functional textiles, the field of environmentally friendly biodegradable textiles with microcapsules is still at an early stage of development. So far, some physicochemical and physical microencapsulation methods using natural polymers or biodegradable synthetic polymers have been applied to produce environmentally friendly antimicrobial, anti-inflammatory or fragranced textiles. Standardised test methods for evaluating the biodegradability of textile materials are available. The stability of biodegradable microcapsules and the durability of coatings during the use and care of textiles still present several challenges that offer many opportunities for further research.

Nanocapsules with excellent biocompatibility and stability in protein solutions

Silica nanocapsules (SiO₂NCs) are usually prepared with cationic surfactants that are not cytocompatible. Dialysis can be used to remove surfactants but leads to instability of the SiO₂NCs when they are in the presence of proteins or biological media. Herein, SiO₂NCs stabilized with a reactive surfactant are synthesized to prevent leaching upon dialysis. The SiO₂NCs show superior stability and biocompatibility compared with SiO₂NCs prepared with conventional surfactants. The SiO₂NCs can be used in self-healing materials, smart agriculture and biomedical applications.

One-Pot Facile Synthesis of Double-Shelled Mesoporous Silica Microcapsules with an Improved Soft-Template Method for Sustainable Pest Management

A controlled release formulation based on silica microcapsules is an ideal selection to improve both the effective utilization and duration of pesticides to decrease ecological damage. Herein, a simple and green method for preparing double-shelled microcapsules was developed using a newly prepared quaternary ammonium ionic liquid (IL) as the functional additive to entrap avermectin (Ave) in mesoporous silica nanospheres (MSNs) and tannic acid-Cu (TA-Cu) complex as the sealing agent to form the core-shell structure (Ave-IL@MSN@TA-Cu). The obtained microcapsules with an average size of 538 nm had pH-responsive release property and good stability in soil. The half-life of microcapsules (34.66 days) was 3 times that of Ave emulsifiable concentrate (EC) (11.55 days) in a test soil, which illustrated that microcapsules could protect Ave from rapid degradation by microorganisms by releasing TA, copper, and quaternary ammonium in the soil. Ave-IL@MSN@TA-Cu microcapsules had better nematicidal activity and antibacterial activity than Ave EC due to the synergistic effect of Ave, IL, and copper incorporated in the microcapsules. Pot experiments showed that the control efficacy of microcapsules was 87.10% against Meloidogyne incognita, which is better than that of Ave EC (41.94%) at the concentration of 1.0 mg/plant by the root-irrigation method after 60 days of treatment owing to the extended duration of Ave in microcapsules. The simple and green method for the preparation of double-shelled microcapsules based on natural quaternary ammonium IL would have tremendous potential for the extensive development of controlled release pesticide formulations.