Eco-Friendly Silica Microcapsules with Improved Fragrance Retention

Current Challenges in Microcapsule Designs and Microencapsulation Processes: A Review

Microencapsulation is an advanced methodology for the protection, preservation, and/or delivery of active materials in a wide range of industrial sectors, such as pharmaceuticals, cosmetics, fragrances, paints, coatings, detergents, food products, and agrochemicals. Polymeric materials have been extensively used as microcapsule shells to provide appropriate barrier properties to achieve controlled release of the encapsulated active ingredient. However, significant limitations are associated with such capsules, including undesired leaching and the nonbiodegradable nature of the typically used polymers. In addition, the energy cost of manufacturing microcapsules is an important factor to be considered when designing microcapsule systems and the corresponding production processes. Recent factors linked to UN sustainability goals are modifying how such microencapsulation systems should be designed in pursuit of "ideal" microcapsules that are efficient, safe, cost-effective and environmentally friendly. This review provides an overview of advances in microencapsulation, with emphasis on sustainable microcapsule designs. The key evaluation techniques to assess the biodegradability of microcapsules, in compliance with recently evolving European Union requirements, are also described. Moreover, the most common methodologies for the fabrication of microcapsules are presented within the framework of their energy demand. Recent promising microcapsule designs are also highlighted for their suitability toward meeting current design requirements and stringent regulations, tackling the ongoing challenges, limitations, and opportunities.

Eco-Friendly Fungal Chitosan-Silica Dual-Shell Microcapsules with Tailored Mechanical and Barrier Properties for Potential Consumer Product Applications

Commercial perfume microcapsules are becoming popular across the globe to fulfill consumers' demands. However, most of microcapsules rely on synthetic polymers and/or animal-sourced ingredients to form the shells. Therefore, replacement of the shell materials is imperative to minimize environmental microplastic pollution, as well as to meeting peoples' needs, religious beliefs, and lifestyles. Herein, we report a methodology to fabricate environmentally benign dual-shell (fungal chitosan-SiO2) microcapsules laden with fragrance oil (hexyl salicylate). Anionically stabilized oil droplets were coated with fungal chitosan via interfacial electrostatic interactions at pH 2, which were then covered by an inorganic coating of SiO2 produced via external alkaline mineralization of sodium silicate. Core-shell microcapsules with a spherical morphology were achieved. Under compression, dual-shell chitosan-SiO2 microcapsules yielded a mean nominal rupture stress of 3.0 ± 0.2 MPa, which was significantly higher than that of single-shell microcapsules (1.7 ± 0.2 MPa). After 20 days in neutral pH water, only ∼2.5% of the oil was released from dual-shell microcapsules, while single-shell microcapsules cumulatively released more than 10%. These findings showed that the additional SiO2 coating significantly enhanced both mechanical and barrier properties of microcapsules, which may be appealing for multiple commercial applications, including cosmetics and detergents.

Efficient strategies for controlled release of nanoencapsulated phytohormones to improve plant stress tolerance

Climate change due to different human activities is causing adverse environmental conditions and uncontrolled extreme weather events. These harsh conditions are directly affecting the crop areas, and consequently, their yield (both in quantity and quality) is often impaired. It is essential to seek new advanced technologies to allow plants to tolerate environmental stresses and maintain their normal growth and development. Treatments performed with exogenous phytohormones stand out because they mitigate the negative effects of stress and promote the growth rate of plants. However, the technical limitations in field application, the putative side effects, and the difficulty in determining the correct dose, limit their widespread use. Nanoencapsulated systems have attracted attention because they allow a controlled delivery of active compounds and for their protection with eco-friendly shell biomaterials. Encapsulation is in continuous evolution due to the development and improvement of new techniques economically affordable and environmentally friendly, as well as new biomaterials with high affinity to carry and coat bioactive compounds. Despite their potential as an efficient alternative to phytohormone treatments, encapsulation systems remain relatively unexplored to date. This review aims to emphasize the potential of phytohormone treatments as a means of enhancing plant stress tolerance, with a specific focus on the benefits that can be gained through the improved exogenous application of these treatments using encapsulation techniques. Moreover, the main encapsulation techniques, shell materials and recent work on plants treated with encapsulated phytohormones have been compiled.

Two-Phase Extraction Processes, Physicochemical Characteristics, and Autoxidation Inhibition of the Essential Oil Nanoemulsion of Citrus reticulata Blanco (Tangerine) Leaves

Combined ultrasound-microwave techniques and pre-enzymatic treatment (hemicellulase and cellulase) enhance essential oil isolation from Citrus reticulata Blanco (tangerine) leaves (CrBL). Subsequently, synergistic effects of modified amorphous octenyl succinic anhydride starch (OSA-MS), almond oil, and high-energy microfluidics were studied in synergy with ultrasound techniques in the production of CrBL essential oil (CrBL-EO) nanoemulsion (CrBL-EONE). GC-MS was used to study the extraction technique. Dynamic light scattering (DLS) analysis was used with confocal laser scanning microscopy (CLSM) techniques to investigate the nanoemulsion matrices' physical and chemical properties. The D-limonene nanoemulsion (D-LNE) reached the optimal size of droplets (65.3 ± 1.1 r.nm), polydispersity index (PDI) (0.167 ± 0.015), and ζ-potential (-41.0 ± 0.4 mV). Besides, the CrBL-EONE obtained the optimal size of droplets (86.5 ± 0.5 r.nm), PDI (0.182 ± 0.012), and ζ-potential (-40.4 ± 0.8 mV). All the nanoparticle treatments showed significant values in terms of the creaming index (CI%) and inhibition activity (IA%) in the β-carotene/linoleate system with a low degradation rate (DR). The current study's findings showed that integrated ultrasound-microwave techniques and pre-enzymatic treatment could enhance the extraction efficiency of the CrBL-EO. In addition, OSA-MS and almond oil can also be employed to produce CrBL-EONE and D-LNE.