Most of the traditional strategies used for facing the management of insect pest and diseases have started to fail due to different toxicological issues such as the resistance of target organism and ...the impact on environment and human health. This has made mandatory to seek new effective strategies, which minimize the risks and hazards without compromising the effectiveness of the products. The use of essential oils, their components and semiochemicals (pheromones and allelochemicals) has become a promising safe and eco-sustainable alternative for controlling insect pest and pathogens. However, the practical applications of this type of molecules remain rather limited because their high volatility, poor solubility in water and low chemical stability. Therefore, it is required to design strategies enabling their use without any alteration of their biological and chemical properties. Oil-in-water nano/microemulsions are currently considered as promising tools for taking advantage of the bioactivity of essential oils and their components against insects and other pathogens. Furthermore, these colloidal systems also allows the encapsulation and controlled release of semiochemicals, which enables their use in traps for monitoring, trapping or mating disruption of insects, and in push-pull strategies for their behavioral manipulation. This has been possible because the use of nano/microemulsions allows combining the protection provided by the hydrophobic environment created within the droplets with the enhanced dispersion of the molecules in an aqueous environment, which favors the handling of the bioactive molecules, and limits their degradation, without any detrimental effect over their biological activity. This review analyzes some of the most recent advances on the use of emulsion-like dispersions as a tool for controlling insect pest and pathogens. It is worth noting that even though the current physico-chemical knowledge about these systems is relatively poor, a deeper study of the physico-chemical aspects of nanoemulsions/microemulsions containing essential oils, their components or semiochemicals, may help for developing most effective formulations, enabling the generalization of their use.
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•Essential oils (EOs), their components (EOCs) or semiochemicals (SE) are allows controlling insect pests and pathogens.•Instability and volatility of EOs, EOCs or SEs require of strategies for taking advantage of their biological activity.•Micro-/nanoemulsions are good tools for design formulations with EOs, EOCs or SEs.•EOs, EOCs or SEs contained within emulsion-like systems commonly present higher biological activity that their free form.•Physico-chemical and operative parameter are essential in the characteristics of the micro−/nanoemulsions.
The current consumer demands together with the international regulations have pushed the cosmetic industry to seek new active ingredients from natural renewable sources for manufacturing more ...eco-sustainability and safe products, with botanical extract being an almost unlimited source of these new actives. Essential oils (EOs) emerge as very common natural ingredients in cosmetics and toiletries as a result of both their odorous character for the design and manufacturing of fragrances and perfumes, and the many beneficial properties of their individual components (EOCs), e.g., anti-inflammatory, antimicrobial and antioxidant properties, and, nowadays, the cosmetic industry includes EOs or different mixtures of their individual components (EOCs), either as active ingredients or as preservatives, in various product ranges (e.g., moisturizers, lotions and cleanser in skin care cosmetics; conditioners, masks or antidandruff products in hair care products; lipsticks, or fragrances in perfumery). However, the unique chemical profile of each individual essential oil is associated with different benefits, and hence it is difficult to generalize their potential applications in cosmetics and toiletries, which often require the effort of formulators in seeking suitable mixtures of EOs or EOCs for obtaining specific benefits in the final products. This work presents an updated review of the available literature related to the most recent advances in the application of EOs and EOCs in the manufacturing of cosmetic products. Furthermore, some specific aspects related to the safety of EOs and EOCs in cosmetics will be discussed. It is expected that the information contained in this comprehensive review can be exploited by formulators in the design and optimization of cosmetic formulations containing botanical extracts.
The fabrication of polyelectrolyte multilayer films (PEMs) using the Layer-by-Layer (LbL) method is one of the most versatile approaches for manufacturing functional surfaces. This is the result of ...the possibility to control the assembly process of the LbL films almost at will, by changing the nature of the assembled materials (building blocks), the assembly conditions (pH, ionic strength, temperature, etc.) or even by changing some other operational parameters which may impact in the structure and physico-chemical properties of the obtained multi-layered films. Therefore, the understanding of the impact of the above mentioned parameters on the assembly process of LbL materials plays a critical role in the potential use of the LbL method for the fabrication of new functional materials with technological interest. This review tries to provide a broad physico-chemical perspective to the study of the fabrication process of PEMs by the LbL method, which allows one to take advantage of the many possibilities offered for this approach on the fabrication of new functional nanomaterials.
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•Layer-by-layer (LbL) method is a powerful tool for the assembly of supramolecular materials.•Absence of any theoretical limitations to the assembled compounds and the geometry of the final material•Assembly of LbL multilayers is governed by an intricate balance of interactions.•Study of physico-chemical properties and structure of the LbL films is critical for their potential applications.
Lung surfactant is a complex mixture of lipids and proteins which plays a major role in the respiratory cycle. This makes necessary to understand the effects of different external factors or agents, ...for example, inhaled particles, as a potential source of alteration of the normal physiological response of lung surfactant. However, in most cases, in vivo studies are difficult to perform, and preliminary studies based in model systems are required. Films of lipids or mixtures of lipids and proteins at the water–vapor interface are accounted as one of the most useful methodologies for initial assessments of the potential toxicity of inhaled particles. Thus, the study of the modifications induced by the incorporation of colloidal particles in the interfacial properties of layers mimicking some of the physicochemical features of lung surfactant might provide a first evaluation of the risks and hazards associated with the inhalation of particulate matter. Considering the importance of particles in technology and industry, it is mandatory to develop strategies providing information about toxicological aspects of these widespread materials. This review focuses its interest on the recent advancements on the application of studied bases on monolayers at the fluid interface as preliminary assay for deepening on a complex situation with biological interest.
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•Lung surfactant film presents a central importance in the respiratory cycle.•Inhalation of particles may modify lung surfactant performance.•Studies based on lipids or lipids and protein mixtures help on the initial assessment of particle toxicity.•Deepening the real situation requires more complex studies.
The interaction of particles with fluid interfaces is ubiquitous in synthetic and natural work, involving two types of interactions: particle–interface interactions (trapping energy) and ...interparticle interactions. Therefore, it is urgent to gain a deep understanding of the main forces controlling the trapping of particles at fluid interfaces, and their assembly to generate a broad range of structures characterized by different degrees of order. This Perspective tries to provide an overview of the main contributions to the energetic landscape controlling the assembly of particles at fluid interfaces, which is essential for exploiting this type of interfacial systems as platforms for the fabrication of interface-based soft materials with technological interest.
The effect of the incorporation of hydrophilic titanium dioxide (TiO2) nanoparticles on the interfacial properties of Langmuir monolayers of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) has ...been evaluated combining interfacial thermodynamic studies, dilatational rheology, and Brewster angle microscopy (BAM). The results show that the TiO2 nanoparticles are able to penetrate DPPC layers, modifying the organization of the molecules and, consequently, the phase behavior and viscoelastic properties of the systems. Measurements of dilational viscoelasticity against the frequency have been performed, using the oscillatory barrier method, at different values of the surface pressure corresponding to different degrees of compression of the monolayer. The presence of TiO2 nanoparticles also affects the dynamic response of the monolayer modifying both the quasi-equilibrium dilatational elasticity and the high frequency limit of the viscoelastic modulus. The principal aim of this work is to understand the fundamental physicochemical bases related to the incorporation of specific nanoparticles of technological interest into the interfacial layer with biological relevance such as phospholipid layers. This can provide information on potential adverse effects of nanoparticles for health and the environment.
Pollution is currently a public health problem associated with different cardiovascular and respiratory diseases. These are commonly originated as a result of the pollutant transport to the alveolar ...cavity after their inhalation. Once pollutants enter the alveolar cavity, they are deposited on the lung surfactant (LS) film, altering their mechanical performance which increases the respiratory work and can induce a premature alveolar collapse. Furthermore, the interactions of pollutants with LS can induce the formation of an LS corona decorating the pollutant surface, favoring their penetration into the bloodstream and distribution along different organs. Therefore, it is necessary to understand the most fundamental aspects of the interaction of particulate pollutants with LS to mitigate their effects, and design therapeutic strategies. However, the use of animal models is often invasive, and requires a careful examination of different bioethics aspects. This makes it necessary to design in vitro models mimicking some physico-chemical aspects with relevance for LS performance, which can be done by exploiting the tools provided by the science and technology of interfaces to shed light on the most fundamental physico-chemical bases governing the interaction between LS and particulate matter. This review provides an updated perspective of the use of fluid films of LS models for shedding light on the potential impact of particulate matter in the performance of LS film. It should be noted that even though the used model systems cannot account for some physiological aspects, it is expected that the information contained in this review can contribute on the understanding of the potential toxicological effects of air pollution.
Liquid–fluid interfaces are ubiquitous systems, having a paramount importance for daily life as well as for academia, providing the basis for the study of different aspects of interest for medicine, ...biology, and physics ...
The study of the interaction between Langmuir monolayers of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC), as the major component of lung surfactant (LS), and nanoparticles of different nature, ...hydrophilic silica (SiO2) and hydrophobic carbon black (CB), has been carried out by measuring the compression Π–A isotherms and the response of the surface pressure to harmonic variations of the interfacial area simulating respiratory cycles in a Langmuir trough. The change of the monolayer interfacial structure induced by nanoparticles was monitored by Brewster angle microscopy. The results point out that nanoparticles incorporating into the monolayers influence the interfacial organization of the molecules and induce important modifications in both the phase behavior and the mechanical properties. Silica has stronger effects on DPPC phase behavior, compared to carbon black, while both affect the monolayer elasticity, the collapse conditions, and the nonlinearity of the surface pressure response to area expansion–compression simulating the respiratory cycles. With DPPC being the major component of pulmonary surfactant, the results here obtained are relevant in the framework of wider studies on the effect of nanoparticles on the pulmonary surfactant interfacial properties.
The assembly of soft colloidal particles at fluid interfaces is reviewed in the present paper, with emphasis on the particular case of microgels formed by cross-linked polymer networks. The dual ...polymer/colloid character as well as the stimulus responsiveness of microgel particles pose a challenge in their experimental characterization and theoretical description when adsorbed to fluid interfaces. This has led to a controversial and, in some cases, contradictory picture that cannot be rationalized by considering microgels as simple colloids. Therefore, it is necessary to take into consideration the microgel polymer/colloid duality for a physically reliable description of the behavior of the microgel-laden interface. In fact, different aspects related to the above-mentioned duality control the organization of microgels at the fluid interface, and the properties and responsiveness of the obtained microgel-laden interfaces. This works present a critical revision of different physicochemical aspects involving the behavior of individual microgels confined at fluid interfaces, as well as the collective behaviors emerging in dense microgel assemblies.
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