Transport and release in nano-carriers for food applications

"Characterization and stability of α-tocopherol loaded solid lipid nanoparticles formulated with different fully hydrogenated vegetable oils"

Solid lipid nanoparticles can be compatible with several bioactive compounds and confer a differentiated crystalline structure. This study aimed to produce α-tocopherol loaded solid lipid nanoparticles with fully hydrogenated oils and fats from palm oil, soybean oil, and crambe oil, by high-pressure homogenization, using lecithin as an emulsifier. After recrystallization of solid lipid nanoparticles, dispersions were evaluated until 60 days of storage for particle size, polydispersity index, zeta potential, microstructure, dispersion stability and α-tocopherol quantification. α-tocopherol loaded solid lipid nanoparticles showed particle sizes and zeta potential values considered adequate for this type of particle. Presence of α-tocopherol altered thermal behavior of the particles, leading to increased crystallinity, with no changes in polymorphism, when compared to the unloaded solid lipid nanoparticles. All α-tocopherol loaded solid lipid nanoparticles dispersions showed stability with no losses of α-tocopherol, indicating their potential as a carrier for this compound in fortified foods.

Smart antibacterial nanocellulose packaging film based on pH-stimulate responsive microcapsules synthesized by Pickering emulsion template

Spoilage results in food waste and endangers consumer health, and the smart antibacterial packaging can effectively inhibit bacterial growth and reduce food spoilage. In this study, the smart antibacterial nanocellulose packaging films were developed by adding the pH-stimulated responsive microcapsules into cellulose nanofibril (CNF) film-forming. The microcapsules were synthesized by interfacial polymerization of Pickering emulsion. Carboxylated cellulose nanocrystals as solid particles stabilized the composited oil phase to prepare the oil-in-water Pickering emulsion. The emulsion with the particle concentration of 1.25 wt% and the oil phase mass fraction of 7.5 % processes excellent stability and uniform particle size, was chosen to synthesize microcapsules. The cinnamaldehyde in the film with the addition amount of microcapsules 0.6 g burst released in the first 1 h and then slowly, and the cumulative release at pH 2.0, 4.0, 5.5 and 7.2 was 28.43 μg/cm2, 18.84 μg/cm2, 16.52 μg/cm2 and 12.89 μg/cm2, respectively. The inhibitory rate of film against both E. coli and L. monocytogenes reached 99 % at pH 4.0. The shelf life of pork packed by the film prolonged to nearly 9 d at room temperature. The developed films have the potential to be used in food packaging.

Characterization and stability of solid lipid nanoparticles produced from different fully hydrogenated oils

The use of lipids from conventional oils and fats to produce solid lipid nanoparticles (SLN) attracting interest from the food industry, since due their varying compositions directly affects crystallization behavior, stability, and particle sizes (PS) of SLN. Thus, this study aimed evaluate the potential of fully hydrogenated oils (hardfats) with different hydrocarbon chain lengths to produce SLN using different emulsifiers. For that, fully hydrogenated palm kern (FHPkO), palm (FHPO), soybean (FHSO), microalgae (FHMO) and crambe (FHCO) oils were used. Span 60 (S60), soybean lecithin (SL), and whey protein isolate (WPI) were used as emulsifiers. The physicochemical characteristics and crystallization properties of SLN were evaluated during 60 days. Results indicates that the crystallization properties were more influenced by the hardfat used. SLN formulated with FHPkO was more unstable than the others, and hardfats FHPO, FHSO, FHMO, and FHCO exhibited the appropriate characteristics for use to produce SLN. Concerning emulsifiers, S60- based SLN showed high instability, despite the hardfat used. SL-based and WPI-based SLN formulations, showed a great stability, with crystallinity properties suitable for food incorporation.

Smart antimicrobial Pickering emulsion stabilized by pH-responsive cellulose-based nanoparticles

Responsive antimicrobial materials can control and slow the release of antimicrobial agents smartly by responding to the stimulation of environmental conditions. In this study, we designed the pH-responsive cellulose-based nanoparticles (TOCNC-g-PEI) with amino and carboxyl groups by grafting polyethyleneimine (PEI) to carboxylated cellulose nanocrystals. Finally, the Pickering emulsion was endowed with smart antimicrobial properties by emulsifying the oregano essential oil (OEO) with nanoparticles. The TOCNC-g-PEI₂₅₀₀₀ had uniform size, greater dispersion, and excellent antimicrobial properties. The contact angles of nanoparticles were 78.70 ± 1.13°, 55.80 ± 1.58° and 55.35 ± 1.56° at neutral conditions, pH 4.0 and 8.0, respectively. The nanoparticles were responding to pH stimulation. The developed emulsion (4:6, 1.30 wt%) had exceptionally stabilized and encapsulated 98.56 ± 1.22 % of the oil phase. The OEO released rapidly within 0-12 h and slowly at 12-36 h. The cumulative release rates quickly reached 93.60 ± 3.73 % (pH 4.0) and 83.25 ± 0.36 % (pH 8.0) and stabilized gradually. The antimicrobial rates of emulsion stimulated for 4 h reached 100 % at pH 4.0, and both of them exceeded 96.10 ± 2.49 % at pH 8.0. The response of Pickering emulsion to pH stimulating controlled release antimicrobial agents and achieved smart antimicrobial.

Bio- and eco-corona related to plants: Understanding the formation and biological effects of plant protein coatings on nanoparticles

The thriving nano-enabled agriculture facilitates the interaction of nanomaterials with plants. Recently, these interactions and their biological effects are receiving increasing attention. Upon entering plants via leaves, roots, stems, and other organs, nanoparticles adsorb numerous biomolecules inside plants and form bio-corona. In addition, nanoparticles that enter plants through roots may have formed eco-corona with root exudates in the rhizosphere environment before contacting with plant exogenous proteins. The most significant biological effects of plant protein corona include changes in protein structure and function, as well as changes in nanoparticle toxicity and targeting ability. However, the mechanisms, particularly how protein corona affects plant protein function, plant development and growth, and rhizosphere environment properties, require further investigation. Our review summarizes the current understanding of the formation and biological effects of nanoparticle-plant protein corona and provides an outlook on future research.

Dynamic process, mechanisms, influencing factors and study methods of protein corona formation

Nanoparticles interacting with proteins to form protein corona represent one of the most fundamental problems in the rapid development of nanotechnology. In the past decade, thousands of studies have pointed out this issue. Within multi-protein systems, the formation of protein corona is a homeostasis process in which proteins compete for the limited surface sites of nanoparticles. Besides, the formation of protein corona generally shows a tendency of evolving with time and involves many different driving forces controlled by properties of nanoparticles, proteins and environment. Therefore, recent research on the dynamic process and mechanisms of protein corona formation in both animals and plants are summarized in this review. The factors that affect the formation and the techniques that commonly used for protein corona analysis are proposed. Furthermore, in order to provide reference for the future research, the limitations and challenges in protein corona studies are assessed and the future perspectives are proposed.

Quercetin delivery characteristics of chitosan nanoparticles prepared with different molecular weight polyanion cross-linkers

The aim of the study was to investigate the effects of cross-linkers on quercetin (QUE) absorption characteristics of QUE-loaded chitosan nanoparticles (CS-NPs). CS-NPs (461.2-482.7 nm) were prepared by ionic gelation at pH 3.5 using tripolyphosphate (367.9 Da), dextran sulfate (>15 kDa), arabic gum (AG, >250 kDa), or hyaluronic acid (HA, >1000 kDa). Mucoadhesion and cell permeation of QUE were significantly increased by positive charged CS-NPs due to interactions with negatively charged mucosal layer. Moreover, CS-AG and CS-HA NPs prepared with relatively higher MW cross-linkers exhibited significantly higher adhesion and permeation than the others. These results were verified by a cellular antioxidant activity assay; CS-AG (137.5 unit) and CS-HA NPs (126.5 unit) showed significantly higher activities after internalization into Caco-2 cells. Therefore, encapsulation within CS-NPs prepared using high MW cross-linkers such as AG and HA is found to be potentially valuable techniques for improving the QUE absorption.

Kinetic Analysis of Ultrasound-Induced Oil Exchange in Oil-in-Water Emulsions through Contrast Variation Time-Resolved Small-Angle Neutron Scattering

Ultrasound is one of the most commonly used methods for synthesizing and processing emulsion systems. In this study, the kinetics of acoustically induced emulsion oil exchange was examined using contrast variation time-resolved small-angle neutron scattering (CV-SANS). A custom-built sample environment was used to deliver acoustic forces while simultaneously performing CV-SANS experiments. It was observed that the oil exchange rate was significantly accelerated when sonicating at high acoustic pressures, where violent cavitation events can induce droplet coalescence and breakup. No significant oil exchange occurred at acoustic pressures below the cavitation threshold within the short time scales of the experiments. It was also observed that the oil exchange kinetics was deterred when emulsions were stabilized by surfactants. In addition, oil exchange rates varied nonlinearly with the concentration of surfactant, and exchange was slowest when the emulsions were stabilized by an intermediate concentration. It is hypothesized that emulsion size, electrostatic repulsion, and Gibbs elasticity of the oil-water interface play significant roles in the observed trends. The observed trends in oil exchange rates versus surfactant concentration coincide well with theoretical models for the fluctuation of the elasticity of the interface. Acoustically induced oil exchange was most inefficient when the interfacial elasticity was at its maximum value.

Contrast-Variation Time-Resolved Small-Angle Neutron Scattering Analysis of Oil-Exchange Kinetics Between Oil-in-Water Emulsions Stabilized by Anionic Surfactants

Contrast-variation time-resolved small-angle neutron scattering (CV-SANS) was used to examine oil-exchange kinetics between identical mixtures of hydrogenated/deuterated hexadecane emulsion systems. Oil-exchange rates were estimated by transforming recorded scattering profiles to a relaxation function and by fitting to exponential decay models. We find that the oil-exchange process was accelerated when the droplets were stabilized by anionic surfactants even at concentrations well below the surfactant critical micelle concentration. Moreover, the exchange rate was not significantly accelerated when surfactant micelles were present. This suggests that micellar-mediated transport mechanisms do not play the dominant role in these systems. Screening electrostatic repulsion by increasing the ionic strength of the medium also had a negligible effect on oil-exchange kinetics. In contrast, the use of oils with shorter alkane chain lengths (e.g., dodecane), having a higher solubility in water, significantly accelerated rates of oil transport between droplets. Oil-transport rates for hexadecane were also found to increase with temperature and to follow Arrhenius behavior. These results were rationalized as an increase in the droplet-collision frequency due to Brownian motion that results in direct oil transport without irreversible coalescence. Thus, primary mechanisms for oil exchange in insoluble anionic surfactant-stabilized emulsion systems are hypothesized to be through direct emulsion contact, reversible coalescence, and/or direct oil permeation through thin liquid films. CV-SANS is also demonstrated as a powerful technique for the study of transport kinetics in all kinds of emulsion systems.

The Functionalization of Nanostructures and Their Potential Applications in Edible Coatings

Nowadays, edible coatings incorporated with nanostructures as systems of controlled release of flavors, colorants and/or antioxidants and antimicrobial substances, also used for thermal and environmental protection of active compounds, represent a gap of opportunity to increase the shelf life of food highly perishable, as well as for the development of new products. These functionalized nanostructures have the benefit of incorporating natural substances obtained from the food industry that are rich in polyphenols, dietary fibers, and antimicrobial substances. In addition, the polymers employed on its preparation, such as polysaccharides, solid lipids and proteins that are low cost and developed through sustainable processes, are friendly to the environment. The objective of this review is to present the materials commonly used in the preparation of nanostructures, the main ingredients with which they can be functionalized and used in the preparation of edible coatings, as well as the advances that these structures have represented when used as controlled release systems, increasing the shelf life and promoting the development of new products that meet the characteristics of functionality for fresh foods ready to eat.

Compound Stability in Nanoparticles: The Effect of Solid Phase Fraction on Diffusion of Degradation Agents into Nanostructured Lipid Carriers

The stability of active compounds encapsulated in nanoparticles depends on the resistance of the particles to diffusion of environmental degradation agents. In this paper, off-lattice Monte Carlo simulations are used to investigate a suspension of nanostructured lipid carriers (NLC) composed of interspaced liquid and solid lipid domains, immersed in a solution containing molecules representing oxidative or other degradation agents. The simulations examine the diffusion of the degradation agents into the nanoparticles as a function of nanoparticle size, solid domain fraction, and domain size. Two types of suspensions are studied: one (representing an infinitely dilute nanoparticle suspension) where the concentration of oxidative agents is constant in the solution around the particle and the other, finite system where diffusion into the nanoparticle causes depletion in the concentration of degradation agents in the surrounding solution. The total number of degradation agent molecules in the NLCs is found to decrease with the solid domain fraction, as may be expected. However, their concentration in the liquid domains is found to increase with the solid domain fraction. Since the degradation reaction depends on the concentration of the degradation agents, this suggests that compounds encapsulated in nanoparticles with high liquid content (such as emulsions) will degrade less and be more stable than those encapsulated in NLCs with high solid domain fraction, in agreement with previous experimental results.

Nanotechnology Approaches for Increasing Nutrient Bioavailability

Health-promoting ingredients such as phenolic compounds, vitamins, and minerals are being increasingly introduced into foods and beverages to produce "functional foods" specifically designed to improve human health, well-being, and performance. However, it is often challenging to incorporate these nutraceuticals into foods because they have poor solubility characteristics, impart undesirable flavor profiles, are chemically unstable, or have low bioavailability. This problem can often be overcome by encapsulating the bioactive components in nanoparticle-based delivery systems. The bioavailability of encapsulated bioactive agents often increases when the size of the particles containing them decreases, due to their faster digestion, ability to penetrate the mucus layer, or direct uptake by cells. Nanoparticles can be formulated to survive passage through specific regions of the gastrointestinal tract and then release their payload at a specified point, thus maximizing their potential health benefits. Nutraceutical-loaded nanoparticles can be fabricated through lipid formulations, natural nanocarriers, specialized equipment, biopolymer nanoparticles, and miscellaneous techniques. Classification into these five groups is based on the main mechanism or ingredient used to fabricate the nanoparticles. This chapter focuses on the utilization of food-grade nanoparticles for improving the performance of nutraceuticals in functional foods and beverages.