Interfacial Stabilizers Research Articles

A Montmorillonite-Based Pickering Nanoemulsion for the Integration of Photothermal Therapy and NIR-Responsive Drug Delivery.

Chemo/photothermal combination therapy is a promising and practical approach for cancer treatment which calls for certain nanovehicles to achieve the spatiotemporal co-occurrence of photothermal conversion and drug delivery. Herein, we developed a montmorillonite-based Pickering emulsion equipped with a near-infrared photothermal agent (indocyanine green, ICG) and anticarcinogen (paclitaxel, PTX). With both montmorillonite and ICG functioning as interfacial stabilizers, the Pickering emulsion showed good stability and nanoscale droplet size, which were favored for cellular applications. Due to the vast oil-water interface, where the majority of amphiphilic ICG was prone to distribute, the Pickering nanoemulsion could achieve a higher local concentration of ICG than the aqueous solution, therefore leading to a higher local photothermal performance under near-infrared irradiation. The Pickering nanoemulsion exhibited fast cell penetration, which promoted the photothermal therapeutic effect of ICG. Moreover, the inner phase of the Pickering nanoemulsion also facilitated the loading of PTX, further improving its killing efficacy against cancer cells under near-infrared irradiation, because the photothermal conversion of the Pickering nanoemulsion could not only cause heat damage by itself but also promote the loaded PTX to diffuse out and induce cell death. Therefore, this clay-based Pickering nanoemulsion as a nanovehicle could realize the synergy of chemo- and photothermal therapy.

Soy proteins with various surface properties prepared by limited enzymatic hydrolysis and their potential on emulsion thickening and controlling lipolysis

In recent years, proteins with designed surface properties as interfacial stabilizers to obtain functional emulsions with controlled lipolysis has received increasing attention. In this work, four types of soy proteins (I, II, III, IV) with different surface properties were obtained by controlled enzymatic hydrolysis (Neutrase). Protein particle size, morphology, surface hydrophobicity and interfacial wettability were analyzed along with changes in subunits composition and secondary structure, aiming to establish a certain relationship between protein surface properties and its capacity in modulating emulsion properties. Specifically, Type I (α’, α, β, A and B subunits) as protein nanoparticles showed high surface hydrophobicity (+84%) and could form a thick interface to delay lipolysis (k1-24.0%, k-24.2%) through Pickering effect. Type II (α, β, A and B subunits) as protein aggregates in larger size showed high surface hydrophobicity (+45%) and roughness, which could enhance viscosity (equivalent to that of φ0.3–0.4 oil fraction) and delay lipolysis (k1-24.0%) by bridge flocculation. Further hydrolysis caused partial precipitation (originated from β and B subunits) and the soluble portion (Type III and IV) with decreased surface hydrophobicity and increased structural flexibility showed poor emulsification capacity and formed weak interface. It can be concluded that regulating subunit composition by enzymatic hydrolysis is an effective way to obtain proteins with multi-surface properties, which plays a vital role in modulating emulsion viscosity and lipolysis behavior. Results from the present study could provide a new strategy for the design of low-calorie emulsions for weight management.

Novel Pickering bigels stabilized by whey protein microgels: Interfacial properties, oral sensation and gastrointestinal digestive profiles

In the ongoing quest to formulate sensory-rich, low-fat products that maintain structural integrity, this work investigated the potential of bigels, especially those created using innovative Pickering techniques. By harnessing the unique properties of whey protein isolate (WPI) and whey protein microgel (WPM) as interfacial stabilizers, WPM-based Pickering bigels exhibited a remarkable particle localization at the interface due to specific intermolecular interactions. The rise in protein concentration not only intensified particle coverage and interface stabilization but also amplified attributes like storage modulus, yield stress, and adhesiveness, owing to enhanced intermolecular forces and a compact gel matrix. Impressively, WPM-based Pickering bigels outshone in practical applications, showcasing exceptional oil retention during freeze–thaw cycles and extended flavor release-a promising indication for frozen food product applications. Furthermore, these bigels underwent a sensory evolution from a lubricious texture at lower concentrations to a stable plateau at higher ones, offering an enriched consumer experience. In a comparative digestibility assessment, WPM-based Pickering bigels demonstrated superior prowess in decelerating the release of free fatty acids, indicating slowed lipid digestion. This study demonstrates the potential to fine-tune oral sensations and digestive profiles in bigels by modulating Pickering particle concentrations.

In situ coupling metallophilic Zn sites and interfacial LiCl stabilizer to achieve one-step reversible hydrogen storage in Li/Na dual-cation borohydride

Dual-cation borohydrides composed of alkali or alkaline-earth metals attract considerable attention for hydrogen storage, thanks to their high hydrogen capacity and low eutectic melt point; however, they still suffer from high-temperature-dependent dehydrogenation and poor reversibility. In-situ catalyzation and nanoconfinemnt are effective for easing these problems, but a simple and efficient method is required to achieve their coulping. Here inspired from the structural stabilization and performance improvement roles on anodes of metal batteries by constructing metallophilic Zn sites and interfacial LiCl layers, we develop a 0.62LiBH4-0.38NaBH4 system with ZnCl2 as reactive additives by one-step ball milling. In-situ evolved LiCl and Zn(BH4)2 are surprisingly identified as interfacial stabilizers and metastable phases to disperse borohydride particles and to trigger hydrogen release below 100 °C, respectively. Further formed Zn from the decomposition of Zn(BH4)2 acts as catalytic nucleation sites to promote the one-step and reversible (de)hydrogenation of LiBH4 and NaBH4, without producing high chemical potential intermediates, benefiting from the strong affinity of Zn towards Li and Na. These factors contribute to a cyclic stability of nearly 70 %, the highest for dual-cation borohydrides reported so far. The present work provides new insights and a feasible scheme for developing promising borohydride-based storage systems towards practical application.

Dynamic Microparticle Assembly at the Interface of Chemoresponsive Liquid Crystal Droplets.

The confinement of liquid crystals (LCs) in spherical microdroplets results in exotic internal configurations and topological defects in response to physical and chemical stimuli. Recent exploration into the placement of colloids on the surface of LC microdroplets has led to the design of a new class of functional materials with patterned surface properties. It is established that the placement of a colloid on a LC droplet surface can pin the topological defect at the interface, thereby restricting changes in the LC configuration. Herein, we build upon the handful of reports published to provide a fundamental understanding of the colloid positioning in response to external stimuli. Using polystyrene (PS) colloids, we explored the dynamics of particle self-assembly in response to an interfacial enzymatic breakdown of poly-l-lysine by trypsin. We found that for a significant population of droplets, the positioning of the colloid is unaffected by the changes in the internal ordering of LC. Inspired by the new observations, we delved deeper to understand the role of interfacial stabilizers in modulating the preferential alignment of LC and the placement of colloidal microparticles. We also demonstrated that for a certain population of droplets, the positioning of the colloids remains unperturbed in response to multistep reversible adsorption of interfacial amphiphiles. Our findings reveal interesting possibilities of correlating the stimuli-responsive switching of internal configurations of LC with colloid placement on the particle-decorated LC droplets.

Regulation of interfacial mechanics of soy protein via co-extraction with flaxseed protein for efficient fabrication of foams and emulsions

Enrichment of plant proteins with functionality is of great importance for expanding their application in food formulations. This study proposed an innovation to co-enrich soy protein and flaxseed protein to act as efficient interfacial stabilizers for generating foams and emulsions. The structure, interfacial properties, and functionalities of the soy protein-flaxseed protein natural nanoparticles (SFNPs) obtained by alkali extraction-isoelectric precipitation (AE) and salt extraction-dialysis (SE) methods were investigated. Overall, the foamability of AE-SFNPs (194.67 %) was 1.45-fold that of SE-SFNPs, due to their more flexible structure, smaller particle size, and suitable surface wettability, promoting diffusion and adsorption at the air–water interface. AE-SFNPs showed higher emulsion stability (140.89 min), probably because the adsorbed AE-SFNPs with smaller size displayed soft particle-like properties and stronger interfacial flexibility, and therefore could densely and evenly arrange at the interface, facilitating the formation of a stiff and solid-like interfacial layer, beneficial for more stable emulsion formation. The findings may innovatively expand the applications of SFNPs as food ingredients.

Confined‐Synthesis of Ceria in Tubular Nanoclays for UV Protection and Anti‐Biofilm Application

AbstractUV radiation is the main cause of skin aging and cancers. Commercial sunscreens suffer from low efficacy and poor safety, while ceria nanocrystals are promising inorganic UV filters. Herein, the lumen of natural halloysite clay nanotubes (HNTs) is employed for the confined growth of ceria nanocrystals, which can effectively tailor the particle size, morphology, distribution, and oxygen vacancies of the ceria. The ceria in HNTs lumen exhibits increased UV protection and catalytic activity, while the outer surfaces of HNTs can be retained for additional modification. Ceria‐loaded HNTs (named CeOx@HNTs) can act as oil–water interfacial stabilizers to develop skin‐friendly Pickering emulsion sunscreens. Attributed to the Pickering emulsion interfacial catalytic effect of CeOx@HNTs, the UV absorption performance of the sunscreens is enhanced by 3.1 times after emulsification, achieving a sun protection factor of 58.5. In vitro and in vivo studies confirm the effectiveness of the prepared sunscreen in mitigating DNA damage, apoptosis, and malignant transformation. In addition, the sunscreen inhibits biofilm formation by disturbing membrane homeostasis through oxidative stress. This work develops a confined‐growth method of rare earth oxides within tubular nanoclays, which shows promising applications in many fields, such as aging resistance, photoluminescence, and chemical catalysis.

In-situ grafting of dextran on oil body associated proteins at the oil–water interface through maillard glycosylation: Effect of dextran molecular weight

Oil bodies, which are lipid-storage organelles in plant seeds, are stabilized by monolayer of phospholipids and oil body associated proteins (OBAPs). OBAPs have unique interfacial characteristics but poor water-solubility because they contain long hydrophobic segments. In this paper, dextran with different molecular weights (5, 10, and 20 kDa) was grafted onto the C- and N-terminal ends of OBAPs through in situ Maillard reaction on the surface of oil bodies. Grafting of dextran increases the length of the hydrophilic region of OBAPs, which improves their solubility and function as interfacial stabilizers. Changes in chemical bonds after grafting were observed via confocal-Raman microscopy. After de-lipidization, the physicochemical properties of OBAPs–dextran conjugates were analyzed using solubility and infrared spectroscopy. The interfacial behavior was evaluated using critical micelle concentration and interfacial rheology. The results showed that grafting of dextran improved the solubility of the OBAPs by 20-fold. The contents of α-helix and β-sheet in the OBAPs–dextran conjugates decreased, when compared with OBAPs. The critical micelle concentration of OBAPs–dextran conjugates ranged from 1.20 to 4.92 μg/mL. Grafting of dextran, especially high molecular weight, improved the capacity of the OBAPs to increase the interfacial pressure. Our results provide an efficient and eco-friend method for modification of membrane proteins.

In situ construction of inorganic component-rich polymers as interfacial stabilizers for high-rate lithium metal batteries

Lithium-metal batteries (LMBs) have attracted special interest owing to their high energy densities. Nevertheless, the unfavorable reactivity of lithium metal (Li metal) leads to the uncontrolled growth of dendrites and formation of unstable solid electrolyte interlayers, which shorten the cycle life of Li metal and limit its wide application. Herein, a conformal and thin protective layer, composed of Sn, an Sn–Li alloy, lithium fluoride (LiF), and polyethylene oxide (PEO) (denoted as Li-Sn-LiF@PEO), is constructed in situ on Li metal via a facile one-step method. This conformal artificial layer not only reduced the subsequent surface reactions of lithium with the electrolytes, but also effectively accommodated the large volume change of the Li-metal anode and suppressed the growth of Li dendrites. Symmetric cells with Li-Sn-LiPEO-modified Li-metal anodes exhibited small voltage hysteresis and outstanding plating/stripping cyclability over 400 h at high current densities and capacities of 20 mA cm−2 and 20 mAh cm−2. When coupled with NCA/NCM523/LiFePO4 cathodes, the corresponding LMBs exhibited remarkable cycling life and superior rate properties. These encouraging results demonstrate a novel and promising method for long-life and large-scale stable LMBs.

Arthrospira platensis protein isolate for stabilization of fluid interfaces: Effect of physicochemical conditions and comparison to animal-based proteins

Proteins from microalgae bear great potential to replace animal-based proteins in the human diet or as functional ingredients, such as interfacial stabilizers of emulsions and foams. To establish microalgae proteins as viable alternative, it is critical to understand the effect of physicochemical conditions on their adsorption behavior and interfacial network formation. Here, we extract a protein isolate from the cyanobacterium Arthrospira platensis and investigate its interfacial performance in a broad range of concentration, pH, ionic strength, and at oils with altering polarity. Compared to reference conditions (pH 7, 20 mM ionic strength) adsorption is accelerated at intermediate pH 5 due to decreased electrostatic repulsion but decelerated at the isolate's isoelectric point (pI = 3.5) due to protein aggregation. Conversely, a lower protein charge at the pI favors the formation of strong viscoelastic interfacial layers. Increased ionic charge screening results in faster adsorption and increased interfacial viscoelasticity. Adsorption at oils with varying polarity revealed that A. platensis isolate adsorption and viscoelasticity is largely independent of oil polarity and is only impeded at extremely polar oils. Based on this adsorption behavior, we conclude that the obtained isolate is a mixture of protein fractions with varying structural stability. Ultimately, we compare the interfacial performance of the A. platensis isolate with fractionated animal-based proteins. The A. platensis isolate is more efficient at reducing interface tension compared to the commonly employed β-lactoglobulin, lysozyme, albumin, or casein. Hence, A. platensis protein isolate is an efficient interfacial stabilizer in a broad range of physicochemical properties which outperforms many currently used animal-based proteins.

Fabrication and characterization of gelatin-EGCG-pectin ternary complex: formation mechanism, emulsion stability, and structure.

Protein-polyphenol-polysaccharide ternary complex particles have better emulsion interfacial stability compared to protein-polysaccharide binary complexes. However, knowledge is scarce when it comes to the fabrication of protein-polyphenol-polysaccharide ternary complexes as interfacial stabilizers and the interactions between the three substances. In the present work, ternary complexes were prepared using gelatin, high methoxyl pectin, and epigallocatechin gallate (EGCG) as raw materials. The effect of different influencing factors on the formation process of ternary complexes was investigated by varying different parameters. physicochemical stability, emulsifying properties, and structural characteristics were analyzed. The ternary complex had a smaller particle size (275 nm) and polydispersity index (0.112) when the mass concentration ratio of gelatin to high methoxyl pectin was 9:1, addition of EGCG was 0.05%, pH value was 3.0, and ionic strength was 10 mmol L-1 . Meanwhile, the complex had the highest emulsifying stability index (691.75 min) and emulsifying activity index (22.96 m2 g-1 ). Scanning electron microscopical observation demonstrated that the addition of EGCG promoted the dispersion of ternary complex more uniformly, and effectively reduced the agglomeration phenomenon. The discrepancy in fluorescence intensity suggested that interactions between EGCG and gelatin occurred, which altered the protein spatial conformation of gelatin. Fourier transform infrared spectroscopic analysis elucidated that hydrogen bond interaction was the primary non-covalent interaction between EGCG and gelatin-high methoxyl pectin binary complex. The aforementioned results purposed to provide some theoretical reference and basis for the rational design of stable protein-polyphenol-polysaccharide ternary complexes. © 2022 Society of Chemical Industry.

Short review on liquid membrane technology and their applications in biochemical engineering

As a branch of membrane separation technology, liquid membrane has attracted great attention and expanded investigations in biological chemical engineering, with life and health concern in ecosystems. Composed of membrane solvent and mobile carrier, liquid membrane was acquired of function, performing the facilitated mass transfer across the diffusive solvent, so as for the separation and delivery achievement with efficacy. In this review, two types of liquid membrane are mainly focused, respectively on supported liquid membrane (SLM) of membrane solvent supporter in necessity, and on emulsion liquid membrane (ELM) of the required interfacial stabilizers and homogenization. Accordingly, the transfer mechanism, compositions, structure and features of SLM and ELM are introduced respectively. Moreover, the current investigations of liquid membrane have been discussed, focusing on the improvements of efficacy and stability in separation & detection, encapsulation and delivery, so as to scale up the favorable and efficient application with bio-life concern. Prospectively, this review could provide comprehensive insight into the bio-applications of liquid membrane, and guidelines for the further investigations on the efficacy and long-term applicable stability, in order to realize the industrialization.

A review on the utilization of flaxseed protein as interfacial stabilizers for food applications

AbstractFlaxseed is one of the main cultivated economic oil crops in the world, with a global output of ~3.06 million tons. Its residual meal, after oil industrial processing, is rich in protein (35%–40%). However, flaxseed protein is mainly used for feed and its processing efficiency is low. The potential for high‐value utilization of flaxseed protein is far from being excavated. Interface dominated‐colloidal systems, such as emulsions and foams, are widely available and have extensive applications in food products. Flaxseed protein possesses high contents of hydrophobic amino acids and sulfur‐containing amino acids, relatively ordered secondary structures, tunable structural properties, and acceptable interfacial behaviors. These characteristics give it the potential to effectively stabilize food emulsions and foams. By modifications of flaxseed proteins, such as physical treatment and the complexation with polysaccharides and polyphenols, their structural properties and interfacial behaviors can be regulated, therefore, leading to the enhancement of emulsifying and foaming properties. In this review article, the fractionation, composition, and structure of flaxseed protein are detailed summarized. Then, the interfacial behaviors of flaxseed protein and their control approach are highlighted. Additionally, the emulsions and foams stabilized by flaxseed protein‐based amphiphilic systems and their applications in food processing are emphasized.

Improved stability of liposome-stabilized emulsions as a co-encapsulation delivery system for vitamin B2, vitamin E and β-carotene.

To realize the co-encapsulation of multiple nutraceuticals with different solubilities, Pickering emulsions stabilized by freshly-prepared liposome suspension stabilized emulsion (Fre-Lip-Sus-E) and hydrated lyophilized liposome stabilized emulsion (Hyd-Lyo-Lip-E) were prepared, in comparison with the phospholipid stabilized emulsion (Pho-E). The particle size, zeta-potential, emulsification activity (EAI), emulsion stability (ESI), morphology, environmental stability and rheological properties of the three emulsions were compared. In addition, the in vitro digestive stability and bioaccessibility of three emulsions loaded with vitamin B2, vitamin E and β-carotene were assessed. The results showed that the Fre-Lip-Sus-E and Hyd-Lyo-Lip-E were characterized by smaller particles and higher environmental stability than the Pho-E. The slight difference between the Hyd-Lyo-Lip-E and Fre-Lip-Sus-E might be due to the partial destruction of the phospholipid bilayer during the lyophilization of lyophilized liposomes. Rheological analysis demonstrated that all emulsions had high interfacial viscosity and significant shear thinning characteristics of pseudoplastic fluids. Compared with the Pho-E, the liposome-stabilized emulsions demonstrated good environmental stability and antioxidant properties, and the Fre-Lip-Sus-E and Hyd-Lyo-Lip-E exhibited comparable stabilising effects. Higher bioaccessibility of vitamin B2 and vitamin E in the Fre-Lip-Sus-E and Hyd-Lyo-Lip-E was observed, while β-carotene had higher bioaccessibility in Pho-E. These results provide valuable insight into the potential for designing emulsion co-encapsulation delivery systems using liposomes as stabilizers.

Aligned artificial solid electrolyte interphase layers as versatile interfacial stabilizers on lithium metal anodes

An aligned artificial SEI layer is innovatively introduced on the surface of a Li metal anode to build in situ generated LiF components and uniformly distributed Li ion-conductive sites at the same time in this work.

Fabrication of ovalbumin-burdock polysaccharide complexes as interfacial stabilizers for nanostructured lipid carriers: Effects of high-intensity ultrasound treatment

Ovalbumin (OVA)-burdock polysaccharide complex emulsifiers were prepared in this work by high-intensity ultrasound (HIU) treatment for nanostructured lipid carriers (NLCs) stabilization. HIU treatment remarkably changed their physicochemical properties and resulted in the cross-linking between these two biopolymers. The diffusion rate of the stabilizers towards oil-water interface and their dilatational elastic modulus increased with increasing ultrasound power at first, reaching a maximum at 400 W cm−2, and decreased thereafter. Therefore, Biopolymers treated with 400 W cm−2 energy intensity were most effective in preventing the polymorphic transition of NLCs and degradation of encapsulated curcumin (Cur) because they assembled a compact interfacial layer that blocked the motion of carrier oil. Moreover, they also contributed to a more sustainable Cur release in the simulated gastrointestinal tract. Cur in NLCs presented remarkably higher cellular antioxidant capacity and ROS-scavenging capacity than free Cur, which might arise from the enhanced solubility and chemical stability of the former.

Pickering emulsions stabilized by hydrophobically modified nanocellulose containing various structural characteristics

Cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) extracted from renewable resources possess many attractive characteristics, making them ideal Pickering emulsion stabilizers. However, unmodified pristine CNCs with high surface charge density are not effective in stabilizing oil–water emulsions, thereby limiting their application as interfacial stabilizers. Grafting hydrophobic polymers onto CNCs enhanced their wettability by the oil phase, which reduced the interfacial tension. Thus, hydrophobic modification was performed by grafting cinnamoyl chloride or butyryl chloride to the surface of CNFs. The modified CNFs were further hydrolyzed for 1 or 2 h to produce nanocellulose of varying sizes and hydrophobicity, and they were effective Pickering emulsifiers. The effect of nanocellulose concentration, polarity of solvents, hydrophobicity, size and electrolyte on the characteristics of the Pickering emulsions were examined and elucidated.

Rapid Stabilization of Droplets by Particles in Microfluidics: Role of Droplet Formation

AbstractDroplet‐based microfluidics has emerged as a powerful technology for the miniaturization and automation of biochemical assays. The replacement of surfactants by nanoparticles as interfacial stabilizers has gained increasing interest. However, the stabilization mechanism of droplets by nanoparticles in microchannels is poorly understood, drastically hindering the development of practical applications. Current methods for droplet stabilization involve a trade‐off between low droplet production throughput and the waste of a large number of nanoparticles. Herein, we introduce a modification to the droplet production junction that reduces the droplet stabilization time by an order of magnitude, and at the same time significantly reduces the particle waste. Our results show that the limiting step in the kinetics of stabilization is the initial time where both phases come into contact and offer a guideline for the design of particle‐stabilized droplet production devices.

Oil-in-water Pickering emulsions via microfluidization with cellulose nanocrystals: 1. Formation and stability

Oil-in-water Pickering emulsions were successfully prepared via high-energy microfluidization using cellulose nanocrystals (CNC) as interfacial stabilizers. The influence of microfluidization pressure, CNC concentration, and oil type on droplet size and emulsion stability was determined. Under optimized homogenization conditions, CNC formed and stabilized emulsions based on corn, fish, sunflower, flax, orange, and MCT oils. The droplet size decreased with increasing microfluidization pressure from 9 to 17 kpsi, but then increased slightly at 19 kpsi. The creaming stability of the emulsions increased with CNC concentration, which was mainly attributed to the decrease in droplet size (mean particle diameter < 1 μm at CNC-to-oil ratios greater than 1:10) and slightly increased viscosity. The Pickering emulsions were stable to droplet coalescence, presumably due to strong electrostatic and steric repulsions between the lipid droplets carrying adsorbed nanoparticles. The Pickering emulsions had good stability over a range of environmental stresses: pH 3 to 10; NaCl ≤ 100 mM; temperature from 30 to 90 °C. Droplet flocculation was, however, observed under more acidic conditions (pH 2) and at high ionic strength (200–500 mM NaCl), owing to electrostatic screening. Our results indicate that microfluidization is an effective method for forming CNC-stabilized Pickering emulsions suitable for utilization in the food industry.

Amphiphilic Cellulose Nanocrystals for Enhanced Pickering Emulsion Stabilization.

Sulfated cellulose nanocrystals (CNC) with high surface charge density are inadequate for stabilizing oil-water emulsions, which limits their applications as interfacial stabilizers. We performed end-group modification by introducing hydrophobic chains (polystyrene) to CNC. Results showed that the modified CNC are more effective in emulsifying toluene and hexadecane than pristine CNC. Various parameters were investigated, such as concentration of particles, electrolytes, and polarity of solvents on the characteristics of the emulsions. This study provides strategies for the modification of cellulose nanocrystals to yield amphiphilic nanoparticles that enhance the stability of emulsions. Such systems, bearing biocompatible and environmentally friendly characteristics, are attractive for use in a wide range of industries spanning food, biomedicine, pharmaceuticals, cosmetics, andpetrochemicals.