Structure Of Droplets Research Articles

Polydopamine Nanobowl-Armoured Perfluorocarbon Emulsions: Tracking Thermal- and Photothermal-Induced Phase Change through Neutron Scattering.

Anisotropic polydopamine nanobowls (PDA NBs) show significant promise in biomedicine, distinguished by their unique optical properties and superior cellular uptake compared to spherical nanoparticles. This study presents a novel approach for creating multistimuli-activated PDA NB-armored emulsions, encapsulating perfluorohexane (NB-H) and perfluoropentane (NB-P) cores, with applications in controlled delivery and ultrasound imaging. Thermal and photothermal activation induced distinct responses in the emulsions, as evidenced by optical microscopy and thermogravimetric analysis. For the first time, neutron scattering techniques (SANS and USANS) under contrast matching conditions are applied to investigate these materials, revealing detailed droplet and microbubble structures and phase transition dynamics. These results show that NB-H droplets resist phase change under direct heating, whereas NB-P droplets respond more readily, exhibiting significant bubble formation. During photothermal activation with short near-infrared (NIR) exposure (15 min at 400mW cm-2), SANS and USANS analyses reveal varying degrees of phase transition, proving this activation method to be more effective than direct heating. Importantly, NB-H and NB-P droplets have excellent ultrasound contrast enhancement and biocompatibility, indicating their potential for contrast-enhanced ultrasound imaging, theranostics, and photothermal applications. This comprehensive study advances the understanding of multifunctional colloidal materials in biomedicine, contributing essential knowledge to this rapidly evolving field.

Polysaccharide-Based Coacervate Microgel Bearing Cationic Peptides That Achieve Dynamic Cell-Membrane Structure Alteration and Facile Cytosolic Infusion of IgGs.

Conjugates of the biocompatible polysaccharide pullulan with a cell membrane permeabilizing peptide L17E (PL-L17Es) were prepared with the aim of producing complex coacervates with pronounced intracellular antibody (IgG) delivery activity and stable structures. Coacervates with diameters of a few μm were formed simply by mixing PL-L17Es with IgG labeled with negatively charged fluorescent moieties of Alexa Fluor 488 [IgG(AF488)]. The coacervate resulted in a pronounced cytosolic infusion of IgG(AF488) and IgG binding to the target proteins inside the cell. The droplet structures were maintained even under high salt conditions, and the fluorescence in the droplet was not recovered after photobleaching, suggesting the formation of complex coacervate microgels. Dynamic changes in cell membrane structure to entrap the coacervate microgels were captured by confocal and electron microscopy, resulting in cytosolic IgG infusion. The use of M-lycotoxin instead of L17E resulted in a coacervate microgel with marked IgG delivery activity even in the presence of serum. Successful IgG delivery to primary hepatocytes, undifferentiated induced pluripotent stem (iPS) cells, and iPS cell-derived intestinal epithelial cells was also achieved. The construction of complex coacervate microgels with design flexibility and the validity of intracellular IgG delivery with high salt stability were thus demonstrated.

The charge layer structure of dispersed liquid droplets of extra-heavy oil and its correlation with the oil–water interface properties in the system

The charge layer structure of dispersed liquid droplets of extra-heavy oil and its correlation with the oil–water interface properties in the system

Self-assembled sub-picoliter liquid periodic structures in a hollow optical fiber

In an experimental exploration, we successfully implemented a self-assembling methodology to construct a periodic liquid-air structure inside a hollow optical fiber (HOF). This fiber comprises a central air hole, a germanosilica ring core, and a silica cladding. A periodic structure of liquid droplets and air was obtained by the application of a microscopic heat source (MHS) traversing along the axial direction of the liquid-filled HOF. In the course of this study, we discerned three distinct zones within the structure. The first zone, referred to as Zone 1, demonstrated near-constant periodicity. The second zone, Zone 2, exhibited adaptable properties with regard to its periodicity, allowing it to be flexibly controlled. In the third zone, Zone 3, we noticed a chaotic response to external parameters, including temperature and the speed at which MHS was traversed. To regulate the liquid-air periodic structures, two different types of MHSs were utilized - a micro hydro-oxygen torch and a metal ring heater, each mounted on a translation stage. The study provides a detailed account of the parameters employed in utilizing these MHSs. Additionally, the optical properties of these liquid-air periodic structures were meticulously analyzed to explore the potential for developing new optofluidic applications.

In Vitro Lipid Digestion of Milk Formula with Different Lipid Droplets: A Study on the Gastric Digestion Emulsion Structure and Lipid Release Pattern.

In this study, the digestive properties of milk formulas (two concept milk formulas L1 and L2 with D4,3 ∼5 μm and a control milk formula S1 with D4,3 ∼0.5 μm) were evaluated using a dynamic digestion model simulating the infant gastrointestinal tract. The results showed that L1 and L2 had a lower lipolysis degree compared to S1 during gastric digestion and no significant difference at the end of the digestion process. Triacylglycerol lipolysis products were highly related to the lipid sources of milk formulas. At the end of digestion, glycerophospholipids in milk formulas were hydrolyzed to lysophospholipids (∼60-80%), while sphingomyelins were barely hydrolyzed. Concept milk formulas showed a complete spherical structure with a mean size of 3-5 μm during gastric digestion, while the control formula had large aggregates consisting of small lipid droplets. This study reveals that the structure of lipid droplets moderates the gastric digestion emulsion structure and further influences the digestive properties of milk formulas.

Impact of Fluid Rheology and Density Ratio in Droplet Collision: A Numerical Investigation

Abstract This research delves into the intricate interplay of fluid rheology, characterized by the power-law model, and density ratio ρr=ρlρg in the context of droplet collision dynamics. The power-law index (n) is systematically varied within the range of 0.5 to 1.5, while the density ratio spans two orders of magnitude, ranging from 101-103. Comprehensive investigations are conducted across various impact parameters (B = 0 - 0.75) and Weber numbers (We = 40 - 160). A noteworthy finding is the cessation of droplet coalescence at elevated Weber numbers (We = 160), revealing a critical threshold beyond which coalescence is no longer sustained. The impact of fluid rheology on internal fluid flow dynamics within the complex droplet structure is substantial. The variation in viscous dissipation with (n) contributes to observable changes in the critical wavelength of the complex droplet rim structure, consequently influencing the size of child droplets. Furthermore, the density ratio is a pivotal factor influencing the deformation rate during collision events. A decrease in density ratio correlates with a reduction in the deformation ratio, shedding light on the significant role of density ratio in shaping the dynamics of droplet collisions.

Sphingomyelin-enriched milk phospholipids offer superior benefits in improving the physicochemical properties, microstructure, and surface characteristics of infant formula

Phospholipids from different sources have varying chemical compositions, but how they contribute to different properties of infant formula is unclear. In this study, four types of phospholipids, milk phospholipids (MPLs), soybean phospholipids (SBPLs), sunflower phospholipids (SFPLs), and egg yolk phospholipids (EYPLs), were added to infant formula to investigate their physicochemical properties, microstructure, and surface characteristics. MPLs uniquely offer high sphingomyelin and saturated fatty acid levels. The MPL-based emulsion had the smallest particle size (334.50 nm), lowest stability constant (0.30), and highest viscosity among all groups tested. Furthermore, the abundance of sphingomyelin in MPLs allowed for a denser interfacial film and the complete phospholipid-coated structure of lipid droplets in infant formula emulsion. This consequently improved the microstructure and fat encapsulation of the powder, leading to significantly lower surface fat content in the MPL group. Therefore, the proper selection of phospholipids is crucial for modulating the stability and surface characteristics of infant formula.

Divergence of Critical Fluctuations on Approaching Catastrophic Phase Inversion in Turbulent Emulsions.

Catastrophic phase inversion, the breakdown of a concentrated emulsion characterized by the most puzzling sudden feature, is crucial in numerous industrial applications. Here we combine well-controlled experiments and fully resolved numerical simulations to study the critical dynamics of catastrophic phase inversion in oil-water emulsions under turbulent flow as the phase-inversion volume fraction is approached. We reveal that the phase inversion is characterized by the critical power-law divergence of fluctuations in the global drag force. We determine the enhanced dynamical heterogeneity in the local droplet structures at approaching the phase inversion, and tightly connect it to the diverging drag fluctuations. Moreover, we show that near to the critical point the phase inversion is triggered as a stochastic process by large fluctuations at both large and small scales. Our findings pave the way to modeling the phase inversion process as an out-of-equilibrium critical-like phenomena.

Correlation study between structural parameters of droplets and rheological properties of O/W high internal phase Pickering emulsions above the closest packing density

The correlation between the structural parameters of droplets and rheological properties of O/W high internal phase Pickering emulsions (HIPPEs) stabilized by soy protein isolate (SPI) nanoparticles was elucidated, with a volume fraction of dispersed phase (ϕ) above the closest packing density (74%). The structural basis of SPI nanoparticles was confirmed to be spherical heat-induced protein aggregates, which had moderate wettability and excellent interfacial activity. The structural parameters of emulsion droplets (contact length L, diameter D, length d1, width d2, the number of adjacent contact droplets Z), and the stability and rheological properties of HIPPEs were characterized by the confocal laser scanning microscopy (CLSM), diffusing wave spectroscopy (DWS), and mechanical rheometer respectively. The results of CLSM indicated the transition of droplets from spherical to polyhedral shapes as increased ϕ, accompanied by an increased L and Z. The rheological and stability analysis confirmed the widened linear viscoelastic range, elevated gel point (εc), and the extended half−life of the intensity autocorrelation function of HIPPEs as ϕ increased. Moreover, the loss factor (tan δ) remained constant at 0.1 within the ϕ of 74%–86%, revealing the solid−like nature of HIPPEs. The correlation between ϕ, structural parameters of droplets, and rheological properties of HIPPEs was further analyzed. The nonlinear regression fitting between the L/D and G' (elastic modulus) yielded a better fitting effect than d1/d2 and Z, suggesting an intrinsic correlation between emulsion structure and rheology. In summary, this study elucidated the intricate relationship between ϕ, droplet structure, and rheological properties of HIPPEs, offering a research foundation and theoretical basis for the development and application of protein particle−stabilized HIPPEs.

Optoelectronic processes in ultrasonic spray coated organic solar cells

In this work, the role of a high boiling point green solvent additive Diphenyl ether (DPE) in device recombination processes in organic solar cell, fabricated using ultrasonic spray coating method is investigated. Without DPE and with 2.4 % DPE, the device series resistance was high of the order of 104 Ω. With 0.3 %, 0.6 %, 1.2 % DPE, series resistance was less. Transient studies show that, for these contents, the rise and decay times of photocurrent was less than 5 µs. For 0.3 % DPE, nearly 3/4th photovoltage decayed with 51.4 µs lifetime and the remaining decays with 4.6 µs lifetime. With higher DPE content (1.2 %), 97 % photovoltage decay was with a longer lifetime 46.1 µs, and remaining with 1.6 µs. With further more DPE content (2.4 %), only 1 % TPV decays with shorter lifetime of 11.6 µs and 99 % decay is in longer time scale of 672 µs. In addition, a longer lifetime of over 1000 µs was also observed for this case, indicating the presence of deep traps, in addition to the shallow traps and bimolecular recombination. Morphology studies show that for 0 % and 0.3 % DPE content, stacked structure of droplets was formed in the film, but with 0.6 % and higher content, the progressively impinging droplets intermix with each other, providing more time for the film to dry. It was shown that the contribution of trap assisted recombination for varying DPE content was due to disordered PTB7 or PC71BM phases, indicating a competition between PTB7 aggregation and PC71BM dispersion in the coated film.

Effects of charge distribution and degree of methylesterification of pectin emulsifier on bioaccessibility of curcumin incorporated in nanoemulsions

The objectives of this study were to elucidate the effects of degree of methyl esterification (DM) and charge distribution of pectin on the stability of emulsions and to analyze bioaccessibility of curcumin incorporated in emulsions stabilized by pectins. Three commercial pectins, CP72 (DM72), CP50 (DM50), and CP7 (DM7), were used. MP50 (DM50) with consecutive demethylesterified galacturonic acid residues was prepared from CP72 via demethylesterification to induce different charge distributions. Emulsions containing curcumin were prepared and were stored for 30 days. The CP72 and CP50 emulsions remained relatively stable for 30 days. However, MP50 and CP7 were less effective at forming stable emulsions. When the pectin emulsions passed through each phase of the simulated gastrointestinal tract (GIT), the CP72 and CP50 emulsions retained their initial droplet structures after in vitro mouth and gastric digestion, whereas the MP50 and CP7 emulsions exhibited gel-like clusters, although the gel-like formation of MP50 was distinct from that observed in CP7. MP50 emulsion showed a high degree of final lipid digestion and high bioaccessibility of curcumin while CP72 emulsion displayed a low degree of final lipid digestion. CP50 exhibited low bioaccessibility of curcumin, which might have been contributed by its fast lipid digestion profiles.

Theory of Lipid Metabolism Disorders in Rhinitis and Asthma (Lipid Droplets).

Lipid droplets are important for the storage of neutral lipids in cells; moreover, they participate in a variety of activities in cells and are multifunctional organelles. In the past few decades, lipid droplets have been extensively studied and found to play important roles in cellular energy balance, signal regulation and metabolic regulation. In particular, the formation and function of lipid droplets in adipocytes and mast cells have received much attention. This article reviews the formation, structure and function of lipid droplets in mast cells and elaborates on the relationship between lipid droplets and both adipocyte metabolism and mast cell-mediated allergic inflammation, to provide ideas for the treatment of allergic inflammation by targeting lipid droplets. This study provides important evidence for the role of lipid metabolism disorders in rhinitis and asthma.

Customized machining of internal structure of droplet based on laser injection and templated self-assembly

Abstract The machining of micro- and nanostructures of droplets holds significant scientific and practical importance. A major challenge lies in customizing the internal architecture of droplets. In this work, we introduce a method that employs laser injection and templated self-assembly to precisely engineer the internal structures of droplets. Laser injection breaks the droplet’s inherent confinement, enabling the injection of any desired number of inner cores. The diverse topological defects of cholesteric liquid crystal droplets facilitate the templated self-assembly of these injected cores into ordered substructures, thus achieving the customization of the droplet’s internal structure. This study explores our capabilities in machining soft matter micro- and nanostructures within closed interfaces and promises potential applications in the development of functional materials, pharmaceuticals, and sensors.

Investigation of physico-mechanical, thermal, morphological, and antibacterial effects of bio-based epoxidized soybean oil plasticizer on PLA-ZnO nanocomposites as flexible food packaging

Polylactic acid (PLA) has attracted considerable attention because of its excellent properties compared to petroleum-based materials. However, improving its toughness, crystallization, and functionalities is challenging. Using a laboratory internal batch mixer, we produced unique blended nanocomposites comprising polylactic acid (PLA) as the host matrix, epoxidized soybean oil (ESO) as the plasticizer, and zinc oxide nanoparticles (ZnO NPs) as the reinforcements. The SEM-EDS test showed that neat PLA had a smooth surface, but the PLA-ZnO nanocomposite had rough micrographs and a uniform dispersion state of the nanoparticles. It was also found that adding ESO to the blend nanocomposites created a matrix droplet structure, and the size of the oil domains decreased as the ZnO content increased. All results derived from FTIR, XRD, and DSC tests were consistent with the morphological features in which ZnO NPs acted as the blend’s compatibilizer and heterogeneous nucleating agent. Our team observed that adding ESO decreased the PLA-ZnO nanocomposites’ glass transition temperature (Tg) by an average of 2 °C and increased the crystallization rate. It was also confirmed that the presence of ESO improved the flexibility and reduced the strength of the PLA. The tensile strength was further enhanced by incorporating ZnO into the blend. Adding 5 wt% of ZnO NPs increased the tensile strength of the PLA containing 10 wt% ESO by approximately 3.5 MPa. Furthermore, the tensile modulus was predicted using theoretical models; for example, the Paul model fitted with experimental findings. The addition of ESO increased the overall surface free energy of the nanocomposites. On the other hand, increasing ZnO content resulted in high contact angles and antibacterial properties of the blended nanocomposites. The favorable characteristics of the resulting films emphasized the potential use of these nanocomposite films as a promising choice for food packaging materials.

Microscopic Mechanism for Gradient Diffusion of Salt-Containing Droplets Induced by Electromagnetic Synergy: A Molecular Dynamics Study.

The electromagnetic synergy has been proven to be highly effective in separating oil-water emulsions. However, the dynamic impact mechanism of electromagnetic fields on the internal structure of salt droplets remains unclear. In this study, the molecular dynamics (MD) simulation was used to investigate the molecular diffusion of salt ions and water molecules, as well as the dynamic behavior of droplets under the combined influence of electromagnetic fields. The results indicate that ions accumulate in the electromagnetic synergistic field, causing the deformation amplitude of droplets to be smaller than that in a single electric field. The magnetic field affects the energy of the system, when the magnetic field strength is between 1 and 5T, the nonbonded energy significantly increases nonlinearly; when the magnetic field strength is greater than 5T, the total energy of the system significantly changes. In addition, the viscosity of the medium is significantly lower when the intensity of the magnetic and electric fields is controlled within a specific range, providing a new way to regulate the fluidity of fluids.

Rational design of an AIEgen for imaging lipid droplets polarity change during ferroptosis

Ferroptosis can regulate cell death by accumulating lipid peroxides, affecting the structure and polarity of lipid droplets (LDs), but clear evidence is still lacking. Fluorescence imaging is the most powerful technique for studying LDs’ function. However, developing AIE fluorescent probes with high selectivity and sensitivity for targeting LDs remains challenging. In this study, we rationally designed an AIEgen, as a novel fluorescent probe TPE-BD, by constructing a push-pull electron structure. The probe has benzo[b]thiophene-3(2H)-one 1,1-dioxide as the electron acceptor, tetraphenylethylene (AIE skeleton) as the electron donor, and thiophene as the bridging group. The optical performance of probe TPE-BD indicated that the UV–visible absorption spectrum of the probe was minimally affected by solvent polarity (except for glycerol and PBS solvents), but the fluorescence of probe is very sensitive to changes in polarity, achieving the goal of polarity detection in LDs. CCK-8 assay and cell imaging experiments demonstrated that probe TPE-BD exhibited good cell compatibility and effectively targeted LDs, enabling the monitoring of LDs’ polarity and quantity during ferroptosis.

High internal phase emulsions gels stabilized by soy protein isolate and rutin complexes: Encapsulation, interfacial properties and in vitro digestibility

High internal phase emulsion gel (HIPEG) stabilized by food-grade protein particles has garnered increasing attention across various fields. However, the limited environmental stability in HIPEGs remain key challenges. In this study, oil-in-water HIPEGs stabilized by soy protein isolate and rutin complexes was used as a model system. The impacts of different conjugation conditions in preparing SPI and rutin (SPI-R) complex and various homogenization rates on HIPEGs formation were investigated. Results demonstrated that HIPEGs stabilized by covalent binding SPI-R complex exhibited excellent interfacial properties with more proteins involved in the formation of the HIPEGs at the interface compared to noncovalent-conjugate-stabilized HIPEGs. Notably, HIPEGs stabilized by SPI-R complex under alkaline conditions showed narrower size distribution and a more compact droplet structure along with a denser gel network and enhanced encapsulation efficiency of rutin compared to other groups. Moreover, the HIPEGs stabilized by these covalent conjugates exhibited better environmental stability and superior digestibility of protein. Specifically, HIPEGs stabilized by alkaline-conditioned SPI-R complex demonstrated excellent kinetically or thermodynamically stable state with minimal loss of stability under different environmental stresses when homogenized at an optimal rate of 15,000 rpm/min. This study provides valuable insights into utilizing protein-polyphenol particles as outstanding emulsifiers for food-grade HIPEGs.

Optically responsive dry cholesteric liquid crystal marbles

Dry liquid crystal marbles are structures that consist of cholesteric liquid crystal (CLC) droplets prepared by the mixture of chiral-doped thermotropic LCs encapsulated by cellulose nanocrystals (CNCs) that have been dried under ambient conditions. The characterizations revealed that CLC droplets were successfully encapsulated by self-standing CNC shells and responsive to the external gaseous stimulus. The dry LC marbles offer several advantages over previously reported LC-based gas sensors, such as fast response against minor external stimuli, and ease of handling, which make them particularly attractive for practical applications in sensing. We demonstrate the use of these marbles for detecting toluene vapor, a common industrial solvent and pollutant, which we also use to understand the response characteristics. The dry CLC marbles exhibit a significant response to toluene vapor with a detection limit below 500 ppm, attributed to the change of pitch size of the helical structure of CLC droplets induced by the toluene vapor. The CNC-capsulated CLC droplets were stable in emulsion for up to two weeks, and their dried form exhibited a sensitive response upon toluene exposure. The real-time experiments revealed that the LC marbles can be used multiple times without a significant loss of sensitivity, where 90 % of the maximum response was observed at 13.3 ± 4.7 s. These dry LC marbles can also be utilized in other areas, including drug delivery, optical devices, and biosensors.

Antimicrobial and antioxidant competence of sustainable grumixama leaves extracts in nanoemulsion system

The spontaneous emulsification method was used to produce nanoemulsions loaded with grumixama leaves extracts (GLE) to protect and improve its functionality as a natural additive in food. Nanoemulsions were characterized for physicochemical stability, morphology, thermal analyses, antioxidant capacity, and antimicrobial activity. The formulations showed encapsulation efficiency (EE%) >89%, sizes between 182 and 290 nm, low polydispersity, and zeta potential near −30 mV. The formulations were kinetically stable since these parameters remained constant for up to 180 days at 4°C. The nanoemulsion with 125 mg GLE exhibited better droplet structure, which favored greater phenolic compounds protection and thermal resistance. The antioxidant capacity of all formulations remained stable over 30 days. The nanoemulsions acted as a bactericidal agent (MBC/MIC ratio ≤ 4) against Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes strains. However, GLE-loaded nanoemulsions offer a sustainable and functional alternative for use as a natural additive to meet trends such as a clean label.

Green and Efficient Extraction of Phenolic Components from Plants with Supramolecular Solvents: Experimental and Theoretical Studies.

The supramolecular solvent (SUPRAS) has garnered significant attention as an innovative, efficient, and environmentally friendly solvent for the effective extraction and separation of bioactive compounds from natural resources. However, research on the use of a SUPRAS for the extraction of phenolic compounds from plants, which are highly valued in food products due to their exceptional antioxidant properties, remains scarce. The present study developed a green, ultra-sound-assisted SUPRAS method for the simultaneous determination of three phenolic acids in Prunella vulgaris using high-performance liquid chromatography (HPLC). The experimental parameters were meticulously optimized. The efficiency and antioxidant properties of the phenolic compounds obtained using different extraction methods were also compared. Under optimal conditions, the extraction efficiency of the SUPRAS, prepared with octanoic acid reverse micelles dispersed in ethanol-water, significantly exceeded that of conventional organic solvents. Moreover, the SUPRAS method demonstrated greater antioxidant capacity. Confocal laser scanning microscopy (CLSM) images revealed the spherical droplet structure of the SUPRAS, characterized by a well-defined circular fluorescence position, which coincided with the position of the phenolic acids. The phenolic acids were encapsulated within the SUPRAS droplets, indicating their efficient extraction capacity. Furthermore, molecular dynamics simulations combined with CLSM supported the proposed method's mechanism and theoretically demonstrated the superior extraction performance of the SUPRAS. In contrast to conventional methods, the higher extraction efficiency of the SUPRAS can be attributed to the larger solvent contact surface area, the formation of more types of hydrogen bonds between the extractants and the supramolecular solvents, and stronger, more stable interaction forces. The results of the theoretical studies corroborate the experimental outcomes.