Fabrication and characterization of emulsion stabilized by table egg-yolk granules at different pH levels.

BACKGROUND: The egg yolk is complex, which makes it difficult to understand why mayonnaise can be stabilized into a high internal-phase emulsion. This study aimed to assess the possibility of developing oil-in-water emulsions through unmodified natural egg-yolk granules (EYGs) at various pH levels, to further understand the precise mechanism of mayonnaise. RESULTS: Egg-yolk granules were obtained from hen egg yolk by centrifugation. The sizes of the EYGs were characterized using dynamic light scattering (DLS). Zeta potential of EYGs was detected by DLS and its microstructure was observed by microscope and scanning electron microscope (SEM). Oil / water emulsions were made with EYGs and the size distribution and creaming index of those emulsions were measured at different storage times (1 h and 14 days). The interfacial morphology of EYGs was observed using the emulsion polymerization method. Our results suggested that the prepared EYGs were mainly in an aggregated state but individual EYGs displayed spherical shapes, with a size of 1.0 ± 0.2 µm. The emulsion stabilized by EYGs displayed better stability against creaming at acidic pH (<4.0). At the same time, the interfacial morphology and microscopic observation of the emulsions strongly demonstrated that the emulsions were of the Pickering type. CONCLUSION: The above results are of great importance for an understanding of the mechanism by which mayonnaise is stabilized by egg, together with the applications of egg in food formulations. © 2019 Society of Chemical Industry.

Advances in Fatigue Performance of Metal Materials with Additive Manufacturing Based on Crystal Plasticity: A Comprehensive Review.

Using metal additive manufacturing processes can make up for traditional forging technologies when forming complex-shaped parts. At the same time, metal additive manufacturing has a fast forming speed and excellent manufacturing flexibility, so it is widely used in the aerospace industry and other fields. The fatigue strength of metal additive manufacturing is related to the microstructure of the epitaxially grown columnar grains and crystallographic texture. The crystal plasticity finite element method is widely used in the numerical simulation of the microstructure and macro-mechanical response of materials, which provides a strengthening and toughening treatment and can reveal the inner rules of material deformation. This paper briefly introduces common metal additive manufacturing processes. In terms of additive manufacturing fatigue, crystal plasticity simulations are summarized and discussed with regard to several important influencing factors, such as the microstructure, defects, surface quality, and residual stress.

Effect of Strain Rate and Temperature on the Tensile Properties of Long Glass Fiber-Reinforced Polypropylene Composites.

Strain rate and temperature are influential factors that significantly impact the mechanical properties of long glass fiber-reinforced polypropylene composites. This study aims to investigate the tensile properties of these composites, analyzing the effects of temperature, strain rate, and their interplay on variables such as tensile stress, tensile strength, fracture stress, and fracture morphology through a series of comprehensive tensile experiments. The experimental results demonstrate a notable increase in both tensile strength and tensile fracture stress when the temperature is set at 25 °C, accompanied by strain rates of 10-4, 10-3, 10-2, and 10-1 s-1. Conversely, a significant decrease is observed in the aforementioned properties when the strain rate is fixed at 10-4, while varying temperatures of -25 °C, 0 °C, 25 °C, 50 °C, and 75 °C are applied. At lower temperatures, cracks manifest on the fracture surface, while matrix softening occurs at higher temperatures. Additionally, in the context of strain rate-temperature coupling, the decreasing trend of both tensile strength and tensile fracture stress decelerates as the temperature ranges from -25 °C to 75 °C at a strain rate of 10-1, compared to 10-4 s-1. These findings highlight the significant influence of both strain rate and temperature on high fiber content long glass fiber-reinforced polypropylene composites.

Vascularized Co-Culture Clusteroids of Primary Endothelial and Hep-G2 Cells Based on Aqueous Two-Phase Pickering Emulsions.

Three-dimensional cell culture has been extensively involved in biomedical applications due to its high availability and relatively mature biochemical properties. However, single 3D cell culture models based on hydrogel or various scaffolds do not meet the more in-depth requirements of in vitro models. The necrotic core formation inhibits the utilization of the 3D cell culture ex vivo as oxygen permeation is impaired in the absence of blood vessels. We report a simple method to facilitate the formation of angiogenic HUVEC (human umbilical vein endothelial cells) and Hep-G2 (hepatocyte carcinoma model) co-culture 3D clusteroids in a water-in-water (w/w) Pickering emulsions template which can overcome this limitation. This method enabled us to manipulate the cells proportion in order to achieve the optimal condition for stimulating the production of various angiogenic protein markers in the co-cultured clusteroids. The HUVEC cells respond to the presence of Hep-G2 cells and their byproducts by forming endothelial cell sprouts in Matrigel without the exogenous addition of vascular endothelial growth factor (VEGF) or other angiogenesis inducers. This culture method can be easily replicated to produce other types of cell co-culture spheroids. The w/w Pickering emulsion template can facilitate the fabrication of 3D co-culture models to a great extent and be further utilized in drug testing and tissue engineering applications.

Fabrication of Angiogenic Sprouting Coculture of Cell Clusteroids Using an Aqueous Two-Phase Pickering Emulsion System.

Tumor cell spheroids and 3D cell culture have generated a lot of interest in the past decade due to their relative ease of production and biomedical research applications. To date, the frontier in tumor 3D models has been pushed to the level of personalized cancer treatment and customized tissue engineering applications. However, without vascularization, the central parts of these artificial constructs cannot survive without an adequate oxygen and nutrient supply. The formation of a necrotic core into in vitro 3D cell models still serves as the major obstacle in their wider practical application. Here, we propose a rapid formation protocol based on using a water-in-water (w/w) Pickering emulsion template to generate phenotypically endothelial/hepatic (ECV304/Hep-G2) coculture cell clusteroids with angiogenic capability. The w/w Pickering emulsion template was based on a dextran/poly(ethylene oxide) aqueous two-phase system stabilized by whey protein particles. The initial cell proportion in the coculture clusteroids can easily be manipulated for optimal performance. The cocultured pattern of the endothelial/hepatic cells could significantly promote the production of angiogenesis-related proteins. Our study confirmed that cocultured clusteroids can stimulate cell sprouting without the addition of vascular endothelial growth factor (VEGF) or other angiogenesis inducers at a 1:2 ratio of Hep-G2/ECV304. Angiogenesis gene production in the coculture clusteroids was enhanced with VEGF, urea, and insulin-like growth factor-binding protein along with angiogenesis-related marker CD34 levels, also indicating angiogenesis progress. Our aqueous two-phase Pickering emulsion templates provided a convenient approach to vascularize a target cell type in 3D cell coculture without additional stimulating factors, which could potentially apply to either cell lines or biopsy tissues, expanding the clusteroids downstream applications.

Emerging nanotechnologies for targeting antimicrobial resistance.

Antimicrobial resistance is a leading cause of mortality worldwide. Without newly approved antibiotics and antifungals being brought to the market, resistance is being developed to the ones currently available to clinicians. The reason is the applied evolutionary pressure to bacterial and fungal species due to the wide overuse of common antibiotics and antifungals in clinical practice and agriculture. Biofilms harbour antimicrobial-resistant subpopulations, which make their antimicrobial treatment even more challenging. Nanoparticle-based technologies have recently been shown to successfully overcome antimicrobial resistance in both planktonic and biofilms phenotypes. This results from the combination of novel nanomaterial research and classic antimicrobial therapies which promise to deliver a whole new generation of high-performance active nanocarrier systems. This review discusses the latest developments of promising nanotechnologies with applications against resistant pathogens and evaluates their potential and feasibility for use in novel antimicrobial therapies.

Novel Pickering High Internal Phase Emulsion Stabilized by Food Waste-Hen Egg Chalaza.

A massive amount of chalaza with nearly 400 metric tons is produced annually as waste in the liquid-egg industry. The present study aimed to look for ways to utilize chalaza as a natural emulsifier for high internal phase emulsions (HIPEs) at the optimal production conditions to expand the utilization of such abundant material. To the author's knowledge, for the first time, we report the usage of hen egg chalaza particles as particulate emulsifiers for Pickering (HIPEs) development. The chalaza particles with partial wettability were fabricated at different pH or ionic strengths by freeze-drying. The surface electricity of the chalaza particles was neutralized when the pH was adjusted to 4, where the chalaza contained a particle size around 1500 nm and held the best capability to stabilize the emulsions. Similarly, the chalaza reaches proper electrical charging (-6 mv) and size (700 nm) after the ionic strength was modified to 0.6 M. Following the characterization of chalaza particles, we successfully generated stable Pickering HIPEs with up to 86% internal phase at proper particle concentrations (0.5-2%). The emulsion contained significant stability against coalescence and flocculation during long term storage due to the electrical hindrance raised by the chalaza particles which absorbed on the oil-water interfaces. Different rheological models were tested on the formed HIPEs, indicating the outstanding stability of such emulsions. Concomitantly, a percolating 3D-network was formed in the Pickering HIPES stabilized by chalaza which provided the emulsions with viscoelastic and self-standing features. Moreover, the current study provides an attractive strategy to convert liquid oils to viscoelastic soft solids without artificial trans fats.

Enhanced clearing of Candida biofilms on a 3D urothelial cell in vitro model using lysozyme-functionalized fluconazole-loaded shellac nanoparticles.

Candida urinary tract biofilms are increasingly witnessed in nosocomial infections due to reduced immunity of patients and the hospital ecosystem. The indwelling devices utilized to support patients with urethral diseases that connect the unsterilized external environment with the internal environment of the patient are another significant source of urinary tract biofilm infections. Recently, nanoparticle (NP)-associated therapeutics have gained traction in a number of areas, including fighting antibiotic-resistant bacterial biofilm infection. However, most studies on nanotherapeutic delivery have only been carried out in laboratory settings rather than in clinical trials due to the lack of precise in vitro and in vivo models for testing their efficiency. Here we develop a novel biofilm-infected 3D human urothelial cell culture model to test the efficiency of nanoparticle (NP)-based antifungal therapeutics. The NPs were designed based on shellac cores, loaded with fluconazole and coated with the cationic enzyme lysozyme. Our formulation of 0.2 wt% lysozyme-coated 0.02 wt% fluconazole-loaded 0.2 wt% shellac NPs, sterically stabilised by 0.25 wt% poloxamer 407, showed an enhanced efficiency in removing Candida albicans biofilms formed on 3D layer of urothelial cell clusteroids. The NP formulation exhibited low toxicity to urothelial cells. This study provides a reliable in vitro model for Candida urinary tract biofilm infections, which could potentially replace animal models in the testing of such antifungal nanotechnologies. The reproducibility and availability of a well-defined biofilm-infected 3D urothelial cell culture model give valuable insights into the formation and clearing of fungal biofilms and could accelerate the clinical use of antifungal nanotherapeutics.

Biofilm-Infected Human Clusteroid Three-Dimensional Coculture Platform to Replace Animal Models in Testing Antimicrobial Nanotechnologies.

Microbial biofilms are a major concern in wound care, implant devices, and organ infections. Biofilms allow higher tolerance to antimicrobial drugs, can impair wound healing, and potentially lead to sepsis. There has been a recent focus on developing novel nanocarrier-based delivery vehicles to enhance the biofilm penetration of traditional antibacterial drugs. However, a feasible in vitro human skin model to mimic the biofilm formation and its treatment for clearance have not yet been reported. This study describes the benefits of using an innovative bacterial biofilm-infected keratinocyte clusteroid model for the first time. It paves a new way for testing innovative nanomedicine delivery systems in a rapid and reproducible way on a realistic human cell-based platform, free of any animal testing. Herein, we have developed a novel composite 3D biofilm/human keratinocyte clusteroid coculture platform, which was used to measure biofilm clearance efficiency of nanoparticle (NP)-based therapeutics. We tested this model by treating the biofilm-infected 3D coculture layers by a ciprofloxacin-loaded Carbopol nanogel particles, surface-functionalized by the cationic protease Alcalase. We measured the antibacterial efficiency of the NP treatment on clearing Staphylococcus aureus and Pseudomonas aeruginosa biofilms on the 3D keratinocyte clusteroid/biofilm coculture model. Our experiments showed that these bacteria can infect the 3D layer of keratinocyte clusteroids and produce a stable biofilm. The biofilms were efficiently cleared by treatment with a formulation of 0.0032 wt % ciprofloxacin-loaded in 0.2 wt % Carbopol NPs surface-functionalized with 0.2 wt % Alcalase. Taken together, these promising results demonstrate that our coculture model can be exploited as a novel platform for testing the biofilm-eliminating efficiency of various NP formulations emulating skin and wound infections and could have wider applicability to replace animal models in similar experiments. This 3D cell culture-based platform could help in developing and testing of more effective antibacterial agents for clinical applications of antiplaque dental treatments, implants, infection control, and wound dressings.

Advanced biomedical applications based on emerging 3D cell culturing platforms.

It is of great value to develop reliable in vitro models for cell biology and toxicology. However, ethical issues and the decreasing number of donors restrict the further use of traditional animal models in various fields, including the emerging fields of tissue engineering and regenerative medicine. The huge gap created by the restrictions in animal models has pushed the development of the increasingly recognized three-dimensional (3D) cell culture, which enables cells to closely simulate authentic cellular behaviour such as close cell-to-cell interactions and can achieve higher functionality. Furthermore, 3D cell culturing is superior to the traditional 2D cell culture, which has obvious limitations and cannot closely mimic the structure and architecture of tissues. In this study, we review several methods used to form 3D multicellular spheroids. The extracellular microenvironment of 3D spheroids plays a role in many aspects of biological sciences, including cell signalling, cell growth, cancer cell generation, and anti-cancer drugs. More recently, they have been explored as basic construction units for tissue and organ engineering. We review this field with a focus on the previous research in different areas using spheroid models, emphasizing aqueous two-phase system (ATPS)-based techniques. Multi-cellular spheroids have great potential in the study of biological systems and can closely mimic the in vivo environment. New technologies to form and analyse spheroids such as the aqueous two-phase system and magnetic levitation are rapidly overcoming the technical limitations of spheroids and expanding their applications in tissue engineering and regenerative medicine.