Mixture Of Glycerol Research Articles

Bio-inspired seaweed-based nanocomposite materials with excellent degradability and multifunctional barrier properties for green packaging

The widespread use of petroleum-based plastics brings potential hazards to the ecological environment. In order to solve this issue, the development of biodegradable materials with both high mechanical, barrier performances and food safety is imminent. In this work, a natural nacre-inspired seaweed-based nanocomposite material with the structure of “brick and mortar” is synthesized by rational assembling mica nanosheets in a mixture of glycerol and sodium alginate. The resultant SA/nano-mica film (1 wt% of phlogopite powder) shows high thermal stability (>180 °C) and exhibits great tensile strength of ∼ 16 MPa at ambient condition, surpassing some other reported nanocomposite materials (1.9–14.74 MPa). Meanwhile, the composite can be easily processed into different shapes for packaging applications, which could long-term preserve the freshness of foods owing to their strong ultraviolet (UV) shielding and gas barrier properties (UV transmittance of ∼ 4 % and oxygen transmission rates (100 µm) of ∼ 18.52 cc m−2 day−1 bar−1). Importantly, the material could completely degrade in soil within 15 days. These results indicate the great application prospect of seaweed-based nanocomposite materials in food packaging.

Effects of Aftermarket Electronic Cigarette Pods on Device Power Output and Nicotine, Carbonyl, and ROS Emissions.

Aftermarket pods designed to operate with prevalent electronic nicotine delivery system (ENDS) products such as JUUL are marketed as low-cost alternatives that allow the use of banned flavored liquids. Subtle differences in the design or construction of aftermarket pods may intrinsically modify the performance of the ENDS device and the resulting nicotine and toxicant emissions relative to the original equipment manufacturer's product. In this study, we examined the electrical output of a JUUL battery and the aerosol emissions when four different brands of aftermarket pods filled with an analytical-grade mixture of propylene glycol, glycerol, and nicotine were attached to it and puffed by machine. The aerosol emissions examined included total particulate matter (TPM), nicotine, carbonyl compounds (CCs), and reactive oxygen species (ROS). We also compared the puff-resolved power and TPM outputs of JUUL and aftermarket pods. We found that all aftermarket pods drew significantly greater electrical power from the JUUL battery during puffing and had different electrical resistances and resistivity. In addition, unlike the case with the original pods, we found that with the aftermarket pods, the power provided by the battery did not vary greatly with flow rate or puff number, suggesting impairment of the temperature control circuitry of the JUUL device when used with the aftermarket pods. The greater power output with the aftermarket pods resulted in up to three times greater aerosol and nicotine output than the original product. ROS and CC emissions varied widely across brands. These results highlight that the use of aftermarket pods can greatly modify the performance and emissions of ENDS. Consumers and public health authorities should be made aware of the potential increase in the level of toxicant exposure when aftermarket pods are employed.

Polyurethane Adhesives for Wood Based on a Simple Mixture of Castor Oil and Crude Glycerin

Developing a new type of polyurethane is essential because conventional options often exhibit shortcomings in terms of environmental sustainability, cost-effectiveness, and performance in specialized applications. A novel polyurethane adhesive derived from a simple mixture of castor oil (CO) and crude glycerin (CG) holds promise as it reduces reliance on fossil fuels and harnesses renewable resources, making it environmentally friendly. Simple CO/CG mixtures, adjusted at three different weight fractions, were used as bio-based polyester polyols to produce polyurethane adhesive for wood bonding. The resulting products are yellowish liquids with moderate-to-high viscosity, measuring 19,800–21,000 cP at 25 °C. The chemical structure of the polyester polyols was characterized using infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). These polyols reacted with polymeric 4,4-methylene diphenyl diisocyanate (p-MDI) at a consistent isocyanate index of 1.3, resulting in the formation of polyurethane adhesives. Crucially, all final adhesives met the adhesive strength requirements specified by ASTM D-5751 standards, underscoring their suitability for wood bonding applications. The addition of CG enhanced the surface and volumetric hydrophobicity of the cured adhesives, resulting in adhesive properties that are not only stronger but also more weather-resistant. Although the thermal stability of the adhesives decreased with the inclusion of CG, FTIR analysis confirmed proper polyurethane polymer formation. The adhesive adjusted for a 2:1 CO:CG weight ratio promoted wood–wood bonding with the highest shear strength, likely due to a higher formation of urethane linkages between hydroxyl groups from the blend of polyols and isocyanate groups from the p-MDI.

On the settling of aligned spherical particles in various quiescent media

We investigated experimentally the settling behaviour of vertically aligned spherical particles within various quiescent media at different release frequencies. The particles had a diameter of $d = 4$ mm and density of $\rho _s = 2200$ kg m $^{-3}$ , and were released near the free surface of water, ethanol, a G60 water–glycerine mixture (60 % glycerine by weight) and oil media at frequencies of $f_P = 4$ , 6 and 8 Hz, thereby allowing study of Galileo numbers, $Ga \in [16, 976]$ . Particle tracking velocimetry quantified the motion of nearly 800 particles in a 600 mm high tank, and particle image velocimetry examined flow patterns around the particles. Results revealed that the centre of mass of the particle trajectories exhibited preferential in-plane motions, with significant lateral dispersion and large $Ga$ in water and ethanol, and nearly vertical paths with low $Ga$ in the G60 mixture and oil media. Varying degrees of particle separation resulted in higher terminal velocities than for a single particle. Hence, particle drag decreased in all cases, with the oil medium showing the highest drag reduction under the closest particle separation, reaching up to nearly 70 % of that for the single particle. The vertical and lateral pair dispersions, $R^2_z$ and $R^2_L$ , exhibited ballistic scaling, with dependences on the initial separation, $r_0$ , and the type of medium. With large $Ga$ , $R^2_z$ displayed a ballistic regime followed by a slower rate, whereas with small $Ga$ , $R^2_z$ maintained a consistent ballistic regime throughout settling. Finally, normalized $R^2_z$ demonstrated distinct scaling (exponent 2/3 and 1) dependent on the normalized initial separation and $Ga$ .

Aqueous Extracts from Hemp Seeds as a New Weapon against Staphylococcus epidermidis Biofilms.

This study investigated the antibiofilm activity of water-soluble extracts obtained under different pH conditions from Cannabis sativa seeds and from previously defatted seeds. The chemical composition of the extracts, determined through GC-MS and NMR, revealed complex mixtures of fatty acids, monosaccharides, amino acids and glycerol in ratios depending on extraction pH. In particular, the extract obtained at pH 7 from defatted seeds (Ex7d) contained a larger variety of sugars compared to the others. Saturated and unsaturated fatty acids were found in all of the analysed extracts, but linoleic acid (C18:2) was detected only in the extracts obtained at pH 7 and pH 10. The extracts did not show cytotoxicity to HaCaT cells and significantly inhibited the formation of Staphylococcus epidermidis biofilms. The exception was the extract obtained at pH 10, which appeared to be less active. Ex7d showed the highest antibiofilm activity, i.e., around 90%. Ex7d was further fractionated by HPLC, and the antibiofilm activity of all fractions was evaluated. The 2D-NMR analysis highlighted that the most active fraction was largely composed of glycerolipids. This evidence suggested that these molecules are probably responsible for the observed antibiofilm effect but does not exclude a possible synergistic contribution by the other components.

Inhalation toxicity of thermal transformation products formed from e-cigarette vehicle liquid using an in vitro lung model exposed at the Air–Liquid Interface

The increasing use of electronic nicotine delivery systems (ENDS), also known as e-cigarettes, has raised serious public health concerns, particularly regarding certain vaping product additives. The solvent carrier liquid, which consists of a mixture of propylene glycol (PG) and vegetable glycerine (VG), representing the main constituents of e-liquid formulations, have in contrast received little attention in health evaluations due to their apparent harmlessness when ingested; however, they can develop into potential lung hazards when heated, aerosolised and inhaled from ENDS with a user-defined heating profile. To assess the acute toxicity of the respirable aerosol, an effect-based in vitro testing strategy was applied in dependence of the heating power settings in ENDS. Human alveolar epithelial cells (A549) were exposed to vaping aerosol at the air–liquid interface (ALI), flanked by targeted chemical analyses of reactive carbonyl species. An exploratory, semi-automated in vitro exposure system provided evidence of a positive connection between vaporisation temperature and aerosol toxicity. Thermochemical transformation of the solvent leads to the formation of both cytotoxic and genotoxic substances that may disrupt lung homeostasis. Toxicity is therefore not limited to the presence of additives, as most harmful volatiles originate from the solvent itself, ultimately related to the device power output.

Artificial Neural Networks for Predicting Pressure in High-Viscosity Two-Phase Flow: A Comparative Analysis

This article presents the procedure undertaken to discover the most suitable model for predicting the outlet pressure of a horizontally oriented pipe with high-viscosity two-phase flow. In order to achieve this, a collection of artificial neural networks (ANN) with diverse architectures was developed, utilizing experimental data for training and validation purposes. The data used in this study were obtained from experiments carried out in a 54-meter-long pipeline, where a mixture of air and glycerin was flowing. The various ANN were constructed based on three different combinations of input variables, namely, the air flow rate (Qa), glycerin flow rate (Qg), and pressure measurements at specific spatial points. Subsequently, a statistical analysis was performed, followed by a comparison of the models' performance across different scenarios.

Volumetric, Optical and Spectroscopic Properties of Binary Mixtures of Glycerol with Butanediol Isomers

Volumetric, Optical and Spectroscopic Properties of Binary Mixtures of Glycerol with Butanediol Isomers

Self-supporting biocatalytic polyelectrolyte complex hollow fiber membranes via salt-dilution induced phase separation

The potential use of biocatalytic membranes in industries such as water treatment, pharmaceuticals, and medicine has attracted much interest in recent years. However, the use of organic solvents in traditional membrane fabrication techniques presents a challenge in the direct integration of enzymes during the membrane production. Thus, enzyme immobilization relies on consecutive modification steps (coating, binding, activation). Yet, recent progress in membrane fabrication using all-aqueous phase inversion of polyelectrolyte complexes (PEC) enables the direct incorporation of enzymes in the polymer solution. We present the fabrication of free-standing, defect-free and mechanically stable biocatalytic PEC hollow fiber membranes via the salt-dilution induced phase separation method. A polymer solution containing poly(sodium-4-styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), KBr, and the enzyme alkaline phosphatase (ALP) was extruded through a spinneret with a mixture of water and glycerol as lumen fluid into a water coagulation bath at 0 °C. The mechanical stability of the fibers is tuned by subsequent photo-induced cross-linking using 4,4’-diazidostilbene-2,2’-difulfonate tetrahydrate (DAS) and UV light. The resulting membranes have a molecular weight cut-off of 400Da, a pure water permeance of 1.5LMH/bar, and a burst pressure of 7bar. The immobilization of ALP proves successful, as the immobilized shows similar catalytic activity to that of the free enzyme, and both storage and thermal stability are improved. Moreover, the enzymes retain 70% of their initial activity after UV cross-linking with DAS and maintain their catalytic activity after repeated wash and filtration cycles. This work highlights the versatility of the fabrication of polyelectrolyte complex hollow fiber membranes via the salt-dilution induced phase separation, serving as a platform technology for the fabrication of porous, selective, and bioactive membranes.

Radiochemical Oxygen Depletion Depends on Chemical Environment and Dose-Rate: Implications for FLASH Effect

FLASH (dose rates > 40 Gy/s) radiotherapy (RT) protects normal tissues from radiation damage, compared with conventional RT (∼Gy/min). Radiation-chemical oxygen depletion (ROD) has been the leading and most-studied mechanism to explain FLASH. Previous studies have reported low ROD values of ∼0.35 µM/Gy, however, they do not accurately model (utilizing water or oxidized substrates such as albumin) the intracellular environment. It has been proposed that the intracellular environment may support higher ROD values due to its specific chemical makeup. As chemical reducing agents, which play a critical role in the cell, may promote ROD, we measured ROD for several well-known cellular reducing agents. Precision polarographic oxygen sensors were used to measure ROD over a ∼100-0 µM oxygen concentration range in solutions containing various types of intracellular reducing agents, either alone or combined with glycerol (1M; to simulate the intracellular hydroxyl-radical-scavenging capacity). A Cs irradiator and a research proton beamline were used for radiation beam generation over a 10,000-fold (0.0085 to 100 Gy/s) dose rate range. Reagents were grouped generally into primary free-radical scavengers (glycerol & lysozyme) and reducing agents (cysteamine, cysteine, glutathione, dextrin-conjugated linoleic acid, NAD(P)H, ascorbate and uric acid). Reducing agents at 1 mM significantly altered ROD values. ROD, at 0.1 Gy/s varied from greater than 1 µM/Gy for NADPH to less than 0.1 µM/Gy for uric acid. Even higher RODs were found at lower dose rates and/or higher reducing agent concentrations. Although most greatly increased ROD, ascorbate and uric acid decreased ROD and additionally imposed an oxygen dependence of ROD at low oxygen concentrations. Interestingly, all agents having high rates of ROD at low dose rates show a decrease at FLASH dose rates and this seems to be a proportional response (i.e., the greater the ROD at low dose rate, the greater the inhibition by FLASH). At FLASH dose rates our data for a simple mixture of glycerol and glutathione showed the same trend as recent studies that, in general, FLASH had ∼25% lower ROD rates than conventional demonstrating agreement between polarographic sensors and optical phosphorescence decay methods. ROD was greatly augmented by some intracellular reducing agents but others effectively reversed this effect. Ascorbate had its greatest impact at low oxygen concentrations. ROD decreased with increasing dose rate and in all cases was less than 1 µM/Gy at 100 Gy/s, potentially posing a fundamental limit of max ROD for FLASH.

Thioflavin-T: A Quantum Yield-Based Molecular Viscometer for Glycerol-Monohydroxy Alcohol Mixtures.

Molecular rotor dye thioflavin T (ThT) is almost nonfluorescent in low-viscosity solvents but highly fluorescent when bound to amyloid fibrils. This unique property arises from the rotation of the dimethylaniline moiety relative to the benzothiazole moiety in the excited state, which drives the dye from an emissive locally excited state to a twisted intramolecular charge-transfer state. This process is viscosity-controlled, and therefore, we can use the quantum yield of ThT to assess the viscosity of the environment. In this study, we have investigated the quantum yield of ThT (φThT) in various compositions of six alcoholic solvent mixtures of glycerol with methanol, ethanol, n-propanol, iso-propanol, n-butanol, and tert-butanol. We have proposed an empirical model using φThT as a function of the mole fraction of glycerol to estimate the interaction parameters between the components of the solvent mixtures. This analysis allowed us to predict the extent of nonideality of the solvent mixtures. The Förster-Hoffmann- and Loutfy-Arnold-type power law relationship was established between the quantum yield of ThT and bulk viscosity for solvent mixtures of methanol, ethanol, n-butanol, and tert-butanol with glycerol, and it was found to be similar in nature in all the four mixtures. Applying this knowledge, we proposed a methodology to quantify and predict the bulk viscosity coefficient values of several compositions of n-propanol-glycerol and iso-propanol-glycerol mixtures which have not been previously documented.

Development of a plastic waste treatment process by combining deep eutectic solvent (DES) pretreatment and bioaugmentation with a plastic-degrading bacterial consortium

Polyethylene terephthalate (PET), a petroleum-based plastic, and polylactic acid (PLA), a biobased plastic, have a similar visual appearance thus they usually end up in municipal waste treatment facilities. The objective of this project was to develop an effective PET and PLA waste treatment process that involves pretreatment with deep eutectic solvent (DES) followed by biodegradation with a plastic-degrading bacterial consortium in a composting system. The DES used was a mixture of choline chloride and glycerol, while the bacterial strains (Chitinophaga jiangningensis EA02, Nocardioides zeae EA12, Stenotrophomonas pavanii EA33, Gordonia desulfuricans EA63, Achromobacter xylosoxidans A9 and Mycolicibacterium parafortuitum J101) used to prepare the bacterial consortium were selected based on their ability to biodegrade PET, PLA, and plasticizer. The plastic samples (a PET bottle, PLA cup, and PLA film) were pretreated with DES through a dip-coating method. The DES-coated plastic samples exhibited higher surface wettability and biofilm formation, indicating that DES increases the hydrophilicity of the plastic and facilitates bacterial attachment to the plastic surface. The combined action of DES pretreatment and bioaugmentation with a plastic-degrading bacterial consortium led to improved degradation of PET and PLA samples in various environments, including aqueous media at ambient temperature, lab-scale traditional composting, and pilot-scale composting.

Effects of anodization conditions of stainless steel on the formation of ordered nanoporous structures with high aspect ratios

The nanoporous structures obtained by the anodization of stainless steel are functional materials with various potential applications. It has been reported that nanoporous structures can be prepared by the anodization of stainless steel in an electrolyte containing fluoride ions. However, under the reported anodization conditions, the control range of the interpore distance of resulting nanoporous structures was narrow. To expand the application fields of the nanoporous structures obtained by the anodization of stainless steel, it is an important challenge to determine the anodization conditions that can control the interpore distance of nanoporous structures over a wide range. In this study, we investigated the effects of the electrolyte composition on the anodization behavior of stainless steel and the interpore distance of the resulting nanoporous structure. As a result, we found that the maximum voltage for the stable anodization of stainless steel increases when a mixture of ethylene glycol and glycerol containing NH4F is used as the electrolyte. Since the interpore distance of nanoporous structures obtained by the anodization of stainless steel is proportional to the anodization voltage, as the voltage range over which stainless steel can be anodized increased, the range of interpore distances of the nanoporous structures obtained also increased. On the basis of these results, ordered nanoporous structures with a large interpore distance (100 nm), which could not be obtained under the previously reported anodization conditions, were fabricated by the anodization of a stainless steel substrate with a depression pattern formed by Ar ion milling using an alumina mask under optimized anodization conditions. The resulting ordered nanoporous structures with controlled interpore distances are expected to be used in various devices such as capacitors and photocatalysts.

Prognostic modeling of polydisperse SiO2/Aqueous glycerol nanofluids' thermophysical profile using an explainable artificial intelligence (XAI) approach

Ceramic nanoparticles have become increasingly popular owing to their wide range of engineering applications in the industry. Silica is one of the most promising nanomaterials for heat transfer applications due to its favorable thermophysical characteristics and dispersion stability. This work investigates the thermophysical properties of polydisperse SiO2 nanoparticles in a glycerol and water mixture. Aqueous glycerol nanofluid comprised 30% glycerol (30 GW) by weight, and SiO2 with mean particle sizes of 15, 50, and 100 nm were prepared for 0.5 and 1.0% volume concentrations using a two-step method. Measurements of properties are made in the temperature range of 30–100oC. The nanofluids behaved as a single-phase liquid remaining stable for four weeks. The viscosity and density of the base liquid and nanofluid decreased while the thermal conductivity increased with temperature. The base liquid-specific heat increased slightly while that of nanofluid decreased significantly with temperature. For 0.5% SiO2 concentration, the thermal conductivity and viscosity varied by 11.1% and 32%, respectively at 60oC compared to the base liquid. Correlations are developed for the estimation of nanofluid properties. An Explainable Artificial Intelligence (XAI) technique called Bayesian approach optimized Gaussian Process Regression was employed to develop a prognostic model for the thermophysical properties of test nanofluids. In addition, the model's predictability and explainability are both enhanced by the use of kernel functions, which makes it possible to include historical data in the representation of a phenomenon. The test XAI approaches were shown as robust one because of the high correlation values, which ranged from 99.68% to 99.99%, along with minimal modeling errors.

A Numerical Study on Labyrinth Screw Pump (LSP) Performance under Viscous Fluid Flow

In this study, fluid viscosity effects on LSP performance in terms of boosting pressure were numerically investigated. A water–glycerin mixture with different concentrations corresponding to varying apparent viscosities was flowed through an in-house manufactured LSP under various flow conditions, e.g., changing flow rates, rotational speeds, and fluid viscosities. The pressure increment between the intake and discharge of the LSP was recorded using the differential pressure transducer. The same pump geometries, fluid properties and flow conditions were incorporated into the numerical configurations, where three-dimensional (3D), steady-state, Reynolds-averaged Navier–Stokes (RANS) equations with a standard SST (shear stress transport) turbulence model were solved by a commercial CFD code. With the high-quality poly-hexcore grids, the simulated pressure increment was compared with the corresponding experimental measurement. The internal flow structures and characteristics within the cavities contained by the LSP impeller and diffuser were also analyzed. The good agreement between the numerical results against the experimental data verified the methodology adopted in this study.

Methods for Calibrating the Electrochemical Quartz Crystal Microbalance: Frequency to Mass and Compensation for Viscous Load

The main output from an Electrochemical Quartz Crystal Microbalance is a frequency shift. This note describes how to separate the mass- and viscous load contributions to this shift by a calibration procedure. The mass calibration is made by electroplating from a copper sulfate solution in ethanol/water with 100% current efficiency. An estimate of viscous load is obtained by measuring the energy dissipation and is related to frequency change using the Kanazawa–Gordon equation. Two approaches are discussed: either by performing calibration experiments in a series of water–glycerol mixtures or by following oscillations in frequency and dissipation by collecting data during the stabilization phase of the experiment.

Investigating the Mechanism of Intravascular Bubble Formation in Designed Arrays of Vascularized Systems on a Chip.

Vascular gas embolism is a rare medical condition, resulting from the existence of air or gas in the venous or arterial system. Gas embolism is associated with a wide range of circulatory, cardiovascular, and neurological complications that can lead to sudden and unexplained death. Despite the recent increase in related studies, gas embolism remains under-reported with a poor understanding of its genesis and pathophysiology. In this work, intravascular bubble formation is investigated in an array of biomimetic microscale systems, where the endogenous generation of gas bubbles is induced by variations in the surrounding pressure. Microfluidic devices, based on polydimethylsiloxane, are designed and fabricated as vascularized systems on a chip with one main channel at two different diameters (30 µm, and 40 µm), surrounded by a pressure chamber (200 µm) on each side, at a separation of 50 µm. Two blood-equivalent solutions, at 20% and 46% hematocrit concentrations were prepared from a glycerin and xanthan gum mixture to mimic the physicochemical characteristics of the blood. As the volume of injected air increased, the events related to gas embolism were occurring at shorter timespans with more significant characteristics, i.e., length and number of bubbles. Additionally, correlations were established between the input parameters, i.e., the vascular diameter and equivalent hematocrit concentration, and the output parameters, i.e., the bubble size, velocity, frequency, and nucleation sites.Clinical Relevance- The reported results constitute a reproducible observation and quantification of intravascular bubble formation induced by global pressure variations, where the emergence of bubbles exhibits different patterns depending on biological characteristics related to gender and medical history.

Polymer Dynamics in Glycerol-Water Mixtures.

Velocity correlation spectra (VAS) in binary mixtures of water and glycerol (G/W), obtained by measurements using the modulated gradient spin echo (MGSE) NMR method, were explained by the interactions of water molecules with clusters formed around the hydrophilic glycerol molecule, which drastically change the molecular dynamics and rheology of the mixture. It indicates a thickening of the shear viscosity, which could affect the dynamics of submerged macromolecules. The calculation of the polymer dynamics with the Langevin equations according to the Rouse model, where the friction was replaced by the memory function of the retarded friction, gave the dependence of the dynamics of the polymer on the rate of shear viscous properties of the solvent. The obtained formula was used to calculate the segmental VAS of the polymer when immersed in pure water and in a G/W mixture with 33 vol% glycerol content, taking into account the inverse proportionality between the solvent VAS and friction. The spectrum shows that in the G/W mixture, the fast movements of the polymer segments are strongly inhibited, which creates the conditions for slow processes caused by the internal interaction between the polymer segments, such as interactions that cause disordered polypeptides to spontaneously fold into biologically active protein molecules when immersed in such a solvent.

Preservation of Mechanical and Morphological Properties of Porcine Cardiac Outflow Vessels after Decellularization and Wet Storage.

Widely used storage methods, including freezing or chemical modification, preserve the sterility of biological tissues but degrade the mechanical properties of materials used to make heart valve prostheses. Therefore, wet storage remains the most optimal option for biomaterials. Three biocidal solutions (an antibiotic mixture, an octanediol-phenoxyethanol complex solution, and a glycerol-ethanol mixture) were studied for the storage of native and decellularized porcine aorta and pulmonary trunk. Subsequent mechanical testing and microstructural analysis showed a slight increase in the tensile strength of native and decellularized aorta in the longitudinal direction. Pulmonary trunk elongation increased 1.3-1.6 times in the longitudinal direction after decellularization only. The microstructures of the tested specimens showed no differences before and after wet storage. Thus, two months of wet storage of native and decellularized porcine aorta and pulmonary trunks does not significantly affect the strength and elastic properties of the material. The wet storage protocol using alcohol solutions of glycerol or octanediol-phenoxyethanol mixture may be intended for further fabrication of extracellular matrix for tissue-engineered biological heart valve prostheses.

Natural Antioxidant-Loaded Nanoemulsions for Sun Protection Enhancement

The aim of this study was to formulate nanodispersions to encapsulate antioxidants extracted from olive mill wastewater (OMW) and phycocyanin extracted from Spirulina maxima to act as enhancers for the skin’s protection against UV radiation. For this purpose, two water-in-oil nanoemulsions were prepared using a low-energy homogenization method. Both systems were based on isopropyl myristate as the continuous phase, while water or a mixture of glycerol and water was used as the dispersed phase. Then, antioxidants extracted from OMW and phycocyanin from Spirulina maxima were encapsulated in the water core of the nanoemulsions. The empty and antioxidant-loaded systems were then structurally studied using dynamic light scattering for the detection of their droplet size and stability over time. Electron paramagnetic resonance (EPR) spectroscopy using adequate probes was applied for the characterization of the surfactants’ monolayer in the presence and absence of antioxidants. It was found that the mean droplet diameter of the emulsions was 200 nm. The nanoemulsions remained stable for over 2 months. The encapsulated antioxidants were assessed for their scavenging activity of a model stable radical by applying EPR spectroscopy. It was found that the loaded systems exhibited an increased antioxidant capacity compared with the empty ones. Finally, the most stable system was added to commercial sunscreen lotions and the overall sun protection factor (SPF) was assessed. The sunscreen lotions that contained the nanoemulsions loaded with OMW extracts or phycocyanin showed an increase in their SPF value.