Structure Of Micelles Research Articles

Impact assessment of nanoparticles on microstructure and rheological behaviour of VES fracturing fluid formulated with mixed surfactant system

The nature and type of fracturing fluid play a vital role in a successful hydraulic fracturing job. The desired fracturing fluid should have non-damaging characteristics and an effective proppant carrying capacity. Though viscoelastic surfactant (VES) fluid has started to replace the polymer-based fluids for the fracturing of specific formations owing to its non-damaging characteristics; however, its wider application to high-temperature formation is still a challenge to the operators. Incorporation of nanoparticle has been able to extent the thermal stability of VES fluid. The current study examined the impacts of different nanoparticles at different concentrations on rheological and structural properties of VES fluid prepared from mixed surfactant system which is composed of NaOA/tween 80, Co-surfactant, oil and water. Nano-enhanced VES fluids were formulated using SiO2, Fe2O3, MgO, and ZnO nanoparticles at varied concentrations, ranging from 250 ppm to 1000 ppm. The rheological and morphological variations of VES fluids were studied at different shear rates and temperatures. MgO and Fe2O3 enhanced VES at 500 ppm concentration fluid showed excellent rheological characteristics with 3529 cp and 2817 cp viscosity at a shear rate of 100 S−1, temperature 35 °C, which is much above the required viscosity value. Zeta potential and surface area of nanoparticles both play an important role in the rheological enhancement of VES fluid. MgO enhanced VES fluid with a surface area (83.7 m2/g) and zeta potential (−15.9, mV) of MgO nanoparticles showed better rheological properties than silica enhanced VES gel with surface area (127.8 m2/g) and zeta potential (–33.8, mV). It was also observed that increasing the nanoparticle concentration improved VES fluid's rheological properties; however, the rate of increment decreased after 500 ppm concentration. The cryo-FESEM images clearly indicate the distict change in the lamellar structure of VES fluids on the addition of nanoparticles compared to that of in its absence. The dynamic rheology tests further confirmed the compact structure and stronger entanglement of micelles in the presence of nanoparticles.All the developed nano-enhanced VES fracturing fluids showed desired viscosity up to the temperature of 150 °C. Among all nano-enhanced fracturing fluid, MgO enhanced VES fracturing fluid showed excellent viscosity (i.e., 200 cP) with respect to time at 100 °C temperature and a shear rate of 100 S−1. All the nano-enhanced VES fluid was miscible with formation water & there were no residues observed. A static column test was also done to check the proppant carrying capacity of VES gel. The MgO enhanced VES gel has also showed lowest proppant settling velocity of 0.305 cm/min which is much lower than the maximum permissible proppant settling velocity of 5 cm/min. The findings of this study can help for a better understanding of nano-enhanced VES fracturing fluid in mitigating the constraints associated with hydraulic fracturing jobs in formation with high temperatures. Thus, the knowledge about the functional characteristics of different nanoparticles in enhancing the fracturing fluid properties will help us to select suitable nanoparticle-surfactant combinations for a particular field.

Quantitative multivalent binding model of the structure, size distribution and composition of the casein micelles of cow milk

Compatible theories describing the size distribution of milk casein micelles, the partition of milk salts and the formation of calcium phosphate nanocluster complexes are combined to provide the first quantitative model of the cow casein micelle. Complexes of caseins with calcium phosphate nanoclusters associate with each other and the remaining (free) caseins to form a stable, polydisperse distribution of micelle sizes. The micelles in the distribution have a highly hydrated coat-core structure in which the calcium phosphate nanoclusters, and caseins bound directly to them, occur only in the core whereas the free caseins are found in both the coat and core. The theory is used to describe the structure, substructure, surface potential, size distribution, and the salt and protein composition of casein micelles in a standard cow milk. Multivalent casein–casein interactions through short, linear, amino acid sequence motifs determine many aspects of casein micelle formation and stability.

Polymeric surfactant micelle structure modulated by ionic liquids

The very low volatility, high thermal and chemical stability, and broad range of intermolecular interactions that many ionic liquids (ILs) exhibit render them promising as solvents or additives in diverse applications. We are interested in the self-assembly in ionic liquids of amphiphiles, in particular those of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block polymer family, commercially available as Poloxamers or Pluronics. We consider here aqueous solutions of a relatively hydrophobic PEO-PPO-PEO block copolymer (Pluronic P123, EO20PO70EO20) with the representative ionic liquids ethylammonium nitrate (EAN) (protic IL) or 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) (aprotic IL). We further compare the effects of ionic liquid electrolytes to those of the classic electrolyte ammonium nitrate (NH4NO3). We report on the block copolymer micelle structure ascertained from analysis of small-angle neutron scattering (SANS) data, and discuss the observed IL effects in the context of the underlying intermolecular interactions. Opposite effects on micelle structure are observed upon addition of EAN or NH4NO3 compared to BmimBF4: an increase in the micelle core radius and association number, and a decrease in the micelle shell thickness indicating dehydration upon addition of EAN or NH4NO3; a decrease in the micelle core radius and association number, and an increase in the shell thickness indicating increased solvation upon addition of BmimBF4. A temperature increase leads to similar effects on the micelle structure as the addition of the kosmotropic electrolytes EAN and NH4NO3. This study for the first time reports PEO-PPO-PEO micelle structure in IL-water mixtures, and utilizes it to proxy the operating intermolecular interactions and the role that ILs play in the self-assembly process.

Self-assembly of Quillaja saponin mixtures with different conventional synthetic surfactants

Saponins are surface active glycosides which can be extracted from a range of different plant species. This class of biosurfactants is of much current interest because of their biocompatibility and biosustainability, and a range of other interesting properties. The Quillaja saponin, the focus of this paper, is extensively used in foods, beverages and cosmetics due to their accessibility and agency approval. Aspects of their wider application rests with their use in combination with different synthetic surfactants, to optimise and tailor performance and functionality. Characterising and understanding the self-assembly of such mixtures is an essential requirement for that wider exploitation. The surface activity of a range of different saponins has been extensively reported, but the self-assembly properties of the Quillaja saponin, and its mixture with different synthetic surfactants has not been reported in any detail. Of particular interest is how the bidesmodic structure of the Quillaja saponin and the mixing with the different cosurfactants affects the evolution in the micelle structure, and this is the focus of this study. Small angle neutron scattering, SANS, has been used to characterise the micelle formation of the Quillaja saponin and of its mixtures with the anionic surfactant sodium dodecyl sulfate, SDS, and the nonionic surfactants, dodecaethylene glycol monododecyl ether, C12E12, and pentaethylene glycol monododecyl ether, C12E5. The Quillaja saponins form relatively small globular micelles with a relatively small aggregation number. In mixtures with SDS and the nonionic surfactants the micelles retain their globular structure. In the mixtures the micelle aggregation number evolves towards the value for the pure synthetic surfactant component, as the packing constraints change with the decreasing mole fraction of saponin in the micelle. The evolution in the micelle structure and size reflects the change in the structure and geometry of the associated surfactant components, and is largely dominated by the Quillaja structure. The results provide an interesting insight into the factors controlling the self-assembly in saponin – surfactant mixtures, and how the saponin structure affects the self-assembly.

Targeted Delivery of Miconazole Employing LL37 Fragment Mutant Peptide CKR12-Poly (Lactic-Co-Glycolic) Acid Polymeric Micelles.

We previously reported that conjugates of antimicrobial peptide fragment analogues and poly (lactic-co-glycolic) acid (PLGA) enhance antimicrobial activity and that the conjugated micelle structure is an effective tool for antimicrobial drug delivery. In recent years, the delivery of antimicrobial peptides to targets for antimicrobial activity has attracted attention. In this study, we targeted Candida albicans, a causative organism of catheter-related bloodstream infections, which is refractory to antimicrobial agents and is currently a problem in medical practice. We evaluated the antifungal activity of CKR12 (a mutant fragment of the human cathelicidin peptide, LL-37)-PLGA-miconazole (MCZ) micelles using nanotechnology with MCZ delivery. The prepared CKR12-PLGA-MCZ micelles were characterised by measuring dynamic light scattering, zeta potential, dilution stability, and drug release. CKR12-PLGA-MCZ micelles showed higher antifungal activity than CKR12-PLGA micelles and MCZ solution. Furthermore, scanning and transmission electron microscopy suggested that CKR12-PLGA-MCZ micelles disrupted both cell wall and cell membrane of C. albicans. Our results revealed a synergistic effect of antifungal activity using a combination of antimicrobial peptide fragment analogues and MCZ, and that MCZ is a promising tool for the delivery to target microorganisms.

Structure and composition of mixed micelles formed by nonionic block copolymers and ionic surfactants in water determined by small-angle neutron scattering with contrast variation

HypothesisComplex fluids comprising polymers and surfactants exhibit interesting properties which depend on the overall composition and solvent quality. The ultimate determinants of the macroscopic properties are the nano-scale association domains. Hence it is important to ascertain the structure and composition of the domains, and how they respond to the overall composition. ExperimentsThe structure and composition of mixed micelles formed in aqueous solution between poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronics or Poloxamers) and the ionic surfactant sodium dodecylsulfate (SDS) are determined from an analysis of small-angle neutron scattering (SANS) intensity data obtained at different contrasts. Different polymers and concentrations have been probed. FindingsThe SDS + Pluronic mixed micelles include polymer and some water in the micelle core that is formed primarily by alkyl chains. This is different than what was previously reported, but is consistent with a variety of experimental observations. This is the first report on the structure of SDS + Pluronic P123 (EO19PO69EO19) assemblies. The effects on the mixed micelle structure and composition of the surfactant concentration and the polymer hydrophobicity are discussed here in the context of interactions between the different components.

Enhanced rehydration behaviors of micellar casein powder: The effects of high hydrostatic pressure treatments on micelle structures

Natural micellar casein is generally dried into powdered forms for commercial transportation and storage. However, the poor rehydration ability of micellar casein powder critically limited the potential applications due to its dense cross-linked structures caused by colloidal calcium phosphate (CCP). In this study, micellar casein solutions were exposed to a high hydrostatic pressure (HHP) ranging from 100 to 500 MPa and were then freeze dried to produce powders. The effects on the casein micelle structures and the rehydration characteristics including wetting, dispersion and dissolving were comprehensively investigated. The results showed that HHP could induce smaller micelle sizes and significantly increase the free calcium in the reconstituted solution. It demonstrated that the majority of CCP bridges in casein micelles were dissociated, which produced porous powders with loose structures and thus significantly improved rehydration behaviors. 300 MPa was the pressure level that caused the quickest dispersion process and best solubility. Consequently, HHP has potential to be a novel physical technique to potentially modify the protein higher-order structures as well as improve the corresponding functionalities.

Role of chain length and electrolyte on the micellization of anionic fluorinated surfactants in water

The micellization of ionic surfactants in aqueous media reflects a balance between the hydrophobic attraction of surfactant tails and the electrostatic repulsion of surfactant headgroups. We investigate here the effect on surfactant micellization of the hydrophobic chain length and electrolyte composition, by focusing on the fluorinated surfactants sodium perfluorohexanoate (NaPFHx) and sodium perfluorooctanoate (NaPFO) in aqueous solution without/with NaCl, and analyzing experimental data from surface tension, pyrene fluorescence, small-angle neutron scattering (SANS), and viscosity techniques. The CMC of NaPFHx in water was 200 mM, much higher than that of NaPFO, 30 mM, due to the additional two -CF2- groups of the latter. Upon addition of 0.25 M NaCl to the aqueous solution, the CMC of NaPFHx and NaPFO decreased by about 50% and 80%, respectively. The NaPFHx and NaPFO micelles are both ellipsoid in shape. NaPFHx forms smaller micelles compared to NaPFO: the association number for NaPFHx in D2O was 15 compared to 25 for NaPFO. Upon NaCl addition, the micelle shape became more elongated. This is the first report on the NaPFHx micelle structure. The information presented here supports the re-formulation and replacement of long-chain fluorinated surfactants with relatively safer long-chain surfactants.

Size-controllable core/shell whey protein microgels with narrow particle size distribution fabricated by a facile method

Biopolymer-based microgels are increasingly being viewed as promising building blocks for diverse applications, including drug delivery, novel food ingredients, sensing, and cell biology. The formation of microgels with a narrow size distribution is of key importance because the functional properties of these microgels largely rely on their sizes. This study describes the use of protein-polysaccharide segregative phase separation as a facile method to fabricate whey protein-based microgels by heating mixtures of whey protein and anionic polysaccharides. The spherical microgels had a narrow size distribution and their size could be precisely controlled to 1, 3, and 6 μm. The scanning electron microscopic images revealed a core-shell morphology of the individual microgel with an internal structure of densely cross-linked protein network and an outer “hairy” layer of polysaccharide, resembling the hair-like structures of the casein micelles. Compared to the whey protein, the core/shell microgels could produce emulsions that were stable without flocculation and creaming during a 28-day storage test. Considering the size-controllable protein-based microgels can be fabricated in a convenient method without using toxic reagents or high energy input, these microgels will have broad applications in the food, pharmaceutical, and personal care industries.

Physico-chemical and functional properties of milk protein concentrates obtained using a two-stage decalcification approach

Effects of decalcification (0–72%) through mixing ultrafiltration retentates of highly acidified and nonacidified skim milk on spray-drying and solubility of milk protein concentrate (MPC) were studied. Powder recoveries increased with decalcification. MPC solubility markedly improved at and above 13% decalcification. Comparison was then made with MPC manufactured directly from moderately acidified milk at a decalcification ratio of 28%, where MPC solubility was satisfactorily high and casein micelle structures were generally maintained. No marked differences were observed in calcium and casein distributions, micelle structures and hence MPC functionalities between the two approaches. After mixing retentates of highly acidified and nonacidified milk, serum calcium and caseins re-associated into micelles to reach an equilibrium similar to that obtained using the one-stage approach. The novel two-stage approach allowed for an efficient and precise manufacture of MPC with different decalcification ratios, and with comparable micelle structures and functionalities to those manufactured using the one-stage approach.

Use of casein micelles to improve the solubility of hydrophobic pea proteins in aqueous solutions via low-temperature homogenization

The dairy industry struggles to maintain consumer attention in the midst of declining fluid milk sales. Current trends create an opportunity to incorporate plant-based proteins with milk to produce a high-protein, multisourced, functional food product. Plant-based proteins, such as those in peas, can be challenging to use in food systems because of their low solubility and undesirable off-flavors. Casein micelles have unique structural properties that allow for interactions with small ions and larger macromolecules that aid in their noteworthy ability as a nanovehicle for hydrophobic compounds. The objective of this study was to use the inherent structure of the casein micelle along with common dairy processing equipment to create a stable colloidal dispersion of casein micelles with pea protein to improve its solubility in aqueous solutions. We created 3 blends with varying ratios of casein-to-pea protein (90:10, 80:20, 50:50). We subjected the mixtures to 3 cycles of homogenization using a bench-top GEA 2-stage homogenizer at 27,580 kPa maintained at 4°C, followed by pasteurization at 63°C for 30 min. The resulting blends were homogeneous liquids with increased stability due to the lack of protein precipitation. Further protein analysis by HPLC and AA sequencing revealed that vicilin, an insoluble storage protein, was the main pea protein incorporated within the casein micelle structure. These results supported our hypothesis that low-temperature homogenization can successfully be used to create a colloidal dispersion with increased stability, in which insoluble plant-based proteins may be incorporated with casein micelles in an aqueous solution. Additionally, 3-dimensional microscope images of the blends indicated a noticeable difference between the surface roughness upon addition of pea protein to the casein micelle matrix. This research highlights a promising application for other plant-based proteins to be used within the dairy industry to help drive future product innovation while also meeting current processing conditions and consumer demands.

Formulation, Solubilization, and In Vitro Characterization of Quercetin-Incorporated Mixed Micelles of PEO-PPO-PEO Block Copolymers.

Quercetin (QCN) is a plant polyphenol with a variety of medicinal effects. Poor water solubility, on the other hand, restricts its therapeutic effectiveness. The purpose of this study was to develop mixed micellar systems using two biocompatible amphiphilic PEO-PPO-PEO triblock copolymers, Pluronic P123 (EO20-PO70-EO20) and Pluronic F88 (EO104-PO39-EO104), in order to enhance the aqueous solubility and oral bioavailability of QCN drug. The critical micelle concentrations (CMCs) of mixed P123/F88 micellar solutions were investigated using UV-visible spectroscopy with pyrene as a probe. Mixed P123/F88 micelles have low CMCs, indicating that they have a stable micelle structure even when diluted. The solubility of QCN in aqueous mixed P123/F88 micellar solutions at different temperatures was investigated to better understand drug entrapment. The QCN solubility increased with increasing temperature in the mixed P123/F88 micellar system. The QCN-incorporated mixed P123/F88 micelles were prepared using the thin-film hydration method and were well characterized in terms of size and morphology, compatibility, in vitro release and antioxidant profile. In addition, the cell proliferation activity of the mixed micelles was evaluated in the MCF-7 cell line. The QCN-incorporated mixed P123/F88 micelles had a small particle size (< 25nm) and a negative zeta potential with a spherical shape. The in vitro release behaviour of QCN from a mixed P123/F88 micellar system was slower and more sustained at physiological conditions. The oxidation resistance of QCN-incorporating mixed P123/F88 micelles was shown to be considerably higher than that of pure QCN. An in vitro cell proliferation study revealed that QCN-incorporated mixed micells were effective in inhibiting tumour cell growth. In conclusion, the QCN-incorporated mixed P123/F88 micelle may be a promising approach to increase QCN oral bioavailability, antioxidant activity, and cell viability.

Design of a salt-tolerant Gemini viscoelastic surfactant and the study of construction of wormlike micelle structure in high-salinity aqueous environment

Herein, a zwitterionic Gemini VES (named VES-C) with double ultra-long hydrophobic tails was designed and synthesized which aimed to construct WLM net-structures in high-salinity aqueous solution. Due to the carboxylic group on the spacer, it exhibits partial carboxyl betaine properties and performs well in high salinity environment. Molecular dynamic simulation was carried out and RDF curves were analyzed to predict and explain the mechanism of salinity tolerance of VES-C. Compared with cationic Gemini VESs, a series of experiments were conducted by varying salinity, including surface tension, DLS, 1H NMR and fluorescent probe, to explain the salt-tolerance mechanism of VES-C. The salinity cloudy point of VES-C surpasses 10 wt%, exhibiting superior salt-tolerance to those cationic Gemini VESs. Trough viscosity measurement, oscillatory measurement and microstructure observation, it proves that VES-C molecules can construct WLM netlike structures within the salinity range from 3 wt% to 10 wt% (optimal salinity: 4 wt%), thus VES-C can be applied as the clean thickener to prepared seawater or brine based fracturing fluid by constructing WLM netlike structure in high salinity aqueous environment, which leaves the preparation of clean fracturing fluid independent of freshwater resources.

Molecular interaction between sodium dodecylbenzene sulfonate and octylphenol polyoxyethylene ether and effect of hydrophilic chain

The micellization behavior of two binary mixtures of an anionic sodium dodecylbenzene sulfonate with a nonionic surfactant octylphenol polyethoxylated ether (including OP-10 or OP-7) was investigated in aqueous solution at 298.15 K using the tensiometry, and the effect of hydrophilic chain of nonionic surfactant was discussed. In the framework of pseudophase separation model and based on the regular solution theory, the related micellization parameters and thermodynamic parameters were estimated by some models including Clint’s model, Rubingh’s model, etc. The two mixtures exist some differences in the micellization behavior. The synergistic effect, the antagonism, nonideal mixing and ideal mixing are observed in the two mixtures. The dependence of the mixed critical micelle concentration, the composition in mixed micelle, the interaction parameter between molecules on the composition in aqueous solution is explained by the electrostatic interaction, the steric effect and the shell structure of mixed micelle, etc. Thermodynamic parameters are adopted to account for the difference in energy and verify the micellization behavior. The two binary mixtures show different contributions of energy to the process of micellization. These findings help with understanding the nature on the interaction between two surfactants and the effect of the length of hydrophilic chain of nonionic surfactant so as to obtain some information in theoretical and practical investigations.

Thermodynamically Originated Stacking Fault in the Close-Packed Structure of Block Copolymer Micelles

Thermodynamically Originated Stacking Fault in the Close-Packed Structure of Block Copolymer Micelles

Photoresponsive Viscoelastic Solutions Based on Chiral Wormlike Micelles in Mixed Solutions Containing an Amphiphile Derived from Rosin.

A novel rosin-based photoresponsive anionic amphiphile, sodium N-azophenyl maleopimaric acid imide carboxylate (AzoMPCOONa), has been successfully synthesized. Its molecular structure was characterized by 1H and 13C NMR and mass spectrometry (MS). The photoisomerization of AzoMPCOONa was evaluated by ultraviolet (UV)-visible spectrometry and 1H NMR. The structure of AzoMPCOONa could be converted between the trans and cis isomers by irradiation with UV/visible light. Importantly, a fascinating photoresponsive viscoelastic solution was prepared by mixing AzoMPCOONa and cetyltrimethylammonium bromide (CTAB). The properties of the photoresponsive viscoelastic solution were further investigated by rheology, circular dichroism (CD), and cryogenic transmission electron microscopy (cryo-TEM). Initially, the AzoMPCOONa/CTAB system was a gel-like solution composed of entangled wormlike micelles possessing the right-handed chiral structure. After UV irradiation for 10 min, the gel-like solution transformed into a slightly viscous solution, its zero-shear viscosity dramatically reduced by 2 orders of magnitude, and the aggregates were converted into rod-like micelles and spherical micelles. In addition, the right-handed chiral structure of the aggregates disappeared. These dramatic changes in the viscosity and the aggregate structure can be attributed to the photoisomerization of the azobenzene group in AzoMPCOONa, which led to changes in the molecular geometry and the packing parameter of the AzoMPCOONa/CTAB system. Interestingly, the right-handed chiral structure of wormlike micelles also is photoresponsive. The results reveal the superiority of forest resources for preparing viscoelastic solutions.

Changeable wettability of electrospun membrane by adjusting self‐assembly micelles structure of amphiphilic block copolymer

AbstractFiber membranes with high specific surface area can be produced when using electrospinning technology combined with amphiphilic block polymers. Due to the solubility difference between the two segments of amphiphilic block polymers, it is easy to be self‐assembly in solvents, which affects the morphology of the spinning fiber and the surface properties of the membrane. In this work, the relationship between the self‐assembly of the amphiphilic block polymer and the morphology of the spinning fiber and the wetting performance of the spinning membrane was explored. Membrane is produced by electrospinning amphiphilic block copolymer PS‐b‐PHEMA (polystyrene‐block‐poly(2‐hydroxyethyl methacrylate) by using co‐solvent system. PS‐b‐PHEMA with controlled molecular weight (Mw) and polymer dispersity index (PDI) was synthesized via atom transfer radical polymerization (ATRP) and characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The electrospun membrane have both super‐hydrophobic and super‐hydrophilic by adjusting the ratio of mixed solvents, demonstrating that the wetting performance of the fiber membrane mainly depends on the shell structure of the self‐assembly micelles.

Intraparticle and Interparticle Transferable DNA Walker Supported by DNA Micelles for Rapid Detection of MicroRNA.

Synthetic DNA walkers are artificially designed DNA self-assemblies with the capability of performing quasi-mechanical movement at the micro/nanoscale and have shown extensive promise in biosensing, intracellular imaging, and drug delivery. However, DNA walkers are usually constructed by covalently or coordinately binding DNA strands specifically to hard surfaces, thereby greatly limiting their movement efficiency. Herein, we report an intraparticle and interparticle transferable DNA walker (dynamic micelle-supported DNA walker, DM-walker) constructed by immobilizing walking tracks and walking arms onto the corona of DNA micelles according to the principle of Watson-Crick base pairing. The DNAzyme-powered walking arm can drive the intraparticle and interparticle movements of the DM-walker due to the fact that the dynamic structure of the DNA micelle helps overcome the spatial barrier between the arms and tracks in the system, resulting in high walking efficiency. Moreover, the whole DM-walker can be constructed by self-assembly, getting rid of the tedious process and low efficiency of fixing DNA strands on hard surfaces. Taking miRNA-10b as a model target, the DM-walker demonstrates high walking efficiency (reaction duration of 20 min) and high sensitivity (LOD of 87 pM). The proposed DM-walker provides an avenue to develop novel DNA walkers on dynamic interfaces and holds great potential in clinical diagnosis.

Vitamin D Fortification of Consumption Cow's Milk: Health, Nutritional and Technological Aspects. A Multidisciplinary Lecture of the Recent Scientific Evidence.

Vitamin D is essential in assuring bone health at all stages of life, but its non-skeletal effects are also essential: This vitamin impacts the physiology of the immune system, skeletal muscles and adipose tissue, glucose metabolism, skin, cardiovascular and reproductive systems, neuro-cognitive functions and cell division. The incidence of vitamin D deficiency is widespread worldwide, at any age, in young and healthy subjects, as well as in pregnant women and the elderly population, due to several factors, including inadequate sunlight exposure, skin pigmentation and coverage, adiposity, lifestyle and low dietary intakes. To overcome this problem, the fortification of foods that are consumed on a daily basis, such as milk, is strongly advisable. This opinion paper aims to discuss, in a multidisciplinary way, the current evidence supporting the importance of vitamin D in health and disease and the role of milk as an optimal carrier of this vitamin, to promote adequate intakes, highlighting its unique physico-chemical characteristics linked to both fat globule membrane and casein micelle structure. Moreover, it addresses the impact of industrial processing and storage of consumption milk on the stability of these structures, thus in determining vitamin D bioavailability and the achievement of adequate intakes.

Enhanced delivery of artesunate by stimuli-responsive polymeric micelles for lung tumor therapy

Artesunate (ART) as a traditional chinese medicine has been reported to have a good antitumor effect on some cancers. However, the poor hydrophilicity and instability in the intestine limit its bioavailability and further application. Herein, this work reported a redox-sensitive micelle system encapsulating ART to enhance the therapeutic effect on lung tumor. Specifically, K5 capsular polysaccharide-SS-d-α-tocopheryl succinate (K5-SS-TOS, KSST) copolymers can self-assemble to form micelles and effectively load ART into the hydrophobic core. Simultaneously, redox-insensitive K5 capsular polysaccharide-d-α-tocopheryl succinate (K5-TOS, KT) copolymers were synthesized as control. ART-loaded micelles (ART/KSST) with a spherical particle size had good polydispersity. The drug loading content and entrapment efficiency of the ART/KSST were (13.5 ± 0.92) % and (81.09 ± 2.61) %, respectively. Moreover, ART/KSST can release ART quickly in the presence of glutathione, showing a good redox release behavior. In addition, the ART loaded micelles had negligible toxicity to normal cells. However, ART/KSST which can be uptaken through energy-dependent pathways by A549 cells showed higher cytotoxicity than ART/KT. The results suggested that disulfide bond can be ruptured in the tumor cells, resulting in disintegration of the micelle structure and fast release of ART to achieve better therapeutic effect. Therefore, the redox-sensitive KSST copolymers as potential nanocarriers can deliver ART effectively to improve the therapeutic effect of lung tumors.