Hydrophobic Shell Research Articles

Self-assembly in amphiphilic spherical brushes.

The structure of amphiphilic spherical brushes, consisting of the nano-SiO2 core, the hyperbranched polyamidoamine subshell, and a grafted layer of long hydrophobically modified polyacrylamide (HMPAM) chains, in aqueous solution was analyzed and described in the framework of the original mean-field approach. The scaling estimations of the hydrodynamic radius of such polymer brushes as a function of the number of grafted macromolecules allow concluding that the HMPAM shells are in a globular state and that the region of the stretched chains adjacent to the grafting surface is a minor part of the grafted macromolecules and does not have a significant impact on the self-assembly of the HMPAM shell caused by the complex hydrophobic-hydrophilic composition of their monomer units. In mean-field theory, the amphiphilic nature of HMPAM was taken into account by attaching the hydrophobic side group H to some fraction of monomer units of the hydrophilic P backbone. The strong attraction of H groups causes the aggregation of macromolecules, whereas the affinity of hydrophilic P groups to solvent forces the aggregates to increase their surface. Due to such effective surface activity, in poor solvent, the grafted amphiphilic macromolecules could form a spherical compacted structure around the nanoparticle or self-assemble into a "hedgehog" structure with several "spines" having hydrophobic core and hydrophilic shell. State diagrams, obtained theoretically, reveal that the "hedgehog" structure is preferable for a wide range of energetic parameters.

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

AbstractThe effect of microencapsulated phase‐change materials (MPCM) on the rheological properties of pre‐set geopolymer and Portland cement mortars was examined. Microcapsules with hydrophilic and hydrophobic shells were compared. The shear rate dependency of the viscosities fitted well to a double Carreau model. The zero shear viscosities are higher for geopolymer mortar, illustrating poorer workability. The time evolution of the viscosities was explored at shear rates of 1 and 10 s−1. New empirical equations were developed to quantify the time‐dependent viscosity changes. The highest shear rate disrupted the buildup of the mortar structures much more than the lower shear rate. Microcapsules with a hydrophobic shell affect the rheological properties much less than the microcapsules with a hydrophilic shell, due to the higher water adsorption onto the hydrophilic microcapsules. Shear forces was found to break down the initial structures within geopolymer mortars more easily than for Portland cement mortars, while the geopolymer reaction products are able to withstand shear forces better than Portland cement hydration products. Initially, the viscosity of geopolymer mortars increases relatively slowly during due to formation of geopolymer precursors; at longer times, there is a steeper viscosity rise caused by the development of a 3D‐geopolymer network. Disruption of agglomerates causes the viscosities of portland cement mortars to decrease during the first few minutes, after which the hydration process (increasing viscosities) competes with shear‐induced disruption of the structures (decreasing viscosities), resulting in a complex viscosity behavior.

Application of a novel pH-responsive gemini surfactant for delivery of curcumin molecules

During the last few decades, extensive studies have been conducted to elucidate the anti-cancer effects of curcumin. Despite promising results indicating curcumin could impede cancer cells ability thrive and proliferation, clinical applications of it have been limited. This limitation is mainly due to low solubility, poor bioavailability, rapid metabolism, and deficient absorption. To improve the physiochemical properties of curcumin, we have synthesized a novel biodegradable gemini surfactant in which curcumin molecules were entrapped. Gemini surfactant-curcumin nanocapsules were prepared using nanoprecipitation method and characterized by several techniques including, DLS, TEM, AFM, FTIR, DSC and XRD. The in vitro MTT assay, cellular uptake, and apoptosis assay were performed using MDA-MB-231 cell line. The gemini surfactant molecules were able to form vesicles in aqueous solution with a narrow size distribution (PDI 0.3). An encapsulation efficiency of 87.45 ± 2.3% and the drug loading content of 4.98 ± 0.12% were acquired. Curcumin molecules were dispersed in the hydrophobic shell of the vesicles, and sustained release profile was observed. Due to the increased cellular uptake and sustained release profile, the gemini surfactant-curcumin nanocapsules exhibited higher cytotoxicity and enhanced apoptosis in MDA-MB-231 cells compared to free curcumin. The results indicate that gemini surfactant-curcumin complex shows considerable promise as an anti-breast cancer drug.

Fluorescence Turn-on and Wavelength-Shift Dual Response for Methylamine Gas Sensing Using HPbBr3/PbBr2@SiO2 Nanospheres

The defect-tolerant nature of lead halide perovskites renders high PLQYs by simply confining them in nanopores. In view of this character, a fluorescence turn-on and wavelength-shift dual responsive methylamine (MA) gas sensor is achieved using HPbBr3/PbBr2@SiO2 nanospheres (NSs). In this composite, the hydrophobic silica shell not only provides mesopores for the penetration of MA gas, but enhances the moisture stability of the MAPbBr3 perovskite nanocrystals generated after reacted with MA gas, improving the sensing performance. When exposed to the MA gas, the fluorescence is rapidly turned on due to the formation of MAPbBr3 perovskite nanocrystals. The enhanced photoluminescence is linearly with the MA concentration in the range of 0.08 – 6.3 μM with a LOD of 3.1 nM (S/N = 3). In addition, the photoluminescence peak is consistently red-shift from 478.7 nm to 510.6 nm when the MA concentration is increased from 0.083 to 6.3 µM. Correspondingly, the emission color is changed from weak blue to cyan, and to bright green, which imparts the potential for colorimetric sensing. By combining the turn-on and wavelength-guide sensing modes, this MA sensor is more flexible and the result is more reliable. Figure 1

Electrical Strength of Natural Esters Doped by Iron Nanopowder in a Hydrophobic Carbon Shell.

The paper presents the results of measurements of electrical strength of Midel 1204 natural ester doped with iron nanopowder in a hydrophobic carbon shell. The research was conducted for different concentrations of the dopant. The samples were prepared in the High Voltage Technique Laboratory. After mixing, they were tightly closed, and the first measurements were taken after 5 weeks of dissolution of the dopant in liquid. The tests were repeated after another 2 weeks and 3 weeks of dissolution of nanoparticles. An increase in both mean and maximum breakdown voltage was shown for the tested liquid mixtures. The concentration for which the value of electrical strength begins to decrease was indicated. It was also shown that a longer time of dissolution of nanoparticles causes an increase in the electric strength value for the tested samples.

Hydrophobic MOFs@Metal Nanoparticles@COFs for Interfacially Confined Photocatalysis with High Efficiency

Converting solar energy to chemical energy via photocatalysis has attracted increasing interest. Simultaneously realizing efficient charge separation and fast reactant/product diffusion/transport is highly significant for improving the photocatalytic activity, which however is difficult. Herein, we reported an interfacially confined strategy by constructing interfacial pores as nanoreactors between metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) with controlled surface wettability for efficient photocatalysis. In the sandwich Ti-MOFs@Pt@DM-LZU1, interfacial pores formed between Ti-MOF@Pt and DM-LZU1, in which Pt nanoparticles (NPs) were encapsulated. The presence of Pt facilitates the charge separation on the photoactive Ti-MOF, while the hydrophobic porous DM-LZU1 shell promotes reactant enrichment. Interfacial pores acting as nanoreactors ensure fast electron and mass transport between the active Pt NPs and the concentrated reactants, leading to high photocatalytic activity. This work presents a new concept for the design of various photocatalysts with considerable activity.

Reversible Cross-Linked Mixed Micelles for pH Triggered Swelling and Redox Triggered Degradation for Enhanced and Controlled Drug Release.

Good stability and controlled drug release are important properties of polymeric micelles for drug delivery. A good candidate for drug delivery must have outstanding stability in a normal physiological environment, followed with low drug leakage and side effects. Moreover, the chemotherapeutic drug in the micellar core should also be quickly and “on-demand” released in the intracellular microenvironment at the tumor site, which is in favor of overcoming multidrug resistance (MDR) effects of tumor cells. In this work, a mixed micelle was prepared by the simple mix of two amphiphilic copolymers, namely PCL-SS-P(PEGMA-co-MAEBA) and PCL-SS-PDMAEMA, in aqueous solution. In the mixed micelle’s core–shell structure, PCL blocks were used as the hydrophobic core, while the micellar hydrophilic shell consisted of two blocks, namely P(PEGMA-co-MAEBA) and PDMAEMA. In the micellar shell, PEGMA provided hydrophilicity and stability, while MAEBA introduced the aldehyde sites for reversible crosslinking. Meanwhile, the PDMAEMA blocks were also introduced in the micellar shell for pH-responding protonation and swelling of the micelle. The disulfide bonds between the hydrophobic core and hydrophilic shell had redox sensitive properties. Reversible cross-linked micelles (RCLMs) were obtained by crosslinking the micellar shell with an imine structure. RCLMs showed good stability and excellent ability against extensive dilution by aqueous solution. In addition, the stability in different conditions with various pH values and glutathione (GSH) concentrations was studied. Then, the anticancer drug doxorubicin (DOX) was selected as the model drug to evaluate drug entrapment and release capacity of mixed micelles. The in vitro release profiles indicated that this RCLM had controlled drug release. In the simulated normal physiological environment (pH 7.4), the drug release of the RCLMs was restrained obviously, and the cumulative drug release content was only 25.7 during 72 h. When it came to acidic conditions (pH 5.0), de-crosslinking of the micelles occurred, as well as protonation of PDMAEMA blocks and micellar swelling at the same time, which enhanced the drug release to a large extent (81.4%, 72 h). Moreover, the drug release content was promoted further in the presence of the reductant GSH. In the condition of pH 5.0 with 10 mM GSH, disulfide bonds broke-up between the micelle core and shell, followed by shedding of the shell from the inner core. Then, the micellar disassembly (degradation) happened based on the de-crosslinking and swelling, and the drug release was as high as 95.3%. The MTT assay indicated that the CLSMs showed low cytotoxicity and good biocompatibility against the HepG2 cells. In contrast, the DOX-loaded CLSMs could efficiently restrain the proliferation of tumor cells, and the cell viability after 48 h incubation was just 13.2%, which was close to that of free DOX. This reversible cross-linked mixed micelle with pH/redox responsive behaviors is a potential nanocarrier for chemotherapy.

Design and synthesis of fluorescent shell functionalized polymer micelles for biomedical application

pH‐sensitive polymers can be defined as polyelectrolytes that include in their structure weak acidic or basic groups that either accept or release protons in response to a change in the environmental pH. This work summarizes the design, synthesis, and potential applications of pH‐responsive fluorescent copolymers in the biomedical field. This was achieved using atom transfer radical polymerization (ATRP) of tert‐butyl acrylate using a CuBr/N,N,N′,N″N″‐pentamethyldiethylenetriamine catalyst system in conjunction with an alkyl bromide as the initiator. Well‐defined macroinitiators based on poly(tert‐butyl acrylate) with narrow molecular weight distributions were obtained by the addition of an appropriate solvent system in order to create a homogeneous catalytic system. The addition of n‐butyl acrylate as a second building block in order to create well‐defined poly(tert‐butyl acrylate)‐b‐poly(n‐butyl acrylate) block copolymers (PtBA‐b‐PnBA) followed by chemical modification of the block copolymers and functionalization with an appropriate fluorescent compound are the basis for the preparation of well‐defined fluorescent pH‐sensitive micelles. Thus, prepared water soluble nanosized pH‐sensitive micelles consisting of hydrophobic poly(n‐butyl acrylate) core and hydrophilic polyacrylic acid shell decorated with an appropriate fluorescent compound determined their potential applications of these systems in the field of biomedicine as biosensors, controlled drug delivery systems, and so on. In this respect, the cell viability and internalization of the polymer micelles were studied.

Recent developments in nano micelles as drug delivery system

Targeting of the drug directly to the cells, tissues, or organs with no impact on healthy cells is a challenge. In the current era, it's been made possible by therapeutic interventions. The novel drug delivery systems such as nano particulates, liposomes, aquasomes, phytosomes, dendrimers, nano sponges, nano micelles are developed. Nano micelles are developed for efficient targeting and are currently in trend as therapeutic carriers of water-insoluble drugs. Micelles are self-assembling Nano-sized colloidal particles with a hydrophobic core and hydrophilic shell. Among the micelle-forming compounds, amphiphilic copolymers, i.e., polymers consisting of hydrophobic block and hydrophilic block, are gaining increasing attention. Polymeric micelles possess high stability both in vitro and in vivo with good biocompatibility. Nano micelles are used widely because of the smaller size range of 10 to 100nm, with greater drug loading capacity. Advantages over other dosage forms include solubilization of poorly soluble drugs, sustained release, protection of drugs from degradation and metabolism. The property discussed includes CMC, size, and aggregation number, and stability. CMC is the minimum polymer concentration required for micelle formation. Aggregation number (Nₐ) is the number of polymeric chains required to form micelles, and it ranges between tens to hundreds. Thermodynamic stability is based on size, the optical clarity of solution, viscosity, and surface tension. Kinetic stability accounts for micellar integrity. This review will discuss some recent trends in using micelles as pharmaceutical carriers such as to deliver drugs in conditions such as TB, cancer, ocular complications, etc.

Poly-thiourea formaldehyde based anticorrosion marine coatings on type 304 stainless steel

In the present study, hexamethylene diisocyanate (HMDI) encapsulated poly-thiourea formaldehyde (PTF) (10wt%) coating was developed in an epoxy-polyamine matrix and their anticorrosion studies on Type SS304 stainless steel substrate have been conducted using electrochemistry techniques. The compact and hydrophobic shell wall of PTF proved to be a potent shell wall material for HMDI encapsulation. The effect of temperature and pH values was found to be decisive factor in the synthesis of microcapsules. The PTF microcapsules were synthesized in acidic condition with a pH value of 3. Over 90% of the core fraction is retained in water after 21 days immersion. However, core content decreased with increasing temperature. The capsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Electrochemical Impedance spectroscopy (EIS). Scanning electron microscopic analysis depicts the uniform morphology of coating with a particle size in the range of 1.08μm–22.06μm. The vibrational band at 2271cm−1 attributed to NCO signal further endorses the successful encapsulation of HMDI into the PTF capsules. Electrochemical testing on steel specifies the appreciable anticorrosion performance of the synthesized poly thiourea formaldehyde (PTF) coating against artificial sea water.

Nanoporous hybrid core-shell nanoparticles for sequential release.

In this article, a new type of core-shell nanoparticle is introduced. In contrast to most reported core-shell systems, the particles presented here consist of a porous core as well as a porous shell using only non-metal materials. The core-shell nanoparticles were successfully synthesized using nanoporous silica nanoparticles (NPSNPs) as the starting material, which were coated with nanoporous phenylene-bridged organosilica, resulting in a total particle diameter of about 80 nm. The combination of a hydrophilic nanoporous silica core and a more hydrophobic nanoporous organosilica shell provides regions of different chemical character and slightly different pore sizes within one particle. These different properties combined in one particle enable the selective adsorption of guest molecules at different parts of the particle depending on the molecular charge and polarity. On the other hand, the core-shell make-up of the particles provides a sequential release of guest molecules adsorbed at different parts of the nanoparticles. As a proof of concept, loading and release experiments with dyes were performed using non polar fluorescein and polar and charged methylene blue as model guest molecules. Non polar fluorescein is mostly adsorbed on the hydrophobic organosilica shell and therefore quickly released whereas the polar methylene blue, accumulated in the hydrophilic silica core, is only released subsequently. This occurs in small doses for an extended time corresponding to a sustained release over at least one year, controlled by the organosilica shell which acts as a diffusion barrier. An initial experiment with two drugs - non polar ibuprofen and polar and charged procaine hydrochloride - has been carried out as well and shows that the core-shell nanoparticles presented here can also be used for the sequential release of more relevant combinations of molecules.

Brushing the surface: cascade reactions between immobilized nanoreactors.

Functionalization of hard or soft surfaces with, for example, ligands, enzymes or proteins, is an effective and practical methodology for the development of new applications. We report the assembly of two types of nanoreactors based upon poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) (PDMS-b-PMOXA) diblock copolymers as scaffold, uricase and lactoperoxidase as bio-catalysts located within the nanoreactors, and melittin as the biopores inserted into the hydrophobic shell. The nanoreactors were immobilized on poly(2-hydroxyethyl methacrylate)-co-poly(2-aminoethyl methacrylate hydrochloride) (PHEMA-co-P(2-AEMA·HCl) brushes-grafted wafer surfaces by utilizing the strong supramolecular interactions between biotin and streptavidin. The (PHEMA-co-P(2-AEMA·HCl) brushes on silicon surfaces were prepared by a surface initiating atom transfer radical polymerization (ATRP) "graft-from" technique. Cascade reactions between different surface-anchored nanoreactors were demonstrated by converting Amplex® Red to the fluorescent probe resorufin by using the H2O2 produced from uric acid and H2O. The detailed properties of the nanoreactors on the functionalized surface including the binding behaviours and cascade reactions were investigated using emission spectroscopy, transmission electron microscopy (TEM), light scattering (LS), atomic force microscopy (AFM) and a quartz crystal microbalance (QCM-D). The results are proof-of-principle for the preparation of catalytically functional engineered surface materials and lay the foundation for applying this advanced functional surface material in biosensing, implanting and antimicrobial materials preparation.

Polyoxometalates encapsulated into hollow double-shelled nanospheres as amphiphilic nanoreactors for an effective oxidative desulfurization.

Although some catalytic hollow nanoreactors have been fabricated in the past, the encapsulated active species focus on metal nanoparticles, and a method for polyoxometalate (POM)-containing hollow nanoreactors has seldom been developed. Herein, we report a synthetic strategy towards POM-based amphiphilic nanoreactors, where the hollow mesoporous double-shelled SiO2@C nanospheres were used to encapsulate Keggin-type H3PMo12O40 (PMo12). The outer hydrophobic carbon shell was beneficial for the enrichment of the organic substrate around the nanoreactor and simultaneously prevented the deposition of POMs on the outer surface of the nanoreactor. The inner hydrophilic silica cavity was modified by two types of organosilanes, which not only created an amphiphilic cavity environment but also acted as an anchor to mobilize PMo12. As the POM nanoreactor had the hydrophilic@hydrophobic SiO2@C shell and an amphiphilic cavity, both dibenzothiophene (DBT) and H2O2 could smoothly diffuse into the nanosized cavity, where the DBT was effectively oxidized (conversion: >99%) by the immobilized PMo12 under mild conditions. Importantly, the control experiments indicated that the confined effect of nanoreactor, amphiphilic SiO2@C double-shell, unique cavity environment, and mesoporous channels accounted for an excellent catalytic performance. Moreover, the nanoreactor was robust and could be reused for five cycles without loss of activity.

Investigating Polymer Transformation during the Encapsulation of Metal Nanoparticles by Polystyrene-b-poly(acrylic acid) in Colloids

The colloidal self-assembly method holds great potential for large-scale synthesis at low expense of energy as compared to methods that assemble molecules by manipulating building blocks one after another. The development of the colloidal method, however, requires careful and intelligent design of the single building blocks as numerous degrees of freedom like isotropic nanoparticles (NPs) generally form highly repetitive, lattice-like structures or random aggregates upon self-assembly because of their identical surfaces throughout. Specifically, it is an interesting direction that if one can precisely control the localization of surface functionalities (i.e., ligands or polymer shells) on the NPs, a plethora of self-assembled structures (e.g., chains, sheets, rings, twisted, and even staircase structures) would be possible. Despite numerous simulations and modeling for this type of NPs, just a handful literature studies reported the controlling synthesis of metal-polymer patchy NPs through polymer shell shrinking/transformation in colloids. However, there are no detailed control experiments showing the mechanism of this polymer shell shrinking or transformation phenomenon. With the absence of a fundamental understanding of the driving forces and interactions between metal NP surface ligands and the hydrophobic polymer shell domain, simple and efficient design and synthesis of unique metal-polymer hybrid nanostructures are still obscure. Here, we report a detailed mechanistic study on the polymer shell transformation by using different types of surface ligands in encapsulation of metal NPs by polymer shells. The polymer shell transformation dynamic is studied after postheating treatment. The polymer shell transformation/shrinking on the metal NP surface depends on its surface ligand size being applied in the encapsulation step (polymer-ligand hydrophobic interaction effect). Longer-chain ligands provide stronger interactions between NPs and the hydrophobic domain of the polymer shell, which inhibits the polymer shell transformation. In contrast, short-chain ligands lead to weaker interactions, which assist in the polymer shell transformation. By understanding the underlying mechanisms, many new types of NPs, such as metal-polymer core-shell NPs, metal-polymer Janus NPs, silica-metal-polymer hybrid NPs, and silica-metal-polymer flower-like NPs have been synthesized for the first time. A new bottom-up platform for the synthesis of anisotropic NPs with the ability to control the patches in a precise manner has been created, which will benefit both nanotechnology (such as self-assembly in the nanoscale) and applications such as selective detection of the underlying ligands on the metal surface by using a surface-enhanced Raman spectrum study.

Bacteria-triggered release of a potent biocide from core-shell polyhydroxyalkanoate (PHA)-based nanofibers for wound dressing applications

Bacterial infections are a serious issue in wound healing. Extensive use of biocides in wound dressings have raised concerns of biocide resistance and unnecessary harm to normal skin cells. In this paper, we report a new approach to realize bacteria-triggered release of a biocide to the sites of bacterial infections from core-shell polyhydroxyalkanoate (PHA)-based nanofibers prepared by coaxial electrospinning. The hydrophobic PHA-based shell can prevent the biocide from undesirable payload release in physiological environments without pathogens. However, in the presence of pathogens, the PHA-based shell is degraded by the pathogens, and the encapsulated biocide is released. The released biocide subsequently can exert targeted antimicrobial effects on the bacteria. Using Pseudomonas aeruginosa as a model bacterium and dodecyltrimethylammonium chloride as a model biocide, we demonstrated that the core-shell PHA-based nanofibers effectively released encapsulated dodecyltrimethylammonium chloride in the presence of Pseudomonas aeruginosa, resulting in targeted inactivation of Pseudomonas aeruginosa cells.HighlightsUnique core-shell nanofibers were successfully fabricated from PHAs generated by bacteria.An on-demand release of biocide was achieved from a PHA-based core-shell nanofibours membrane.The membrane’s mechanical properties closely match those of the human skin.

Synthesis of Water-soluble Bottlebrush Polymer with Hydrophobic Core and Hydrophilic Shell as Cylindrical Host for Guest Uptake

A water-dispersible bottlebrush polymer with well-regulated length (300 nm) and width (20 nm) was developed for uptake of hydrophobic guest in aqueous media. This bottlebrush polymer was designed to adopt a core-shell structure, being composed of a polynorbornene backbone that is densely grafted with side chains with an AB diblock sequence (inside A block = polystyrene; outside B block = poly{[2-(methacryloyloxy)ethyl]trimethylammonium iodide}. Owing to the cationically charged shell part, the core-shell type of bottlebrush polymer was stably dispersed in water and also was able to accommodate a hydrophobic guest chromophore at the core part.

Influence of cations of the first group of the Periodic Table of Elements on the thermodynamic stabilization of cholic and deoxycholic acid anion micelles

From the dependence of the specific conductivity on the total concentration of surfactants approximation can be made that micelles of cholic acid (SC) anions and deoxycholic acid (SDC) anions in the vicinity of the critical micelle concentration (cmc) do not bind counterions (β = 0). Thermodynamic stabilization of SC and SDC micelles is greatest if the aqueous solution contains CsCl, although Cs+ has the smallest surface charge density. This indicates that the mechanism that exerts the effect of the cations of the first group of the Periodic Table of Elements (PTE) on the micellization of SC and SDC depends on the ionic radii of cations, i.e. the mechanism is different for cations with a large ionic radius and for cations with a small ionic radius. If the micelles do not bind counter ions, then the cations exhibit their activity on water molecules located in the hydrophobic shell above the hydrophobic surface of the monomer. From β = 0 it follows that the excess Gibbs energy of micellization in the presence of cations of the first group of the PTE in the aqueous solution does not contain Debye-Hückel's Gibbs excess energy. Equation analogous to the Dér's equation can be obtained for the critical micellar concentration ratio ln(cmc/cmc′). The paper demonstrated that Der's equation applied to the micelles of bile salts describes the excess Gibbs energy of micellization.

Effect of Temperature and Ionic Strength on Micellar Aggregates of Oppositely Charged Thermoresponsive Block Copolymer Polyelectrolytes.

The self-assembly of two oppositely charged diblock copolymers that have a common thermosensitive nonionic block of poly(N-isopropylacrylamide) (pNIPAAM) has been investigated. The effect of the mixing ratio and total polymer concentrations on the self-assembly of the components and on the phase stability of the mixtures was studied by dynamic light scattering, electrophoretic mobility, and turbidimetry measurements in water at 20 °C. The effect of the competing electrostatic and hydrophobic interactions on the nanostructure of negatively charged electrostatically self-assembled micelles bearing a pNIPAAM corona was investigated by small-angle X-ray scattering (SAXS). The electrostatic and hydrophobic interactions were controlled independently by tuning the ionic strength (from pure water to 50 mM NaCl) and the temperature (20-50 °C) of the investigated mixtures. The SAXS data could be fitted by a spherical micelle model, which has a smoothly decaying radial profile and a Gaussian star term that describes the internal structure of the micellar structures and possible attractive interactions between the polymer chains. At high temperature, a cluster structure factor was included for describing the formation of bulky clusters of the formed micelles. At low temperature and ionic strength, the formation of micelles with a coacervate core and hydrated pNIPAAM shell was observed. The structural evolution of the self-assembled micelles with increasing ionic strength and temperature could be followed, and finally at high ionic strength and temperature, the formation of inverted micelles with a hydrophobic core and polyelectrolyte shell could be identified.

Three-Dimensional-Printed Core-Shell Structured MFI-Type Zeolite Monoliths for Volatile Organic Compound Capture under Humid Conditions.

Crystalline aluminosilicate zeolites with high sorption capacity and low production cost have been recognized as a promising adsorbent for volatile organic compound (VOC) capture. However, the ubiquitous water vapor in the VOC streams may compete with VOCs during the practical separation process because of the hydrophilic property of aluminosilicate zeolites. Herein, a self-supporting core-shell structured MFI-type zeolite monolith was fabricated by 3D-printing aluminosilicate ZSM-5 zeolites as the core, followed by coating silicalite-1 zeolites as a hydrophobic shell via post-hydrothermal crystallization. Natural sepiolite nanofibers (SNFs) were employed as printing ink additives for reinforcing the mechanical stability of 3D-printed ZSM-5 monoliths. Colloidal silica was also introduced into the printing inks, affording continuous growth of silicalite-1 layers (with a thickness of ∼200 nm) over ZSM-5 crystals. Such core-shell structured MFI-type zeolite monoliths exhibited superior dynamic adsorption performance for toluene at 298 K under humid conditions (relative humidity: 50%), with a saturated adsorption capacity of 44.3 mg/g. This work provides a facile strategy for designing self-supporting zeolite monoliths with core-shell architectures for adsorption/separation and other advanced applications.

Temperature-Responsive Polymersomes of Poly(3-methyl-N-vinylcaprolactam)-block-poly(N-vinylpyrrolidone) To Decrease Doxorubicin-Induced Cardiotoxicity.

Despite being one of the most potent chemotherapeutics, doxorubicin (DOX) facilitates cardiac toxicity by irreversibly damaging the cardiac muscle as well as severely dysregulating the immune system and impairing the resolution of cardiac inflammation. Herein, we report synthesis and aqueous self-assembly of nanosized polymersomes from temperature-responsive poly(3-methyl-N-vinylcaprolactam)-block-poly(N-vinylpyrrolidone) (PMVC-PVPON) diblock copolymers and demonstrate their potential to minimize DOX cardiotoxicity compared to liposomal DOX. RAFT polymerization of vinylpyrrolidone and 3-methyl-N-vinylcaprolactam, which are structurally similar monomers but have drastically different hydrophobicity, allows decreasing the cloud point of PMVCm-PVPONn copolymers below 20 °C. The lower critical solution temperature (LCST) of the PMVC58-PVPONn copolymer varied from 19.2 to 18.6 and to 15.2 °C by decreasing the length of the hydrophilic PVPONn block from n = 98 to n = 65 and to n = 20, respectively. The copolymers assembled into stable vesicles at room temperature when PVPON polymerization degrees were 65 and 98. Anticancer drug DOX was entrapped with high efficiency into the aqueous PMVC58-PVPON65 polymersomal core surrounded by the hydrophobic temperature-sensitive PMVC shell and the hydrophilic PVPON corona. Unlike many liposomal, micellar, or synthetic drug delivery systems, these polymersomes exhibit an exceptionally high loading capacity of DOX (49%) and encapsulation efficiency (95%) due to spontaneous loading of the drug at room temperature from aqueous DOX solution. We also show that C57BL/6J mice injected with the lethal dose of DOX at 15 mg kg-1 did not survive the 14 day treatment, resulting in 100% mortality. The DOX-loaded PMVC58-PVPON65 polymersomes did not cause any mortality in mice indicating that they can be used for successful DOX encapsulation. The gravimetric analyses of the animal organs from mice treated with liposome-encapsulated DOX (Lipo-DOX) and PMVC58-PVPON65 polymersomes (Poly-DOX) revealed that the Lipo-DOX injection caused some toxicity manifesting as decreased body weight compared to Poly-DOX and saline control. Masses of the left ventricle of the heart, lung, and spleen reduced in the Lipo-DOX-treated mice compared to the nontoxic saline control, while no significant decrease of those masses was observed for the Poly-DOX-treated mice. Our results provide evidence for superior stability of synthetic polymersomes in vivo and show promise for the development of next-generation drug carriers with minimal side effects.