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Fabrication of biocompatible core-shell microcapsules in a controllable and scalable manner remains an important but challenging task. Here, we develop a one-step microfluidic approach for the high-throughput production of biocompatible microcapsules, which utilizes single emulsions as templates and controls the precipitation of biocompatible polymer at the water/oil interface. The facile method enables the loading of various oils in the core and the enhancement of polymer shell strength by polyelectrolyte coating. The resulting microcapsules have the advantages of controllability, scalability, biocompatibility, high encapsulation efficiency and high loading capacity. The core-shell microcapsules are ideal delivery vehicles for programmable active release and various controlled release mechanisms are demonstrated, including burst release by vigorous shaking, pH-triggered release for targeted intestinal release and sustained release of perfume over a long period of time. The utility of our technique paves the way for practical applications of core-shell microcapsules.

To obtain a rapid processible LED encapsulant that leads to high and stable light extraction efficiency (LEE), UV curable ZrO2/phenyl-siloxane nano-composite (ZSC) double-layer encapsulants were prepared and optimized. The highly crystalline ZrO2 nanoparticles with a diameter of ∼14 nm were synthesized through a modified hydrothermal method at mild conditions, and a UV curable methacryl-diphenyl-polysiloxane (MDPS) with a refractive index (RI) of 1.54 (at 633 nm) was synthesized from self-condensation of diphenylsilanediol and an end-capping reaction. High refractive indexes (RIs) from 1.54–1.61 have been obtained for ZSC composites by adding 0–20 wt% ZrO2. Before and after sulfur vapor erosion, the double-layer encapsulated sample (M-10/M) showed 11.2% and 64.8% higher LEE respectively than that of Dow Corning OE-7662. Meanwhile, the variation of LED light color temperature (Tc) was less than 1%. The effect of the ZrO2 nanoparticle content on LEE of double-layer and single-layer encapsulation were compared and discussed based on Fresnel loss and Rayleigh scattering theories. The double-layered UV curing processing took only 1/6 of the time needed for common thermal curing.

Nanoparticles with diverse structures and unique properties have attracted increasing attention for their widespread applications. Co-precipitation under rapid mixing is an effective method to obtained biocompatible nanoparticles and diverse particle carriers are achieved by controlled phase separation via interfacial tensions. In this Minireview, we summarize the underlying mechanism of co-precipitation and show that rapid mixing is important to ensure co-precipitation. In the binary polymer system, the particles can form four different morphologies, including occluded particle, core-shell capsule, dimer particle, and heteroaggregate, and we demonstrate that the final morphology could be controlled by surface tensions through surfactant, polymer composition, molecular weight, and temperature. The applications of occluded particles, core-shell capsules and dimer particles prepared by co-precipitation or microfluidics upon the regulation of interfacial tensions are discussed in detail, and show great potential in the areas of functional materials, colloidal surfactants, drug delivery, nanomedicine, bio-imaging, displays, and cargo encapsulation.

In this paper, a series of D–π–A type benzo[e]indolium salts with highly efficient nonlinear optical performance has been synthesized. Out of the three new benzo[e]indolium salts, (E)-2-(2-hydroxy-3-methoxystyryl)-1,1,3-trimethyl-1H-benzo[e]indol-3-ium iodide (HMTB-1) and (E)-2-(2-hydroxy-4-methoxystyryl)-1,1,3-trimethyl-1H-benzo[e]indol-3-ium iodide (HMTB-2) possess SHG properties, and their maximum powder second harmonic generation (SHG) efficiency is around 0.6 times that of DAST (4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate) at a non-resonant wavelength of λ = 1570 nm. Single crystals of the two noncentrosymmetric salts were successfully grown by using a slow cooling method, and we were able to obtain very large bulk single crystals, about 17 mm × 9 mm × 3 mm, of HMTB-2. X-ray crystallographic analysis indicated that both of the new salts belong to the monoclinic space group Cc (point group m, Z = 4). HMTB-1 forms a noncentrosymmetric phase with methanol through hydrogen bonding.

Tetraphenylethylene-naphthopyran (TPE-NP) and tetraphenylethylene-spirooxazine (TPE-SO) with conjugated photochromic groups and fluorophores were designed and synthesized. Both of them exhibit the comprehensive effects of aggregation-induced emission (AIE) and photochromism while different photochromic groups lead to a unique photochromic rate and fluorescence intensity. Among them, TPE-NP has significant photochromic and fluorescence effects with good stability. Therefore, it could be used as an anti-counterfeiting ink and is expected to be used in fluorescence switches in the future.

Porous silicon nanoparticles (PSiNPs) and gold nanorods (AuNRs) can be used as biocompatible nanocarriers for delivery of therapeutics but undesired leakage makes them inefficient. By encapsulating the PSiNPs and AuNRs in a hydrogel shell, we create a biocompatible functional nano carrier that enables sustained release of therapeutics. Here, we report the fabrication of AuNRs-conjugated PSi nanoparticles (AuNRsPSiNPs) through two-step chemical reaction for high capacity loading of hydrophobic and hydrophilic therapeutics with photothermal property. Furthermore, using water-in-oil microemulsion templates, we encapsulate the AuNRsPSiNPs within a calcium alginate hydrogel nanoshell, creating a versatile biocompatible nanocarrier to codeliver therapeutics for biomedical applications. We find that the functionalized nanohydrogel effectively controls the release rate of the therapeutics while maintaining a high loading efficiency and tunable loading ratios. Notably, combinations of therapeutics coloaded in the functionalized nanohydrogels significantly enhance inhibition of multidrug resistance through synergism and promote faster cancer cell death when combined with photothermal therapy. Moreover, the AuNRs can mediate the conversion of near-infrared laser radiation into heat, increasing the release of therapeutics as well as thermally inducing cell damage to promote faster cancer cell death. Our AuNRsPSiNPs functionalized calcium alginate nanohydrogel holds great promise for photothermal combination therapy and other advanced biomedical applications.

To study polymer-dispersed liquid crystal (PDLC) films doped with indium tin oxide (ITO) nanoparticles (NPs), samples were prepared by ultraviolet-initiated polymerisation based on the thiol–acryla...

To study effects of the crosslinking agent/diluents/thiol on morphology of the polymer matrix and the electro-optical properties of polymer-dispersed liquid crystal (PDLC) films, samples were prepa...

Biocompatible microcapsules with a water core are widely used to encapsulate hydrophilic actives. Here, a facile method to fabricate monodisperse biocompatible microcapsules with a water core in large quantity is reported. Microfluidic technology is utilized to emulsify the inner aqueous phase containing the shell polymer into monodisperse drops in the outer oil phase. As the cosolvent in the inner aqueous phase diffuses into the outer oil phase, the solubility of the shell polymer decreases, which eventually precipitates. Since the shell polymer, shellac, contains both hydrophilic and hydrophobic groups, it tends to wet both the inner aqueous phase and the outer oil phase, thus forming a solid shell at the periphery of the drop. We show that the diffusion rate of hydrophilic molecules encapsulated in the water core decreases as their molecular weight increases and the property of the microcapsules could further be modified by polyelectrolyte multilayer coating. These microcapsules are fabricated using FDA-approved polymer and non-toxic solvents and are of great use in drugs, cosmetics and foods.

Natural colorants, which impart a vivid color to food and add additional health benefits, are favored over synthetic colorants; however, their applications are limited by their low solubility in water and low stability. Here, we develop a versatile microfluidic strategy to incorporate natural colorants in shellac nanoparticles with controlled physicochemical properties. The rapid mixing in the microfluidic channels ensures that the mixing time is shorter than the aggregation time, thus providing control over the co-precipitation of the colorant and the polymer. By introducing molecular interactions, colorant nanoaggregates are efficiently embedded in the polymer matrix, forming hierarchical colorant-loaded nanoparticles. The colorant-loaded nanoparticles dispersed in water are transparent and stable over a wide pH range and their polymer matrix also provides a favorable microenvironment that greatly improves the shelf life of the colorants. The improved solubility, stability and bioavailability of the natural colorants suggest that shellac nanoparticles are ideal carriers and the stable, transparent dispersions of biocompatible colorant-loaded nanoparticles in water are well-suited for the development of functional foods, such as natural color drinks.

Effective cancer therapies often demand delivery of combinations of drugs to inhibit multidrug resistance through synergism, and the development of multifunctional nanovehicles with enhanced drug loading and delivery efficiency for combination therapy is currently a major challenge in nanotechnology. However, such combinations are more challenging to administer than single drugs and can require multipronged approaches to delivery. In addition to being stable and biodegradable, vehicles for such therapies must be compatible with both hydrophobic and hydrophilic drugs, and release drugs at sustained therapeutic levels. Here, we report synthesis of porous silicon nanoparticles conjugated with gold nanorods [composite nanoparticles (cNPs)] and encapsulate them within a hybrid polymersome using double-emulsion templates on a microfluidic chip to create a versatile nanovehicle. This nanovehicle has high loading capacities for both hydrophobic and hydrophilic drugs, and improves drug delivery efficiency by accumulating at the tumor after i.v. injection in mice. Importantly, a triple-drug combination suppresses breast tumors by 94% and 87% at total dosages of 5 and 2.5 mg/kg, respectively, through synergy. Moreover, the cNPs retain their photothermal properties, which can be used to significantly inhibit multidrug resistance upon near-infrared laser irradiation. Overall, this work shows that our nanovehicle has great potential as a drug codelivery nanoplatform for effective combination therapy that is adaptable to other cancer types and to molecular targets associated with disease progression.

A biodegradable multifunctional carrier for combination therapy with high efficiency and low side effect is essential for effective cancer treatment and for advancing biomedical applications. Therapeutics combination could reduce multidrug resistance and minimize doses through synergism. This study develops biodegradable gold nanorods@calcium carbonate particles coated with pH-responsive acetalated dextran and phospholipid as an advanced platform for the incorporation of versatile molecular targeted therapeutics, including hydrophilic and hydrophobic drugs, as well as the model enzyme, green fluorescent protein, or antibody. The developed calcium carbonate based hybrid particles show good biocompatibility, stability with photothermal, and pH responsiveness, which protect the payloads from premature release, and maintain the enzyme activity. The therapeutics co-loaded CaCO3 based hybrid particles efficiently induce cancer cell death and reduce the multidrug resistance and HER2 expression with synergism. The photothermal effects promote ultrafast therapeutics release and induce significant cytotoxicity. Importantly, Anti-HER2 antibody or HER2 targeted therapeutic is more effective in reducing HER2 expression when combined with drug or drugs via synergism. Overall, the cheap and simply manufactured biodegradable hybrid platform has great potential for advancing biomedical applications, including targeted photothermal combination therapy by co-delivery of different types of therapeutics, including molecular targeted drugs, antibodies, and enzymes.

Co-precipitation is generally refers to the co-precipitation of two solids and is widely used to prepare active-loaded nanoparticles. Here, it is demonstrated that liquid and solid can precipitate simultaneously to produce hierarchical core-shell nanocapsules that encapsulate an oil core in a polymer shell. During the co-precipitation process, the polymer preferentially deposits at the oil/water interface, wetting both the oil and water phases; the behavior is determined by the spreading coefficients and driven by the energy minimization. The technique is applicable to directly encapsulate various oil actives and avoid the use of toxic solvent or surfactant during the preparation process. The obtained core-shell nanocapsules harness the advantage of biocompatibility, precise control over the shell thickness, high loading capacity, high encapsulation efficiency, good dispersity in water, and improved stability against oxidation. The applications of the nanocapsules as delivery vehicles are demonstrated by the excellent performances of natural colorant and anti-cancer drug-loaded nanocapsules. The core-shell nanocapsules with a controlled hierarchical structure are, therefore, ideal carriers for practical applications in food, cosmetics, and drug delivery.

The reflectivity control device, initially developed for attitude control, is utilised to control the solar sail orbit by switching the states between absorption and specular reflection. Actually, ...

Biocompatible, multifunctional, stimuli responsive, and high drug loading capacity are key factors for the new generation of drug delivery platforms. However, it is extremely challenging to create such a platform that inherits all these advanced properties in a single carrier. Herein, porous silicon nanoparticles (PSi NPs) and giant liposomes are assembled on a microfl uidic chip as an advanced nano-in-micro platform (PSi NPs@ giant liposomes), which can co-load and co-deliver hydrophilic and hydrophobic drugs combined with synthesized DNA nanostructures, short gold nanorods, and magnetic nanoparticles. The PSi NPs@giant liposomes with photothermal and magnetic responsiveness show good biocompatibility, high loading capacity, and controllable release. The hydrophilic thermal oxidized PSi NPs encapsulate hydrophobic therapeutics within the hydrophilic core of the giant liposomes, endowing high therapeutics loading capacity with tuneable ratio and controllable release. It is demonstrated that the DAO-E A B DNA nanostructures have synergism with drugs and importantly they contribute to the signifi cant enhancement of cell death to doxorubicin-resistant MCF-7/DOX cells, overcoming the multidrug resistance in the cancer cells. Therefore, the PSi NPs@giant liposomes nanoin-micro platform hold great potential for a cocktail delivery of drugs and DNA nanostructures for effective cancer therapy, controllable drug release with tuneable therapeutics ratio, and both photothermal and magnetic dual responsiveness.

We encapsulate the hydrophilic anti-cancer drug doxurubicin hydrochloride (DOX) with about 94% drug encapsulation efficiency, either alone or with nanomagnetite, in monodisperse biocompatible phospholipid vesicles. Glass capillary microfluidics is used to generate monodisperse water in oil in water (w/o/w) double-emulsion templates with a core-shell structure by using a mixture of liquid unsaturated phospholipids and powdered saturated phospholipid. This combination would overcome the low transition temperature of unsaturated powdered phospholipid and the solubility limitation of saturated phospholipid, as well as improving the fabrication of stable monodisperse phospholipid vesicles. The double-emulsion droplet is controlled from 50 to 200 μm according to different flow rates, and the final phospholipid vesicles are retained after a solvent removal step by dewetting. DOX-loaded phospholipid vesicles show sustained release compared with free DOX water solution. The in vitro cell viability of 100 μg/mL phospholipid vesicles on HeLa or MCF-7 cells after 24 h incubation at 310 K is above 90%, confirming the excellent biocompatibility of the phospholipid vesicles. These biocompatible phospholipid vesicles are promising oral drug delivery vehicles for biomedical applications and magnetic resonance imaging contrast agents for biomedical diagnosis.

We investigate the thermodynamic properties of a water-soluble polymer poly(ethenol) (PVOH) with and without ionic surfactant sodium dodecyl sulfate (SDS) by viscosity, surface tension, and dynamic light scattering (DLS) measurements at 298 K. The viscosity, refractive index, and hydrodynamic radius values of polymer PVOH aqueous solutions without surfactant SDS increase with increasing PVOH concentration, but the surface tension of PVOH aqueous solution decreases with increasing PVOH concentration. For SDS+PVOH aqueous solutions, both viscosity and surface tension values decrease with an increase of SDS concentration when SDS concentration is lower than the critical aggregation concentration (CAC) of SDS+PVOH aqueous solutions, and the relative minimum viscosity value indicated the shrinkage of the polymer PVOH chain resulting in the formation of compact structure at the binding site of SDS+PVOH. But the viscosity increases with an increase of SDS concentration when surfactant SDS concentration is larger...

The interaction between sodium dodecyl sulfate (SDS) and the nonionic water-soluble polymer poly(ethylene glycol) (PEG) with electrolytes has been studied by viscosity and surface tension measurements at different temperatures, (298.15, 308.15, and 318.15) K. The experimental results showed that the critical aggregation concentration (CAC) value of SDS + (1, 3, and 5) g·kg−1 PEG with NaOH is lower than the critical micelle concentration (CMC) of SDS and that the PEG concentration has little effect on this value. When the SDS concentration is below the CAC, the viscosity of the SDS + PEG solutions with NaOH decreases with increasing SDS concentration, and the minimum viscosity of SDS + PEG complexes at the binding site confirmed the contraction of the polymer chain and the formation of a more compact structure. When the SDS concentration is above the CAC, the viscosity increases with increasing SDS concentration, indicating that the PEG chains are extended. The surface tension decreases remarkably with inc...

The diameter of water-in-oil reverse micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) with water and with protein Bovine serum alumin (BSA) was investigated by dynamic light scattering (DLS) measurement of AOT/isooctane solution at 298.15 K. The diameter and viscosity of AOT reverse micelle increases with increasing ω0 (mole ratio of water to surfactant: ω0 = nw/ns). The viscosity of AOT/isooctane with water or BSA inside did not change with shear rate, exhibiting Newtonian behavior. For ω0 = 8.3, the diameter of AOT reverse micelles increases with increasing BSA concentration from 2 mg of BSA·mL−1 of H2O to 145 mg of BSA·mL−1 of H2O. The diameter of AOT reverse micelles increases only slightly with BSA inside compared with water inside at the same ω0. Incorporation of protein into the micelles does not affect their mean diameter significantly. The hydrodynamic diameter of BSA from 10 mg to 100 mg of BSA·mL−1 of H2O in 0.1 mol·L−1 AOT reverse micelles increased almost linearly with ω0 whic...

Gold nanorods, DNA origami, and porous silicon nanoparticle-functionalized biocompatible double emulsion are developed for versatile molecular targeted therapeutics and antibody combination therapy. This advanced photothermal responsive all-in-one biocompatible platform can be easily formed with great therapeutics loading capacity for different cancer treatments with synergism and multidrug resistance inhibition, which has great potential in advancing biomedical applications.

The properties of synthesized side‐chain liquid crystalline polymer (SCLCP)/liquid crystal (LC)/chiral dopant composites having a chiral nematic (N*) phase at room temperature were investigated by polarized optical microscopy (POM) and a UV/VIS/NIR spectrophotometer. The composite exhibited a planar texture after it was filled into cells under homogeneous boundary conditions and it was transparent. When an electric field was applied to the composite, a focal conic texture was formed and the composite became light scattering. After the electric field was turned off, the light‐scattering state remained stable for some time, i.e. the light‐scattering state exhibited a memory effect. The focal conic texture changed into the planar texture when the composite was heated and the composite became transparent again. Therefore, the composite had electrically induced and thermally erased properties. The SCLCP had some influence on the memory effect and on the thermo‐electro‐optical properties of the composite.

The interaction between sodium dodecyl sulfate (SDS) and the cationic polymer poly(diallyldimethylammonium chloride) (PDAC) was investigated by viscosity, conductivity, and dynamic light scattering measurements at 298 K in order to monitor the changes in the charged nature and size of SDS + PDAC complexes. The experimental results showed that the critical aggregation concentration (CAC) value of SDS + 1 % mass fraction PDAC is almost 2 orders of magnitude lower than the critical micelle concentration of SDS. The viscosity of the SDS + PDAC solution increased with decreasing shear rate, exhibiting non-Newtonian behavior. The minimum viscosity and hydrodynamic diameter of SDS + PDAC complexes at the binding site confirmed the contraction of the polymer chain and the formation of a more compact structure. When the SDS concentration was above the CAC, the viscosity and hydrodynamic diameter increased, indicating that the PDAC chains first extended and finally collapsed and precipitated. The binding degree of ...

The hydrophobically modified nitroxide radical molecule 2,4-dinitrophenylhydrazone of 2,2,6,6-tetramethyl-4-piperidind-1-oxyl (DNPHTEMPO) was synthesized and used as electron spin resonance (ESR) and a UV probe to investigate the interaction between sodium dodecyl sulfate (SDS) and poly(ethylene glycol) (PEG). The ESR results showed that the headgroups of SDS adsorbed on PEG were more tightly packed than those of the unperturbed micelles and a more compact structure was formed at the binding site of the polymer-micelle aggregate due to a strong decrease of the viscosity at the micelle-polymer interface. The nitroxide group of DNPHTEMPO consisted of ∼55 % water and ∼45 % hydrocarbon. The two breakpoints of the SDS + PEG system critical aggregation concentration (cac) and polymer saturation point (PSP) were obtained from the maximum absorption bands λ max at room temperature and the viscosity measurement at different temperatures. The average location of 2,4-dinitrophenylhydrazone in the micelle consisted of an environment containing approximately 90 % water and 10 % hydrocarbon. The η/C p (viscosity/PEG concentration) decreased with the increase of PEG concentration and temperature and exhibited a polyelectrolyte character. The electroviscosity effect increased with increasing SDS concentration. The PEG concentration had little effect on the cac of the SDS + PEG system.

The interaction between sodium dodecyl sulfate (SDS) and nonionic polymer polyacrylamide (PAM) was investigated by viscosity and conductivity measurements at 298 K. The experimental results show that the critical aggregation concentration (CAC) value of SDS + 1 % mass fraction PAM only decreases a little as compared with the value of critical micelle concentration (CMC) of the surfactant SDS. The maximum viscosity of SDS + 1 % mass fraction PAM indicated that PAM chain extended at the binding site. When SDS concentration is above the CAC, the viscosity of SDS + 1 wt % PAM decreases reflecting the contraction of polymer PAM chains. The free energy of polymer-bound micelle is negative, indicating a strong interaction between SDS and PAM.

The mechanism of release of two fluorescent markers, fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) and fluorescein, from water-in-oil-in-water (w/o/w) emulsions was investigated using a rapid and sensitive method based on fluorescence-activated cell sorting (FACS). The release of FITC-BSA from a w/o/w emulsion was controlled by diffusion rather than by simple breakdown of the multiple droplets or by formation of reverse micelles in the oil phase. In contrast, the release of fluorescein from a double emulsion was controlled by formation of reverse micelles rather than by diffusion or simple breakdown of multiple droplets. A significant difference in the yield and fraction of FITC-BSA and fluorescein released from double emulsions was observed due to their different molecular structure and properties. The yield of FITC-BSA incorporation in a double emulsion increased with increasing FITC-BSA concentration in the internal water phase, while the yield of fluorescein decreased with increasing concentration. The fraction of FITC-BSA released from a w/o/w emulsion after 24 h decreased with an increasing concentration of FITC-BSA in the internal phase. The w/o/w emulsion with internalized FITC-BSA was more stable than that with fluorescein, indicating its further application for sorting or enriching size-controlled double droplets that contained genes and water-soluble drugs.

DNA origami is designed by folding DNA strands at the nanoscale with arbitrary control. Due to its inherent biological nature, DNA origami is used in drug delivery for enhancement of synergism and multidrug resistance inhibition, cancer diagnosis, and many other biomedical applications, where it shows great potential. However, the inherent instability and low payload capacity of DNA origami restrict its biomedical applications. Here, this paper reports the fabrication of an advanced biocompatible nano-in-nanocomposite, which protects DNA origami from degradation and facilities drug loading. The DNA origami, gold nanorods, and molecular targeted drugs are co-incorporated into pH responsive calcium phosphate [Ca3 (PO4 )2 ] nanoparticles. Subsequently, a thin layer of phospholipid is coated onto the Ca3 (PO4 )2 nanoparticle to offer better biocompatibility. The fabricated nanocomposite shows high drug loading capacity, good biocompatibility, and a photothermal and pH-responsive payload release profile and it fully protects DNA origami from degradation. The codelivery of DNA origami with cancer drugs synergistically induces cancer cell apoptosis, reduces the multidrug resistance, and enhances the targeted killing efficiency toward human epidermal growth factor receptor 2 positive cells. This nanocomposite is foreseen to open new horizons for a variety of clinical and biomedical applications.

Solubility of methane in aqueous solutions of sodium dodecyl sulfate (SDS), SDS + 0.1 M NaCl, SDS + 0.1 M NaOH, SDS + 0.1 wt % poly(ethylene oxide) (PEO), SDS + 0.1 wt % PEO + 0.1 M NaCl, and SDS +...

The solubility of propane in aqueous solutions of sodium dodecyl sulfate (SDS)–0.1 wt.% polyacrylamide (PAM) and SDS–0.1 wt.% PAM–NaOH (0.1 mol L-1) has been determined at 298.15, 308.15 and 318.15 K. The concentration of SDS (mSDS) is up to 50 mmol kg-1. The solubility decreases with increasing temperature, and increases linearly with the concentration of SDS above its critical micelle concentration (CMC) or critical aggregation concentration (CAC), indicating that micelles in the solutions solubilize the gas molecules. It was found that the solubilization properties of the micelles bound to PAM and the free micelles are nearly the same. The solubilization property of SDS is changed by addition of PAM, although the solubilizing effect of the polymer alone is not considerable. Addition of NaOH decreases the ability of SDS to solubilize the hydrophobic gas. The standard Gibbs energies for the transfer of propane from bulk phase to the micelle phase are large negative values, indicating that the hydrophobic gas prefers to exist in the hydrophobic interior of the micelles.

The vapor pressure of aqueous solutions of sodium dodecyl sulfate (SDS) + 0.1 mass % polyacrylamide (PAM) and SDS + 0.1 mass % PAM + 0.1 M NaOH were measured at 298.15 K, 308.15 K, and 318.15 K, and the concentration of SDS (mSDS) was up to 50 mmol/kg. The activity coefficient of water in the solution was calculated. The surface tension of the solutions was also determined. The results show that the effect of the solutes on the vapor pressure of water is very limited under the experimental conditions although the surface tension changes significantly with SDS concentration.

We present a new and facile method to evaluate w/o/w emulsions containing fluorescent markers by flow cytometry. Flow cytometry allows simultaneous measurement of w/o/w emulsion droplets "marked" with a fluorescent marker or "blank" without the need for complicated sample preparation. The yield of preparation of the w/o/w emulsion and the release rate of the fluorescent marker FITC-BSA were investigated by this new method. The release fraction (after 24 h) of FITC-BSA from the w/o/w emulsion decreased with increasing concentration of FITC-BSA inside the internal phase, just like the release fraction of NaCl as marker from the w/o/w emulsion. Flow cytometry results show that the yield and release behavior in w/o/w emulsions are in agreement with results reported by more complicated methods.

Water-in-oil (w/o) emulsions can be used to compartmentalize and select large gene libraries for a predetermined function. The aqueous droplets of the w/o emulsion function as cell-like compartments in each of which a single gene is transcribed and translated to give multiple copies of the protein (e.g., an enzyme) it encodes. While compartmentalization ensures that the gene, the protein it encodes, and the products of the activity of this protein remain linked, it does not directly afford a way of selecting for the desired activity. Here we show that re-emulsification of w/o emulsions gives water-in-oil-in-water (w/o/w) emulsions with an external (continuous) water phase through which droplets containing fluorescent markers can be isolated by fluorescence-activated cell sorting (FACS). These w/o/w emulsions can be sorted by FACS, while the content of the aqueous droplets of the primary w/o emulsion remains intact. Consequently, genes embedded in these water droplets together with a fluorescent marker can be isolated and enriched from an excess of genes embedded in water droplets without a fluorescent marker. The ability of FACS instruments to sort up to 40,000 events per second may endow this technology a wide potential in the area of high-throughput screening and the directed evolution of enzymes.

Dispersing Hydrophobic Natural Colorant β-carotene in Shellac Particles for Enhanced Stability and Tunable Color

Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.