Mesoporous Silicon‐PLGA Composite Microspheres for the Double Controlled Release of Biomolecules for Orthopedic Tissue Engineering

In this study, poly(dl ‐lactide‐co‐glycolide)/porous silicon (PLGA/pSi) composite microspheres, synthesized by a solid‐in‐oil‐in‐water (S/O/W) emulsion method, are developed for the long‐term controlled delivery of biomolecules for orthopedic tissue engineering applications. Confocal and fluorescent microscopy, together with material analysis, show that each composite microsphere contained multiple pSi particles embedded within the PLGA matrix. The release profiles of fluorescein isothiocyanate (FITC)‐labeled bovine serum albumin (FITC‐BSA), loaded inside the pSi within the PLGA matrix, indicate that both PLGA and pSi contribute to the control of the release rate of the payload. Protein stability studies show that PLGA/pSi composite can protect BSA from degradation during the long term release. We find that during the degradation of the composite material, the presence of the pSi particles neutralizes the acidic pH due to the PLGA degradation by‐products, thus minimizing the risk of inducing inflammatory responses in the exposed cells while stimulating the mineralization in osteogenic growth media. Confocal studies show that the cellular uptake of the composite microspheres is avoided, while the fluorescent payload is detectable intracellularly after 7 days of co‐incubation. In conclusion, the PLGA/pSi composite microspheres offer an additional level of controlled release and could be ideal candidates as drug delivery vehicles for orthopedic tissue engineering applications.     

Harnessing Interfacial Phenomena to Program the Release Properties of Hollow Microcapsules

The generation of near‐infrared (NIR)‐sensitive microcapsules is presented and it is demonstrated that the release properties of these microcapsules can be tailored by controlling their morphology. A biocompatible polymer, poly(DL‐lactic‐co‐glycolic)acid (PLGA) is used to form hollow microcapsules from monodisperse water‐in‐oil‐in‐water (W/O/W) double emulsions. Both the composition of PLGA and the oil phase of W/O/W double emulsions significantly affect the morphology of the subsequently formed microcapsules. PLGA microcapsules with vastly different morphologies, from spherical to “snowman‐like” capsules, are obtained due to changes in the solvent quality of the oil phase during solvent removal. The adhesiveness of the PLGA‐laden interface plays a critical role in the formation of snowman‐like microcapsules. NIR‐sensitive PLGA microcapsules are designed to have responsive properties by incorporating Au nanorods into the microcapsule shell, which enables the triggered release of encapsulated materials. The effect of capsule morphology on the NIR responsiveness and release properties of PLGA microcapsules is demonstrated.     

Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering

Injection of cell‐laden scaffolds in the form of mesoscopic particles directly to the site of treatment is one of the most promising approaches to tissue regeneration. Here, a novel and highly efficient method is presented for preparation of porous microbeads of tailorable dimensions (in the range ≈300–1500 mm) and with a uniform and fully interconnected internal porous texture. The method starts with generation of a monodisperse oil‐in‐water emulsion inside a flow‐focusing microfluidic device. This emulsion is later broken‐up, with the use of electric field, into mesoscopic double droplets, that in turn serve as a template for the porous microbeads. By tuning the amplitude and frequency of the electric pulses, the template droplets and the resulting porous bead scaffolds are precisely produced. Furthermore, a model of pulsed electrodripping is proposed that predicts the size of the template droplets as a function of the applied voltage. To prove the potential of the porous microbeads as cell carries, they are tested with human mesenchymal stem cells and hepatic cells, with their viability and degree of microbead colonization being monitored. Finally, the presented porous microbeads are benchmarked against conventional microparticles with nonhomogenous internal texture, revealing their superior performance.     

Nonflammable and Magnetic Sponge Decorated with Polydimethylsiloxane Brush for Multitasking and Highly Efficient Oil–Water Separation

Developing sponge materials integrating excellent flame retardancy, multitasking separation performance, and efficient emulsion‐breaking ability is significant but challenging for the remediation of oil spills causing fires and environmental damages. Herein, a superhydrophobic oil–water separation sponge material, containing a melamine‐formaldehyde (MF) sponge substrate, magnetic polydopamine (PDA) coating, and branched polydimethylsiloxane (PDMS) brush, through dopamine‐mediated surface initiated atom transfer radical polymerization (SI‐ATRP) is fabricated. The synergistic flame resistance of the MF substrate and PDMS brush significantly improves its adaptability in fire. More importantly, the decorated PDMS brushes can effectively overcome the size mismatch between sponge macropores and tiny emulsified droplets, while remaining the intrinsic macroporous characteristic. When treating W/O emulsions, the PDMS brushes stretch up to act as “interface‐breaking blades” to accelerate the coalescence of emulsified water droplets. Meanwhile, such PDMS brushes can serve as “oil‐trapping tentacles” to efficiently capture oil droplets when treating O/W emulsions. Such material design synergistically contributes to satisfactory separation efficiency (98.7%) and ultrahigh permeation flux (up to 1.35 × 10⁵ L m^?2 h^?1), even for treating high viscosity emulsions. Besides, the reported sponge also inherits robust durability, superior recyclability, and convenient magnetic collection. These features make the sponge promising for multitasking and highly efficient oil–water separation.     

Surfactant‐Assisted Emulsion Self‐Assembly of Nanoparticles into Hollow Vesicle‐Like Structures and 2D Plates

The emulsion‐based self‐assembly of nanoparticles into low‐dimensional superparticles of hollow vesicle‐like assemblies is reported. Evaporation of the oil phase at relatively low temperatures from nanoparticle‐containing oil‐in‐water emulsion droplets leads to the formation of stable and uniform sub‐micrometer vesicle‐like assembly structures in water. This result is in contrast with those from many previously reported emulsion‐based self‐assembly methods, which produce solid spherical assemblies. It is found that extra surfactants in both the oil and water phases play a key role in stabilizing nanoscale emulsion droplets and capturing hollow assembly structures. Systematic investigation into what controls the morphology in emulsion self‐assembly is carried out, and the approach is extended to fabricate more complex rattle‐like structures and 2D plates. These results demonstrate that the emulsion‐based assembly is not limited to typical thermodynamic spherical assembly structures and can be used to fabricate various types of interesting low‐dimensional assembly structures.     

Synergy of Pickering Emulsion and Sol‐Gel Process for the Construction of an Efficient,Recyclable Enzyme Cascade System

An efficient, easily recyclable enzyme cascade system based on nanoparticle‐stabilized capsules (NPSCs) is constructed through a synergy of a Pickering emulsion and sol‐gel process. Specifically, oligodopa‐coated titania nanoparticles (biomimetic titania) containing the first enzyme (FateDH) are synthesized through a bioadhesion‐assisted biomimetic mineralization approach. The biomimetic titania is then spontaneously assembled at the interface between the oil phase (hexadecane/butyl titanate (BuTi) mixture) and water phase during the formation of Pickering emulsions. The sol‐gel process of BuTi can produce not only butanol for assisting the formation of Pickering emulsions but also titania gel particles (sol‐gel titania) for cross‐linking the biomimetic titania through catechol‐titanium chelating. The NPSCs obtained, which contain the first enzyme, conjugate the second enzyme (FaldDH) onto the surface for constructing the enzyme cascade system. The system exhibits high activity and stability, particularly, superior recyclability for conversion of CO₂ into formaldehyde. In detail, the system shows a formaldehyde yield of 50.0%, and can quickly float onto the air/water interface soon after stopping the agitation of reaction mixtures, which ensures that the formaldehyde yield keeps almost unaltered after 10 times recycling. This study will be useful for facile construction of a wealth of catalytic systems with efficient, recyclable attributes.     

3D-Printed Robust Dual Superlyophobic Ti-Based Porous Structure for Switchable Oil/Water Emulsion Separations

Smart surfaces with responsive wettability are unstable, and depend upon continuous external stimuli, which limits their widespread application in switchable oil/water emulsions separations. In this study, a Ti-based 3D porous structure (SLM-3DTi) is printed using advanced selective laser melting (SLM) technology for the switchable separation of oil/water emulsion. With the assistance of the computer program, porous structure and re-entrant texture can be easily designed and printed in one step. Without any continuous external stimulus, the wettability of SLM-3DTi can be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing cycles. The SLM-3DTi achieves switchable surfactant-stabilized oil-in-water emulsion (SSE(o/w)) and surfactants-stabilized water-in-oil emulsion (SSE(w/o)) separation with purity above 99.8% at a flux of more than 2000 L m⁻² h⁻¹. In addition, the re-entrant texture of the SLM-3DTi surface is formed with the partially melting powder particles on the part contour, which has much stronger mechanical durability than any binder. Furthermore, SLM-3DTi has excellent corrosion resistance due to the material properties of Ti. More importantly, based on the visualization analysis of the simulation, the mechanism of SLM-3DTi emulsion separation is further elucidated. Therefore, SLM-3DTi has broad practical application potential for high-flux, high-purity, and switchable oil/water emulsion separation.     

Thermal and Electrical Properties of Nanocomposites Based on Self‐Assembled Pristine Graphene

Thermodynamically‐driven exfoliation and self‐assembly of pristine graphene sheets is shown to provide thermally and electrically functional polymer composites. The spreading of graphene sheets at a high energy liquid/liquid interface is driven by lowering the overall energy of the system, and provides for the formation of water‐in‐oil emulsions stabilized by overlapping graphene sheets. Polymerization of the oil phase, followed by removal of the dispersed water phase, produces inexpensive and porous composite foams. Contact between the graphene‐stabilized water droplets provides a pathway for electrical and thermal transport through the composite. Unlike other graphene foams, the graphite used to synthesize these composites is natural flake material, with no oxidation, reduction, sonication, high temperature thermal treatment, addition of surfactants, or high shear mixing required. The result is an inexpensive, low‐density material that exhibits Joule heating and displays increasing electrical conductivity with decreasing thermal conductivity.     

Tailored Silica Macrocellular Foams: Combining Limited Coalescence‐Based Pickering Emulsion and Sol–Gel Process

Solid‐sate monolithic macrocellular foams are synthesized by mineralizing the continuous phase of oil‐in‐water Pickering emulsions, used as templates, with the sol–gel process. For the first time, taking advantage of the limited coalescence phenomenon occurring in emulsions stabilized by solid particles, concentrated emulsions with calibrated drop size are produced, leading to the synthesis of monolithic foams with nearly monodisperse macroscopic voids. Such a strategy allows independent tuning of the macrocellular void diameters from 20 to 800 μm and the diameter of the windows connecting adjacent cells. The obtained macrocellular foams also bear micro‐ and mesoporosity, leading to Brunauer, Emmet and Teller (BET) surface area values between 700 and 900 m² g^?1 with a good mesopores monodispersity.     

Self‐Healing Properties of Protein Resin with Soy Protein Isolate‐Loaded Poly(d,l‐lactide‐co‐glycolide) Microcapsules

Self‐healing soy protein isolate (SPI)‐based “green” thermoset resin is developed using poly(d,l ‐lactide‐co‐glycolide)(PLGA) microcapsules containing SPI, as crack healant. The SPI–PLGA microcapsules with an average diameter of 778 nm that contain sub‐capsules are prepared using a water‐in‐oil‐in‐water double‐emulsion solvent evaporation technique. The encapsulation efficiency is found to be high, up to 89%. Thermoset green SPI resin containing the SPI–PLGA microcapsules successfully arrests and retards the microcracks. The healing efficiency is investigated using mode I fracture toughness test for resins containing different concentrations of microcapsules from 5 to 20 wt% and glutaraldehyde as a crosslinker at 9 or 12 wt%. The SPI resin containing 12 wt% glutaraldehyde and 15 wt% microcapsules shows self‐healing efficiency of up to 48%. It is observed that the SPI released from SPI–PLGA microcapsules can react with the excess glutaraldehyde present in the resin when the two come in contact within the microcracks and bridge the two fracture surfaces. The results of this study show for the first time that SPI–PLGA microcapsules can self‐heal protein‐based green resins. The same method can be extended to self‐heal other proteins as well as protein‐based green composites resulting in higher fracture toughness and longer useful life.     

Contactless Interfacial Thin-Film Breaking Caused Splash-Like Demulsification of Floating Micron Emulsions via Ionic Wind

Emulsified oil leakage onto the bulk water surface causes severe issues on global ecology and health. Developing efficient, rapid, and universal separation methods of emulsions has been a significant topic in scientific studies. However, a contactless and additive-free strategy to achieve continuous floating emulsion separation and oil collection remains to be discovered. Herein, a universal contactless demulsification, transportation, and collection method to dispose floating emulsions by ionic wind, which contains active charged particles generated by corona discharge is reported. The splash-like demulsification process of floating emulsions is attributed to the rupture of water film enveloped on oil droplet surface, simultaneously and respectively. The evidence of this process recorded by a high-speed camera with 20 000 fps has a referential significance for other works. This study may clean up universal floating emulsions discharged on water in real situations such as oil stations, chemical plants, and restaurants, and furthermore increase the potential of remote control in liquid dynamics by corona discharge.     

Diffusion Controlled and Temperature Stable Microcapsule Reaction Compartments for High‐Throughput Microcapsule‐PCR

A novel approach to perform a high number of individual polymerase chain reactions (PCR) in microcapsule reaction compartments, termed “Microcapsule‐PCR” was developed. Temperature stable microcapsules with a selective permeable capsule wall were constructed by matrix‐assisted layer‐by‐layer (LbL) Encapsulation technique. During the PCR, small molecular weight building blocks – nucleotides (dNTPs) were supplied externally and diffuse through the permeable capsule wall into the interior, while the resulted high molecular weight PCR products were accumulated within the microcapsule. Microcapsules (∼110.8 µm average diameter) filled with a PCR reaction mixture were constructed by an emulsion technique having a 2% agarose core and a capsule formed by LbL coating with poly(allylamine‐hydrochloride) and poly(4‐styrene‐sulfonate). An encapsulation efficiency of 47% (measured for primer‐FITC (22 bases)) and 98% PCR efficiency was achieved. Microcapsules formed by eight layers of polyelectrolyte and subjected to PCR cycling (up to 95 °C) demonstrated good temperature stability without any significantly changes in DNA retention yield and microcapsule morphology. A multiplex Microcapsule‐PCR experiment demonstrated that microcapsules are individual compartment and do not exchange templates or primers between microcapsules during PCR cycling.     

3D Multiscale Superhydrophilic Sponges with Delicately Designed Pore Size for Ultrafast Oil/Water Separation

Developing novel filtering materials with both high permeation flux and rejection rate presents an enticing prospect for oil/water separation. In this paper, robust porous poly(melamine formaldehyde) (PMF) sponges with superwettability and controlled pore sizes through introducing layered double hydroxides (LDH) and SiO₂ electrospun nanofibers are reported. The LDH nanoscrolls endow the sponge with inherent superhydrophilicity and the SiO₂ nanofibers act as pore size regulators by overlapping the PMF mainframe. This approach allows the intrinsic large pores in the pristine sponge to decrease quickly from 109.50 to 23.35 µm, while maintaining porosity above 97.8%. The resulting modified sponges with varied pore sizes can effectively separate a wide range of oil/water mixtures, including the surfactant‐stabilized emulsions, solely by gravity, with ultrahigh permeation flux (maximum of 3 × 10⁵ L m^?2 h^?1 bar^?1) and satisfactory oil rejection (above 99.46%). Moreover, separation of emulsions stabilized by different surfactants, such as anionic, nonionic, and cationic surfactants has been investigated for further practical evaluation. It is expected that such a pore size tuning technology can provide a low cost and easily scaled‐up method to construct a series of filtering materials for high‐efficient separation of target oil/water mixtures.     

Tuning the Porosity of Bimetallic Nanostructures by a Soft Templating Approach

Hexagonal mesophases made of oil‐swollen surfactant‐stabilized tubes arranged on a triangular lattice in water and doped with metallic salts are used as templates for the radiolytic synthesis of nanostructures. The nanostructures formed in this type of soft matrix are bimetallic palladium‐platinum porous nanoballs composed of 3D‐connected nanowires, of typical thickness 2.5 nm, forming hexagonal cells. Using electron microscopy and small‐angle X‐ray scattering it is demonstrated that the pore size of the nanoballs is directly determined by the diameter of the oil tube of the doped mesophases, which is varied in a controlled fashion from 10 to 55 nm. Bimetallic nanostructures composed of various proportions of palladium and platinum can be synthesized. Their alloy structure is studied using X‐ray photoelectron spectroscopy, energy‐dispersive X‐ray spectroscopy, and high‐angular dark field scanning transmission electron microscopy experiments. The templating approach allows the synthesis of bimetallic nanoballs of tunable porosity and composition.     

Optimization of Von Mises Stress Distribution in Mesoporous α‐Fe2O3/C Hollow Bowls Synergistically Boosts Gravimetric/Volumetric Capacity and High‐Rate Stability in Alkali‐Ion Batteries

Hollow structures are often used to relieve the intrinsic strain on metal oxide electrodes in alkali‐ion batteries. Nevertheless, one common drawback is that the large interior space leads to low volumetric energy density and inferior electric conductivity. Here, the von Mises stress distribution on a mesoporous hollow bowl (HB) is simulated via the finite element method, and the vital role of the porous HB structure on strain‐relaxation behavior is confirmed. Then, N‐doped‐C coated mesoporous α‐Fe₂O₃ HBs are designed and synthesized using a multistep soft/hard‐templating strategy. The material has several advantages: (i) there is space to accommodate strains without sacrificing volumetric energy density, unlike with hollow spheres; (ii) the mesoporous hollow structure shortens ion diffusion lengths and allows for high‐rate induced lithiation reactivation; and (iii) the N‐doped carbon nanolayer can enhance conductivity. As an anode in lithium‐ion batteries, the material exhibits a very high reversible capacity of 1452 mAh g^?1 at 0.1 A g^?1, excellent cycling stability of 1600 cycles (964 mAh g^?1 at 2 A g^?1), and outstanding rate performance (609 mAh g^?1 at 8 A g^?1). Notably, the volumetric specific capacity of composite electrode is 42% greater than that of hollow spheres. When used in potassium‐ion batteries, the material also shows high capacity and cycle stability.     

Solvent‐Resistant PDMS Microfluidic Devices with Hybrid Inorganic/Organic Polymer Coatings

This study presents a method for the fabrication of solvent‐resistant poly(dimethylsiloxane) (PDMS) microfluidic devices by coating the microfluidic channel with a hybrid inorganic/organic polymer (HR4). This modification dramatically increases the resistance of PDMS microfluidic channels to various solvents, because it leads to a significant reduction in the rate of solvent absorption and consequent swelling. The compatibility of modified PDMS with a wide range of solvents is investigated by evaluating the swelling ratio measured through weight changes in a standard block. The HR4‐modified PDMS microfluidic device can be applied to the formation of water‐in‐oil (W/O) and oil‐in‐water (O/W) emulsions. The generation of organic solvent droplets with high monodispersity in the microfluidic device without swelling problems is demonstrated. The advantage of this proposed method is that it can be used to rapidly fabricate microfluidic devices using the bulk properties of PDMS, while also increasing their resistance to various organic solvents. This high compatibility with a variety of solvents of HR4‐modified PDMS can expand the application of microfluidic systems to many research fields.     

Scaffolds Based on Biopolymeric Foams

A new approach for the preparation of hydrophilic and biocompatible porous scaffolds is described. The procedure involves the derivatization of a biopolymer by the introduction of vinylic moieties, formation of a high‐internal‐phase oil‐in‐water emulsion, and its subsequent polymerization. The ensuing materials are characterized by a highly porous morphology represented by pores completely interconnected by a plurality of holes. The hydrophilic and biocompatible nature of these materials make them good candidates for application as scaffolds for tissue engineering.     

Structure Formation in Tailor-Made Buriti Oil Emulsion During Simulated Digestion (Adv. Funct. Mater. 49/2023)

Functional food emulsions enriched in health-promoting nutrients can help to maintain and improve health and lifestyle. The oil extracted from the Amazonian buriti fruit is renowned for its high levels of carotenoid, vitamin E, and unsaturated fatty acids, which have been linked to improvements in cardiometabolic health. Here, buriti oil in water emulsions are developed and their colloidal transformations are investigated in an advanced digestion model with oral, gastric, and intestinal parts with in situ synchrotron small-angle X-ray scattering, cryogenic electron microscopy, and dynamic light scattering under simulated “healthy” and “compromised” digestive conditions. The interior oil phase of whey-stabilized buriti oil-in-water emulsion transforms into highly ordered lyotropic liquid crystalline structures during simulated intestinal digestion at compromised bile conditions. Simulated gastric digestion influences intestinal digestion by slowing it down, resulting in less ordered structures. The digestion-triggered structure formation is pH- and bile salt-dependent and can be modulated by adding vitamin E to the oil. This tailoring of structures during digestion offers a new pathway to steer digestion kinetics and nutrient bioavailability.     

One‐Pot Synthesis and Hierarchical Assembly of Hollow Cu2O Microspheres with Nanocrystals‐Composed Porous Multishell and Their Gas‐Sensing Properties

Hierarchical assembly of hollow microstructures is of great scientific and practical value and remains a great challenge. This paper presents a facile and one‐pot synthesis of Cu₂O microspheres with multilayered and porous shells, which were organized by nanocrystals. The time‐dependent experiments revealed a two‐step organization process, in which hollow microspheres of Cu₂(OH)₃NO₃ were formed first due to the Ostwald ripening and then reduced by glutamic acid, the resultant Cu₂O nanocrystals were deposited on the hollow intermediate microspheres and organized into finally multishell structures. The special microstructures actually recorded the evolution process of materials morphologies and microstructures in space and time scales, implying an intermediate‐templating route, which is important for understanding and fabricating complex architectures. The Cu₂O microspheres obtained were used to fabricate a gas sensor, which showed much higher sensitivity than solid Cu₂O microspheres.     

Zwitterionic Nanohydrogel Grafted PVDF Membranes with Comprehensive Antifouling Property and Superior Cycle Stability for Oil‐in‐Water Emulsion Separation

Fouling caused by oil and other pollutants is one of the most serious challenges for membranes used for oil/water separation. Aiming at improving the comprehensive antifouling property of membranes and thus achieving long‐term cyclic stability, it is reported in this work the design of a kind of zwitterionic nanosized hydrogels grafted poly(vinylidene fluoride) (PVDF) microfiltration membrane (ZNG‐g‐PVDF) with superior fouling‐tolerant property for oil‐in‐water emulsion separation. Sulfobetaine zwitterionic nanohydrogels with the diameter of ≈ 50 nm are synthesized by an inverse microemulsion polymerization process. They are then grafted onto the surface of PVDF microfiltration membrane, endowing the membrane a superhydrophilic and nearly zero oil adhesion property. This ZNG‐g‐PVDF membrane exhibits great tolerance and resistance to salts pH, especially an excellent antifouling property to oil‐in‐water emulsions containing various pollutants such as surfactants, proteins, and natural organic materials (e.g., humic acid). The comprehensive antifouling property of the membrane gives rise to the cyclic stability of the membrane greatly improved. A nearly 100% recovery ratio of permeating flux is achieved during several cycles of oil‐in‐water emulsion filtration. The ZNG‐g‐PVDF membrane shows great potential in treating practical oily wastewater containing complicated components in the effluent.