Artificial stimuli-responsive surfaces that can mimic the dynamic function of living systems have attracted much attention. However, there exist few artificial systems capable of responding to dual- or multistimulation as the natural system does. Herein, we synthesize a pH and glucose dual-responsive surface by grafting poly(acrylamidophenylboronic acid) (polyAAPBA) brush from aligned silicon nanowire (SiNW) array. The as-prepared surface can reversibly capture and release targeted cancer cells by precisely controlling pH and glucose concentration, exhibiting dual-responsive AND logic. In the presence of 70 mM glucose, the surface is pH responsive, which can vary from a cell-adhesive state to a cell-repulsive state by changing the pH from 6.8 to 7.8. While keeping the pH at 7.8, the surface becomes glucose responsive--capturing cells in the absence of glucose and releasing cells by adding 70 mM glucose. Through simultaneously changing the pH and glucose concentration from pH 6.8/0 mM glucose to pH 7.8/70 mM glucose, the surface is dual responsive with the capability to switch between cell capture and release for at least 5 cycles. The cell capture and release process on this dual-responsive surface is noninvasive with cell viability higher than 95%. Moreover, topographical interaction between the aligned SiNW array and cell protrusions greatly amplifies the responsiveness and accelerates the response rate of the dual-responsive surface between cell capture and release. The responsive mechanism of the dual-responsive surface is systematically studied using a quartz crystal microbalance, which shows that the competitive binding between polyAAPBA/sialic acid and polyAAPBA/glucose contributes to the dual response. Such dual-responsive surface can significantly impact biomedical and biological applications including cell-based diagnostics, in vivo drug delivery, etc.

The separation of oil–water mixtures in highly acidic, alkaline, and salty environment remains a great challenge. Simple, low‐cost, efficient, eco‐friendly, and easily scale‐up processes for the fabrication of novel materials to effective oil–water separation in highly acidic, alkaline, and salty environment, are urgently desired. Here, a facile approach is reported for the fabrication of stable hydrogel‐coated filter paper which not only can separate oil–water mixture in highly acidic, alkaline, and salty environment, but also separate surfactant‐stabilized emulsion. The hydrogel‐coated filter paper is fabricated by smartly crosslinking filter paper with hydrophilic polyvinyl alcohol through a simple aldol condensation reaction with glutaraldehyde as a crosslinker. The resultant multiple crosslinked networks enable the hydrogel‐coated filter paper to tolerate high acid, alkali, and salt up to 8 m H2SO4, 10 m NaOH, and saturated NaCl. It is shown that the hydrogel‐coated filter paper can separate oil–water mixtures in highly acidic, alkaline, and salty environment and oil‐in‐water emulsion environment, with high separation efficiency (>99%).

Interfacial polymerization, where a chemical reaction is confined at the liquid–liquid or liquid–air interface, exhibits a strong advantage for the controllable fabrication of films, capsules, and fibers for use as separation membranes and electrode materials. Recent developments in technology and polymer chemistry have brought new vigor to interfacial polymerization. Here, we consider the history of interfacial polymerization in terms of the polymerization types: interfacial polycondensation, interfacial polyaddition, interfacial oxidative polymerization, interfacial polycoordination, interfacial supramolecular polymerization, and some others. The accordingly emerging functional materials are highlighted, as well as the challenges and opportunities brought by new technologies for interfacial polymerization. Interfacial polymerization will no doubt keep on developing and producing a series of fascinating functional materials.

The separation of microsized oil droplets from water is strongly required by the environmental protection and petroleum industry. However, the separation of microsized oil droplets from water is often ignored. Herein, magnetic Janus particles are reported with a convex hydrophilic surface/concave oleophilic surface by emulsion interfacial polymerization and selective surface assembly, realizing the rapid and efficient separation of microscaled tiny oil droplets from water. These magnetic Janus particles exhibit significant abilities to separate microscaled oil droplets from water, which usually occurs within 120 s with a separation efficiency >99%. Theoretical and experimental results demonstrate that these magnetic Janus particles can capture tiny oil droplets to make them coalesce into larger ones during the process of separation. Further studies reveal that these Janus particles can self-assemble and closely pack onto the interface of larger oil droplets, acting as surfactants to stabilize them. Moreover, the shape effect of the Janus particle is demonstrated on the coalescence of the oil droplets.particles are fabricated by emulsion interfacial polymerization between hydrophilic acrylic acid (AA) and oleophilic styrene/ divinyl benzene (St/DVB) followed by selective electrostatic assembly of Fe 3 O 4 nanoparticles on the convex surface of the resulting Janus particles. These magnetic Janus particles exhibit a remarkable ability to rapidly separate tiny oil droplets from water with a high separation efficiency (>99%). The influence of the interfacial activity of Janus particles with different shapes on the oil-water separation is comprehensively investigated. Results and DiscussionMagnetic Janus particles were fabricated by emulsion interfacial polymerization and interfacial assembly (Figure 1a). The

Existing nanoparticle-mediated drug delivery systems for glioma systemic chemotherapy remain a great challenge due to poor delivery efficiency resulting from the blood brain barrier/blood-(brain tumor) barrier (BBB/BBTB) and insufficient tumor penetration. Here, we demonstrate a distinct design by patching doxorubicin-loaded heparin-based nanoparticles (DNs) onto the surface of natural grapefruit extracellular vesicles (EVs), to fabricate biomimetic EV-DNs, achieving efficient drug delivery and thus significantly enhancing antiglioma efficacy. The patching strategy allows the unprecedented 4-fold drug loading capacity compared to traditional encapsulation for EVs. The biomimetic EV-DNs are enabled to bypass BBB/BBTB and penetrate into glioma tissues by receptor-mediated transcytosis and membrane fusion, greatly promoting cellular internalization and antiproliferation ability as well as extending circulation time. We demonstrate that a high-abundance accumulation of EV-DNs can be detected at glioma tissues, enabling the maximal brain tumor uptake of EV-DNs and great antiglioma efficacy in vivo.

Herein, recent progress in interfacial polymerization from the aspects of theory models, fabrication methods, and applications has been summarized.

Synthetic polymer actuators have attracted increasing attention for their potential applications in artificial muscles, soft robotics and sensors. The majority of previous efforts have focused on smart hydrogels with bilayer structures that can change their shape in response to environmental stimuli, such as temperature, light and certain chemicals. However, the practical application of hydrogels is limited because of their low modulus and weak mechanical strength. Here we synthesized a robust monolithic actuator of a macro-scale hydro/organo binary cooperative Janus copolymer film. The process involves direct, one-step interfacial polymerization of immiscible hydrophilic and hydrophobic vinyl monomer solutions, and the resultant product exhibited binary cooperative shape transformation to multiple external stimuli. The Janus copolymer film can work in both aqueous solutions and organic solvents, with bidirectional and site-specific bending arising from cooperative asymmetric swelling/shrinking of the hydrogel and organogel networks. In addition, the as-prepared Janus copolymer film can act as a sensor element for solvent leakage detection. This binary cooperative strategy is applicable to most immiscible monomer systems and provides a general approach to developing novel functional copolymer materials. NPG Asia Materials (2017) 9, e380; doi:10.1038/am.2017.61; published online 19 May 2017 INTRODUCTIONThe shape transformations of biological organisms [1][2][3][4][5][6] have been the inspiration for many products in the field of artificial muscles, 7-13 soft robotics, 14-19 sensors 20 and complex shape engineering. 21,22 For example, the leaves of the Venus flytrap snap together to capture insects by virtue of the synergy between the hydroelastic instability and asymmetric expansion of the inner and outer surfaces at the cellular level. 2 The layered anisotropic orientated cellulose fibrils induce hygroscopic movements of pine cones, 1 wheat awns, 3 orchid tree seedpods 6 and other plants. By mimicking the sophisticated hierarchical structures present in nature, the motion of polymer films has been successfully demonstrated in several cases. [23][24][25][26][27][28][29][30] For example, hydrogel bilayers embedded with intersecting inorganic platelets or cellulose fibrils have exhibited pine-cone-like bending and pod-like twisting motions. 24,31 However, the practical applications of these actuators were limited because of the low modulus and weak mechanical strength of the hydrogels. 32 Elastomer single layer films, such as azobenzene polymer films synthesized using an elaborate molecular design, 13,27 can achieve smart responsive curving. However, these films require a unidirectional stimulus to generate anisotropic contraction/expansion of their two sides; this factor limits the film thickness to the micrometer or sub-millimeter level. 27,[33][34][35] Therefore,

New strategies for synthesis of Janus particles are of essential importance in the advancement of material science and technology. However, it remains a great challenge to synthesize uniform Janus particles with controllable topological and chemical anisotropy. To overcome this challenge, we have recently developed a general emulsion interfacial polymerization approach. This approach can be applicable to a wide variety of vinyl monomers, including positively charged, neutrally charged, and negatively charged monomers. Different from the traditional seed swelling emulsion polymerization that usually involved using cross-linked polystyrene (PS) particles as seeds to produce Janus particles, we preloaded non-cross-linked PS particles in the emulsion system to construct an interfacial polymerization system. However, the role of these non-cross-linked PS particles in the emulsion interfacial polymerization is unclear. In this work, we revealed the role of non-cross-linked PS particles preloaded in emulsion interfacial polymerization for fabricating uniform Janus particles with controllable topology. We found that the introduction of non-cross-linked PS particles could significantly control the topology and uniformity of Janus particles. Theoretical simulation results by dissipative particle dynamics simulation coupled with stochastic reaction model revealed that the polymer chains of PS inside oil droplets play a decisive role in the topographic control of Janus particles. These hydrophobic PS chains could slow down the polymerization inside oil droplets due to shielding effect of the PS chains to the newly formed poly­(styrene–divinylbenzene) (PSDVB) nucleus. Meanwhile, we demonstrated that the diverse topology features of Janus particles could be tuned by regulating the concentration of PS polymer and monomers. These results may help us to comprehensively understand the mechanism of emulsion interfacial polymerization methodology and design new functional particle materials.