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Biohybrid microcylinders are fabricated using electrohydrodynamic cojetting followed by a surface chemistry approach to maximize cell-adhesive characteristics. As proper cell alignment and mechanical stiffness are important components of bioactuator design, spatial cell selectivity and stress/strain properties of microcylinders are characterized to demonstrate their capability of response to rat cardio-myocyte contraction. These microcylinders can find applications in a host of micromechanical systems.

Selective growth of metal organic framework materials on the surface of compartmentalized polymer microparticles is achieved by electro-hydrodynamic co-jetting, selective surface modification, and anisotropic crystal growth.

A novel synthetic route for the preparation of amphiphilic Janus particles based on electrohydrodynamic cojetting has been developed. In this approach, selective encapsulation of hydrophobic fluorodecyl-polyhedral oligomeric silsesquioxane (F-POSS) in one compartment and a poly(vinyl alcohol) in the second compartment results in colloidal particles with surfactant-like properties including the self-organization at oil-water and air-water interfaces. Successful localization of the respective polymers in different compartments of the same particle is confirmed by a combination of fluorescence microscopy, vibrational spectroscopy, and ζ-potential measurements. We believe that this straightforward synthetic approach may lead to a diverse class of surface-active colloids that will have significant relevance ranging from basic scientific studies to immediate applications in areas, such as pharmaceutical sciences or cosmetics.

Nature’s particles, such as spores, viruses or cells, are adaptive—i.e., they can rapidly alter major phenomenological attributes such as shape, size, or curvature in response to environmental changes. Prominent examples include the hydration-mediated opening of ice plant seeds, actuation of pine cones, or the ingenious snapping mechanism of predatory Venus flytraps that rely on concave-to-convex reconfigurations. In contrast, experimental realization of reconfigurable synthetic microparticles has been extremely challenging and only very few examples have been reported so far. Here, we demonstrate a generic approach towards dynamically reconfigurable microparticles that explores unique anisotropic particle architectures, rather than direct synthesis of sophisticated materials such as shape-memory polymers. Solely enabled by their architecture, multicompartmental microcylinders made of conventional polymers underwent active reconfiguration including shape-shifting, reversible switching, or three-way toggling. Once microcylinders with appropriate multicompartmental architectures were prepared by electrohydrodynamic cojetting, simple exposure to an external stimulus, such as ultrasound or an appropriate solvent, gives rise to interfacial stresses that ultimately cause reversible topographical reconfiguration. The broad versatility of the electrohydrodynamic cojetting process with respect to materials selection and processing suggests strategies for a wide range of dynamically reconfigurable adaptive materials including those with prospective applications for sensors, reprogrammable microactuators, or targeted drug delivery.

Colloidal micro- and nanoparticles with controlled internal architectures have attracted recent interest because of their promising properties for drug delivery, molecular imaging and self-assembly. A variety of interesting and efficient particle strategies have been investigated spanning from polymeric, organic, to inorganic and metallic materials. In spite of intense activities in this area, accurate engineering of anisotropy in sub-micron particles remains challenging. Here, we summarize and discuss current trends related to particles that are complex in shapes, surfaces, and compartments. Additionally, this review article aims at presenting the benefits and limitations of current methods and identifies future directions for research in the field.

We demonstrate spatially controlled photoreactions within bicompartmental microparticles and microfibers. Selective photoreactions are achieved by anisotropic incorporation of photocrosslinkable poly(vinyl cinnamate) in one compartment of either colloids or microfibers. Prior to photoreaction, bicompartmental particles, and fibers were prepared by EHD co-jetting of two compositionally distinct polymer solutions. Physical and chemical anisotropy was confirmed by confocal laser scanning microscopy, Fourier-transformed infrared spectroscopy, and scanning electron microscopy. The data indicate adjustment of polymer concentrations of the jetting solutions to be the determining factors for particle and fiber structures. Subsequent exposure of poly(vinyl cinnamate)-based particles and fibers to UV light at 254 nm resulted in spatially controlled crosslinking. Treatment of the crosslinked bicompartmental colloids with chloroform produced half-moon shaped objects. These hemishells exhibited a distinct porous morphology with pore sizes in the range of 70 nm. Based on this novel synthetic approach, Janus-type particles and fibers can be prepared by EHD co-jetting and can be selectively photocrosslinked without the need for masks or selective laser writing.

Anisotropically compartmentalized microparticles have attracted increasing interest in areas ranging from sensing, drug delivery, and catalysis to microactuators. Herein, a facile method is reported for the preparation of helically decorated microbuilding blocks, using a modified electrohydrodynamic cojetting method. Bicompartmental microfibers are twisted in situ, during electrojetting, resulting in helical microfibers. Subsequent cryosectioning of aligned fiber bundles provides access to helically decorated microcylinders. The unique helical structure endows the microfibers/microcylinders with several novel functions such as translational motion in response to rotating magnetic fields. Finally, microspheres with helically patterned compartments are obtained after interfacially driven shape shifting of helically decorated microcylinders.

A combinatorial approach for the colorimetric differentiation of organic solvents is developed. A polydiacetylene (PDA)-embedded electrospun fiber mat, prepared with aminobutyric acid-derived diacetylene monomer PCDA-ABA 1, displays colorimetric stability when exposed to common organic solvents. In contrast, a fiber mat prepared with the aniline-derived diacetylene PCDA-AN 2 undergoes a solvent-sensitive color transition. Arrays of PDA-embedded microfibers are constructed by electrospinning poly(ethylene oxide) solutions containing various ratios of two diacetylene monomers. Unique color patterns are developed when the conjugated polymer-embedded electrospun fiber arrays are exposed to common organic solvents in a manner which enables direct colorimetric differentiation of the tested solvents.

A combination of top-down (electrospinning for fabrication of high surface area micro/ nanofibers) and bottom-up (creation of supramolecular structures through self-assembly processes in fiber) approaches has enabled the generation of conjugated polymer-embedded fibers. The efficiency of fiber formation, encapsulated with colorimetric, and fluorogenic conjugated polydiacetylene supramolecules, was dependent on electrospinning conditions, such as concentration, molecular weight, type of matrix polymer, and solvent. In general, electrospinning of a chloroform solution containing 1.6 wt.-% of a diacetylene monomer and 4 wt.-% PEO of molecular weight 300000 g·mol -1 followed by 254 nm UV irradiation resulted in clean formation of polydiacetylene-embedded fibers. In addition, UV irradiation during electrospinning can be used for in situ and continuous generation of polydiacetylenes-encapsulated fibers.

Micrometer-sized polydiacetylene (PDA) vesicle patterns on titanium substrates have been successfully fabricated by using a micromolding in capillaries (MIMIC) technique. The shape and width of the PDA patterns are well matched with polydimethylsiloxane (PDMS) molds used in the MIMIC process. However, the thicknesses of the patterned films are less than the depths of the PDMS molds, which may be a consequence of the poor water wettability of the PDMS and/or low concentrations of the PDA solutions. Heat-treatment of the solid substrate, immobilized with blue-phase PDAs, induces a blue-to-red-phase transition and results in the formation of patterned fluorescence images.

The generation of functional supramolecular structures through the self-assembly of small molecules continues to be a significant scientific endeavour. Molecularly assembled monomers that contain polymerizable units often serve as precursors to unique supramolecular structures that have meritorious features, for example, enhanced stability and chromogenic functions. In this regard, polydiacetylene (PDA) supramolecules, readily prepared by UV or c irradiation of molecularly assembled diacetylene (DA) monomers, are attractive substances. The polymer backbone of PDAs consists of alternating alkene–alkyne structures. Owing to their intriguing stress-induced chromic transition (blue to red) and nonlinear optical properties, PDAs have been extensively investigated as potential chemosensors and photonic materials. Recently, the embedment of PDA supramolecules in matrices and host molecules has been used advantageously for the creation of well-defined nanoand microscale structures and substances with unique optical, electronic, and mechanical properties. Several examples include helical tubular inorganic architectures that are prepared by using a chiral diacetylene monomer as a template molecule, PDA-silica nanocomposites that possess hexagonal, cubic, and lamellar structures, and hybrid sol-gel matrices with encapsulated antibody-containing PDAs for biosensor applications. The encapsulation of PDA supramolecules in polymer nanoor microfibers has not yet been reported. Electrospinning has proven to be an efficient method for the formation of long polymer fibers with diameters in the range of nanometers to several micrometers. In this technique a high voltage is applied to a conductive capillary, which is attached to a reservoir containing a polymer solution. A charged polymer jet is ejected from the surface of the polymer solution when the charge imbalance exceeds the surface tension of the polymer solution. Polymer fibers are formed when the jet stream, driven by electrostatic forces, moves to the grounded screen collector. Its characteristic merits allow the electrospinning technique to be uniquely applied to the rapid, cost-effective fabrication of PDA conjugated polymers in the form of microfibers with a large surface area. In this Communication we describe a simple but elegant approach for the generation of polymer microfibers containing embedded PDA supramolecules, based on the electrospinning technique. The strategy employed in this study, schematically presented in Figure 1, initially involves DA monomers that are randomly distributed in an organic solvent before electrospinning. As the solvent evaporates during fiber formation, self-assembly of DA monomers takes place because the attractive forces between the DA monomers are larger than those between the DA monomers and matrix polymers. Polymerization of the self-assembled DA monomers should result in the formation of PDAs embedded within the polymer fibers. 10,12-Pentacosadiynoic acid (PCDA, CH3(CH2)11C C– C C(CH2)8COOH), a frequently employed DA monomer in C O M M U N IC A IO N

The fabrication and properties of pH-responsive colloidal particles are reported, which change shape rapidly (less than 200 ms), nearly independent of the diffusion of the pH altering species that trigger their actuation, and far more rapid than their Brownian motion. These particles are mechanically bistable, as revealed by their hysteretic shape response. Finite element analysis (FEA) shows that mechanical hysteresis and bistability derives from the colloids' spherical curvature. Mechanical characterization of the bilayered polymers comprising the colloidal particles shows that viscoelastic relaxation plays a non-negligible role in limiting the shape switching rate; however, energy landscapes obtained from FEA simulations suggest that by tuning the elastic moduli and thicknesses of the constituent polymer layers, microparticles of the size shown here may be fabricated to actuate on timescales as fast as 1 μs.

A novel water insoluble, multifunctional poly(ethylene glycol), poly(hydrazide ethylene glycol-co-benzyl glycidyl ether) (P(HZ-co-BnGE)), is synthesized via thiol-ene click reaction of poly(allyl glycidyl ether-co-benzyl glycidyl ether) (P(AGE-co-BnGE)). The base polymer P(AGE-co-BnGE) is previously prepared by anionic ring-opening copolymerization of the corresponding monomers. To demonstrate utility, bicompartmental microspheres and microcylinders containing P(HZ-co-BnGE) in one of the compartments are prepared via electrohydrodynamic (EHD) co-jetting. Next, spatially controlled surface reactivity toward sugars is demonstrated by selective binding of 2α-mannobiose to the P(HZ-co-BnGE) compartment only, as confirmed by a carbohydrate-lectin-binding assay. These sugar-reactive hydrazide-presenting microparticles have potential applications for glyco-targeted drug delivery.

Janus microcylinders composed of different polymers were prepared through coaxial co-jetting with dual-core flows, followed by cross-linking, microsectioning, and shell removal. Uniquely shaped building blocks can be fabricated by photo-patterning of one hemisphere of the microcylinders.

Polymer particles with controlled internal architecture are currently under development for a number of emerging applications. In compartmentalized particles, well-defined pockets of distinct materials can be designed that can give rise to a set of orthogonal (i.e., dissimilar) properties within the same particle. While this aspect appears crucial, when multifunctional particles for sensing, imaging or drug delivery are sought after, their experimental realization has only recently been explored in broader terms. In this review, we highlight current progress related to the design and fabrication of multicompartmental particles and discuss potential benefits and experimental challenges associated with different synthetic routes.