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ABSTRACT: 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.
Proceedings of the National Academy of Sciences 09/2012; 109(40):16057-62. · 9.68 Impact Factor
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ABSTRACT: Multifunctional, multicompartmental particles can be fabricated by electrohydrodynamic co-jetting, capable of both imaging and siRNA delivery. These particles are able to sense and respond to the endosomal environment allowing for effective delivery of siRNA.
Advanced Materials 05/2012; 24(28):3850-6. · 13.88 Impact Factor
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ABSTRACT: The bends: Surface modification of multi-compartmental microcylinders by spatio-selective click chemistry and subsequent surface-initiated atom-transfer radical polymerization (ATRP) yield novel amphiphilic microcylinders. Depending on the aspect ratio of the microcylinders, they can be bent or coiled.
Angewandte Chemie International Edition 12/2011; 51(3):660-5. · 13.45 Impact Factor
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ABSTRACT: 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.
Macromolecular Rapid Communications 03/2011; 32(5):431-7. · 4.60 Impact Factor
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ABSTRACT: Along with traditional attributes such as the size, shape, and chemical structure of polymeric micro-objects, control over material distribution, or selective compartmentalization, appears to be increasingly important for maximizing the functionality and efficacy of biomaterials. The fabrication of tri- and tetracompartmental colloids made from biodegradable poly(lactide-co-glycolide) polymers via electrohydrodynamic co-jetting is demonstrated. The presence of three compartments is confirmed via flow cytometry. Additional chemical functionality is introduced via the incorporation of acetylene-functionalized polymers into individual compartments of the particles. Direct visualization of the spatioselective distribution of acetylene groups is demonstrated by confocal Raman microscopy as well as by reaction of the acetylene groups with azide-biotin via 'click chemistry'. Biotin-streptavidin binding is then utilized for the controlled assembly and orientation of bicompartmental particles onto functionalized, micropatterned substrates prepared via chemical vapor deposition polymerization.
Small 02/2011; 7(6):812-9. · 8.35 Impact Factor
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ABSTRACT: Control over nano-and microscale architecture of polymeric materials is highly desirable for improved versatility, utility, and performance of biomedical devices, which include smart drug release systems, biomedical coatings and multiplexed bioassays. Apart from size and shape of polymeric micro-objects, phase distribution, or selective material compartmentalization has been shown to be increasingly important for maximizing device performance. In this work, we summarize the recent advances we have made in the synthesis and applications of biodegradable multicompartmental biomaterials from polylactide-co-glycolic acid (PLGA) polymers via electrohydrodynamic co-jetting. In its simplest form, two polymer solutions are flown through a modified side-by-side capillary system. Application of an electric field results in the formation of an electrospray, and solvent evaporation results in particle formation. The interface between two polymer solutions is sustained during jet fragmentation and size reduction. Because of its intrinsic simplicity and generality, the electrohydrodynamic co-jetting process can be applied to a wide range of specialty and non-specialty materials. Furthermore, simple variations of different solution and process parameters, such as concentration, flow rate, applied voltage, etc. provides access to a vast repertoire of shapes and sizes of particles. We herein demonstrate fabrication of a variety of non-equilibrium biphasic shapes, such as discs, rods and others, in addition to spheres. Such novel particle geometries enable independent control of key parameters, such as chemical composition, surface functionalization, biological loading, shape, and size for each compartment. We then demonstrate spatio selective control over surface chemistry of these biphasic particles via Huisgen 1, 3-dipolar cycloaddition. The selective surface functionalization is combined with biotin-streptavidin interactions to show orientation and assembly of bicompartmental particles in suspension. The optical effects achieved through this specific orientation can be employed as diagnostic markers and have applications in developing analyte specific biological assays.
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Small 01/2010; 6(3). · 8.35 Impact Factor
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ABSTRACT: Biomaterials form the basis of current and future biomedical technologies. They are routinely used to design therapeutic carriers, such as nanoparticles, for applications in drug delivery. Current strategies for synthesizing drug delivery carriers are based either on discovery of materials or development of fabrication methods. While synthetic carriers have brought upon numerous advances in drug delivery, they fail to match the sophistication exhibited by innate biological entities. In particular, red blood cells (RBCs), the most ubiquitous cell type in the human blood, constitute highly specialized entities with unique shape, size, mechanical flexibility, and material composition, all of which are optimized for extraordinary biological performance. Inspired by this natural example, we synthesized particles that mimic the key structural and functional features of RBCs. Similar to their natural counterparts, RBC-mimicking particles described here possess the ability to carry oxygen and flow through capillaries smaller than their own diameter. Further, they can also encapsulate drugs and imaging agents. These particles provide a paradigm for the design of drug delivery and imaging carriers, because they combine the functionality of natural RBCs with the broad applicability and versatility of synthetic drug delivery particles.
Proceedings of the National Academy of Sciences 12/2009; 106(51):21495-9. · 9.68 Impact Factor
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ABSTRACT: Biodegradable, compositionally anisotropic microparticles with two distinct compartments that exhibit controlled shapes and sizes are fabricated. These multifunctional particles are prepared by electrohydrodynamic co-jetting of poly(lactide-co-glycolide) polymer solutions. By varying different solution and process parameters, namely, concentration and flow rate, a variety of non-equilibrium bicompartmental shapes, such as discoid and rod-shaped microparticles are produced in high yields. Optimization of jetting parameters, combined with filtration, results in near-perfect, bicompartmental spherical particles in the size range of 3-5 microm. Simultaneous control over anisotropy, size, shape, and surface structure provides an opportunity to create truly multifunctional microparticles for a variety of biological applications, such as drug delivery, diagnostic assays, and theranostics.
Small 11/2009; 6(3):404-11. · 8.35 Impact Factor
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ABSTRACT: Because the local microstructure plays a pivotal role for many biological functions, a wide range of methods have been developed to design precisely engineered substrates for both fundamental biological studies and biotechnological applications. However, these techniques have been by-and-large limited to flat surfaces. Herein, we use electrohydrodynamic co-spinning to prepare biodegradable three-dimensional fiber scaffolds with precisely engineered, micrometre-scale patterns, wherein each fiber is comprised of two distinguishable compartments. When bicompartmental fiber scaffolds are modified via spatially controlled peptide immobilization, highly selective cell guidance at spatial resolutions (<10 µm), so far exclusively reserved for flat substrates, is achieved. Microstructured fiber scaffolds may have utility for a range of biotechnological applications including tissue engineering or cell-based assays.
Macromolecular Rapid Communications 10/2009; 30(19):1638-44. · 4.60 Impact Factor
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Advanced Materials 09/2009; 21(48):4920 - 4925. · 13.88 Impact Factor
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ABSTRACT: Colorful columns: A simple yet scalable method that yields multicompartmental microcylinders with controllable internal architectures, aspect ratios, and controlled surface modification uses electrohydrodynamic co-spinning followed by microsectioning. Compartments are discriminated by different colored dyes (see CLSM images; scale bars = 10.0 microm).
Angewandte Chemie International Edition 06/2009; 48(25):4589-93. · 13.45 Impact Factor
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ABSTRACT: We demonstrate herein the fabrication of novel multicompartmental biodegradable microstructures via electrohydrodynamic cospinning of two or more polymer solutions. Under optimized processing conditions, the interface between the solutions can be sustained continuously for long time intervals, yielding fibers with multiple chemically distinct compartments. Simultaneous control over internal fiber architecture and the spatial arrangement of individual compartments combined with precise long-range fiber alignment makes these fibers potential candidates for applications such as tissue engineering or cell culture studies.
Journal of the American Chemical Society 06/2009; 131(19):6650-1. · 9.91 Impact Factor
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ABSTRACT: Multicompartmental microcylinders can be produced by a combination of electrohydrodynamic co-spinning and microsectioning, as described by J. Lahann et 14al. in their Communication on page 144589 14ff. The number of individual compartments, relative compartment orientation, chemical composition and functionality, and aspect ratio can be precisely tuned. Each color in the longitudinal and cross-sectional micrograph images depicts an individual compartment.
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ABSTRACT: Mikrozylinder mit mehreren Kompartimenten lassen sich mit einer Kombination aus elektrohydrodynamischem Spinnen und Mikroabtrennen herstellen, wie J. Lahann et 14al. in der Zuschrift auf S. 144659 14ff. beschreiben. Die Zahl der einzelnen Kompartimente, ihre relative Orientierung, chemische Zusammensetzung und FunktionalitÄt sowie das SeitenverhÄltnis kÖnnen maßgeschneidert eingestellt werden. Jede Farbe in den LÄngs- und Querschnitt-Mikrographen entspricht einem individuellen Kompartiment.
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ABSTRACT: Precise nano- and microscale control of the architecture of biodegradable biomaterials is desirable for several biotechnological applications such as drug delivery, diagnostics, and medical imaging. Herein, we combine electrohydrodynamic co-jetting and highly specific surface modification (via Huisgen 1,3-dipolar cycloaddition) to prepare particles and fibers with spatioselective surface modification. We first prepared biphasic particles and fibers from commercial poly(lactide- co -glycolide) copolymers via electrohydrodynamic co-jetting of two organic solutions loaded with fluorescent macromolecules and acetylene-modified PLGA derivatives. (i) Spatially controlled reaction of poly[lactide- co -(propargyl glycolide)] with O -(2-aminoethyl)- O ′-(2-azidoethyl)heptaethylene glycol and (ii) subsequent conversion of the newly introduced amino groups with fluorescence probes resulted in particles and fibers with surface modification of one hemisphere only. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/61239/1/1655_ftp.pdf
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ABSTRACT: This paper describes partially fluorinated poly- p -xylylenes prepared by CVD polymerization. The synthesis, characterization, and surface modification of two partially fluorinated polymer coatings, namely poly(4,12-dibromo-1,1,9,9-tetrafluoro- p -xylylene) ( 2 ) and poly(4-heptadecafluorononanoyl- p -xylylene-co- p -xylylene) ( 4 ), is described. Polymer 2 is synthesized from 4,12-dibromo-1,1,9,9-tetrafluoro[2.2]paracyclophane ( 1 ), which is fluorinated at the aliphatic bridge, while 4-heptadecafluorononanoyl[2.2]paracyclophane ( 3 ), which contains a perfluorinated keto group at the aromatic ring, is used to synthesize polymer 4 . Furthermore, the keto-functionalized polymer 4 introduces both extreme hydrophobicity and surface reactivity towards hydrazide-containing ligands.
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ABSTRACT: FarbenprÄchtige SÄulen : Eine einfache und dabei skalierbare Methode zur Herstellung multikompartimentalisierter Mikrozylinder, bei denen innerer Aufbau, SeitenverhÄltnis und OberflÄche gezielt eingestellt werden kÖnnen, nutzt elektrohydrodynamisches Spinnen und Mikroabtrennen. Die Kompartimente werden mithilfe verschiedenfarbiger Farbstoffe unterschieden (siehe CLSM-Bilder; Maßstab: 10 14Μm).
