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Spontaneous shape reconfigurations in multicompartmental microcylinders.

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.

SUBMITTER: Lee KJ

PROVIDER: S-EPMC3479567 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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Spontaneous shape reconfigurations in multicompartmental microcylinders.

Lee Kyung Jin KJ Yoon Jaewon J Rahmani Sahar S Hwang Sangyeul S Bhaskar Srijanani S Mitragotri Samir S Lahann Joerg J

Proceedings of the National Academy of Sciences of the United States of America 20120919 40

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 ...[more]

PMID: 22992652

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Project description:Successful periodontal repair and regeneration requires the coordinated responses from soft and hard tissues as well as the soft tissue-to-bone interfaces. Inspired by the hierarchical structure of native periodontal tissues, tissue engineering technology provides unique opportunities to coordinate multiple cell types into scaffolds that mimic the natural periodontal structure in vitro. In this study, we designed and fabricated highly ordered multicompartmental scaffolds by melt electrowriting, an advanced 3-dimensional (3D) printing technique. This strategy attempted to mimic the characteristic periodontal microenvironment through multicompartmental constructs comprising 3 tissue-specific regions: 1) a bone compartment with dense mesh structure, 2) a ligament compartment mimicking the highly aligned periodontal ligaments (PDLs), and 3) a transition region that bridges the bone and ligament, a critical feature that differentiates this system from mono- or bicompartmental alternatives. The multicompartmental constructs successfully achieved coordinated proliferation and differentiation of multiple cell types in vitro within short time, including both ligamentous- and bone-derived cells. Long-term 3D coculture of primary human osteoblasts and PDL fibroblasts led to a mineral gradient from calcified to uncalcified regions with PDL-like insertions within the transition region, an effect that is challenging to achieve with mono- or bicompartmental platforms. This process effectively recapitulates the key feature of interfacial tissues in periodontium. Collectively, this tissue-engineered approach offers a fundament for engineering periodontal tissue constructs with characteristic 3D microenvironments similar to native tissues. This multicompartmental 3D printing approach is also highly compatible with the design of next-generation scaffolds, with both highly adjustable compartmentalization properties and patient-specific shapes, for multitissue engineering in complex periodontal defects.

Project description:BackgroundTrauma is associated with widespread inflammation, neuroendocrine activation, and an inadequate bone marrow response to anemia. During late-stage erythropoiesis, erythroid progenitors/erythroblasts form clusters on the surface of specialized bone marrow macrophages where they are supported through terminal differentiation and enucleation. We hypothesized that these erythroblastic islands (EBIs) are adversely impacted by severe trauma.MethodsMale Sprague-Dawley rats (n = 8/group) were subjected to either multiple injuries (PT) (lung contusion, hemorrhagic shock, cecectomy, and bifemoral pseudofractures), PT plus 2 hours of daily chronic restraint stress (PT/CS), or naive controls. Bone marrow was harvested on days 2 and 7. Nuclear-stained, enriched bone marrow EBIs were fixed and stained for CD71, VCAM-1, and CD163, and confocal images were obtained at 20 times magnification. Numbers of erythroid cells/EBI and ratio of reticulocytes/EBI were counted by a blinded observer. Differences were compared using analysis of variance, with significance defined as p < 0.05.ResultsPT and PT/CS had significantly reduced numbers of erythroid cells per EBI on day 2 when compared with naive (PT: 5.9 ± 1.0 cells [ p < 0.05], PT/CS: 6.8 ± 0.8 cells [ p < 0.05] vs. naive: 8.5 ± 0.8 cells). On day 7, the number of erythroid cells/EBI increased following PT (8.3 ± 0.4 cells) but remained reduced following PT/CS (5.9 ± 0.5 cells [ p < 0.05]). This correlated with an increased proportion of reticulocytes/EBI on day 7 following PT, which was not present following PT/CS (PT: 54% [ p < 0.05] vs. PT/CS: 28%).ConclusionLate-stage erythropoiesis was altered following multicompartmental PT early after injury, and these alterations persisted with the addition of daily chronic stress. Alterations in EBI structure and function after severe trauma and critical illness may serve as a promising new area of study to improve mechanistic understanding of persistent anemia after trauma.

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Spontaneous shape reconfigurations in multicompartmental microcylinders.

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Spontaneous shape reconfigurations in multicompartmental microcylinders.

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