Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2011-10-21
    Description: In nature, helical macromolecules such as collagen, chitin and cellulose are critical to the morphogenesis and functionality of various hierarchically structured materials. During tissue formation, these chiral macromolecules are secreted and undergo self-templating assembly, a process whereby multiple kinetic factors influence the assembly of the incoming building blocks to produce non-equilibrium structures. A single macromolecule can form diverse functional structures when self-templated under different conditions. Collagen type I, for instance, forms transparent corneal tissues from orthogonally aligned nematic fibres, distinctively coloured skin tissues from cholesteric phase fibre bundles, and mineralized tissues from hierarchically organized fibres. Nature's self-templated materials surpass the functional and structural complexity achievable by current top-down and bottom-up fabrication methods. However, self-templating has not been thoroughly explored for engineering synthetic materials. Here we demonstrate the biomimetic, self-templating assembly of chiral colloidal particles (M13 phage) into functional materials. A single-step process produces long-range-ordered, supramolecular films showing multiple levels of hierarchical organization and helical twist. Three distinct supramolecular structures are created by this approach: nematic orthogonal twists, cholesteric helical ribbons and smectic helicolidal nanofilaments. Both chiral liquid crystalline phase transitions and competing interfacial forces at the interface are found to be critical factors in determining the morphology of the templated structures during assembly. The resulting materials show distinctive optical and photonic properties, functioning as chiral reflector/filters and structural colour matrices. In addition, M13 phages with genetically incorporated bioactive peptide ligands direct both soft and hard tissue growth in a hierarchically organized manner. Our assembly approach provides insight into the complexities of hierarchical assembly in nature and could be expanded to other chiral molecules to engineer sophisticated functional helical-twisted structures.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chung, Woo-Jae -- Oh, Jin-Woo -- Kwak, Kyungwon -- Lee, Byung Yang -- Meyer, Joel -- Wang, Eddie -- Hexemer, Alexander -- Lee, Seung-Wuk -- R21DE018360/DE/NIDCR NIH HHS/ -- England -- Nature. 2011 Oct 19;478(7369):364-8. doi: 10.1038/nature10513.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioengineering, University of California, Berkeley, California 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22012394" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacteriophage M13/chemistry/*physiology ; Biomimetic Materials/chemical synthesis/*chemistry ; Cell Line ; Macromolecular Substances/chemistry ; Mice ; Optical Rotation ; Tissue Culture Techniques/instrumentation ; Virion/chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Bronchial asthma is characterized by airway inflammation, which underlies the phenomenon of bronchial hyperresponsiveness. The concentration of serum haploglobin (Hp), one of the acute phase reactant proteins, has been reported to correlate with bronchial hyperresponsiveness. The extent to which bronchoconstriction or airway inflammation contributes to airflow obstruction of exacerbation is presumed to determine the responsiveness to the initial bronchodilator therapy.Objective To see whether the Hp levels vary with the disease status of asthma, and also to test whether the Hp level at an acute exacerbation(AE) is correlated with the degree of response to initial bronchodilator therapy.Methods We measured serum Hp levels in 50 children with asthma at the times of an AE and a clinical remission(CR), and analysed the data according to the response to the initial bronchodilator therapy at AE.Results The serum concentration of Hp at AE (228.5 ± 80.8mg/dl, mean ± SD) was significantly (P 〈 0.01) higher than that at CR (152.3 ± 49.8mg/dl) in the total study population. The difference of Hp levels between AE and CR was more marked (101.7 ± 82.2 mg/dl) in the subjects (n= 19) who responded poorly (post-bronchodi-lator FEV1 〈 75% predicted) to the initial bronehodilator therapy at AE than that (61.0 ± 56.5mg/dl) of those (n= 31) who responded well (post-bronchodilator FEV1± 75% predicted). The Hp level at AE eorrelated with the degree of response to initial bronchodilator therapy (r=−0.36, P 〈 0.05), whereas it had no relationship with the severity of exacerbation (r= 0.04. P= 0.79).Conclusion Our results showed that Hp levels may be increased al ihe time of exacerbation in a given asthma patient. The finding that the elevation of Hp level at AE is more marked in the cases with poor response to initial bronchodilaior therapy at AE suggests that the increased Hp level at AE in asthma might relied the degree of airway inflammation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study aimed to determine whether a preceding airway response to one allergen leads to priming of the airway responses to another allergen. Twelve asthmatic children who had positive prick tests to two allergens, Dermatophagoides pteronyssinus (D.p.) and German cockroach (CR), participated in a randomized, placebo-controlled crossover study. We performed two consecutive inhalation challenges, D.p. challenge being followed 48 h later by CR challenge. The effect of initial (D.p.) challenge on the early and late airway responses to the subsequent (CR) challenge (CR2) was examined by comparing the responses with those to CR challenge preceded by sham challenge (CR1). The geometric mean PD20 of CR allergen in the CR2 was 2.8 BU (breath unit) (range of 1 SD; 0.77-10.4), which was 12.0-fold less than that (33.7 BU, 10.8-105.2) in the CR1. The administration of a 6.1–fold less dose (8.9 BU, 2.7-28.8) in the CR2 than hi the CR1 (54.5 BU, 44.1-69.3) provoked a similar degree of late-phase reactions (18.7±7.3% vs 15.8 ± 9.6%). Our data indicated that the early- and late-phase reactions to CR challenge were augmented by the preceding reaction to D.p. This suggests that a preceding airway response to one allergen may lead to priming, with enhancement of the early and late airway responses to the subsequent challenge with another allergen.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...