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Silvia Vignolini

Richard M Parker, Giulia Guidetti, Cyan A Williams, Tianheng Zhao, Aurimas Narkevicius, Silvia Vignolini, Bruno Frka-Petesic
By controlling the interaction of biological building blocks at the nanoscale, natural photonic nanostructures have been optimized to produce intense coloration. Inspired by such biological nanostructures, the possibility to design the visual appearance of a material by guiding the hierarchical self-assembly of its constituent components, ideally using natural materials, is an attractive route for rationally designed, sustainable manufacturing. Within the large variety of biological building blocks, cellulose nanocrystals are one of the most promising biosourced materials, primarily for their abundance, biocompatibility, and ability to readily organize into photonic structures...
December 18, 2017: Advanced Materials
Edwige Moyroud, Tobias Wenzel, Rox Middleton, Paula J Rudall, Hannah Banks, Alison Reed, Greg Mellers, Patrick Killoran, M Murphy Westwood, Ullrich Steiner, Silvia Vignolini, Beverley J Glover
Diverse forms of nanoscale architecture generate structural colour and perform signalling functions within and between species. Structural colour is the result of the interference of light from approximately regular periodic structures; some structural disorder is, however, inevitable in biological organisms. Is this disorder functional and subject to evolutionary selection, or is it simply an unavoidable outcome of biological developmental processes? Here we show that disordered nanostructures enable flowers to produce visual signals that are salient to bees...
October 26, 2017: Nature
Bodo D Wilts, Xiaoyuan Sheng, Mirko Holler, Ana Diaz, Manuel Guizar-Sicairos, Jörg Raabe, Robert Hoppe, Shu-Hao Liu, Richard Langford, Olimpia D Onelli, Duyu Chen, Salvatore Torquato, Ullrich Steiner, Christian G Schroer, Silvia Vignolini, Alessandro Sepe
Most studies of structural color in nature concern periodic arrays, which through the interference of light create color. The "color" white however relies on the multiple scattering of light within a randomly structured medium, which randomizes the direction and phase of incident light. Opaque white materials therefore must be much thicker than periodic structures. It is known that flying insects create "white" in extremely thin layers. This raises the question, whether evolution has optimized the wing scale morphology for white reflection at a minimum material use...
June 22, 2017: Advanced Materials
Bruno Frka-Petesic, Giulia Guidetti, Gen Kamita, Silvia Vignolini
The self-assembly of cellulose nanocrystals is a powerful method for the fabrication of biosourced photonic films with a chiral optical response. While various techniques have been exploited to tune the optical properties of such systems, the presence of external fields has yet to be reported to significantly modify their optical properties. In this work, by using small commercial magnets (≈ 0.5-1.2 T) the orientation of the cholesteric domains is enabled to tune in suspension as they assemble into films...
August 2017: Advanced Materials
Olimpia D Onelli, Thomas van de Kamp, Jeremy N Skepper, Janet Powell, Tomy Dos Santos Rolo, Tilo Baumbach, Silvia Vignolini
Structural colours in living organisms have been observed and analysed in a large number of species, however the study of how the micro- and nano-scopic natural structures responsible of such colourations develop has been largely ignored. Understanding the interplay between chemical composition, structural morphology on multiple length scales, and mechanical constraints requires a range of investigation tools able to capture the different aspects of natural hierarchical architectures. Here, we report a developmental study of the most widespread strategy for structural colouration in nature: the cuticular multilayer...
May 2, 2017: Scientific Reports
Silvia Vignolini, Thomas Gregory, Mathias Kolle, Alfie Lethbridge, Edwige Moyroud, Ullrich Steiner, Beverley J Glover, Peter Vukusic, Paula J Rudall
The bright and intense blue-green coloration of the fruits of Margaritaria nobilis (Phyllanthaceae) was investigated using polarization-resolved spectroscopy and transmission electron microscopy. Optical measurements of freshly collected fruits revealed a strong circularly polarized reflection of the fruit that originates from a cellulose helicoidal cell wall structure in the pericarp cells. Hyperspectral microscopy was used to capture the iridescent effect at the single-cell level.
November 2016: Journal of the Royal Society, Interface
Soraya Caixeiro, Matilda Peruzzo, Olimpia D Onelli, Silvia Vignolini, Riccardo Sapienza
Cellulose is the most abundant biopolymer on Earth. Cellulose fibers, such as the one extracted form cotton or woodpulp, have been used by humankind for hundreds of years to make textiles and paper. Here we show how, by engineering light-matter interaction, we can optimize light scattering using exclusively cellulose nanocrystals. The produced material is sustainable, biocompatible, and when compared to ordinary microfiber-based paper, it shows enhanced scattering strength (×4), yielding a transport mean free path as low as 3...
March 8, 2017: ACS Applied Materials & Interfaces
Radwanul Hasan Siddique, Silvia Vignolini, Carolin Bartels, Irene Wacker, Hendrik Hölscher
The butterfly genus Hypolimnas features iridescent blue colouration in some areas of its dorsal wings. Here, we analyse the mechanisms responsible for such colouration on the dorsal wings of Hypolimnas salmacis and experimentally demonstrate that the lower thin lamina in the white cover scales causes the blue iridescence. This outcome contradicts other studies reporting that the radiant blue in Hypolimnas butterflies is caused by complex ridge-lamellar architectures in the upper lamina of the cover scales. Our comprehensive optical study supported by numerical calculation however shows that scale stacking primarily induces the observed colour appearance of Hypolimnas salmacis...
November 2, 2016: Scientific Reports
André Espinha, Giulia Guidetti, María C Serrano, Bruno Frka-Petesic, Ahu Gümrah Dumanli, Wadood Y Hamad, Álvaro Blanco, Cefe López, Silvia Vignolini
Biopolymer-based composites enable to combine different functionalities using renewable materials and cost-effective routes. Here we fabricate novel thermoresponsive photonic films combining cellulose nanocrystals (CNCs) with a polydiolcitrate elastomer exhibiting shape memory properties, known as hydroxyl-dominant poly(dodecanediol-co-citrate) (PDDC-HD). Iridescent films of CNCs are first made by evaporation-induced self-assembly, then embedded in the PDDC-HD prepolymer, and finally cured to obtain a cross-linked composite with shape memory properties...
November 23, 2016: ACS Applied Materials & Interfaces
Giulia Guidetti, Siham Atifi, Silvia Vignolini, Wadood Y Hamad
The fabrication of self-assembled cellulose nanocrystal (CNC) films of tunable photonic and mechanical properties using a facile, green approach is demonstrated. The combination of tunable flexibility and iridescence can dramatically expand CNC coating and film barrier capabilities for paints and coating applications, sustainable consumer packaging products, as well as effective templates for photonic and optoelectronic materials and structures.
December 2016: Advanced Materials
Richard M Parker, Bruno Frka-Petesic, Giulia Guidetti, Gen Kamita, Gioele Consani, Chris Abell, Silvia Vignolini
Complex hierarchical architectures are ubiquitous in nature. By designing and controlling the interaction between elementary building blocks, nature is able to optimize a large variety of materials with multiple functionalities. Such control is, however, extremely challenging in man-made materials, due to the difficulties in controlling their interaction at different length scales simultaneously. Here, hierarchical cholesteric architectures are obtained by the self-assembly of cellulose nanocrystals within shrinking, micron-sized aqueous droplets...
September 27, 2016: ACS Nano
Chris J Chandler, Bodo D Wilts, Silvia Vignolini, Juliet Brodie, Ullrich Steiner, Paula J Rudall, Beverley J Glover, Thomas Gregory, Rachel H Walker
The marine world is incredibly rich in brilliant and intense colours. Photonic structures are found in many different species and provide extremely complex optical responses that cannot be achieved solely by pigments. In this study we examine the cuticular structure of the red alga Chondrus crispus (Irish Moss) using anatomical and optical approaches. We experimentally measure the optical response of the multilayer structure in the cuticle. Using finite-difference time-domain modelling, we demonstrate conclusively for the first time that the dimensions and organisation of lamellae are responsible for the blue structural colouration on the surface of the fronds...
July 3, 2015: Scientific Reports
Morgan Stefik, Stefan Guldin, Silvia Vignolini, Ulrich Wiesner, Ullrich Steiner
The ability to control and modulate the interaction of light with matter is crucial to achieve desired optical properties including reflection, transmission, and selective polarization. Photonic materials rely upon precise control over the composition and morphology to establish periodic interactions with light on the wavelength and sub-wavelength length scales. Supramolecular assembly provides a natural solution allowing the encoding of a desired 3D architecture into the chemical building blocks and assembly conditions...
August 7, 2015: Chemical Society Reviews
Matteo Burresi, Lorenzo Cortese, Lorenzo Pattelli, Mathias Kolle, Peter Vukusic, Diederik S Wiersma, Ullrich Steiner, Silvia Vignolini
No abstract text is available yet for this article.
2014: Scientific Reports
Stefano Salvatore, Silvia Vignolini, Julian Philpott, Morgan Stefik, Ulrich Wiesner, Jeremy J Baumberg, Ullrich Steiner
Polymer self-assembly of a 3D continuous gyroid morphology was replicated into a network consisting of hollow gold struts. This was achieved by first replicating a gyroid structured film into nickel. The Ni network was employed as an electrode for electrochemical Au deposition, followed by the removal of Ni. The resulting hollow network of plasmonic gold exhibited a substantial optical transmission enhancement by a factor of nearly 3, compared to a network of full Au struts. The overall transmission across the hollow wave-guide morphology depends sensitively on the wall-thickness of the hollow struts down to 1 nm...
January 21, 2015: Nanoscale
Matteo Burresi, Lorenzo Cortese, Lorenzo Pattelli, Mathias Kolle, Peter Vukusic, Diederik S Wiersma, Ullrich Steiner, Silvia Vignolini
Whiteness arises from diffuse and broadband reflection of light typically achieved through optical scattering in randomly structured media. In contrast to structural colour due to coherent scattering, white appearance generally requires a relatively thick system comprising randomly positioned high refractive-index scattering centres. Here, we show that the exceptionally bright white appearance of Cyphochilus and Lepidiota stigma beetles arises from a remarkably optimised anisotropy of intra-scale chitin networks, which act as a dense scattering media...
August 15, 2014: Scientific Reports
Silvia Vignolini, Edwige Moyroud, Thomas Hingant, Hannah Banks, Paula J Rudall, Ullrich Steiner, Beverley J Glover
Living organisms can use minute structures to manipulate the reflection of light and display colours based on interference. There has been debate in recent literature over whether the diffractive optical effects produced by epoxy replicas of petals with folded cuticles persist and induce iridescence in the original flowers when the effects of petal pigment and illumination are taken into account. We explored the optical properties of the petal of Hibiscus trionum by macro-imaging, scanning and transmission electron microscopy, and visible and ultraviolet (UV) angle-resolved spectroscopy of the petal...
January 2015: New Phytologist
Ahu Gümrah Dumanli, Hanne M van der Kooij, Gen Kamita, Erwin Reisner, Jeremy J Baumberg, Ullrich Steiner, Silvia Vignolini
Cellulose nanocrystals (CNCs) form chiral nematic phases in aqueous suspensions that can be preserved upon evaporation of water. The resulting films show an intense directional coloration determined by their microstructure. Here, microreflection experiments correlated with analysis of the helicoidal nanostructure of the films reveal that the iridescent colors and the ordering of the individual nematic layers are strongly dependent on the polydispersity of the size distribution of the CNCs. We show how this affects the self-assembly process, and hence multidomain color formation in such bioinspired structural films...
August 13, 2014: ACS Applied Materials & Interfaces
Francesco Riboli, Niccolò Caselli, Silvia Vignolini, Francesca Intonti, Kevin Vynck, Pierre Barthelemy, Annamaria Gerardino, Laurent Balet, Lianhe H Li, Andrea Fiore, Massimo Gurioli, Diederik S Wiersma
Disordered photonic materials can diffuse and localize light through random multiple scattering, offering opportunities to study mesoscopic phenomena, control light-matter interactions, and provide new strategies for photonic applications. Light transport in such media is governed by photonic modes characterized by resonances with finite spectral width and spatial extent. Considerable steps have been made recently towards control over the transport using wavefront shaping techniques. The selective engineering of individual modes, however, has been addressed only theoretically...
July 2014: Nature Materials
Silvia Vignolini, Edwige Moyroud, Beverley J Glover, Ullrich Steiner
The outer layers of a range of plant tissues, including flower petals, leaves and fruits, exhibit an intriguing variation of microscopic structures. Some of these structures include ordered periodic multilayers and diffraction gratings that give rise to interesting optical appearances. The colour arising from such structures is generally brighter than pigment-based colour. Here, we describe the main types of photonic structures found in plants and discuss the experimental approaches that can be used to analyse them...
October 6, 2013: Journal of the Royal Society, Interface
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