My research interest focuses on using cellulose as a new platform to develop cheap and sustainable bio-inspired optical materials. Replicating cellulose-based architectures is, in fact, extremely interesting to understand how plants assemble these structures in the cell wall. Moreover, it equips us to fabricate novel photonic structures using low cost materials in ambient conditions.
Selected Publications
[1] S. Vignolini et al. J. R. Soc. Int 10, 20130394, (2013). Analysing photonic structures in plants
[2] S. Vignolini et al. PNAS 109, 15712–15715, (2012). Pointillist structural colour in Pollia fruit
[3] S. Vignolini et al. J. R. Soc. Int 9, 1295 (2012). Directional scattering from Ranunculus acris: how the buttercup lights up your chin
[4] S. Vignolini et al. Adv. Mat. 24, OP23–OP27, (2012). A 3D Optical Metamaterial Made by Self-Assembly
[5] S. N. Fernandes, Y. Geng, S. Vignolini et al. accepted in Macromol. Chem. & Phys. 1, 25 (2013). Structural color and iridescence in transparent sheared cellulosic films
Colour in nature is everywhere: animals and plants develop structures on sub-micrometer scale to manipulate light and to obtain brilliant and iridescent colours. This kind of colouration, named structural since it is not obtained using pigmentation, results from various mechanisms, including multilayered materials, crystalline inclusions and surface diffraction gratings. Pollia condensata fruits are one of the most striking examples of strong iridescent colouration in plants. The colour is caused by Bragg-reflection of helicoidally stacked cellulose microfibrils, which form multilayers in the cell walls of the epicarp. The bright blue colour of this fruit is more intense than that of many previously described biological materials. Uniquely in nature, the reflected colour differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or ’pointillist’ appearance.
PNAS 109, 15712–15715, (2012)
Silvia Vignolini has been appointed in 2013 as a Lecturer in the Chemistry Department in Cambridge. Her research is focused on the light interaction with complex nanostructures. Between 2010-2013 she worked as a Research Associate with Prof. Ullrich Steiner and Jeremy Baumberg at the Cavendish Laboratory in Cambridge on photonic structures in plants. During her PhD studies (completed 2009) with Prof. Diederik Wiersma at the European Laboratory for Non-Linear Spectroscopy in Florence Italy, she worked with nano-photonic materials ranging from photonic crystals to complex photonic structures.
BBSRC David Phillips fellowship
Biological photonic structures, optimized over millennia by the rigorous process of evolution, can provide broad inspiration for novel artificial and multifunctional photonic materials. The most brilliant and striking colours in nature are in fact obtained without the use of any pigments, but by nano-structuring transparent materials: for example, colour in plants can be obtained using only cellulose. By periodically arranging cellulose nano-fibres in the cell wall, different plant species obtain incredibly vivid colours across the entire visible spectrum, from the deepest violet to the most intense red. This fellowship allows us to study how cellulose can be use as a new photonic material. In particular, it gives us the possibility to fabricate structures ranging from photonic crystals to completely random structures, providing materials with strong colouration and ultra-white response, respectively. Such materials will find uses in everyday life. As an example, edible cellulose-based nanostructures with structural colour can be use to substitute toxic dyes and colorants in food. Moreover, mimicking natural photonic structures using the same materials that are involved in Nature, unveils information regarding the mysterious processes of the natural development of plant cells.