Silvia Vignolini

Research and career Vignolini's research interests are on photonic structures in plants, metamaterials and photonic crystals. After graduating from her PhD, she moved to the University of Cambridge, where she worked in the laboratory of Ullrich Steiner. colour that occurs due to the interaction of light with sub-micrometer scale structures as opposed to pigmentation. Structural colour originates from multi-layered materials and surface-level diffraction gratings. Her early work investigated coloration in Pollia condensata, She has shown that it is possible to tune the colour of self-assembled block copolymer thin films by changing the molecular structure. Vignolini developed the fabrication techniques to guide the self-assembly of the rigid-rod like cellulose nanocrystals and hydroxypropyl cellulose. Cellulose nanocrystals adopt a cholesteric stack-like structure when low concentrations cellulose nanocrystals are suspended in water and left to dry. As the water starts to evaporate, the concentration of cellulose increases, which results in the formation of a cholesteric lyotropic liquid crystalline phase. In this phase the twisted configuration repeats over a distance known as the pitch. The pitch determines the colour of light reflected by the cellulose nanocrystals (larger pitches reflect lower energy, longer wavelength light). Vignolini has shown that optical uniformity and material efficiency can be optimized by drying the cellulose nanocrystal suspension in sessile droplets under a thin oil layer. She has also shown that magnetic fields can be used to manipulate the orientation of the cholesteric domains. Vignolini has studied the reflectance spectrum at a range of different angles, which provides insight into the mechanisms of the self-assembly upon solvent evaporation. Vignolini also highlighted the important role played by bundles of cellulose nanocrystals leading to their chiral arrangement in cholesteric phases.

Vignolini has used her understanding of the interaction of light with complex natural structures to understand the interaction of light and anthocyanin vacuolar inclusions. This understanding can inform the design bionic materials that can achieve outstanding photosynthetic quantum efficiencies. In 2020, she was awarded a European Research Council (ERC) consolidator grant to study how organisms create symbiotic relationships to manage interactions with light.

Selected publications Her publications Biomimetic layer-by-layer assembly of artificial nacre A 3D optical metamaterial made by self-assembly

Awards and honours She was awarded the American Chemical Society (ACS) KINGFA young investigator award and the Gibson-Fawcett Award from the Royal Society of Chemistry (RSC) in 2018.