Silvia Vignolini (born 1981) is an Italian physicist who is Professor of Chemistry and Bio-materials in the

Yusuf Hamied Department of Chemistry The Yusuf Hamied Department of Chemistry is the University of Cambridge's chemistry department. It was formed from a merger in the early 1980s of two separate departments that had moved into the Lensfield Road building decades earlier: the Depar ...

at the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

. Her research investigates natural photonics structures, the

self-assembly Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. When the ...

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

and light propagation through complex structures. She was awarded the KINGFA young investigator award by the

American Chemical Society The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all ...

and the

Gibson-Fawcett Award The Gibson-Fawcett Award is awarded by the Royal Society of Chemistry every two years to recognise outstanding work in the field of materials chemistry. In particular, the emphasis is on the originality and independence of the work carried out. The ...

in 2018.

Early life and education

Vignolini was born in Italy and grew up in

Florence Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico ...

. She became interested in physics at high school, and remembers reading ''

A Brief History of Time ''A Brief History of Time: From the Big Bang to Black Holes'' is a book on theoretical cosmology by English physicist Stephen Hawking. It was first published in 1988. Hawking wrote the book for readers who had no prior knowledge of physics. I ...

'' as a teenager. She studied materials physics at the

University of Florence The University of Florence ( Italian: ''Università degli Studi di Firenze'', UniFI) is an Italian public research university located in Florence, Italy. It comprises 12 schools and has around 50,000 students enrolled. History The first univer ...

, which she graduated

summa cum laude Latin honors are a system of Latin phrases used in some colleges and universities to indicate the level of distinction with which an academic degree has been earned. The system is primarily used in the United States. It is also used in some So ...

. She remained at the University of Florence for her doctoral research, where she studied

photonic crystal A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of natural crystals gives rise to X-ray diffraction and that the ato ...

s at the European Laboratory for Non-Linear Spectroscopy supervised by Diederik Wiersma.

Research and career

Vignolini's research interests are on photonic structures in plants,

metamaterial A metamaterial (from the Greek word μετά ''meta'', meaning "beyond" or "after", and the Latin word ''materia'', meaning "matter" or "material") is any material engineered to have a property that is not found in naturally occurring materials. ...

s and

s. After graduating from her PhD, she moved to the

, where she worked in the laboratory of Ulrich Steiner. Vignolini was appointed a lecturer at

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = � ...

(UCL) in 2014, but returned to the University of Cambridge less than a year later. Vignolini's research investigates

structural coloration Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of pigments, although some structural coloration occurs in combination wi ...

. colour that occurs due to the interaction of light with sub-micrometer scale structures as opposed to

pigmentation A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

. Structural colour originates from multi-layered materials and surface-level

diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structural ...

s. Her early work investigated coloration in ''

Pollia condensata ''Pollia condensata'', sometimes called the marble berry, is a perennial herbaceous plant with stoloniferous stems and hard, dry, shiny, round, metallic blue fruit. It is found in forested regions of Africa. The blue colour of the fruit, created ...

'', a type of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...

that produces strong

iridescence Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfly ...

. The iridescence occurs due to

Bragg reflection In physics and chemistry , Bragg's law, Wulff–Bragg's condition or Laue–Bragg interference, a special case of Laue diffraction, gives the angles for coherent scattering of waves from a crystal lattice. It encompasses the superposition of wave ...

from cellulose

microfibril A microfibril is a very fine fibril, or fiber-like strand, consisting of glycoproteins and cellulose. It is usually, but not always, used as a general term in describing the structure of protein fiber, e.g. hair and sperm tail. Its most frequently ...

s. These fibrils are stacked in a helicoidal-like architecture and the total thickness of the multi-layer structure changes throughout the surface of the ''Pollia condensata'' fruits. Vignolini has also studied the bright white shell of the '' Cyphochilus'' beetle, whose scales are so thin that they scatter light incredibly efficiently. She has shown that it is possible to tune the colour of self-assembled

block copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...

thin films by changing the molecular structure. Vignoli developed the fabrication techniques to guide the self-assembly of the rigid-rod like cellulose nanocrystals and

hydroxypropyl cellulose Hydroxypropyl cellulose (HPC) is a derivative of cellulose with both water solubility and organic solubility. It is used as an excipient, and topical ophthalmic protectant and lubricant. Chemistry HPC is an ether of cellulose in which some of t ...

. Cellulose

nanocrystal A ''nanocrystal'' is a material particle having at least one dimension smaller than 100 nanometres, based on quantum dots (a nanoparticle) and composed of atoms in either a single- or poly-crystalline arrangement. The size of nanocrystals disti ...

s adopt a cholesteric stack-like structure when low concentrations cellulose nanocrystals are immersed 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 crystal Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. The ...

line 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 adding salt to the cellulose nanocrystals can result in a more compact assembly, blue-shifting the colour of light emitted. She has also shown that

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and t ...

s can be used to manipulate the orientation of the cholesteric domains. Vignolini has studied the

reflectance The reflectance of the surface of a material is its effectiveness in Reflection (physics), reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the respon ...

spectrum at a range of different angles, which provides insight into the precise molecular packing. Vignolini has used her understanding of the interaction of light with complex natural structures to understand the interaction of light and

anthocyanin Anthocyanins (), also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart gave the name Anthokyan to a chemical co ...

vacuolar inclusions. This understanding can inform the design bionic materials that can achieve outstanding

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

quantum efficiencies. In 2020, she was awarded a

European Research Council The European Research Council (ERC) is a public body for funding of scientific and technological research conducted within the European Union (EU). Established by the European Commission in 2007, the ERC is composed of an independent Scientif ...

(ERC) consolidator grant to study how organisms create symbiotic relationships to manage interactions with light.

Selected publications

Her publications include: * ''Pointillist structural color in Pollia fruit'' * ''Biomimetic layer-by-layer assembly of artificial nacre'' * ''A 3D optical metamaterial made by self-assembly''

Awards and honours

She was awarded the

(ACS) KINGFA young investigator award and the

from the

Royal Society of Chemistry The Royal Society of Chemistry (RSC) is a learned society (professional association) in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Ro ...

(RSC) in 2018.

References

{{DEFAULTSORT:Vignolini, Silvia 1981 births Italian women physicists Italian materials scientists Members of the University of Cambridge Department of Chemistry Academics of University College London University of Florence alumni Living people