Name:

Dr. Silvia Scarmagnani

Contact details

Qualifications

Ph. D. in Chemistry, Dublin City University (Ireland), January 2010

M. Sc., Pharmaceutical’s Chemistry and Tecnology, University of Padua (Italy), First Honours Degree (110/110), October 2006 

Project Summary

Adaptive Surfaces for Optical Sensing using Molecular Photoswitches

Photochromism and spiropyrans

The key-objective of this research project is to develop adaptive surfaces that change reversibly in response to external stimuli (photonic).

The key-molecules of this surfaces are photochromic compounds, such as spiropyran derivatives, that change their structure and their reactivity in response to electromagnetic radiation among the UV-vis range.

Photochromism is defined as the reversible interconversion of a chemical species between two states with different absorption spectra.

Spiropyrans refers in general to a (substituted) 2H-1-benzopyran having a second ring system, usually (but not necessarily) heterocyclic, attached to the 2-carbon atom of the pyran in a spiro manner with a common tetrahedral carbon atom.

The two halves of the molecule are in two orthogonal planes.

Spiropyrans exist in a closed, uncharged, inactive, non-planar and colourless “spiropyran” form (SP) (leuco dye) which is converted by exposure to ultraviolet (UV) light to an open, planar, active, highly conjugated, highly coloured “merocyanine” form (MC).

Upon irradiation, the C-O spiro bond in the SP form is cleaved heterolytically and the "spiro" carbon which was sp³-hybridized achieves sp² hybridization and becomes planar. The aromatic group rotates, aligns its π-orbitals with the rest of the molecule, and it forms the conjugated system of the morocyanine form, with ability to absorb photons of visible radiation, and therefore appear colorful. When the UV source is removed, the molecules gradually relax to their ground state, the carbon-oxygen bond renews, the spiro atom becomes sp³ again, and the molecule returns to its colorless state.

In solution the SP form presents an absorption spectrum in the UV range with an actinic band situated near 320-380 nm. The absorption in this range leads to the formation of the MC form with a maximum wavelength of the MC form between 560-570 nm. (the picture below shows the conversion between SP and MC in Ethanol solution.

The merocyanine form could also bind metal ions through a negatively charged phenolate group.

The binding results in a shift in absorbance, which correspond to a colour change (self-indicating) and the complex has a

Then, upon irradiation of the complex with visible light, the metal can be expelled and the merocyanine reverts to the original spiropyran, and this process can be repeated.

Amino acids are also potential guests thanks to their ability to form complementary zwitterionic forms. L-tryptophan, L-tyrosine and L-dopa have been demonstrated to be interesting guests for the merocyanine form.

Typically the light sources used for controlling the spiropyrans switching are high power sources such as mercury arc lamps or lasers. It has been demonstrated that the switching of spiropyran-doped polymer films could be realised by using LEDs (light emitting diodes). 

Using LEDs switch is fast and can be repeted hundreds times avoiding the formation of photodegradation products.

This provides a very flexible and low power and inexpensive alternative to induce the photochromic switching of SP avoiding photobleching.

New concept of chemical sensing

In this proposal, we will develop a new concept for chemical sensing based on the following principles:

• the sensor surface should be in an inactive or passive state when a measurement is not being conducted;
• the surface is converted into an active state under an external stimulus;
• the active surface binds with the target species and generates a signal that enables the analytical measurement to be made;
• after the measurement is completed, the target species is expelled by an external stimulus and the surface returns to its inactive form. 

Using molecular-switches based on spiropyran-like molecules, it is possible to produce surfaces whose physico-chemical properties can be controlled under an external stimulus. 

In this project, my aim is to generate smart or adaptive surfaces based on spiropyran moeities attached to a polymer substrate.

In the context of this project, we are to:

• investigate the characteristics of various spiropyran photoswitches in solution;
• immobilize the modified photoswitches on different substrates such as microspheres and polimeric films;
• characterization of modified surfaces: investigation of the optical and electrochemical properties of the immobilized photoswitches.
• evaluate the interactions of the immobilized photoswitches with various target species e.g. heavy metals and amino acids (simple amino acids, amino acids with aryl groups, amino acid mimics)

Beads Based system for Optical sensing using Spiropyran Photoswitches

On the context of generating smart adaptive surfaces based on spiropyran photochromic moieties, it has been performed a covalent immobilization of a spiropyran derivative on the surface of polystirene microspheres. The polymeric beads functionalised with spiropyran can be switched using low power light sources, such as LEDs, between a pink, active form and a white, passive form. The colour change on the microbeads correspond to the reversible interconversion of the spiropyran between a coloured, planar merocyanine form, upon irradiation with UV-LEDs (370 nm), and a colorless spiro form by exposure to white or green (525 nm) LEDs. The photochromic behaviour of the coated beads has been characterised using different LEDs, reflectance measurement and as a reference, a sample of polystirene microspheres where the spiropyran derivatives has been simply physically absorbed. Future studies will be focused on the photoswitchable retention of coated microbeads, used as a stationary phase for separations of guest species, such as metals cations or amino acids.

Publications

Peer-Reviewed Journal Articles

1. Photonic modulation of surface properties: a novel concept in chemical sensing. Radu, A.; Scarmagnani, S.; Byrne, R.; Slater, C.; Lau, K. T.; Diamond, D., Journal of Physics D: Applied Physics 2007, (23), 7238-7244.

2. Wireless Sensor Networks and Chemo-/Biosensing. Diamond, D.; Coyle, S.; Scarmagnani, S.; Hayes, J., Chem. Rev. 2008, 108, (2), 652-679.

3. Polystyrene Bead-Based System for Optical Sensing using Spiropyran Photoswitches. Scarmagnani, S.; Walsh, Z.; Slater, C.; Alhashimy, N.; Paull, B.; Macka, M.; Diamond, D., Journal of Materials Chemistry 2008, 18, 5063-5071.

4. Photoswitchable Stationary Phase based on Packed Spiropyran Functionalized Silica Microbeads. Scarmagnani, S.; Walsh, Z.; Benito-Lopez, F.; Slater, C.; Macka, M.; Paull, B.; Diamond, D., e-Journal of Surface Science and Nanotechnology 2009, 7, 649 - 652.

5. Spiropyran modified micro-fluidic chip channels as photonically controlled self-indicating system for metal ion accumulation and release. Benito-Lopez, F.; Scarmagnani, S.; Walsh, Z.; Paull, B.; Macka, M.; Diamond, D., Sensors and Actuators B: Chemical 2009, 140, (1), 295-303.

6. Spiropyran-based reversible, light-modulated sensing with reduced photofatigue. Radu, A.; Byrne, R.; Alhashimy, N.; Fusaro, M.; Scarmagnani, S.; Diamond, D., Journal of Photochemistry and Photobiology A: Chemistry 2009, 206, 109-115.

7. Delinquent Sensors & Schizophrenic Materials: Using Molecular Switches to Make Materials with multiple personalities. Byrne, R.; Scarmagnani, S.; Benito-Lopez, F.; Radu, A.; Diamond, D., Irish Chemical News - Nanotechnology edition 2009, 21, (January), 26-28.

8. Structure-activity analysis of 2'-modified cinnamaldehyde analogues as potential anticancer agents. Gan, F. F.; Chua, Y. S.; Scarmagnani, S.; Palaniappan, P.; Franks, M.; Poobalasingam, T.; Bradshaw, T. D.; Westwell, A. D.; Hagen, T., Biochemical and Biophysical Research Communications 2009, 387, (4), 741-747.

9. Photoreversible Ion-Binding using Spiropyran Modified Silica Microbeads. Scarmagnani, S.; Walsh, Z.; Paull, B.; Macka, M.; Diamond, D., International Journal of Nanomanufacturing 2010, 5, 38-52.

10. Chemical Modification of Polyaniline Nanofibres: Towards Broadening Potential Applications. Lahiff, E.; Scarmagnani, S.; Schazmann, B.; Cafolla, A.; Diamond, D., International Journal of Nanomanufacturing 2010, 5, 88-99.

11. Cinnamaldehydes inhibit thioredoxin reductase and induce Nfr2: potential candidates for cancer therapy and chemoprevention. Chew, E.-H.; Nagle, A.A.; Zhang, Y.; Scarmagnani, S.; Palaniappan, P.; Bradshaw, T.D.; Holmgren, A. and Westwell A.D., Free Radical Biology and Medicine 2010, 48, 98-111.

CONFERENCE CONTRIBUTIONS

Conference proceedings

1. Beads-based system for optical sensing using spiropyran photoswitches. Scarmagnani, S.; Walsh, Z.; Alhashimy, N.; Radu, A.; Paull, B.; Macka, M.; Diamond, D., IEEE Eng. Med. Biol. Soc., 23-26 August 2007, Lyon (France), 4096-4097.

2. Photoswitchable Surfaces: A New Approach to Chemical Sensing. Radu, A.; Scarmagnani, S.; Byrne, R.; Slater, C.; Alhashimy, N.; Diamond, D., SPIE Europe-Remote Sensing for Environmental Monitoring, 17 - 20 September 2007, Florence (Italy), pp. Z7491.

3. Schizophrenic Molecules and Materials with Multiple Personalities - How Materials Science could Revolutionise How we do Chemical Sensing. Diamond, D.; Byrne, R.; Benito-Lopez, F.; Scarmagnani, S.; Radu, A., Spring MRS Meeting, 13-17 April 2009, San Francisco (USA), DOI: 10.1557/PROC-1190-NN08-01.

Oral Presentations

1. Beads-based system for optical sensing using spiropyran photoswitches. Scarmagnani, S.; Walsh, Z.; Alhashimy, N.; Radu, A.; Paull, B.; Macka, M.; Diamond, D., IEEE Eng. Med. Biol. Soc., 23-26 August 2007, Lyon (France).

2. Photoswitchable Stationary Phase based on Packed Spiropyran Functionalized Silica Microbeads. Scarmagnani, S.; Walsh, Z.; Benito-Lopez, F.; Slater, C.; Macka, M.; Paull, B.; Diamond, D., International Symposium on Surface Science and Nanotechnology, 9-13 November 2008, Tokyo (Japan).

3. Incorporation of Photochromic Spiropyran Compounds and Spiropyran Modified Substrates into Flow Micro-systems. Scarmagnani, S.; Walsh, Z.; Benito-Lopez, F.; Abele, S.; Macka, M.; Paull, B.; Diamond, D., Analytical Research Forum, 12-15 July 2009, University of Kent, Canterbury (UK).

4. Towards the development of adaptive nanostructured platforms. Scarmagnani, S.; Lahiff, E.; Wallace, G.; Diamond, D., IUPAC, 2-7 August 2009, Glasgow, (Scotland).

5. Dye Based and Dye Functionalised Monolithic Materials for Chromatography and Electroosmotic Pumps. Walsh, Z.; Scarmagnani, S.; Norton, M.; Benito-Lopez, F.; Nie, F.-Q.; Abele, S.; Svec, F.; Diamond, D.; Paull, B.; Macka, M., IICS 2009 - International Ion Chromatography Symposium, 21-24 September 2009, Malahide, Co. Dublin (Ireland).

6. Spiropyran modified PDMS micro-fluidic chip device for photonically controlled sensor array detection of metal ions. Benito-Lopez, F.; Scarmagnani, S.; Walsh, Z.; Paull, B.; Macka, M.; Diamond, D., ICTBSB-2009 - International Conference on Trends in Bioanalytical Sciences and Biosensors, 26-28 January 2009, Dublin (Ireland).

Posters

1. Beads-Based System for Optical System using Spiropyran Phoswitches. Scarmagnani, S.; Walsh, Z.; Alhashmi, N.; Slater, C.; Lopez, F. B.; Paull, B.; Macka, M.; Diamond, D., Pittcon 2008-59th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, 2-7 March 2008, New Orleans (USA).

2. Monolithic Photochromic Stationary Phases with Light Switchable Retention. Walsh, Z.; Scarmagnani, S.; Alhashimy, N.; Connoly, D.; Abele, S.; Paull, B.; Diamond, D.; Macka, M., Analytical Research Forum, 16-18 July 2007, Glasgow (UK).

3. Eluition by Light: Photochromic Monolithic Stationary Phases with Light Switchable Retention. Walsh, Z.; Scarmagnani, S.; Alhashimy, N.; Connoly, D.; Abele, S.; Paull, B.; Diamond, D.; Macka, M., HPLC 2007, 17-21 June 2007, Ghent (Belgium).

4. Photochromic Monolithic Stationary Phases: Study of Covalent Linkage to the Underlying Monolithic Scaffold. Walsh, Z.; Scarmagnani, S.; Abele, S.; Moyna, Á.; Connolly, D.; Alhashimy, N.; Diamond, D.; Paull, B.; Macka, M., Pittcon 2008-59th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, 2-7 March 2008, New Orleans (USA).

5. Spiropyran Modified Microfluidic Chip Channels for Photonically Controlled Sensor Array Detection of Metal Ions. Benito-Lopez, F.; Scarmagnani, S.; Walsh, Z.; Paull, B.; Macka, M.; Diamond, D., CIMTEC’08, 3rd International Conference on Smart Materials, Structures and systems, 9-13 June 2008, Acireale, Sicily (Italy).

6. Spiropyran Modified Polyaniline Nanofibers. Scarmagnani, S.; Lahiff, E.; Diamond, D., ACES Electroactive Materials Symposium, 4-6 February 2009, Wollongong (Australia).

7. Photo-Controlled Electroosmotic Pumps Based on Spiropyran Polymeric Monoliths for Micro-Fluidic Devices. Walsh, Z.; Scarmagnani, S.; Benito-Lopez, F.; Abele, S.; Diamond, D.; Paull, B.; Macka, M., HPLC 2009, 28 June - 2 July 2009, Dresden (Germany).

8. Immobilisation and incorporation of photochromic spiropyran dyes in polymeric substrates for metal ion sensing and micro-fluidics. Scarmagnani, S.; Walsh, Z.; Benito-Lopez, F.; Macka, M.; Paull, B.; Diamond, D., IICS 2009 - International Ion Chromatography Symposium, 21-24 September 2009, Malahide, Co. Dublin (Ireland).

9. Vapor Phase Polymerisation of Polyaniline into spiropyran photoresponsive poly(N-isopropylacrylamide) hydrogels. Scarmagnani, S.; Lahiff, E.; Byrne R.; Dennany, L.; Little, S.; Wallace, G.; Diamond D., Pittcon 2010-61st Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, 28 February – 5 March 2010, Orlando (USA).

Further Information

Previous project

March 2006 - September 2006:

THESIS WORK (Pharmaceutical’s Chemistry and Technology Degree):

“SYNTHESIS of NOVEL DERIVATIVES of 2-HYDROXICINNAMALDEHYDE as ANTICANCER AGENTS”

Cardiff University (School of Pharmacy)

Supervisors: Dr. Andrew Westwell, Dr. Andrea Brancale