Diarylethene chromophores undergo reversible ring-closing and ring-opening reactions when exposed to two different colours of light.
Ultraviolet light converts dithienylethene chromophores from colourless to coloured forms. The colour depends on the conjugation.
Mixed co-polymers of photoresponsive chromophores can be 'blended' to obtain a range of colours.
Photoresponsive polymers can be patterned when cast as thin films and exposed through mask.
It is not just the colour that changes when diarylethenes are exposed to light. Other electronic and steric properties can be modulated.
We are developing photoswitches to modulate structure-function relationships in molecules and materials. Our chromophores interconvert between two isomers when exposed to two different colours of light, each isomer having unique electronic and structural properties.
We use them to:
We take advantage of the fact that gold nanoparticles absorb green or red light and convert it to heat to break bonds in small molecules and release them from the surface of the nanoparticles. Our original studies focused on releasing fluorescent dyes and single-strands of DNA, and we have demonstrated this in live cells. We are using light to heat nanoparticles and release singlet oxygen (a known therapeutic), which has the advantage over traditional photodynamic therapy that the system brings the oxygen along with the nano-assembly and one does not have to rely on the presence and collision of molecular oxygen with the sensitizer. We are combining our photoswitches with our nanoparticles to show that two colors of light are needed to break bonds and release small molecules from the surface of the nanoparticles, providing (much like a ‘logic gate’) a heightened level of control over release processes.
We use lanthanide-doped upconverting nanoparticles (UCNPs) to convert multiple near infrared photons (again, less damaging to tissue and better penetration) into UV and visible light to trigger photochemistry on and near the surface of the nano-systems in a ‘remote control’ fashion. This approach is very general and can be used to “uncage” sequestered molecules, to trigger the dissociation of block copolymer micelles and release biomacromolecules from hydrogels. Our systems are also potentially useful as optical probes when combined with some of our photoswitches. The emission from the UCNPs can be turned on and off depending on which isomeric form the switch is in and this is effective in live organisms where the organic ligands reversibly quench the emission from the nanoparticles as a new motif for imaging technologies. We are developing advanced nano-systems where based on the power of the NIR light, either UV or visible light can be generated, which can be used for two-way photoswitching. This an illustrative example where only one nanoparticle and only one type of light are needed to induce selective photochemistry.
We are developing UCNPs that are water compatible but still allow organic photochemistry to take place. We achieve this by wrapping our UCNPs in amphiphilic polymer shells that provide nano-environments for organic species to be sequestered. This ‘plug-and-play’ strategy represents a relatively universal method to synthesize complex systems for use in imaging applications, where many photoreactions of organic compounds are suppressed (or the chromophore is simply not soluble in water).
Other materials we have investigated are:
Ph.D. – Massachusetts Institute of Technology, Cambridge, MA – Chemistry (1994)
B.Sc. – University of Toronto, Toronto, ON – Chemistry (1989)
Current Professional Positions
Professor – Department of Chemistry, Simon Fraser University (since 2004)
Canada Research Chair in Materials Science (Tier I) – Simon Fraser University (since 2006)
Executive Director – 4D LABS (since 2007)
Founder & Chief Technology Officer – SWITCH Materials, Inc. (since 2007)
Affiliated Investigator – Vancouver Coastal Health Research Institute (since 2005)
Associate Faculty Member – Department of Molecular Biology & Biochemistry, Simon Fraser University (since 2003)
Previous Professional Positions
Founder & Director – NanoCommunity Canada Research Network (2008-2013)
Director, Molecular Systems – 4D LABS (2004-2007)
Associate Professor – Department of Chemistry, Simon Fraser University (2001-2004)
Canada Research Chair in Materials Science (Tier II) – Simon Fraser University (2001-2004)
Assistant Professor – Department of Chemistry, University of Alberta (1996-2001)
NSERC Post-Doctoral Fellow – Laboratoire de Chimie Supramoleculaire, Université Louis Pasteur (1994-1996)
Awards and Honours
Canada Research Chair (Tier I) in Materials Science (2013)
Beilstein Inaugural Lecturer – Regensburg, Germany (2012)
Japan Society for the Promotion of Science Fellowship (2009)
New Journal of Chemistry Award Lecturer – Rennes, France (2008)
Canadian Who’s Who Biographee (2007)
Canada’s Top 40 Under 40 (2006)
Canada Research Chair (Tier I) in Materials Science (2006)
E.W.R. Steacie Memorial Fellowship (2005)
INNOVATEC Guest Chair – Deutscher Akademischer Austauschdienst/Universitaet Regensburg (2004)
Canada Research Chair (Tier II) in Materials Science (2001-2005)
ICNC/UPAC Travel Award (2001)
Delta Chi Teacher’s Excellence Award (2001)
Petro-Canada Young Innovators Award (2000)
Ichikizaki Award for Young Chemists (1999)
Research Innovation Award, Research Corporation (1998)
Natural Sciences and Engineering Research Council of Canada Post-Doctoral Fellowship (1994-1996)
You can view all of Neil’s publications on the 'publications' page of this web site.
Invited Book Chapters
Hamid Farmani (Iran)
John Christopher Boyer
Shirin Safaei Mohammadabadi
Tuoqi (Tony) Wu
Amir Asadirad (visit Amir’s website)
Tuoqi (Tony) Wu
Amir Samsam Bakhtiari
Solène Bechu (France)
Stéphanie Boutault (France)
Sébastien Graule (France)
Ulrich Jacquemard (France)
Prakriti Kalra (India)
Anika Kolb (Germany)
Peter Raster (Germany)
Marie Reulier (France)
Camille Rouillon (France)
Ankit Tiwari (India)
Daniel Vomasta (Germany)