10 August 2016:
Researchers from the CNBP have published a paper representing the first major study of the stability and compatibility of the major classes of photochromic compounds within the microstructured optical fibre (MOF) environment.
In developing light-responsive surfaces, investigators face several challenges, not only in achieving high photostationary states and fully reversible switching, but also in fluorescence properties and fatigue resistance upon continuous exposure to high intensity light. However, information on the latter two are often lacking as studies on photochromic compounds are often focused on photoswitching, or absorbance and colour changes. To address this gap in literature, the fluorescence and photostability of four major types of photochromic molecules (azobenzene, spiropyran, indolyfulgide and diarylalkene) when dissolved in DMSO, or acetonitrile, or adsorbed to a MOF silica surface were investigated.
Journal: Sensors and Actuators B: Chemical.
Publication title: A Comparative Study of the Fluorescence and Photostability of Common Photoswitches in Microstructured Optical Fibre.
Authors: Daniel B. Stubing (pictured top left), Sabrina Heng, Tanya M. Monro and Andrew D. Abell.
Abstract: The fluorescence spectra and photostability under 532 nm laser excitation of four different common photoswitches (an azobenzene, spiropyran, indolylfulgide, and a diarylperfluorocyclopentene) were investigated in a silica microstructured optical fibre. An example of each photoswitch was examined in solution and physically adsorbed to the silica fibre surface. This comparison was made to define fluorescence behaviour in these two states and to determine which photoswitch has the best performance in this light intense microenvironment. The azobenzene and the spiropyran switches demonstrated the strongest fluorescence response and the least degradation of the fluorescence signal.
The paper is available online.
21 March 2016:
CNBP researchers Daniel Stubing, Sabrina Heng and Andrew Abell recently published a full paper in the journal ‘Organic and Biomolecular Chemistry’.
The published work presents three new spiropyran photoswitchable sensors and compares their sensitivity to different monovalent metal ions to develop a new reversible lithium ion sensor. These sensing molecules are now able to be further used to create optical devices for the sensing of biological lithium ions, which could help further understanding and treatment of neurological diseases such as manic-depressive illness.
Title: Crowned spiropyran fluoroionophores with a carboxyl moiety for the selective detection of lithium ions
Authors: D. B. Stubing, S. Heng and A. D. Abell
Abstract: The absorbance and fluorescence spectra of carboxylated spiropyrans containing methyl-1-aza-12-crown-4, methyl-1-aza-15-crown-5, methyl-1-aza-18-crown-6 moieties are compared. Characteristic changes in spectra after addition of the alkali metal salts of Li+, Na+, K+ and Cs+ were observed. Chromism induced by the binding of the metal cations was observed as an increase in absorbance and fluorescence. Of these metal cations, the Li+ ion produced the largest change in all three spiropyran systems. Reversible photoswitching of the spiropyran-metal complexes was observed on irradiation with alternating 352 nm UV and white light. This results in reversible fluorescence based sensing of lithium ions with potential for use in a biological sensor device.
The paper is accessible online.
7 February 2016:
CNBP researchers Peipei Jia (pictured), Philipp Reineck, Ivan Maksymov, Sabrina Heng and Daniel Stubing all attended the International Conference on Nanoscience and Nanotechnology (ICONN), in Canberra (7-11 February 2016).
Peipei Jia, CNBP Research Fellow, presented an invited talk on the topic ‘Large-area Gold Nanomembrane by Template Transfer with a Soluble Polymer’.
Philipp presented a poster on the nanoparticle comparison project, Daniel presented a poster titled “Reversible Ion Sensing With a Flip of a Switch”, while Ivan gave an oral talk on “Photoacoustic nanoantennae for intravascular imaging.”
Sabrina’s poster presentation was titled, “Microstructured Optical Fibers and Photoswitches: Light-Driven Sensors for Metal Ions.”
The event covered the areas of nanostructure growth, synthesis, fabrication, characterization, device design, theory, modeling, testing, applications, commercialisation, and health and safety aspects of nanotechnology.
Further information on the conference is available online.
8 January 2015: Adelaide seminar series
CNBP ECRs Michelle Zhang, Daniel Stubing and Malcolm Purdey delivered short presentations about this work on photo switches and chemical sensors as part of the IPAS Seminar series.
7 December 2014: Poster Presentation
Daniel Stubing presented a poster the RACI National congress in Adelaide (7-12 December 2014).
Several other CNBP chemists attended the congress including PhD student Mr Malcolm Purdy.
13 December 2014: Poster Presentation at upcoming conference
Daniel Stubing presented a poster at the 22nd annual RACI Research and Development Topics Conference, 2014 held at Flinders University between the 13th and 15th December.