CNBP researcher Roman Kostecki presented his latest research paper at the 8th International Conference on Materials for Advanced Technologies (ICMAT2015). The conference, twinned with the 4th Photonics Global Conference took place in Singapore 28 June – 3 July 2015.
The paper, titled “Thin-film Polymer Functionalization of Optical Fiber Enabling Multiligand Chemosensing” was published with an author list consisting of Roman KOSTECKI, Sabrina HENG, Heike EBENDORFF-HEIDEPRIEM, Andrew ABELL, and Tanya MONRO.
Silica exposed-core microstructured optical fibers (EC-MOFs) are a platform for distributed, in situ, and/or remote sensors based on fluorescence. The portion of light guided outside of the glass core, often described as ‘evanescent field’, is affected by the refractive index and absorption characteristics of the surrounding medium. This light-matter overlap provides opportunities for fluorometric measurements of the composition and concentration of an analyte along the fiber length. Functionalizing the core with a chemosensor removes the need for chemosensor/analyte premixing. Detection of aluminum cations (Al) is of particular interest as a means to monitor corrosion, human health and the environment.
We demonstrate the first example of a photo-switchable chemosensor for Al detection using a modified photochromic spiropyran (SP-I), which is appended to an ionophore for cation binding. Photochemical switching of the spiropyran allows ion binding to be switched on and off, creating a multiple use chemosensor. The SP-I sensor binds Al or calcium cations as multi- or single-ligand complexes respectively, and was modified for surface attachment. Silane- or polyelectrolyte-based methodology allows subsequent attachment of the SP-I to a glass surface. Studies with the dual ion binding SP-I integrated with the EC-MOF sensing platform provide evidence that covalent attachment is ineffective, where multiligand binding chemosensors are needed. Functionalizing EC-MOFs with a thin-film (50 nm) polymer doped with SP-I demonstrates capacity to use both multi- and single-ligand binding chemosensors. This demonstrates that the integration of photo-switchable chemosensor, thin-film polymer, and silica optical fiber elements creates a sensor capable of multiligand chemosensing anywhere along the fiber’s length. The work demonstrates a new pathway to next generation reusable and continuous operation ion sensing platforms, and that the local molecular environment of a chemosensor affects its function which can be used to control how metal ions interact with chemosensors.