The use of soft thermoresponsive polymers as thin films in medical devices and drug delivery systems is widespread. One challenge for their use in regulated medical devices is their characterisation as deposited on surfaces. Moisture uptake in polymers is a very important factor in the manufacture of thin film polymer coatings. Water ingress can have adverse effects on parameters such as long term storage, drug elution rate, and device efficacy.[1, 2] This is because water infiltration can significantly transform physicochemical properties. Therefore we need non-destructive, non-contact methods for the analysis of polymer physicochemical properties which can be implemented during manufacture such as for drug eluting polymer coatings. We are trying to develop a robust florescence method for the quantitative analysis of biomedical polymers and do this we require fluorescent probes that are both sensitive to some environmental factors (e.g. water) and are yet very photostable to allow for imaging based diagnostics. Here we explore the photophysics and photostability of a novel fluorophore, 5-propan-one-5-(N-phenylformimidoyl)-2,4,6-triphenyl-2,5-dihydro-1,2,3-triazine (PhTr), its hydrolysed form, (hTR), and a keto phenyl triazine derivative (kpTR) in thin polymer films. These 1,2,3-triazine based fluorophores have a complex tri band emission.
The emission properties of all these fluorophores (band area, full width at half maximum and band position) were relatively insensitive to water infiltration and phase changes when incorporated into Poly (N-isopropylacrylamide), PNIPAm (Fig. 1a). However, in Poly vinyl alcohol, PVA this was not the case and larger changes were observed which may be due to absorb greater amounts of water and generating an acidic microenvironment (Fig. 1b). Of the three fluorophores, pTR was the most photostable in PNIPAm (Fig. 1c) and thus was thus potentially very suitable for extended-timeframe fluorescence imaging applications, e.g. such as assessing polymer thin film quality on medical devices.
1. Morris, C., B. Szczupak, A.S. Klymchenko, and A.G. Ryder. Macromolecules, 2010. 43(22): p. 9488-9494.
2. Szczupak, B., A.G. Ryder, D.M. Togashi, A.S. Klymchenko, Y.A. Rochev, A. Gorelov, and T.J. Glynn. Journal of Fluorescence, 2010. 20(3): p. 719-731.
3. Butler, R.N., A.M. Fahy, A. Fox, J.C. Stephens, P. McArdle, D. Cunningham, and A. Ryder. The Journal of organic chemistry, 2006. 71(15): p. 5679-5687.