Platinum (II) porphyrin-containing thermoresponsive poly(N-isopropylacrylamide) copolymer as fluorescence dual oxygen and temperature sensor

A random copolymer, poly(NIPAAm-co-PtPorphyrin), consisting of N-isopropylacrylamide (NIPAAm) and platinum (II) porphyrin units, behaves as an optical dual sensor for oxygen and temperature. The dual sensor is designed by incorporating an oxygen-sensitive platinum (II) porphyrin (M1) into a temperature-sensitive polymer (PNIPAAm). The polymer exhibited low critical solution temperature (LCST) property at 31.5 degrees C. This LCST affected the polymer's aggregation status, which in turn affected the nanostructures, fluorescence intensities, and responses to dissolved oxygen. This enables the polymer to functionalize as a dual temperature and dissolved oxygen sensor. Oxygen response of the platinum (II) porphyrin probes in the polymer followed a two-site Stern-Volmer model, indicating the nonuniform distribution of the probes. The copolymer was used to preliminarily monitor the oxygen consumption of Escherichia coli (E. coli) bacteria. The results indicate a potential application of the polymer in biological fields. (C) 2011 Elsevier B.V. All rights reserved.