Aqueous polyfluorene probe for the detection and estimation of Fe3+ and inorganic phosphate in blood serum

A novel anionic polyfluorene derivative, poly(9,9-bis(6'-sulfate)hexyl)fluorene-alt-1,4-phenylene sodium salt (P1) is synthesized. P1 exhibits exemplary activity towards the selective detection of Fe3+ and phosphates (P-i) under physiological conditions. On binding to Fe3+, exceptional fluorescence quenching of P1 occurred, demonstrated by a >97% reduction in the fluorescence intensity. Furthermore, the P1-Fe3+ assay is highly selective for inorganic phosphate (P-i) anions at biological pH values, observed by complete fluorescence dequenching and confirmed through a >95% fluorescence enhancement. In order to validate its diagnostic potential, this assay was employed to monitor the P-i levels in a competing biological environment like blood serum. At pH 7.4 this assay showed a high specific activity to detect P-i in the bioassay environment, observed by the unique enhancements in fluorescence intensities for varying and low P-i concentrations. Since this assay performed P-i detection at very low concentrations we utilized it successfully for the fluorometric estimation of P-i in blood serum with high accuracy and within short duration. This remarkable ability of P1 to accomplish in situ monitoring and estimation of indispensable biological targets like Fe3+ and P-i rapidly and in label-free conditions, corroborates the extension of this assay system for clinical application.