Ratiometric Sensing for Alkaline Phosphatase Basedon Two Independent Signals from in Situ Formed Nanohybrids of SemiconductingPolymer Nanoparticles and MnO2 Nanosheets

摘要

Ratiometric sensing systems transduced through independent analyte-sensitive response signals, which are simultaneously obtained from a single material, are highly desired to improve sensing reliability and sensitivity. In this study, a dual-model ratiometric sensing system with fluorescence and second-order light scattering (SOS) as transducing signals has been designed for the ratiometric detection of alkaline phosphatase (ALP). Semiconducting polymer nanoparticles (SPNs) made of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadiazole)] are prepared and used as reducing and stabilizing agents to prepare MnO2 nanosheets in situ through the reduction of KMnO4. The formed SPNs@MnO2 nanohybrids exhibit independent fluorescence and SOS response to ALP by using l-ascorbic acid 2-phosphate trisodium salt as the enzyme substrate. Benefiting from the simultaneous availability of fluorescence and SOS signals under the same excitation, a ratiometric probe has been constructed successfully for ALP sensing. Under optimal conditions, the SPNs@MnO2 nanohybrids for ALP detection show a good linear detection range from 0.1 to 9.0 U L^–1 with a detection limit of 0.034 U L^–1. Additionally, a visual and portable sensing device for ALP detectionis also constructed based on the fluorescent performances of the SPNs@MnO2 nanohybrids. We believe the proposed method with the in situpreparation of SPN-based hybrid probes via the reducing ability ofSPNs will pave a new way for the construction of multifunctional sensingmaterials in chemo-/biosensing applications.