Optimization of Molecularly Imprinted Polymer Method for Rapid Screening of 17 beta-Estradiol in Water by Fluorescence Quenching

A new method was optimized for rapid screening of 17 beta-estradiol (E2) in water under 10 min. Molecularly imprinted polymer (MIP) particles (325 +/- 25 nm) were added in a water sample at pH 5.5 and 20 degrees C to forma suspension. Fluorescence emission from E2 nonspecifically bound onto the MIP particles was first quenched by large gold nanoparticles (43 +/- 5 nm). The Stern-Volmer plot was linear, with dynamic quenching constants (K-sv) of 2.9 x 10(4) M-1. Fluorescence emission from E2 specifically bound inside the MIP particles was next quenched by small nitrite anions that easily penetrated the imprinted cavities. The Stern-Volmer plot became nonlinear, with K-sv = 2.1 x 10(2) M-1 and static quenching constant (V) below 1.0 M-1. The difference between these two emission intensities varied as the initial E2 concentration in water, generating a Scatchard calibration curve with R-2 > 0.97 from 0.1 to 10 ppb.