Optimization of molecularly imprinted polymer method for rapid screening of 17β-estradiol in water by fluorescence quenching.

A new method was optimized for rapid screening of 17β-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°C to form a 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 ×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 × 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.