Biomimetic GNPs-interwoven photonic molecularly imprinted polymer for the colored determination of trace 17β-estradiol

A new biomimetic film was developed for the detection of 17β-estradiol (E2), drawing inspiration from the hydrophilic and hydrophobic (HI-HO) pattern of the beetle's back. The film had a non-densely packed face-centered cubic (FCC) structure of interwoven hydrophobic gold nanoparticles (GNPs) and hydrophilic poly ionic liquid methyl methacrylate (PILMMA) spheres. The film exhibited reflection (RE) and fluorescence (FL) emissions. The GNPs demonstrated a localized surface plasmon resonance effect (LSPR) and collaborated with PILMMA spheres to form a pronounced HI-HO pattern that promoted the concentration of target E2 molecules and increased sensitivity. After optimization, the film showed direct, ultrasensitive (as low as 1.5 nM), fast (11 min), and selective detection of E2 with a wide concentration range. During detection, RE and FL changes of the film were observed by the naked eye without any color display equipment. The recovery of E2 was between 87.0 % and 111.2 % in real samples.