Enhanced fluorescence detection of enrofloxacin with curved-surface responsive inverse opal polymers and molecular imprinting

Abstract

Enhanced fluorescence sensing of enrofloxacin (ENR) was realized via imprinted responsive inverse opal polymers (RIOPs) by the slow photon effect. Dropropizine, as a dummy template, was adopted instead of ENR to overcome the background interference. Unlike conventional planar-surface RIOPs, curved-surface RIOPs were prepared with crystal moldings formed on the inner face of glass bottles, which showed symmetrical reflective colors perpendicular to the bottle axis. Four RIOPs were prepared, which were named as M170, M200, M220, and M240. M220 had the largest enhancement effect, with a factor of 1.68 times compared with bare ENR solution. This could be related to its better bandgap definition and a slightly large overlap with the ENR emission spectrum. Due to the imprinting effect and enhancement range of the blue band edge, M220 could selectively detect ENR without signals toward the two analogues flumequine and dropropizine. It was also found that the enhancement was most prominent at pH 5.5 in an acetonitrile-acetate ammonium buffer. After incubation with M220, higher slope for the working curve could be obtained, but with a similar detection limit. Probably, the current measurement setup produced the deviation. This study provides the verification for fluorescence enhancement of the ENR target by adsorption on the dummy template-imprinted RIOPs.