Fluorescence nanoplatform based on conjugated polymer nanoparticles-transition metal hydroxide composite for the detection of Butyrylcholinease

Abstract

Butyrylcholinesterase (BChE) as a valuable biochemical indicator could evaluate liver's function in clinical diagnosis by blood. The traditional Ellman colorimetric method needs enzymatic cascades and additional substances, which greatly limits its practical application. The fluorescence strategy was broadly applied because of great selectivity, sensitivity and convenience. Here, a novel fluorescence sensing platform was built by internal filtering effect (IFE) based on conjugated polymer nanoparticles (CPNsPBOC-COOH) and transition metal hydroxides (MOOH) for the detection of BChE. In order to get an optimized detection platform, three different MOOH (FeOOH/ CoOOH/ NiOOH) were selected, and their preparation conditions, water solubility, the morphology, the absorption and the fluorescence quenching efficiency were investigated. The results showed FeOOH preparated at 120°C for 4 h have the better water solubility and size uniform, the broad absorption and the high quenching efficiency of 95.3%. At the same time, the fluorescence platform of CPNsPBOC-COOH@FeOOH is highly selective with lower interference. So the optimized fluorescence detection platform of CPNsPBOC-COOH@FeOOH (CCPNsPBOC-COOH =1 µg·mL−1, CFeOOH =60 µg·mL−1) was selected and obtained. Furthermore, the fluorescence platform of CPNsPBOC-COOH@FeOOH has a detection range of 0.02∼2.6 µg·mL−1 and a very low detection limit of 3.5 ng·mL−1, showing it very sensitive for the BChE. The determination of BChE in human serum and plasma was applied using this detection technology, and the result was satisfactory. At the same time, the detection mechanism was explored. The result data indicate that FeOOH is decomposed by thiocholine (TCh), an enzymatic digestion product from acetylcholine (ATCh) hydrolyzed by BChE, and then the fluorescence of CPNsPBOC-COOH@FeOOH platform is recovered. The Fe2+ in products can be verified by specifically reacting with [Fe (CN)6]3−.