Point-of-care testing of butyrylcholinesterase activity through modulating the photothermal effect of cuprous oxide nanoparticles

Integrated in silico and experimental discovery of trimeric peptide ligands targeting Butyrylcholinesterase

Butyrylcholinesterase (BChE) is recognized as a high value biotherapeutic in the treatment of Alzheimer's disease and drug addiction. This study presents the rational design and screening of an in-silico library of trimeric peptides against BChE and the experimental characterization of peptide ligands for purification. The selected peptides consistently afforded high BChE recovery (> 90 %) and purity, yielding up to a 1000-fold purification factor. This study revealed a marked anti-correlated conformational movement governed by the ionic strength and pH of the aqueous environment, which ultimately controls BChE binding and release during chromatographic purification; and highlighted the role of residues within and allosteric to the catalytic triad of BChE in determining biorecognition, thus providing useful guidance for ligand design and affinity maturation.

Co, N co-doped porous carbon-based nanozyme as an oxidase mimic for fluorescence and colorimetric biosensing of butyrylcholinesterase activity

A Co, N co-doped porous carbon-based nanozyme (Co-N-C nanozyme) has been fabricated. Taking advantages of the excellent oxidase catalytic activity and significant stability of Co-N-C nanozyme, we propose a fluorescence and colorimetric system based on Co-N-C nanozyme and red-emitting carbon quantum dots (RCDs) for butyrylcholinesterase (BChE) sensing. As the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) was catalyzed and oxidized by Co-N-C nanozyme, the generated oxTMB had a new absorption peak at 652 nm, which resulted in the significant quenching of the fluorescence of the carbon quantum dots at 610 nm. Under the catalysis of BChE, thiocholine was generated from the hydrolysis of S-butyrylthiocholine iodide (BTCh), and the as-generated thiocholine effectively inhibited the oxidation of TMB catalyzed by Co-N-C nanozyme, leading to a decrease of the absorption of oxTMB at 652 nm and effective fluorescence recovery of RCDs. By measuring the absorbance of produced oxTMB at 652 nm and the fluorescence of RCDs at 610 nm, the fluorescence and colorimetric system both exhibited an outstanding linear response to the activity of BChE in the range 0.5 to 40 U L^-1, with a detection limit of 0.16 U L^-1 and 0.21 U L^-1, respectively. Furthermore, this established dual-channel biosensing strategy has been successfully applied to the determination of BChE in human serum samples. The present work has effectively expanded the development and application of nanozyme in biosensing.

Construction of a copper nanocluster/MnO2 nanosheet-based fluorescent platform for butyrylcholinesterase activity detection and anti-Alzheimer's drug screening

An abnormal level of butyrylcholinesterase (BChE) activity is highly connected with hepatic damage and Alzheimer's disease. Herein, a facile and efficient method was proposed for BChE detection by incorporating polyethyleneimine-capped copper nanoclusters (PEI-CuNCs) with manganese dioxide (MnO₂) nanosheets. The emission of PEI-CuNCs can be significantly quenched by MnO₂ nanosheets via the inner filter effect. With the addition of BChE, the hydrolysis of butyrylthiocholine iodide produces thiocholine which can reduce MnO₂ nanosheets to Mn²⁺, thus resulting in the fluorescence recovery of PEI-CuNCs. Based on that, a fluorescence "turn-on" sensing platform for BChE activity determination was constructed with a detection limit of 2.26 U L^-1. This sensing method is able to detect BChE in human serum samples and identify the serums of normal persons and cirrhotic patients effectively, indicating its great potential in the clinical diagnosis of liver diseases. Furthermore, the approach can also be used to screen BChE inhibitors, which are promising medications to alleviate the symptoms of Alzheimer's disease.