Li_2025_Spectrochim.Acta.A.Mol.Biomol.Spectrosc_336_126005

In this work, Acetylcholinesterase (AChE)-immobilized cellulose membrane biosensors (CBS) with the capability of indirectly detecting chlorpyrifos (CPF) were successfully developed by covalent bonding AChE to the modified cellulose membrane surface. In the presence of active AChE, thiocholine (TCh) was produced by hydrolyzing acetylthiocholine (ATCh) and reacted with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) to produce yellow chromophore thionitrobenzoic acid (TNB(-)). CPF can interrupt the process above by inhibitory attacking at the active serine (ser) site. The change of color intensity was shown to enable quantitative and qualitative detection of CPF. The structures and properties of membranes were characterized by scanning electron microscopy (SEM), energy spectrometry (EDS), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), etc. Experiments proved that CBS had high selectivity, long shelf life, and wide detection limits for qualitative and semi-quantitative detection of CPF, and its limit of detection (LOD) was 5 nmol/L over a linear range of 15-120 nmol/L. The contrast experiment with a filter paper-based strip showed that the CBS had better detectability. The design of CBS offered an excellent strategy for the covalent immobilization of enzymes and visual colorimetric detection of CPF.