Fluorescent Peptide Probes For Organophosphorus Pesticides Detection

Organophosphorus pesticides(OPs)are widely used in crop protection because of their low cost,quick effect,and inhibition of various pests.However,extensive use of pesticides can contaminate soil,air and surface water,and even enter the human body through the food chain,which has a negative impact on our life and health.At present,there are many methods to detect OPs,such as chromatography,spectroscopy,capillary electrophoresis,biosensor and so on.These analytical methods are widely used in the detection market of OPs and have their own significant advantages and application fields.However,each analytical method has more or less certain limitations,such as difficult operation,time consuming and high cost,which limit their use in field application and rapid identification.Therefore,constructing an effective method for detecting OPs that is simple to operate,short in time,low in cost and quick in response is of great significance to human health.A fluorescent peptide probe was successfully designed to detect OPs by fluorescence spectrum in this study.In this work,we have designed 11 peptides and peptides attached with tetraphenylethylene(TPE)molecule were synthesized to form a aggregation-induced emission fluorescent probes(TPE-Peptide)for the determination of OPs.Four probes with better activity were obtained by fluorescence spectrum screening.The designed peptides were consisted of the catalytic triad containing serine and the LHLHLRL peptide with hydrophilic and hydrophobic amino acid.In the presence of OPs,the OPs were reacted with the serine active site in the peptide and the serine was phosphorylated.The hydrophobicity of the peptide chain was enhanced,and the aggregation under the hydrophobic interaction can induce the TPE-peptide probe to emit fluorescence.The mechanism of the reaction between the probes and OPs was investigated by mass spectrometry.OPs can make the probe self-assemble into fibers and aggregation-induced emission fluorescence by transmission electron microscopy,atomic force microscopy and fluorescence confocal microscopy characterization.After the reaction with OPs,The probes size have increased to different degrees by dynamic light scattering characterization.The optimal probe P11 was characterized by circular dichroism spectra and has showed a more obvious β folding structure,which was easier to aggregate and form fibers.Experimental results have showed that the TPE-peptide probe exhibited higher sensitivity to fluorescence response to OPs.The detection limit was 0.6 μM and the linear detection range was 0.6 to 100 μM.TPE-peptide probe can be used for the detection of OPs in actual samples.The TPE-peptide probe has the characteristics of rapid,stable,simple operation,convenient preparation,and provides new ideas and methods for the detection of OPs in vegetables and other pesticide residues detection.The TPE-peptide probe could be applied to the development of biosensors.