Nanosilver Hydrogel Surface Enhanced Raman Scattering Biosensing Technology For Detection Of Paraoxon

Surface-Enhanced Raman Scattering?SERS?is established from the enhancement of 4-6 orders of raman scattering of pyridine molecules on rough silver electrodes.Millions of times enhancement can be observed from a single layer or even a single target molecule on a metal surface,which greatly enhances and broadens the sensitivity and application/using range of raman spectroscopy.SERS technology is widely used in chemistry,materials science,chemical analysis,surface physics,and biomedicine.Acetylcholinesterase?AChE?,a hydrolase commonly found in the brain and central nervous system of organisms,can terminate the transmission of nerve impulse signals by catalyzing the hydrolysis of acetylcholine?ACh?in the organism to produce choline and acetic acid,maintaining the normal operation of the entire cholinergic nervous system.In clinical medicine,Parkinson's disease and Alzheimer's disease are related to the activity of acetylcholinesterase in human body.Organophosphorus pests?OPs?achieve the purpose of killing pests by inhibiting the activity of acetylcholinesterase in insects.However,organic phosphorus will accumulate in the environment,and the inhibitor will enter the human cholinergic nervous system,inhibiting the activity of acetylcholinesterase,leading to the accumulation of acetylcholine in the nervous system,causing a series of nervous system diseases.This paper combines surface-enhanced raman scattering and biosensing technology,developed a simple,label-free and highly sensitive method to detect organophosphorus pesticides by using acetylcholinesterase-modified nanosilver hydrogel as SERS substrate.The mainly content is as follows:?1?The uniform size surface enhanced raman scattering?SERS?substrate was prepared by photochemical,using one-pot method and without other reducing agents.Silver nanoparticles of about 200 nm were grown inside the hydrogel,realizing the idea of preparing a large-area silver-hydrogel SERS substrate.Quantitative detection of 4-mercaptobenzoic acid was achieved while maintaining the sensitivity and repeatability of raman signal detection.A low-cost SERS substrate with good performance was obtained,and it provides a basis for the future development of bio-molecular and enzyme-based external response biosensors.?2?In order to apply the prepared SERS substrate as a biosensor,we further modified acetylcholinesterase on the hydrogel and successfully developed a new AChE method based on SERS to detect organic phosphorus.Acetylcholinesterase hydrolyzes thioacetylcholine to product the thiocholine with raman signal,and the presence of organophosphorus can reduce the production of thiocholine by inhibiting the activity of Acetylcholinesterase,and the corresponding raman signal is reduced at the same time.According to the change of raman signal,it is well achieved a quantitative detection of organophosphorus pesticides.Improved sensitivity towards the AChE inhibitor with a detection limit of 1 ng·mL^-1.Compared to other methods,this technology does not require the use of additional molecular beacon,and is expected to achieve simple and rapid detection of organophosphorus pesticides.