A Novel Bifunctional Nanogold Surface MIP Recognition And Nanocatalytic Amplification-SERS/RRS Dimode Sensor For Ultratrace Acetamiprid

Specific template molecules and corresponding functional monomers are used to produce network polymers under the action of crosslinking agents.After the template molecule are washed away,molecularly imprinted polymer（MIP）with specific imprinted cavities are formed.With good biocompatibility,MIP is commonly used as adsorbent,recognition element and biosensor,which is widely used in sample identification and adsorption in environmental analysis.However,due to the complexity of preparation conditions,its application is limited.At present,the known methods for the preparation of MIP are diversified,including bulk polymerization,precipitation polymerization,suspension polymerization,and multi-step swelling polymerization,each method has its own advantages and disadvantages.It has been shown that microwave synthesis can effectively reduce the preparation time of materials.The microwave irradiation assisted polymerization method is used to prepare uniform MIP or Au@MIP to achieve the purpose of rapid synthesis of MIP and Au@MIP.In this paper,the exposed catalytic active site on MIP or Au@MIP was used as a catalyst to catalyze the REDOX reaction of HAu Cl₄-dopamine（DA）to generate Au NPs,and MIP or Au@MIP was also used as a recognition element to detect acetamiprid（AP）,combined with Au NPs as SERS/RRS dual-function indicator.We designed a surface-enhanced Raman Scattering（SERS）and resonance Rayleigh scattering（RRS）dual-mode sensor to identify trace amounts of AP.The details are as follows:1.Preparation and characterization of molecularly imprinted polymersA noval MIP particle was prepared under microwave irradiation.Taking the catalytic effect of MIP on HAu Cl₄-DA nanoreaction as the evaluation criterion,the preparation conditions of MIP were optimized,including the influence of the molar ratio of template molecule to functional monomer,the molar ratio of template molecule to crosslinker,the influence of initiator dosage,the influence of reaction temperature and reaction time.Subsequently,the optical properties of MIP were studied with a variety of spectral instruments.The shape,appearance and functional group structure of MIP were characterized by transmission electron microscopy（TEM）,surface area and aperture analysis.Finally,the optimal synthesis conditions of MIP materials were obtained through experiments,and the MIP with the best catalytic effect was selected.Meanwhile,gold nano surface molecularly imprinted polymer（Au@MIP）was prepared using gold nanoparticles as substrate.The dual-function MIP or Au@MIP nanomaterial not only had the function of recognizing AP,but also had a strong catalytic effect on the gold nanoindicator reaction of HAu Cl₄-DA.2.Detection of acetamiprid on SERS/RRS platform with a novel bi-functional nano surface molecularly imprinted polymer nanoprobe catalyzed amplificationAP was selected as the substance to be tested,that is a new type of nicotinoid drug with strong water solubility,so that it can penetrate soil into rivers,lakes and seas,and further enrich AP in the body through the food chain,which is extremely likely to cause environmental and human abnormalities.The surface electrons of MIP nanocatellator could significantly promote the formation of Au NPs from HAu Cl₄-DA.When AP was added,it was embedded in the imprinting site of imprinted polymer,and AP contained functional groups such as N≡C,C=N and benzene ring,which producedπbonds that coupling with the nanosurface electrons of MIP or Au@MIP.The catalyst promoted the electron transfer ability of the REDOX reaction.The Au NPs were significantly responsive to SERS/RRS signals,and the dual-mode signal was linearly enhanced with the increase of imprinted molecule AP.Accordingly,a new SERS/RRS dual-mode nano sensing platform was constructed in this study,which detected 0.25-20 pmol/L and 0.50-50 pmol/L AP through SERS and RRS monitoring,respectively.The detection limit of SERS was 0.19 pmol/L（MIP）and 0.16pmol/L（Au@MIP）,and the detection limit of RRS was 0.42 pmol/L（MIP）and 0.35 pmol/L（Au@MIP）.In addition,a reliable nanocatalytic mechanism was proposed.