Metal-like/Metal Double-shell Structure:Fabrication,Characterization,and Applications In β-agonist’s Detection

Surface plasmon resonance(SPR)is the resonant oscillation of conduction electrons of metal/metal-like nanostructured materials that is stimulated by incident light.When the light frequency matchs well with the oscillation frequency,which can be controlled by the parameters including material type,shape,size and dielectric environment,nearfield enhancement will be gernerally realized.Up to now,this unique local-field enhancement has presented a great potential in applications of physics,chemistry,materials,biology and so on.When the SPR effect is applied to molecular detection,the enhanced local-field can significantly improve the Raman signals’s intensity,which is well accepted as surface enhanced Raman scattering(SERS).In SERS detection,noble metals are generally used as the plasmonic materials,especially Ag,which shows superior plasmonic properties in visible region.However,silver is easy to be oxided and sulfided in ambient air,and also with chemical/thermal instability,low melting point and high optical loss in visible range,resulting in a limited application in practical conditions.Titanium nitride(TiN),as one of transition metal nitrides with high melting point,good chemical stability,low cost and super hardness,presents a certain plasmonic property and therefore has been considered as one of the important alternative low-loss plasmonic materials.In this work,TiN/Ag double-shell nanostructure arrays were successfully fabricated and demonstrated as an ideal SERS substrate with high sensitive and stable performance.Further application to β-agonists’s detection in animal derived food also has been verified.The detailed work is represented as the following:Firstly,the efficient preparation processes for TiN/Ag composited double-shell nanostructures were developed.Self-assembled template method with the film deposition and solution treatment was introduced to fabricate the monolayer hollow nanosphere arrays.Then,the specific SPR properties of the TiN-Ag double-shell structure were systematially investigated by employing morphological,structural,and optical characterization and FDTD simulation methods.High sensitive and stable SERS performance was verified to be originated from the synergistical multiple mode SPR effect and charge transfer mechanism.Furthermore,the application of TiN/Ag double shell SERS chips in β-agonists’s sensitive detection was investigated.The Raman spectra of clenbuterol,salbutamol and ractopamine in powder and methanol standard solution samples were measured to identify the characteristic Raman resonance modes in those β-agonists.The satisfied linear relationship between probe concentration and Raman resonance intensities in methanol standard solution samples further demonstrated the qualitative and quantitative detections by using this TiN/Ag composite SERS substrate.Within an additional recovery process,a relative consistence in the SERS detection compared with the chromatography-mass spectrometry method was accomplished,which evidences the feasibility and reliability of SERS detection method.In summary,the TiN/Ag composite double shell array structure was successfully fabricated in this work and realized both sensitive and stable SERS performance.The substrates were also applied to the practical application in β-agonists’s detection.This work,not only presents the idea of introduing alternative plasmonic materials,but also carried out the meaningful research in related experiments,simulations and applications,laying a foundation for the further development of Raman screening technology in the application of food detection.