Research Of Preparation And Performance Of 3D SERS Substrate

Surface-enhanced Raman spectroscopy?SERS?is a“fingerprint”spectroscopic analysis technique for detecting ultra-low concentration molecules.In the past decades,SERS,due to its high sensitivity and accuracy,has attracted a lot of attention and has gradually been applied in many fields such as environmental protection,biomedicine and trace detection.However,the traditional SERS substrates are mostly composed of a noble metal nanoparticles within a 2D plane,which bring about many challenges on sensitivity and stability.The new 3D SERS substrates can provide high-density“hot spots”to greatly improve the substrates'performances,therefore are more favoured by researchers.In this paper,a 3D magnetic nanoparticle?F-NPs?SERS substrate is fabricated by magnetic-assisted self-assembly and SERS substrate has been successfully applied in detection of hexachlorobenzene residues in complex soil environments and colon-rectal cancer in blood serum samples.First,this paper studies the effects of nanoparticle coatings,sizes,gaps,and micro/nano-structures on the performance of SERS substrate by finite element method simulation.The results intrduce that“hot spots”often exist between the gaps of nanoparticles coated with noble metals,meanwhile,the sizes and gaps of nanoparticles have an important impact on the performance of the sensing substrate,mismatches in the sizes and excessive gaps will directly reduce the signal enhancement.In addition,it is also found that the density of“hot spots”in 3D SERS substrate is much higher than2D SERS substrate.Secondly,the manufacturing process of SERS substrate is discussed.Four different SERS substrates?including 3D F-NPs,3D polystyrene particles?PS-NPs?,2D F-NPs,2D PS-NPs SERS?are prepared and characterized respectively.At the same time,the effects of materials,magnetic assistance,and size on the performance of the SERS substrate are analyzed by comparative experiments.Finally,the best performing 400 nm3D F-NPs SERS substrate is selected.Further tests on the performance of the device show that the enhanced performance of 400 nm 3D F-NPs SERS substrate is approximately 35 times stronger than the substrate with single-layered F-NPs and 2times stronger than the substrate with multilayer PS-NPs.In addition,the 400 nm 3D F-NPs SERS substrate has ultra-high sensitivity(limit detection concentration of ATP is10^-12 M)and high stability?can be stored in vacuum for at least 7 days?.Finally,SERS substrate is used in environmental detection and medical diagnosis.In medical diagnosis,the Raman spectra of blood serum samples from colon-rectal cancer patients and healthy volunteers are collected by SERS substrate,and the difference between the two serum samples is found through the analysis of data.The machine learning methods are used to analyse and predict cancer patients and healthy volunteers.The accuracy of this method is 88.7%and the specificity is 100%.In terms of environmental detection addition,the 3D F-NPs SERS substrate can successfully detect hexachlorobenzene residues in natural soil,indicating that the device has many application prospects.