Construction And Performance Of Flexible Plasmonic Nanohole/dot Hybrid Arrays

Surface-enhanced Raman spectroscopy?SERS?detection based on the electromagnetic field enhances Raman spectrum signal,is non-destructive for analyte,and has high detection sensitivity,which has been widely used in environmental protection,analytical chemistry,biological detection,food safety and other fields.The key of such detection lies in the preparation of substrate with high stability,high sensitivity and good reproducibility.Compared to plasmonic nanoparticles,nanoarrays have better stability and reproducibility and been widely used in the study of SERS substrates.In addition,flexible substrates have good mechanical endurance,infrangible,low-cost and can be cut arbitrarily over conventional rigid substrates,which makes the flexible SERS substrates develop rapidly.At present,microcontact printing,nanoimprint and AAO templates et al.are used to construct flexible nanoarrays.These methods require the preparation of seals,configuration,separation and other steps,which are complex.In order to improve the sensitivity of the detection,some teams have improved the sensitivity through the construction of composite arrays.Therefore,it is important to fabricate the flexible plasmonic nanoarrays with high sensitivity and reproducibility in a fast way.In summary,nanosphere lithography?NSL?and reactive ion etching?RIE?techniques were used in this work to fabricate flexible nanopore/dot hybrid arrays and nanopore arrays on PDMS substrates by one-step method.When PDMS under the oxygen plasma,it can form a pleated hard layer of SiO_x on the surface,then increase the number of“hot spots”.In order to evaluate the SERS performance of the structure,the optimal structure of SERS performance was explored by adjusting the period and the thickness of gold.Then studying the application of the optimal SERS substrate in biological detection,the LSPR-SERS double detection model was used to detect antigen-antibody specific reaction.The main research includes the following three aspects:?1?One-step method to fabricate the flexible nanoarrays based on PS monolayers:NSL and RIE techniques were used in this chapter to fabricate flexible nanoarrays on PDMS substrates in a fast way.By controlling the etching time,the flexible nanopore/dot hybrid arrays and nanopore arrays with periods of1000,500 and 300 nm were obtained.The hybrid arrays have good periodicity,which provide a good basis for improving the reproducibility of SERS detection.After analyzing the results of AFM,SEM and so on,the formation of nanoarrays was mainly due to the gap between the etched PS acting as a space limiting effect,resulting in the wall growing up along the gap.?2?The study on SERS performance of the flexible plasmonic nanoarrays:flexible plasmonic nanopore/dot hybrid arrays and nanopore arrays with different periods were obtained as the flexible SERS substrates based on the flexible nanoarrays in the previous chapter by evaporating different thickness?40,60 and 80 nm,respectively?of gold on the flexible nanoarrays through thermal evaporation.The SERS performance of as-prepared plasmonic nanoarrays were studied by using the ethanol solution of 4-MBA as the probe molecules.By optimizing the experimental parameters,the flexible plasmonic nanopore/dot hybrid arrays with the period of 500 nm,etching time of 45 s and gold's thickness of 40 nm have the highest sensitivity,the minimum detection concentration for 4-MBA solution is 10^-14 M.They also have excellent reproducibility,the relative standard deviations?RSD?of the two strong peaks at 1073 cm^-1 and1587 cm^-1 were 5.24%and 5.27%,respectively,and the enhancement factor?EF?reached 3.62×10⁶.Such hybrid nanoarrays with good sensibility and reproducibility will have good application prospect in the application of SERS.?3?Using LSPR-SERS double detection mode to detect antigen-antibody specific reaction:the flexible plasmonic nanopore/dot hybrid arrays with period of 500 nm,etching time of 45 s and gold's thickness of 40 nm were used as the substrates,and LSPR-SERS double detection mode was applied to detect antigen-antibody specific reaction.The specific reaction of IgG and Anti-Rabbit IgG was detected through the surface modification,activation,IgG fixation,BSA closure,and the introduction of Anti-Rabbit IgG.The dual LSPR-SERS detection for the specific reaction of IgG and anti-Rabbit IgG can not only analyze the existence of Anti-Rabbit IgG by the peak shift of LSPR,but also recognize the specific molecular characteristics of Anti-Rabbit IgG by SERS.