Fabrication Of Embedded Flexible Substrates And Semiconductor/Noble Metal Composites And Their Applications For Quantitative SERS Analysis

In recent years,with extensive attention of the safety problem paying to food industry,developing a sensitive,rapid,accurate as well as reliable analytical method to evaluate food safety is particularly urgent in the food industry.As is known to all,Surface-enhanced Raman spectroscopy(SERS)has the merits of high sensitivity,selectivity,it's strong non-destructiveness and significantly enhanced Raman signal of target analytes,which has great application potential in fast and ultra-sensitive detection in the food industry.For the quantitative analysis of SERS,the preparation of highly active SERS substrate is the most important step.In this paper,a simple and rapid method was used to prepare silver nanowires(Ag NWs)-embedded flexible materials in polydimethylsiloxane(PDMS).Combined with the high SERS activity of silver and the flexibility of PDMS,the residues of malachite green in fruit epidermis were explored the wiping and fingerprint residue detection applications;use green synthesis method to prepare three-dimensional Ni O nanoflower-loaded silver nanoparticles composite structure,exploring the mechanism of multiple SERS signal amplification effects based on oxygen incorporation,and carrying out quick detection research on amoxicillin residues in animal meat.The main contents are as follows:Part 1:Multimodal SERS detection of malachite green using flexible Ag NWs@PDMS-embedded films.Swab sampling for the trace surface-enhanced Raman scattering(SERS)analysis of an aromatic dye(e.g.,malachite green,MG)residue in fruits as well as fingerprints is promising due to its practical utility and efficiency in food security and forensic science.However,the durability and recyclability of the SERS substrates pose an enormous challenge.In this study,a novel flexible film was constructed by embedding a commercial Ag nanowire suspension into a polydimethylsiloxane film(Ag NWs@PDMS),which simultaneously exhibits SERS activity,durability and recyclability.High SERS performance was still maintained,even against 20 times stretchability,corrosion by HNO₃,destruction by ultrasonication and a broad working temperature of-20 to 80?.Excellent recyclability for MG sensing was achieved in ten cycles.Ag NWs@PDMS was successfully used for the quantitative detection of MG in juices of fruits(such as apple and pear)by drop dripping,with a limit of detection of10 n M and good anti-interference.Meanwhile,the sensitive detection of the MG residue(only 3 ng/cm~2)on fruits was enabled by the on-site surface swabbing by recycling for five cycles.Portable detection of the MG residue was further achieved from the 10th fingerprint after successively touching a dye drop onto the functional film combined with a portable Raman spectrometer.Part 2:Multiple SERS signal amplifying detection of Amoxicillin in animal meat based on oxygen incorporated Ni O/Ag nanocomposite.For the overuse of antibiotics,a low-cost and portable surface-enhanced Raman scattering(SERS)sensor for antibiotics detection is an everincreasing need.The popular sensor involves in a multiple signal amplifying system with the advantages of easy operation,low cost and multiple signal enhancement modes,which provides high sensitivity and selectivity.In this work,an ultrasensitive SERS sensor was developed for antibiotics detection,with amoxicillin(AMO)as model target,based on 3D Ni O nanomaterial decorated with small Ag nanoparticles.This sensor enabled quadruple signal amplifying functions including strong localized surface plasmon resonance excitation of Ag,synergistic CT effect of Ag and Ni O,and annealing-induced oxygen introduction in Ni O.The quadruple functions were discussed in detail.Its basic SERS performance was evaluated using rhodamine 6G,which displayed high enhancement factor of 1.60?×?10~7,uniformity,reproducibility and good transferable nature onto grid and flexible sheets.Through signal amplifying,the Ni O/Ag sensor was further employed for quantitative SERS detection of AMO in animal meat.A low LOD of 1n M(?0.4 ppb)was obtained,along with good selectivity and recoveries ranging from94.13%to 104.10%.