Highly Reproducible SERS Substrates For Detecting Illegal Additives In Food And Drug

With the increasing problems in food and drug safety,the task of developing food and drug safety detection technology is imminent,especially the identification and confirmation technology of key hazards in food and drug,evading the illegal addition of certain lawless elements and unscrupulous manufacturers.At present,It is urgent to develop high-throughput,high-precision,rapid identification and confirmation technologies for hazardous substances in food and drug.Surface-enhanced Raman spectroscopy(SERS)technology is considered to be a promising analytical technique for its rapid detection,high sensitivity,selectivity and fingerprint characteristics.There are lots of advantages in sensitive detection,but there are still many problems in the field of rapid detection of complex systems.This study carries out the construction of high reproducibility of SERS substrates with high stability and high sensitivity for application of the practical application,combined the common probe strategy,micro-extraction technology and nano-cell assembly method.The following work is shown in below:(1)The use of surface modification methods to functionalize gold nanopartices(Au NPs)enabled highly sensitive and highly reproducible detection of acid pigment molecules.The acid pigment molecules cannot approach the surface of Au NPs which exhibit weak affinity for Au NPs.The cysteamine(CA)was chosen as a probe which could be rapidly functionalizedon the surface of Au NPs.On the one hand,positively charged cysteamine molecule has electrostatic effect with pigment molecules of negative charge.On the other hand,hydroxyl and sulfonic acid group of pigment molecule were bonded with the amino group of cysteamine molecule through hydrogen bonding,the distance became shorter between the pigment molecule and Au NPs was closer with the acidic pigment.The molecules could quickly reach surface of Au NPs,causing SERS resonance.In addition,strong adsorption between polyamide and acid pigment molecules was used to extract the pigment in actual sample,effectively avoiding the interference of other molecular signals in complex systems.The cysteamine-modified SERS substrate enabled rapid detection of acidic pigments in a variety of complex systems.(2)The micro-extraction was combined with the interface SERS active substrate to achieve high sensitivity and high reproducibility detection of hypoglycemic antihypertensive drugs.By constructing the interface SERS active substrate in a mixture of methanol and chloroform,and utilizing the interfacial tension and the energy reduction of the Ag NPs on the interface,the conditions for the stable presence of Ag nanosols on the interface were explored.On the one hand,the agglomeration of NPs and the "coffee ring" effect are avoided.On the other hand,the molecules to be detected were driven by the micro-extraction,and the methol carried the molecules to be detected and uniformly distributed in the gaps of the Ag NPs.thereby realizing the hypoglycemic drug highly sensitive and reproducible detection of drug molecules.(3)The combination of multi-well plate,micro-extraction and interface SERS substrate enabled high-throughput rapid detection of illegally added components of drugs in health products.Firstly,the pharmaceutical ingredients in the health supplement were extracted by using methanol,and then chloroform was added to induce self-assembly of the Au NPs on the interface.When the concentrated Ag sol assembled on the interface,the methanol carries the molecules to be detected distributed in the interstices of the Ag NPs.In addition,we optimized the size and concentration of the Ag sol to match the muti-well plate for on-site detection.Finally,the portable Raman instruments used for rapid detection of illegal drug additives in health products.