Quantitative And Sensitive Detection Of Chloramphenicol By Surface-enhanced Raman Scattering

Chloramphenicol(CAP),a common broad-spectrum antibiotic,is widely used in animal husbandry.Nonetheless,CAP brings serious adverse effects on human hematopoietic and nervous systems once it is utilized for a long time.Therefore,it is important to detect CAP for our health,especially for CAP residue with low concentration.Moreover,it is urgent to solve the problems from the traditional detection methods for CAP,containing long detection period,low sensitivity,expensive equipment,high cost,complex pretreatment and low detection limit.Importantly,it is meaningful to design a new method with simple process,high sensitivity and low cost to detected CAP rapidly,quantitatively and sensitively.Surface-enhanced Raman scattering(SERS)is called as a“fingerprint spectrum" with short detection period,simple process,high sensitivity,nondestructive testing and low cost,which can be used to identify molecular structure.The basic mechanism is that the surface plasma resonance(SPR)caused the local electric field enhanced,which lead to enhancing SERS signals.The SPR comes from the interaction between nearly free electrons on the surface of noble metal and incident light.In this paper,three SERS active substrates,containing Ag/Au nanoparticles(NPs)and satellite Au NPs multimer have been designed and prepared by hydrothermal reduction to detect CAP rapidly and quantitatively.Multiple testing methods,containing transmission electron microscope(TEM),high performance liquid chromatography(HPLC),ultraviolet-visible absorption spectrometry(Uv-vis)and Raman spectra,are used to analyze the particle size,morphology,UV absorbing property and SERS enhancement of three SERS active substrates,and detect the pristine CAP,the concentration of CAP solution and eyedrops.Moreover,finite difference time domain(FDTD)method was used to simulate the feature of the structure and analyze the SERS enhancement.The follows show the main content of this paper.Firstly,30 nm Ag NPs were designed and prepared to detect the CAP rapidly and quantitatively due to the good SERS enhancement.The TEM images show the nice dispersibility and homogeneity of 30 nm Ag NPs.The unknown concentration of antibiotic can be detected by the quantitative relation curve.The Raman signals of 10-6 M CAP solution can be detected with the 30 nm Ag NPs as substrate,which means a low detection limit.Importantly,this method can be used to detect the micro/trace residues.Secondly,five Au NPs(10,20,30,40 and 50 nm)have been designed and fabricated to detect the CAP rapidly and quantitatively due to the good SERS enhancement.The TEM images show the nice dispersibility and homogeneity for 10,30 and 50 nm NPs.The SERS enhancement from three lasers(532,633 and 785 nm)was analyzed systematacially.And the result shows that 785 nm laser gives the strongest SERS signals.Moreover,30 nm Au NPs also show the strongest SERS enhancement among the five substrates.Therefore,785 nm laser was chosen as the excitation light source and 30 nm Au NPs was chosen as the SERS active substrate.The SERS signals of 10--17M R6G solution and 10-8 M CAP solution can be detected with 30 nm Au NPs substrate,which means a low detection limit.Importantly,this method can beused to detect the micro/trace residues.Two CAP eyedrops with knownconcentrations can be detected by the quantitative relation curve based on the data of 10-3 M to 10-8 M CAP solutions.And test result is very close to the actual result,which means that CAP solution with unknown concentration canbe detected by this method.Therefore,this method was used to detect theCAP solution with unknown concentration,and HPLC was used todemonstrate the veracity of this method.Importantly,the two results are same.In this paper,CAP residues were detected quantitatively,sensitively and rapidly base on SERS.Thirdly,four satellite Au NPs multimer substrates(20 nm@10 nm,30 nm@10 nm,40 nm@10 nm and 50 nm@10 nm)have been designed and fabricated to detect the CAP rapidly and quantitatively due to the good SERS enhancement.The TEM images show the nice dispersibility and homogeneity.Among the four satellite Au NPs multimer substrates,50 nm@10 nm shows the strongest SERS enhancement.Moreover,according to the size and structure of four substrates,FDTD method was used to simulate the feature of the structure and analyze the SERS enhancement.The simulated result also shows that 50 nm@10 nm satellite Au NPs multimer shows the strongest SERS enhancement,in accordance with the experimental result.The Raman signals of 10-6 M CAP solution can be detected with the 50 nm@10 nm satellite Au NPs multimer as substrate,which means a low detection limit.Importantly,this method can be used to detect the micro/trace residues.