| Oxytetracycline(OTC),belongs to TCs,has become the most widely used antibiotics.The issue of drug resistance,caused by antibiotic residues is of particular concern.At present,most of the detection methods for antibiotics require complex instruments,complicated pre-treatment,or longer cycles,etc.There are some rapid detection methods either having the issue of accuracy or sensitivity.Thus,it is important to develop a simple,rapid,and sensitive method for the detection of oxytetracycline.Surface enhanced Raman spectroscopy(SERS)has the advantages of fingerprint recognition and high sensitivity,which makes it widely used in disease diagnosis,food detection and environmental testing.Based on the enhancement effect of nanomaterials on Raman,Raman hotspot was formed by gold nanoparticles self-assembly.OTC SERS detection with good specificity and high sensitivity was constructed.The main research work included:Firstly,an OTC SERS detection was constructed by self-assembly of gold nanoparticles based on liquid phase.In this study,20 nm and 80 nm gold nanoparticles were prepared firstly.The single-stranded DNA sequence with OTC aptamer was modified on the surface of 80 nm gold particles,20 nm gold particles were modified to the 5 ’ end of the DNA sequence.The Raman molecules were modified on 20 nm gold particles.Thus,OTC aptasensors was constructed with SERS.Under the optimum of experimental conditions,the logarithm of the concentration of oxytetracycline showed good linearity when the concentration range of oxytetracycline was 4.96×10-2-4.96×102 fg/mL(y=1948.97+148.52 x,R2=0.9979)with a detection limit of 4.35×10-3 fg/mL.The specific experiment of oxytetracycline was carried out by using tetracycline,chlortetracycline,doxycycline,metacycline and minocycline.The recovery experiment was carried out with dairy.Recovery rate was 85.08-93.80%.The experiment proved that this method was specific and could be used for the detection of actual samples.Secondly,an OTC SERS detection was constructed by self-assembly of gold nanoparticles based on silver nanofilm.Considering that the effect of silver nanofilm on SERS was more obvious.Based on the previous experiment,the silver nanofilm was prepared by chemical deposition method,20 nm gold particles were assembled onto the surface of silver nanofilm in the presence of the DNA sequence containing the oxytetracycline aptamer.Under the optimum of experimental conditions,the logarithm of the concentration of oxytetracycline showed good linearity when the concentration range of oxytetracycline was 4.96×10-3-49.65 fg/mL(y=27747.68+10535.74 x,R2=0.9912)with a detection limit of 2.03×10-3 fg/mL.The results of specific experiment and spiked recovery experiment proved that this method was specific and can be used for the detection of actual samples.Finally,double SERS detection of tetracycline(TET)and OTC was constructed by self-assembly of gold nanoparticles based on ultrafiltration membrane.Considering simplifying separated operation during the experiment,and to enhance multiple detection capabilities,based on the previous experiments,a double detection was constructed with TET aptamer and OTC aptamer.Under the optimum of experimental conditions,the logarithm of TET concentration showed a good linear relationship with the peak intensity at 1094 cm-1(4-MBA)when the concentration range of TET was 0.48-4.81×103 fg/mL(y=996.07x+5861.01,R2=0.9963)and the detection limit was 2.14×10-1 fg/mL.Similarly,when the concentration range of OTC was 0.49-4.96×103 fg/mL,the logarithm of OTC concentration was the same as that at 1330 cm-1(DTNB)The peak intensity showed a good linear relationship(y=1316.85x+7386.72,R2=0.9918)with a detection limit of 0.17 fg/mL.Specific experiment and spiked recovery experiment showed this method was reliable and can be used for the detection of actual samples. |
