A Novel Molecularly Imprinted Polymer On Upconversion Fluorescence For Highly Selective Optosensing Of Ochratoxin A

Ochratoxin(OT)is a toxic widely occurring in a variety of food,feed and other agricultural and sideline products and metabolite produced by Aspergillus and Penicillium and other toxigenic strains.OT has seven kinds of compounds with similar chemical structure.In recent years,Ochratoxin A residues in food have been of great concern and developed Ochratoxin A maximum limit.Thus,it is necessary to develop a high selective method for Ochratoxin A detection.In the study,we put forward a novel method of highly selective and sensitive determination of Ochratoxin A.Firstly,we prepared hydrophobic hexagonal phase ?-NaYF4:Yb3+,Er3+ using Y(N03)3·6H20,Yb(N03)3·5H20 and Er(N03)3?5H2O,modifyed it into hydrophilic by Triton X-100,then synthesized UCNPs@SiO2 by classic Stober Alkalinehydrolysis,which can also be used as signal material.HNA-Phe which is Ochratoxin A analogue was chosen as the template.UCNPs@SiO2@MIPs was prepared by a sol-gel polymerization process with APTES as functional monomer,TEOS as cross-linker and UCNPs@SiO2 as support vector.Hydrophobic UCNPs,hydrophilic UCNPs,UCNPs@Si02 and UCNPs@Si02@MIPs were characterized by SEM,TEM,XRD,fluorescence spectrophotometer,FT-IR and adsorption experiments.The adsorption experiments showed that after binding Ochratoxin A,the fluorescence intensity of UCNPs@SiO2@MIPs quenched.Under optimal conditions,the relative fluorescence intensity of UCNPs@SiO2@MIPs decreased linearly with the increasing concentration of Ochratoxin A in the range of 0.05-1.0 mg L-1.The fluorescent sensor was proposed with a detection limit of 0.031 mg L-1.To evaluate the usefulness of the proposed method,Ochratoxin A in rice,corn,and feed was detected,respectively.The standard addition recovery experiments showed,at three spiked concentration levels(50,100 and 200 ?g kg-1),the recovery ranges were 80.2%-91.6%(RSD<4.6%),89.2%-90.4%(RSD<5.5%)and 88.0%-91.6%(RSD<5.4%),respectively.Furthermore,to verify the validity of the new proposed method in the study,high performance liquid chromatography-fluorescence detector(HPLC-FLD)was used to detect OTA in the above samples.The recovery ranges were 81.5%-90.8%(RSD<3.1%),80.8%-91.6%(RSD<1.7%)and 89.6%-91.2%(RSD<4.9%),respectively.It shows that the proposed method based on UCNPs@SiO2@MIPs for detection of Ochratoxin A in samples is accurate and feasible.