Surface Molecularly Imprinted Polymer Capped Mn-doped ZnS Quantum Dots As A Phosphorescent Nanosensor For Detecting Patulin In Apple Juice

Patulin?PAT?,as one of the highly toxic mycotoxin,is a common contaminant in apple juice and the related products.Conventional analytical methods for PAT have several shortages such as time-consuming and high-cost,thus the development of simple,rapid and new method for PAT is very important.Manganese doped ZnS QDs?Mn-Zn S?is superior in sensing small molecules duo to their nontoxicity,easy preparation and phosphorescence emission which could improve the detection sensitivity of a method.However,there are no available antibodies for PAT to construct an efficient immunoprobe because PAT has low molecular weight and high reaction acitivity in vivo which results in difficulties to prepare effective haptens and high titer antibodies.Molecularly imprinted polymers?MIPs?are synthetical “host-guest” co-polymers which are known as “artificial antibodies” for selective recognition of specific chemicals.In this study,we use MIPs capped Mn-ZnS QDs?MIP-Mn:ZnS?as a phosphorescent nanosensor for detecting PAT in apple juice.The preparation,adsorption capacity,selectivity and analytical performances of MIP-Mn:ZnS were investigated,and then the nanosensor was used to detect PAT in real apple juice samples.The main results were listed as follows:1.MIP-Mn:ZnS with particle size of ²4 nm were successfully synthesized via surface imprinting sol-gel process using 6-hydroxynicotinic acid?6-HNA?as dummy template,3-aminopropyltriethoxysilane?APTES?as monomer and tetraethyl silicate?TEOS?as cross linker under the optimum molar ratio of 6-HNA:APTES:TEOS=1:4:8.2.Adsorption tests which utilized 0.1 mol/L PBS?pH 6.0?as the optimized buffer solution,demonstrated that the MIP-Mn:ZnS possessed higher adsorption capacity and mass transfer rate than non-imprinted polymers?NIP-Mn:ZnS?.MIP-Mn:ZnS showed a specific recognition for PAT among competitive mycotoxins?eg.OTA,DON and AFB1?and its analogues?eg.2-HNA,6-HNA,CA and 5-HMF?with the maximal imprinting factor of 2.02.5-HMF with the concentration less than 30.9 ?mol/L had no effect on the phosphorescent detection of PAT by MIP-Mn:ZnS.The results indicated that MIP-Mn:ZnS had high affinity and recognizability for PAT.3.Under the optimum conditions?pH 6.0,MIP-QDs conc.of 0.04 mg/mL and incubation time of 30 min?,the MIP-Mn:ZnS could respond to PAT in a Stern-Volmer linear range of 0.43-6.5 ?mol/L with a correlation coefficient?R2?of 0.9945.Detection limit?LOD?was calculated to be 0.32 ?mol/L and the KSV,MIP was 48400 M-1.4.Interference tests revealed that the possible organic substances in the juice?eg.sodium citrate,sucrose,glucose and fructose?and the common ions(K+?Na+?Ca²⁺?Mg²⁺?Zn²⁺?Cu²⁺?Mn²⁺?Ni²⁺?Al3+?NO3-?Cl-?SO42-?PO43-)had no effects on sensing PAT by MIP-Mn:ZnS,indicating that MIP-Mn:ZnS possessed strong anti-interference ability and might be a potential phosphorescence probe for detecting PAT in apple juice.5.Recoveries of 102.9-127.2%?spiked 1-3 ?mol/L of PAT?with relative standard deviations less than 4.95% were achieved in real apple juice samples which were in good agreement with high performance liquid chromatography?HPLC??P>0.05?,indicated good accuracy and feasibility of the proposed method.The present paper has developed a simple,rapid and feasible phosphorescence method for the non-immune detection of PAT,which might provide a theoretical and technical reference for the rapid detection of PAT in complex food matrixes.