Studies On Metal-Organic Frameworks Based Sensing Methods For The Detection Of Mycotoxins

Due to health and economic concerns,several toxic and hazardous compounds in food that cause health problems,particularly mycotoxins,have gained greater attention.Therefore,developing simple,low-cost mycotoxin detection devices will significantly influence food safety worldwide.Metal-organic Frameworks（MOFs）,a promising porous crystalline material,have high porosity,flexible structure,and ease of modification.Many MOFs exhibit fluorescence sensing capabilities,and the incorporation of unique functional aptamers into the construction of aptamer-MOFs composite platforms have attracted the attention of researchers and has been used in a variety of disciplines.Biocatalysis,sensing,separation,imaging,and drug delivery are some examples.Therefore,in this study,a variety of Luminescent Metal-organic Frameworks（LMOFs）materials were synthesized for the high-sensitivity detection of mycotoxins.Simultaneously,an aptamer sensor based on MOFs was designed.By incorporating aptamers into MOFs,an aptamer-MOFs composite platform for super-sensing mycotoxins was created,which improved the accuracy of MOFs-based mycotoxin analysis methods.Therefore,the specific research results are as follows:Several MOFs were synthesized successfully.Among them,ten MOFs（Ui O-66,NET-Zn-MOF,Cd-MOF,NBT-Zn-MOF,Eu-MOF,BUT-16-2-MOF,Cu-MOF,NBT-Zr-MOF,NBP-Zr-MOF,and NTC-Zr-MOF）have been applied in the development of MOF-based analytical methods for mycotoxin detection in food and feeds.MOFs are synthesized with a significant specific surface area.Furthermore,their PXRD pattern demonstrated that these synthesized MOFs are stable in water and may be utilized to determine food safety.Meanwhile,all MOFs demonstrate outstanding water stability and luminescence detection under hostile water environment circumstances.Furthermore,certain MOFs that have been synthesized have been developed as luminous MOFs that can display fluorescence and have been created to detect mycotoxin in food through mycotoxin fluorescence quenching.Therefore,MOFs were chosen for future research,Zr-MOFs were chosen,and non-toxic MOFs were also selected.Four highly luminescent MOFs（Ui O-66,NET-Zn-MOF,Cd-MOF,and NBT-Zn-MOF）have been applied in developing MOF-based analytical methods for mycotoxin detection.Under optimized conditions,fluorescent MOFs can act as highly selective luminescent probes for quantitatively detecting mycotoxins through a fluorescent quenching mechanism.For incidence,（1）mycotoxin citrinin was detected and removed simultaneously using a Stable Fluorescent Zirconium（IV）-based Metal-Organic Framework（MOF）Ui O-66.Ui O-66 adsorption equilibrium for citrinin（CIT）can be achieved in 60 minutes,with an adsorption efficiency greater than 80%and an adsorption capacity of 150mg/g.At concentration ranges of 0.08 to 1.00μM,the SV plots of Ui O-66 towards citrinin were nearly linear,with a calculated detection limit（DL）of 0.042μM.（2）Aflatoxin B1 successfully quenched NET-Zn-MOF,Zearalenone successfully quenched Cd-MOF,and other tested mycotoxins had a sling quenching effect,proving their application in mycotoxin sensing in food.In addition,the quenching ability of Aflatoxin B₁ and Zearalenone to the MOFs has demonstrated the use of NBT-Zn-MOF in mycotoxin detection.The application of this assay to the detection of citrinin in wheat and feed samples showed that it could be a promising sensing platform for citrinin detection in the food system.（3）A novel strategy to improve the detection performance of the analytical MOF-based method to detect mycotoxin in food and feeds was presented.A fluorescent sensing analytical method using an aptamer modified with FAM（6-Carboxyfluorescein）and stronger water-stable MOFs used as a quenching agent for the higher efficient detection of mycotoxin was developed.Used MOFs show greater adsorption capability against FAM-modified aptamer viaπ-πstacking,electrostatic,hydrogen bond,and coordination interactions.Experiment and literature studies show that the used MOFs have a great quenching ability through fluorescence resonance energy transfer（FRET）and photoinduced electron transfer（PET）.When mycotoxins（Aflatoxin B₁,Ochratoxin A,and Zearalenone）are present,FAM-modified aptamers have been released from the surface of the used MOF,resulting in the recovery of quenched fluorescence.For example,the detection limit of the developed biosensor based on MOF for OTA was 0.014μM,with a wide linear range of 0.7 to 0.1μM.Therefore,the platform enables faster,highly sensitive,and highly specific sensing of mycotoxin and has extremely good universality and multimode analytical efficiency.