| Ensuring agro-product safety is an important issue for human healthy and sustainable development of economy.The abuse of pesticides,organic fertilizers and potential harmful chemicals have posed serious challenge on the development of new technology for rapid sensing and collection.To address this,it is urgent to enrich and transfer the targets in agricultural samples,such as enrichment of heavy metal ions and rapid detection of toxins.The researchers have developed various carriers to achieve this goal.Metal-organic frameworks(MOFs)is a serial of crystalline porous materials with high porosity,rich chemical properties and flexible pore structures.It has been widely reported in various applications including gas molecule enrichment,pollutants removal,sensing and drug transport in recent years.However,most of the MOFs synthesis methods are prepared by hydrothermal method and presented as powders,which is not appliable for material engineering.Therefore,researchers have developed a series of methods to make MOFs materials into high-performance films or sponges,including in-situ method,seed method,adhesive method,etc.However,current methods for MOFs composite have the disadvantages of complicate preparation methods,poor film density,and so on.In order to solve the above problems,a series of preparation methods and devices were developed in this research for agro-product safety as following:1.Preparation of MOFs hybrid membranes for collection of hazards in waterMOFs possess superior adsorbability,but their poor processability hampers the fabrication of MOFs-based devices for applications.Inspired by biomineralization,we propose the preparation of electrospun-silk-nanofiber(ESF)@MOFs(ZIF-8 or ZIF-67)hybrid membranes with pristine MOFs densely loaded to efficiently remove pollutants in water.The biomineralization-mimetic in-situ growth of MOFs on ESF led to high coverage of MOFs,with loading rates reaching 36% and 34% for ZIF-8 and ZIF-67,respectively,which were among the highest level of that for commonly used polymer membranes and reported analogues.The hybrid membranes achieved removal rates reaching nearly 100% to two kinds of heavy metal ions and organic dyes.A filtration device was also constructed with removal rate being close to 100% in one filtration round.2 Water-stable Zr-LMOF for aflatoxin B1 detection in waterSensitive and rapid detection of aflatoxin B1(AFB1)without using antibody or biomolecular modifications in water is achieved using a novel water-stable luminescent metal–organic framework(LMOF)termed Zr-CAU-24.The 1,2,4,5-tetrakis(4-carboxyphenyl)benzene(H4TCPB)-based LMOF with high water-stability has demonstrated drastic fluorescence fading in the presence of AFB1.The detection limit for AFB1 using this porous nanomaterial reaches as low as 20 ppb(64 nM),which is below the applicable action level for peanut and corn products set by the US FDA and among the most sensitive sensors reported for AFB1.The prepared water-stable LMOF was directly used for the detection of AFB1 in spiked walnut and almond beverages.High recovery rates(91%–108%)were achieved in 5-min detection.3 Preparation of Zr-CAU-24/MF hybrid sponge for rapid mycotoxins collection and detectionIn this section,the fluorescent Zr-CAU-24 nanoparticles were successfully made into Zr-CAU-24/MF composite sponge for rapid mycotoxins detection and removal in water.Further experiments on the quenching of the fluorescence of the sponge in the presence of AFB1 proved that this hybrid sponge was able to detect AFB1 in 5 min.The adsorption of AFB1 results showed that AFB1 molecules were adsorbed by the hybrid sponge and the collection efficiency reached as high as 90%.Further experiments show that the hybrid sponge also has a strong adsorption effect on other mycotoxins and the collection rates reached 80%.4 Cargo loaded MOF-capillary hybrid material for drug delivery via acoustofluidicsProtein and DOX were successfully encapsulated into ZIF-8 MOF nanoparticles.In collaboration with Duke university,we have developed an acoustofluidic-enabled delivery platform capable of sustainably delivering various functional agents into cells in a biocompatible and efficient manner.By aligning the pressure node of a standing bulk acoustic wave(BAW)with the sidewall of a nanoparticle-coated capillary,the target cells were pressed against the capillary sidewall for continuous cell-nanoparticle contact without compromising cell viability.During this contact,the cells are compressed under the acoustic pressure and the nanoparticles affixed to the capillary wall are attached to the cell membrane.Moreover,the controllable platform has been demonstrated for actively loading cargos into the cytoplasm of both suspension and adherent cells.With these advantages,this acoustofluidic system provides a valuable enriching platform for the development of novel sub-micrometer-based sensors. |
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