| With the rapid development of modern industry,the problems caused by organic pollutants have become more and more serious.Current researchs indicated that organic pollutants in the environment can affect and interfere with the growth of animals and plants,destroy ecological balance and damage human health.Most organic pollutants can cause certain damage to human body,which can lead to cell distortion and mutation.Therefore,it is very important to develop a series of sensing methods that can detect organic pollutants sensitively and quickly.Current methods for detecting organic contaminants mainly include high performance liquid chromatography?HPLC?and liquid chromatography-tandem mass spectrometry?LC-MS?.But they are time consuming,require expensive and complicated equipment,thus limiting their application for routine analysis.Therefore,there is an urgent need to develop simple and rapid methods that are ultra-sensitive,specific,and capable of detecting multiple targets simultaneously in the same system.In this paper,we have constructed a series of fluorescent probes based on metal organic frameworks?MOFs?,which utilize the superior fluorescence characteristics of LMOFs,the excellent fluorescence quenching effect of two-dimensional MOFs?2D-MOFs?,combined with stirring bar phase separation and DNA amplification strategy.A variety of simple,fast,highly sensitive,and highly specific methods have been developed to achieve detection of organic contaminants in environmental water and food.The main contents of this study are as follows:1.Antibiotic tetracycline?TC?is a sort of main contaminates in water,and of adverse effect on ecosystems and human health.The development of simple and efficient methods for both detection and removal of TC in water is highly desirable but remains challenging.Herein,a dual-functional platform for detection and removal of antibiotic tetracycline?TC?is developed by a highly stable luminescent zirconium-based MOF?PCN-128Y?.The detection is based on the efficient luminescence quenching of the PCN-128Y toward TC.Theoretical/experimental studies reveal that the luminescence quenching can be attributed to a combined effect of the strong absorption of TC at the excitation wavelength and the photo-induced electron transfer process from the ligand of PCN-128Y to TC.The strong cheating metal-ligand bonding between Zr6 nodes and TC through solvent-assisted ligand incorporation is suggested to mainly account for the high adsorption capability of PCN-128Y toward TC in water.The preconcentration of TC within the pores of PCN-128Y induced by the adsorption process makes TC contact with the framework more sufficient,thus significantly enhances the efficiency of TC sensing.This work is the first example demonstrating that MOF materials can integrate the functions of detection and removal of antibiotic TC in water,which highlights the opportunity of luminescent MOFs in the application of wastewater treatment.2.Hydroxypyrene?1-HP?is a urinary metabolite of polycyclic aromatic hydrocarbons?PAHs?,and can function as a convenient biomarker for human intoxication of PAH carcinogens.The development of simple 1-HP sensors with high sensitivity and fast response is highly desirable.Herein,we demonstrate that a robust microcrystalline MOF with fluorescent pyrene cores,NU-1000,exhibits sensitive luminescent detection of urinary 1-HP.The pyrene core within NU-1000behave as the signal converter,which luminescence is significantly quenched upon contacting with1-HP owing to the efficient?-?charge transfer interactions between highly conjugated 1HP and pyrene cores in NU-1000.The pore confinement effect of the molecular-sized channel of NU-1000facilitates the preconcentration of 1-HP within NU-1000,which makes 1-HP contact with NU-1000 more sufficient and therefore enhancing the detection efficiency.The charge transfer-related quenching mechanism is elucidated by diffuse-reflectance UV-vis and electron paramagnetic resonance?EPR?measurements,and a radical pair state is observed in NU-1000 upon accommodation of 1-HP.This work provides important insights into the development of MOF-based luminescent sensors for 1-HP,and should stimulate further studies toward designing more efficient MOFs with highly conjugated luminescent cores for 1-HP sensing.3.In the study,a novel two dimensional metal–organic framework?Cu-TCPP nanosheets?based fluorescence resonance energy transfer?FRET?aptasensing platform was developed for detecting antibiotics.Cu-TCPP nanosheets were employed for quenching the background fluorescence and circular strand-replacement DNA polymerization?CSRP?for signal amplification.To fulfill the purpose,we designed an aptamer hairpin probe?HP?whose stem can be opened while specifically binding to target.Then the opened HP would bind with the primer.Under the action of polymerase,extension reaction was induced to generate double-stranded DNA?dsDNA?,and then the target was released for the next cycle.Finally,SYBR Green I?SG?can bind with dsDNA to produce strong fluorescence response for quantification of target.It's worth mentioning that the fluorescence of HP/SG complex and free SG could be completely quenched by Cu-TCPP nanosheets while that of dsDNA/SG complex wouldn't be affected.Thus,the sensor produced negligible background signals.It can produce 7.5-fold improved S/N compared to a graphene oxide?GO?-based FRET aptasensor.Chloramphenicol?CAP?was chosen as the model analyte to demonstrate the feasibility of the sensor system.The detection range is broad from 0.001 to 10ng·mL-1 with a detection limit down to 0.3 pg·mL-1.The proposed assay was label free and can be used in homogenous detection which greatly simplifies the complexity of operations.The strategy opens a new way to develop sensitive,in-situ and simple assay for antibiotics in foods.4.The abuse of antibiotics poses a threat to human health.Developing effective methods for high sensitivity and rapid screening of specific antibiotics is critical for human health.Two dimensional metal organic frameworks?2D-MOFs?with large specific surface area and long-range fluorescence quenching coupled with biomolecular recognition events opens up a new direction for biomolecular diagnosis.Here,we proposed a 2D-MOFs-based multicolor fluorescent aptamer nanoprobe use double stirring bar assisted target replacement?DSBTR?system for enzyme-free signal amplification.It utilizes the interaction between 2D-MOFs and DNA molecules to detect multiple antibiotics quickly,sensitively and selectively.Since the high quenching efficiency of 2D-MOFs for the fluorescence of dye-labeled single-stranded DNA?ssDNA?,and the fluorescence of ssDNA is extremely low.When ssDNA forms a double helix double-stranded DNA?dsDNA?with a specific complementary ssDNA,the fluorescence is enhanced,resulting in a high signal ratio.The assay was testified by detecting chloramphenicol?CAP?,oxytocin?OTC?and kanamycin?KANA?in food samples.The proposed aptasensor exhibited high sensitivity to antibiotics with a low detection limit of 1.5 pM,2.4 pM and 1 pM?S/N=3?toward CAP,OTC and KANA,respectively.The strong fluorescence quenching ability of 2D-MOFs in combination with DSBTR signal amplification strategy contributes to the high sensitivity,with a limit of detection 2 orders of magnitude lower than that of traditional methods. |
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