Preparation Of Novel Lanthanide MOFs Optical Composite Materials And Their Fluorescence Sensing Application

In recent years,Metal-organic frameworks（MOFs）have been widely concerned for their advantages such as high porosity,large surface area and adjustable structure.MOFs composites with better performance can be obtained by modifying the original MOF with guest molecules.The emergence of MOFs composites has greatly enriched the types of fluorescence sensing platforms,and its excellent performance enables it to cope with more complex environmental systems.In this paper,we construct a variety of MOFs composite materials based on the MOFs framework and successfully apply them to the high sensitivity detection of target compounds.The work of this paper is as follows:1.Hypertension can further induce renal insufficiency,cerebral infarction,and hypertension heart disease.Felodipine is the wonder drug of hypertension,but its abuse can cause bardycardia.It is significant to develop highly sensitive detection platform of felodipine for efficient treatment of hypertension diseases.In this work,to highly efficiently detect felodipine,multi-emission near-infrared（NIR）hierarchical magneticcore-shelllanthanide-MOFsnanoparticles,namely Nd-MOF@Yb-MOF@Si O₂@Fe₃O₄（NIR-1）,has been synthesized by layer-by-layer（LBL）method.LBL method can adjust the optical properties of NIR-1and expose more active sites to improve the sensitivity of detection.NIR-1 has near-infrared luminescence emission,which can efficiently avoid the interference of autofluorescence in biological tissues.Photo-luminescent（PL）experiment also reveal that NIR-1 could be used as the first near-infrared ratiometric luminescent sensor for felodipine detection with high selectivity and sensitivity,the low of detection limit（LOD）is 6.39 n M.It is also noted the shell thickness of NIR-1 can affect the detection sensitivity,NIR-1 obtained by 14 cycle steps has the best detection performance in felodipine detection.The development of detection application of NIR-1 for felodipine detection is also performed in the real biological samples.In addition,NIR-1 can be used as a ratiometric thermometer could also be applied in the temperature sensing from 293K to 343K.The maximum relative thermal sensitivity（S_r）for NIR-1 is 2.17%K^-1at 343 K.Finally,detection mechanisms for felodipine and temperature sensing performance based on near-infrared（NIR）emission were also investigated and discussed in detail.2.Currently,the high amount of L-lysine can increase the potential risk of cardiovascular disease.On the other hand,2-methoxybenzaldehyde（2-MB）has high toxicity can easily pollute the environment.In this work,carbon quantum dots（CQDs）can be encapsulated into Eu-BTB（H₃BTB=1,3,5-tri（4-carboxyphenyl）benzene）forming the multi-emission composite material Eu-BTB@CQDs,Eu-BTB@CQDs applied as the bi-functional ratiometric“off&on”luminescent sensor for L-lysine and2-MB with high sensitivity and selectivity.The low limit of detection（LOD）for L-lysine is 3.68μM and for 2-MB is 0.54μM,respectively.In addition,Eu-BTB@CQDs can quantitatively discriminate L-lysine in the mixed D-and L-lysine water solutions（five different concentrations ratio of L/D-lysine has been set）,which make the chiral detection of L-lysine are more meaningful.On the other hand,Eu-BTB@CQDs identify 2-MB over 4-Methoxybenzaldehyde（4-MB）with high selectivity.Further the detection of 2-MB and L-lysine in the lake water samples with good recovery rate.Finally,the detection mechanisms for L-lysine and 2-MB were also investigated and discussed in detail.3.Epilepsy is a disease of the nervous system,usually it can be diagnosed by electroencephalography and brain imaging,this method is highly cost and low efficiency.In contrast,epilepsy can be diagnosed more efficiently by detecting epileptic biomarkers such as human serum albumin（HSA）and relative DNA.Pregabalin is an effective drug for epilepsy,but the dosage of it needs to be strictly controlled.In this work,to realizing highly efficiently detect epileptic biomarkers（pregabalin,epilepsy-DNA-1 and HSA）,Gd-MOF as the parent framework and it was modified with L-3-Br-PHE-OH,thioflavin T and fluorescein isothiocyanate isomer I（FITC）labeled anti-HSA,respectively.After post-synthetic modification（PSM）method,three Gd-MOF composite materials with good luminescence performance were obtained,namely Gd-MOF@L-3-Br-PHE-OH,Gd-MOF@Th T and Gd-MOF@anti-HSA/FITC.These three composites can be used for the detection of pregabalin,epilepsy-DNA-1 and HSA with high selectivity and sensitivity.The limit of detection（LOD）is 45.41 n M for pregabalin,5.56 n M for epilepsy-DNA-1 and 5.11n M for HSA.The development of detection application of Gd-MOF composite materials for epileptic biomarkers were also performed in the real biological samples.Principal component analysis（PCA）and hierarchical cluster analysis（HCA）results prove that Gd-MOF based composites have strong ability to identify and detect epileptic biomarkers.Finally,detection mechanisms for epileptic biomarkers were also investigated and discussed in detail.