Research On The Application Of Luminescent Metal-organic Framework Materials In The Detection Of Small Biological Molecules

Metal-organic frameworks?MOFs?,which are formed by the self-assembly of inorganic metal centers and organic ligands,are a class of crystalline porous materials with a periodic structure formed network.MOFs show great development potential and attractive development prospects in modern materials research and they have been widely used in molecular separation,gas adsorption and storage,catalysis,chemical biosensing,energy storage,drug loading and sustained release.In this paper,three fluorescence detection platforms were developed based on MOFs materials,which were applied to the analysis of hypochlorite,Fe³⁺,ascorbic acid and?-glucosidase??-GCU?,including:?1?Organic small-molecule fluorescent sensors based on redox mechanism are essential tools for the determination of hypochlorite.However,they suffer from drawbacks,such as interference by other oxidants,tedious synthetic steps,as well as relatively high cytotoxicity.In contrast,inorganic nanosensors,especially two-photon nanosensors based on energy transfer?ET?exhibit advantages of simple production process,excellent biocompatibility,high cell membrane permeability and photobleaching resistance.Here,we present an excellent luminescent metal organic framework?LMOF?probe of UiO-66-NH₂,for specific and sensitive detection of trace hypochlorite in complex water samples and living cells based on ET.The ET mechanism ensures the specificity,while MOF luminescent change provides the sensitivity.The proposed MOF nanoprobe overcomes the strong interference of traditional probes based on redox mechanism,and offers a great prospect model for detection of hypochlorite in bio-system.?2?Fe³⁺plays a vital role in cellular homeostasis.However,the detection of Fe³⁺with rhodamine B?RhB?has potential problems,such as poor selectivity and low photostability.To address these problems,we rationally designed an RhB@MOF-5nanocomposite-based“on-off-on”fluorescent switching nanoprobe for highly sensitive and selective detection of Fe³⁺and ascorbic acid.This RhB@MOF-5nanoprobe was prepared through a facile one-pot synthesis.Here,MOF-5 served as a selectivity regulator for the detection of Fe³⁺.By embedding RhB into the porous crystalline MOF-5,enhanced photostability and fluorescence lifetime were achieved.The as-prepared RhB@MOF-5 was demonstrated to be an ultrasensitive and selective nanoprobe for the detection of Fe³⁺in human serum and ascorbic acid in rat brain microdialysate.Furthermore,inner filter effect?IFE?and photoinduced electron transfer?PET?were proposed and discussed to explain the selectivity and sensitivity of RhB@MOF-5 to Fe³⁺against other interfering substances.Our novel“on-off-on”fluorescent nanoprobe provides insight into the rational design of MOF-based biosensors for selective and sensitive detection of analytes.?3??-GCU is closely related to the occurrence of multiple diseases,and it has been applied as biomarker and therapeutic target in clinical diagnosis.However,reliable methods with high selectivity and sensitivity for monitoring?-GCU are still lacked.Herein,we created a novel fluorescent nanoprobe,RhB encapsulated MOF-5?RhB@MOF-5?,forthedetectionof?-GCUthroughIFE.4-Nitrophenyl-?-D-glucuronide?PNPG?not only acted as the?-GCU substrate but also served as the vigoroso absorber in IFE.In the process of testing,the excitation spectrum of the RhB@MOF-5 could be absorbed by PNPG,leading to the dramatically decrease of fluorescence emission.After adding?-GCU,the substrate of PNPG would be enzymatic hydrolyzed to p-nitrophenol?PNP?and glucose,then IFE disappearance and the fluorescence recovered.This proposed fluorescence probe not only exhibited a broad linearity relationship for?-GCU range of 0.1-10 U L^-1?R²=0.9957?with a limit of detection as low as 0.03 U L^-1,but also showed high selectivity for?-GCU detection.Therefore,the method of encapsulating dyes with porous nanoparticles is of great significance for the design of novel nano-fluorescent probes.