The Preparation Of Lanthanide Luminescent Nanozymes/Probes And Their Applications In Catalysis And Sensing

Due to the universality of enzyme applications,fabricating highly active,stable,and cheap artificial enzymes has been the most exciting frontier topic of biomimetic chemistry over the past few decades.Recently,several nanomaterials(such as Fe3O4,gold/platinum/GO nanoparticles)have been found to have unexpected enzyme-like activity,known as nanozyme.Nanozymes are considered a new generation of artificial enzymes that are being rapidly used in biosensing,medical diagnosis and treatment,and contaminant removal.The unique luminescence properties of lanthanide ions(large Stokes shift,long luminescence lifetime,sharp emission peaks,etc.)enable the lanthanide luminescence probe to effectively eliminate the interference of various nonspecific fluorescence through time-resolved fluorescence technologies,with extremely high detection sensitivity.The metal organic frameworks(MOFs)composed of metal ions and organic bridge-linked ligands is ideal as a functional material assembly platform due to their structural and composition flexibility.In this paper,new lanthanide luminescence probes and a series of luminescent nanozymes are designed and synthesized through the MOF structures,and enzymatic luminescence detection methods based on these nanozymes are established.The main results are as follows:1.A reaction-triggered luminescent Ce4+/Tb3+MOF material for the detection of SO2 and its derivatives in human serumSulfur dioxide molecule is increasingly recognized as a gasotransmitter associated with multiple physiological processes.A bimetallic lanthanide MOF fluorescent probe(Ce4+/Tb3+MOF)was designed and synthesized for the detection of gaseous sulfur dioxide(SO2)and its derivative sulfite(SO32-).This bislanthanide ion MOF probe consists of reactive Ce4+,fluorescent Tb3+and bridge-linked ligand m-phthalic acid(PA).Ce4+can react with SO2 or SO32-,and the energy generated from the reaction can be transferred to Tb3+,enhancing the luminescence of Tb3+.This new sensing principle makes the prepared Ce4+/Tb3+MOF material a highly sensitive,turn-on type fluorescent probe,which can sense SO32-as low as 50 nM and 2 ppm SO2 molecules in human serum.The SO2 test strips prepared with the Ce4+/Tb3+MOF material can sense 40 ppm gaseous SO2 molecules.This reaction-responsive sensing strategy provides new ideas for the design of biological probes and for the analysis of biological samples.2.Luminescent Tb-MOF nanozyme for the detection and degradation of estrogen endocrine disruptorsBy means of flexible structures and components of MOF materials,we designed and made an artificial nanozyme with dual functions of catalysis and luminescent sensor specifically for the determination and degradation of hormone 17β-estradiol(E2)and its derivatives(E1,E3 and EE2),a class of environmental pollutants with strong disturbing effect on the human endocrine system.This nanozyme composed of luminescent Tb3+ion,catalytic coenzyme factor hemin and light-harvesting ligand OBBA can be used to both degrade E2 like natural horseradish peroxidase(HRP)and sense E2 as low as 50 pM by its luminescence.The nanozyme catalyzes the decomposition of E2 and its derivatives through a mechanism of active hydroxyl radicals and oxidative high-valent iron-oxo intermediates.The prepared nanozyme has advantages of versatility,service life and manufacturing costs.For the detection,this luminescent nanozyme that integrates catalysis and luminescence-sensing can replace the current widely used combination of natural enzyme and chromogenic substrate,and has broad application prospects in biological analyses/sensors and other aspects.This strategy of constructing artificial enzymes directly from functional units provides new ideas for the design and development of smart,multifunctional artificial enzymes.3.Detection of tyrosine catalyzed by a luminescent nanozyme Tb-IDA-Fe3O4A luminescent nanozyme for detecting tyrosine(Tyr)by its luminescence was designed and synthesized.The luminescent nanozyme(Tb-IDA-Fe3O4)consists of luminescent Tb3+,catalytic Fe3O4 nanoparticles,and the antenna ligand 4,5-imidazole dicarboxylic acid(IDA)via the MOF structure.The sensing mechanism by which the catalytic reaction triggers the luminescence of Tb3+can be used to sense pM level of tyrosine in human serum.Tb-IDA-Fe3O4 has the dual functions of peroxidase and luminescence-sensing,and can be used to replace the currently widely used combination of natural enzymes and chromogenic substrate,providing new methods to revolutionize various enzyme-based assays.4.High-performance,synergistically-catalytic luminescent nanozyme CeO2@Tb-Cu MOF for the degradation and detection of diethylstilbestrol(DES)A synergistically-catalytic luminescent nanozyme was designed and synthesized for the degradation and enzymatic fluorescence detection of diethylstilbestrol,an environmental pollutant.Because of the integration of co-catalytic Cu2+ ion and CeO2 particle,luminescent Tb3+ion and functional ligand dipicolinic acid through flexible MOF structure,this nanozyme has not only the dual functions of luminescence and multienzyme like laccase and horseradish peroxidase but also synergistically-catalytic effect via a regeneration of Cu2+oxidized by CeO2.The synergistically-catalytic effect of nanozyme greatly enhances the degradation of diethylstilbestrol.The resultants sensitized the luminescence of Tb3+ions,which was used to sense pM level of diethylstilbestrol in environmental samples.Such a high-performance catalytic luminescent nanozyme can be used to replace natural enzymes for the enzyme-based degradations and ultrasensitive assays.The strategy of integrating multi-catalytic centers for a synergistically-catalysis provides a new way for developing efficient artificial enzymes targeting contaminants.5.Copper nanoclusters act as laccase for catalytically sensing the neurotransmitter molecule epinephrineReferring to the structure of natural laccase,we took copper atoms as the catalytic center,selected cysteine and histidine as protective agents and reducing agents respectively.This copper nanocluster integrates the catalytic properties and luminescence properties,which not only has the same catalytic activity as the laccase,but also has the unique luminescence performance of the copper nanocluster,which we call "ultramini-luminescent laccase(Cys-HisCu)".It can replace laccase to catalyze the neurotransmitter molecule epinephrine,and be used to detect epinephrine via its luminescence.Ultrailuminescence laccase has great value for the development of inexpensive and efficient nanocluster nanozymes.