| Chemiluminescence(CL)analytical methods are constructed using CL emission as signal output.They show various advantages such as wide linear range,high sensitivity and low background signal.Therefore,CL analytical methods have been widely used in environmental monitoring,food safety,drug analysis and clinical diagnosis.However,the traditional CL methods suffer from low luminescence quantum yield.It is necessary to enhance CL signal with catalysts to improve the sensitivity of CL analytical methods.Unlike traditional natural enzyme catalysts,nano catalysts show the advantages of lower cost and better stability.However,the reported nanomaterials are generally restricted by the disadvantages of difficult preparation,easy aggregation and low catalytic activity.Therefore,it is of great significance to explore novel nanomaterials with simple preparation,good dispersion and high catalytic activity.The metal centers of atomic-scale catalysts are distributed on the support in atomic dispersion state,which have the maximum utilization of active atoms and show high catalytic efficiency.Due to the unique spatial site structure and excellent catalytic performance of atomic-scale catalysts,they have been research frontier.According to the number of metal atoms in the active center of atomic-scale catalysts,they can generally be divided into single-atom catalysts,double-atom catalysts and triple-atom catalysts.The choice of supports poses an important influence on the synthesis of atomic-scale catalysts.Moreover,metal organic frameworks(MOFs)have high specific surface area and adjustable structure,which can be used as supports to synthesize atomic-scale catalysts.In this study,two Co double-atom catalysts(CoDACs)with high catalytic efficiency were synthesized based on Pearson’s hard and soft acid-base theory and defect engineering.Both of them showed high catalytic effects on CL,and their CL reaction mechanisms were explored.Cell wall bind domain(CBD)at the C-terminal of bacteriophage lysin has a specific recognition effect on host bacteria and can be used as a recognition reagent to detect pathogenic bacteria.Subsequently,two CL analytical methods for the detection of methicillin-resistant Staphylococcus aureus(MRSA)were constructed by labeling the synthesized atomic-scale catalysts to CBD.The related works have been published in Sens.Actuators,B and other publications.The specific research contents are described as following:1.Chemiluminescent analysis of MRSA using Co double-atom catalysts prepared based on Pearson’s hard and soft acid-base theoryAs new types of catalysts,dual or multiple atoms catalysts have displayed high atom utilization rate and superior catalytic activity.In the present work,a metal binuclear atom pair with unique Co coordination environment of Co2-O8 were prepared on the supports of MOFs MIL-53(Al),and named as CoDACs.Fascinatingly,CoDACs with desirable water dispersibility display very high catalytic efficiency for redox-based CL reaction by generating abundant reactive oxygen species.The catalysts boosted the CL signal of luminol-H2O2 system for 1192 times at the concentration of 1.0 μg m L-1,thus can be applied as superior CL probes for tracing biorecognition events.To verify their application potential,CoDACs were used to establish a CL method for analyzing MRSA strains by adopting CBD of bacteriophage lysin as a recognizer.The method displays a dynamic range of 6.1×102-6.1×107 CFU m L-1 and a detection limit of 220 CFU m L-1.The results for analysis of MRSA in biological,drug and food samples manifest their reliability for real application.2.Chemiluminescent analysis of MRSA using Co double-atom catalysts prepared by defect engineeringDouble-atom catalysts have attracted extensive interest in heterogeneous catalysis due to their remarkable atom utilization efficiency and synergetic catalytic activity of adjacent diatomic sites.In this work,defect engineering MOF-808 was used as support for implanting Co dimers,and CoDACs with Co2-O10 coordination structure were prepared by a simple two-step solvothermal method.The loading capacity of CoDACs was significantly improved,and the content of Co element was up to 11.1 wt%.In addition,they showed excellent peroxidase-like activity.Therefore,CoDACs can generate a large number of reactive oxygen radicals by decaying H2O2.As key intermediates,reactive oxygen radicals can promote the luminescence signal of redox-based CL system.CoDACs can enhance CL signal of luminol-H2O2 system by 5852 times as the concentration is 1.0 μg m L-1.Because CoDACs have good water dispersibility and excellent CL reaction performance,they are used as ultra-sensitive CL signal probes for monitoring MRSA with a detection linear range of 1.0 ×102-1.0 ×107 CFU m L-1,and the detection limit is 47 CFU m L-1.This work provides a new avenue for the development of double-atom catalysts by using defect engineering MOF-808 as supports.The constructed CL method shows practical application potential in the field of food and biological samples.And the results of antibiotic susceptibility test by CL method are consistent with the micro broth dilution method,which proves the reliability of this analytical method.In summary,two Co-based double-atom catalysts have been synthesized based on Pearson’s hard and soft acid-base theory and defect engineering,which can catalyze the CL signal of luminol-H2O2 system by producing a large amount of reactive oxygen radicals.As new types of catalysts,double-atom catalysts have almost 100% atom utilization and high catalytic efficiency.The CL analytical methods constructed by combining double-atom catalysts with CBD of bacteriophage lysin have the advantages of high sensitivity,strong specificity and wide detection linear range,which provides a new avenue for expanding the application of atom-scale catalysts in the field of analytical chemistry. |
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