Synthesis And Analytical Application Of Chemiluminescent Functionalized Two-Dimensional Nanomaterials

In this dissertation,the state of arts in the field of(electro)chemiluminescence,as well as nano-luminophores and their applications in bioassays were reviewed.In particular,two-dimensional nanomaterials have attracted much attention in(electro)chemiluminescence due to their unique structural characteristics,superior physicochemical properties and great application potential.Although(electro)chemiluminescence bioassays have been increasingly applied to clinical diagnosis,environmental monitoring and food safety assessment,their analytical performance is not only limited by the(electro)chemiluminescence efficiency of luminophores,but also greatly affected by random error and systemic errors during laborious assembly procedures.Therefore,it is of importance to explore novel nano-luminophores with high efficiency and to develop simple and stable bioassay methodologies with self-correcting function,finally achieving ultrasensitive,accurate and rapid determination of analytes.In this work,the synthesis and analytical application of chemiluminescent functionalized two-dimensional nanomaterial were investigated.Highly active graphene oxide-supported cobalt single-ion catalyst was developed.And the catalytic property and mechanism for chemiluminescence reaction were explored.Furthermore,the synthetic methods and(electro)chemiluminescent performances of two novel functionalized nanomaterials(g-C3N4/ABEI and ABEI/AuNPs/CuTCPP)as well as their applications in bioassays were studied.The main results are as follows:1.A facile approach for preparing GO-supported single metal ion catalyst was developed.Metal ion(e.g.Co2+)was directly immobilized on the surface of GO by virtue of electrostatic and coordination interactions.The Co2+/GO hybrid catalyst exhibited excellent catalytic activity as well as good stability on luminol-H2O2 and lucigenin-H2O2 CL reactions.The integrated CL intensity of Co2+/GO-catalyzed luminol-H2O2 reaction was 115 times higher than that of the luminol-H2O2 and the peak intensity of Co2+/GO-catalyzed lucigenin-H2O2 reaction was 20 times higher than that of the lucigenin-H2O2.Theoretical studies revealed that the coupling between Co2+ and GO induced effective polarization charges,improving chemical activity of reaction site,which promoted the generation of intermediate radicals and accelerated the CL reactions.GO-supported single metal ion as a catalyst is superior to GO supported single metal atom or nanoparticles in synthesis and stability.More importantly,this work may be generalized to GO-supported other metal ions as catalysts for a wide range of chemical reactions.The developed GO-supported cobalt single-ion nanocomposites as nanointerfaces may find future applications in CL bioassays.2.A novel nano-luminophore(g-C3N4/ABEI)has been synthesized.The morphology and the surface composition of the nano-luminophore have been fully characterized by various techniques.The nano-luminophore exhibited unique potential-resolved eletrochemiluminescence(ECL)performance at the anodic and cathodic potentials in the presence of H2O2 and K2S2O8 as coreactants in aqueous media.Two distinct ECL peaks,ECL-1 with a peak potential of+1.2 V and ECL-2 with a peak potential of-1.6 V,were observed,where generated blue emissions peaked at～450 nm.ECL-1 was mainly due to the reaction between ABEI·-and O2·-or HO2-.ECL-2 was mainly due to reaction between g-C3N4·-and S2O8·-or HO·.It was found that the ECL intensity could be influenced by the concentration ratio of H2O2 and K2S2O8 due to the synergistic effects between the active species involved in the ECL mechanism.Based on its superior two-dimensional structural quality and adjustable potential-resolved ECL property,g-C3N4/ABEI can function as nanointerface and holds bright application prospect in the field of bioassays,biosensors and bio-imaging.3.A label-free and all-in-one ratiometric ECL bioassay combined with rolling circle amplification(RCA)strategy is designed for the efficient determination of miR-133a,a potential biomarker in early diagnosis of acute myocardial infarction(AMI).Taking g-C3N4/ABEI as ECL sensing platform,we have found that Hg2+could be assembled on the surface of g-C3N4/ABEI,leading to the modulation of the ECL signals with an inverse variation trend.Utilizing Hg2+ as the ECL signal moderator and RCA as target amplification method,a potential-resolved ratiometric ECL bioassay was developed for the detection of miR-133a.In the presence of miR-133a,RCA would proceed,and prolonged single-stranded T-rich DNA molecules were synthesized which further extract Hg2+ out from the g-C3N4/ABEI nanointerfaces by forming T-Hg(Ⅱ)-T duplex complexes,leading to a great change of ECL ratio(I1/I2).The proposed methodology possessed several merits,such as superior amplification efficiency of the RCA strategy,one-step and time-saving assembly procedure,more explicit signal ratio variations,leading to an exceptional analytical performance with a wide dynamic range from 0.1 fM to 1.0 pM and a remarkable detection limit of 48.0 aM.The results represented in this work manifest that the proposed ratiometric ECL bioassay holds promising potential capabilities in early clinical AMI diagnosis.More importantly,this study opens a window to a wide range of miRNA-based detection strategies as a rapid and sensitive methodology in clinical diagnosis and prognosis evaluation in future studies.4.A CL reagent and noble metal nanoparticle dual-functionalized two-dimensional metalloporphyrinic metal-organic framework nanosheets(ABEI/AuNPs/CuTCPP)were developed through surfactant-assisted and in-situ growth synthetic method.During the synthesis process,CuTCPP nanosheets served as nanoplatform with abundant functional groups and large specific areas,ABEI functioned as reductive reagents and CL species,Au(III)was in-situ reduced to Au(0)and ABEI was assembled on the surfaces of CuTCPP nanosheets.Benefiting from the impressive structural features,such as the large lateral size and ultrathin thickness,abundant metal catalytic centers with atomic distribution and outstanding biocatalytic activity of metalloporphyrin building blocks,ABEI/AuNPs/CuTCPP nanocomposites exhibited strong and stable CL property with relatively slow and delayed CL kinetic curves,which is totally different from most of CL nanocomposites.Under the identical measurement conditions,the CL intensity of ABEI/AuNPs/CuTCPP was 60 times higher than that of ABEI system and was much superior to other nanocomposites synthesized in our lab before.Furthermore,ABEI/AuNPs/CuTCPP also possessed peroxidase-mimicking activity and its CL intensity was closely related to the concentration of H2O2 in the range from 10-7 to 10-3 M.Inspired by its outstanding characteristics,ABEI/AuNPs/CuTCPP nanocomposites were used as advanced platforms and a model biosensor was developed for the detection of small molecular.The proposed biosensor showed an extremely sensitive response to choline chloride in a linear range from 0.3 μM to 300 μM with a detection limit of 82.6 nM.Significantly,this bioanalysis methodology can be generalized to the monitoring of other metabolic processes involved with the production of H2O2,which are strongly related with many diseases such as diabetes,Alzheimer’s disease etc.The strong and slow CL property may provide some inspiration for the development of bioimaging.