Novel Electrochemiluminescent Biosensors Based On Sulfur-doped Rare Earth Oxides

A novel technique,electrochemiluminescence(ECL),was developed based on the integration of electrochemistry and chemiluminesence.With no need for extra light source in ECL assay,which would greatly reduce the background signal and improve the sensitivity.The fast development of new ECL emitter vastly enhance the property of the ECL biosensor.Rare earth nanomaterials have attracted extensive attention in the field of life medicine due to their special electronic structure,good luminescent ability and strong biocompatibility.The following two highly sensitive biosensors were de-signed to improve the luminescence intensity of rare earth oxides by doping with ele-ments:1.In recent years,develop single or several-atom-thick ultrathin two-dimensional nanocrystals(2D)attract many researchers great attentions which exhibit unique prop-erties in many fields.Rare earth elements have promising potential in the field of elec-trochemiluminescence(ECL)biosensor because of their good biocompatibility and high photoelectric conversion performance.In this work,a new emitter,S-doped yt-trium oxide ultrathin nanosheets(NSs),were synthesized successfully which had better ECL properties than material with different morphology.Through combining this NSs with small molecule linked DNA as the substrate,the small molecule linked DNA can used be a flexible recognition elements to recognize anti-Dig antibodies,a sensitive and simple biosensor was designed with a good performance.Based on prominent steric hindrance to impede the electron transfer of ECL reagents towards the electrode surface,a broad linear detection range from 1 nM-100 nM of anti-Dig antibodies and a low detection limit of 0.72 nM were obtained.It’s worth noting that the introduction of sul-phur(S)into yttrium oxide ultrathin NSs can affect the surface states at atomic level,which create more active sites and promote electron-hole recombination statistics.Due to it specific structure and elementary composition,the S-doped yttrium oxide ultrathin NSs have great potentials in ECL which is suitable for assemble biological sensor.The newly synthesized two-dimensional rare earth luminescent materials and the method for sample and sensitive quantification anti-Dig antibodies of this proposed ECL sensor might give a new thought for developing novel materials and design other biosensor.2.The development of sensitive detection methods for microRNAs has practical significance for the early prevention and accurate diagnosis of cancers and related dis-eases.In this work,a dual amplification strategy which including DNA walker and a new S-doped Lu2O3/Ag2S electrochemiluminescence resonance energy transfer(ECL-RET)system was proposed to construct a sensitive electrochemiluminescence(ECL)sensor for detection of microRNA-141.Using magnetic-responsive silica-coated fer-riferrous oxide nanoparticles with high payload efficiency of DNA as a platform,and Nt.BsmAl nicking endonuclease as the recognition scissor to cleavage recognition sites,they were constituted DNA walker for converting trace microRNAs to numerous trans-formational DNAs and achieving significant the first stage target amplification.We also combine the S-doped Lu2O3/Ag2S ECL-RET system with triple-helix molecular switch and arouse the second stage signal amplification.The newly modified S-doped Lu2O3 shows better ECL performance than Lu2O3,at～3 times increase,which were chose as the donor in this ECL-RET system.Furthermore,Ag2S quantum dots(QDs)were used as the acceptor.They exhibited overlapping of spectra and efficient energy transfer be-tween each other.And the triplex-helix Ag2S beacon shows better quenching effect than traditional hairpin DNA linked Ag2S QDs which also lower signal-to-noise ratio of this biosensor.When transformational DNAs exist,the conformation of triplex-helix Ag2S beacons will change,the sensor shows on-off-on pattern.As a result,the proposed ECL biosensor for microRNA-141 detection exhibited higher detection sensitivity and good analytical performance with a wide linear range from 0.05 fM to 50 pM and a low detection limit of～0.016 fM(S/N＝3).The proposed sensor not only utilized dual am-plification strategy for biosensor platform construction,but also provided a novel ECL emitters—S-doped Lu2O3 which may offer some new thoughts in materials design,sig-nal amplification and clinical analysis.