Sensitive Detection Of Target Analytes Based On Electronic Effects Of GO Nanomaterials

Nowadays,with the gradual improvement of people’s living standards,diseases are also on the rise sharply.Most diseases are caused by gene mutations or abnormal content of small molecules in the human body.For example,abnormal content of dopamine(DA)can lead to diseases such as Parkinson’s disease,while genetic mutations in the body are the inducer of most cancers.Therefore,the monitoring of the relevant molecules in vivo has become a hot topic in today’s social research.Graphene oxide(GO),as a common nanomaterial,has a wide range of potential applications due to its extraordinary chemical,optical,thermal,mechanical and other properties.It is often used in multiple target analysis systems such as fluorescence resonance energy transfer,fluorescence probes,and molecular ion through internal filtration effect.In order to detect target analytes more sensitively,nucleic acid molecular probes with low cytotoxicity and controllable assembly functions are gradually being developed.In this paper,three signal amplification sensors are developed for ultra-sensitive detection of target substances with the aid of nucleic acid probes and GO.Firstly,based on the performance analysis of nano-enzymes,the Ag~+/GO-TMB sensing system was constructed and used for the determination of dopamine(DA)by colorimetry.In the range of 1μM-80μM,due to the addition of metalase Ag~+/GO,the colorless TMB will be rapidly oxidized to blue.We can observe obvious UV-visible absorption peak at 652 nm,and the color of the solution will immediately turn blue.The addition of DA reduces the absorbance at 652 nm.There is a good linear relationship between the decrease of absorbance and DA concentration,and the limit of detection is 0.33μM,which verifies the feasibility of this method.At 37℃,the detection of DA can be completed in 5 min.This simple,practical,convenient,fast,high sensitivity and good selectivity sensor has a broad application prospect in medical diagnosis.Secondly,we use the unique separation and enrichment of magnetic beads,as well as the adsorption of a single stranded DNA(ssDNA)by GO and the quenching of fluorescent groups.A fluorescence sensor based on amplification of chain replacement signal was designed for the detection of target object let-7a.In the presence of target gene let-7a,the sensor was activated,chain replacement amplification took place,and the target gene was recycled.At the same time,ssDNA was generated to pair with the pre-quenched single stranded fluorescence group on GO.The quenched fluorescent group is made to GO away,showing fluorescence.The data showed that there was a good linear relationship between the fluorescence signal and the concentration of the target gene,and the LOD was 15.01 p M.The method is also suitable for the detection of complex environments and actual samples,providing a new technical support for early clinical treatment and diagnosis.Finally,in the absence of protease and nanomaterials,we designed another signal amplifier to detect miRNA-21.This sensor detects the intensity of the fluorescence signal mainly through the proximity and distance of fluorescence and quenching groups in the presence of the target gene miRNA-21,so as to detect the content of the target gene.With a detection line of 83.33 p M,the sensor also provides excellent detection performance in complex environments.The method has been a huge help in the treatment of early stage cancers.