Application Of MoS₂-based Nanocomposites In Electrochemical Sensors

Taking the advantage of fast response,high sensitivity,good selectivity,easy operation and low cost,electrochemical sensors have great application prospect in various fields such as clinical medical care,environmental monitoring,food safety,transportation,national defense and so on.T o improve the performance of electrochemical sensors,nanomaterials have been introduced into constructing new electrochemical biosensors due to their excellent biocompatibility,good conductivity and catalytic properties,and large specific surface area.Molybdenum disulfide?MoS₂?is a graphenelike nanomaterial,which is widely used in catalysis,lithium batteries,biosensing,drug delivery and treatment and other fields due to its unique physical/chemical properties and good biocompatibility.In this paper,we mainly focused on the preparation of MoS₂-based nanocomposites and their application in the field of electrochemical biosensors.Herein,we designed the following three MoS₂-based electrochemical sensors for different chemical or biomolecules detection.1.Four MoS₂-based electrochemical sensors were constructed for the detection of catechol?CC?based on noble metallic nanoparticles supported on the surface of MoS₂ nanosheet.It could be found that MoS₂ nanosheet and its derivatives could detect CC effectively.More interestingly,the gold nanoparticles-functionalized MoS₂ nanosheet?MoS₂-Au?,platinum nanoparticles-functionalized MoS₂ nanosheet?MoS₂-Pt?and gold-platinum core-shell nanoparticles-functionalized MoS₂ nanosheet?MoS₂-Au@Pt?modified electrodes exhibited better detection performances than that of pure MoS₂ nanosheet due to their synergistic effect.As expectedly,MoS₂-Au@Pt nanocomposites exhibited the widest linear range and lowest detection limit in all MoS₂-based nanomaterials.All the MoS₂-based electrochemical sensing platforms were employed to determine CC both in buffer and in real samples with satisfactory results,suggesting MoS₂-based nanomaterials maybe the potential candidates for constructing electrochemical sensors for chemical and biological molecules detection.2.A dual-mode electrochemical biosensor was developed for microRNA-21 detection based on MoS₂-Au nanocomposite.[Fe?CN?6]3-/4-and [Ru?NH3?6]3+ were selected as electrochemical indicators,EIS and DPV were used to monitor the performance of electrochemical biosensors.Experimental results showed that this MoS₂-based biosensor exhibited excellent performance for microRNA-21 detection in the range from 10 fM to 1 nM with detection limit of 0.78 fM and 0.45 fM for DPV and EIS technique,respectively.Besides,the biosensor displayed high selectivity and stability,which could used to determine microRNA-21 in human serum samples.All results suggested that MoS₂-based biosensor had a potential application for DNA/microRNA detection.3.An ultrasensitive sandwich-type electrochemical immunosensor for the quantitative detection of carcinoembryonic antigen?CEA?was designed based on MoS₂-Au nanocomposite.MoS₂-Au nanocomposites were employed as both a modifier to constrcut modified electrode and a substrate to prepare nanoprobe conjugated with antibody.In the presence of antigen,a classical "sandwich" structure electrochemical immunosensor was formed.In this work,horseradish peroxidase?HRP?was used as a sealing agent to block the active site of the nanoprobe and as a amplifier to amplify the detection signal by catalyzing O-phenylenediamine in the presence of hydrogen peroxide.The results showed the immunosensor exhibited a low detection limit of 0.85 fg mL-1 and wide linear range from 10 fg mL-1 to 1 ng mL-1 for the detection of CEA.Moreover,such biosensor exhibited good selectivity and stability,which can be applied to determine CEA in human serum samples with good results.All results indicated that MoS₂-based immunosensor could detect tumor biomarkers in ideal buffer and real sample.