Investigation Of SPR Sensor Based On AuNPs-MoS₂ Composites And DNA Tetrahedron

Surface plasmon resonance?SPR?sensor is a tool for monitoring interactions between biomolecules.SPR sensor has the advantages of label-free,real-time and continuous monitoring of the dynamic process of the reaction,low cost and easy operation,which has been widely used in the fields of therapeutic diagnosis,biopharmaceutical,food safety and environmental monitoring.However,there is still a great challenge for low-abundance biological targets from complex matrix in SPR sensors.This is mainly because the sensitivity is not high enough and there is nonspecific adsorption.In this paper,microRNA?miRNA?was chosen as a model target,and high sensitiveand low-fouling SPR biosensors were designed for the detection of miRNAs based on gold nanoparticles-decorated molybdenum sulfide?AuNPs-MoS₂?nanocomposites and DNA tetrahedron probes?DTPs?.The details were as follows:1.A high sensitive SPR biosensor was proposed based on AuNPs-MoS₂ for the first time.This SPR platform using the AuNPs-MoS₂ nanocomposites as signal labels for the sensitive and facile measurement of miRNA was executed in only two steps.Performance of SPR biosensor was enhanced by taking advantage of the AuNPs-MoS₂nanocomposites.Thus,this sensing assay exhibited high sensitivity toward miRNA with a detection limit of 0.5 fM.Furthermore,the method showed high specificity,resulting in distinguishing differences among miRNA-200 family members,and could be feasible for determining miRNA in 10%human serum.Especially,the assay could also be used to detect human miRNA from cancer cells,and the results were in excellent accord with the ones obtained using qRT-PCR.This assay may provide a great potential as miRNA quantification method in complex samples.2.An antifouling surface made by the covalent attachment of DTPs on gold surface demonstrated superior antifouling capability against protein and cell.DTPs modified Au?DTPs-Au?film for two single protein samples?1 mg/mL myoglobin,48 mg/mL HSA?and five complexmatrix?100%serum,100%plasma,9.85×10⁸ red cell numbers/mL,5%whole blood and cell lysate?had low or ultralow adsorption amounts?<8 ng/cm²?.More interestingly,DTPs-Au surfaces could also aviod Au deposition.Thus,DTPs-Au film was applied to the SPR sensor for the sensitive detection of miRNA in complex matrix.Exploiting the amplification of catalytic growth of gold nanoparticles?AuNPs?,the detection limit was 0.8 fM toward let-7a.Moreover,the SPR sensor revealed good selectivity and could distinguish let-7a from homologous family.More importantly,the SPR sensor displayed excellent reproducibility,and could be feasible for determining miRNA in 100%human serum.Especially,the assay could also be used to detect human miRNA from cancer cells,and the results were in excellent accord with the ones obtained using qRT-PCR.This assay may provide a great potential as miRNA quantification method in complex samples.