Impedimetric Detection of MicroRNAs by the Signal Amplification of Streptavidin Induced In Situ Formation of Biotin Phenylalanine Nanoparticle Networks.

This work proposed a strategy for impedimetric detection of microRNAs (miRNAs) by the signal amplification of insulating biomaterials. Specifically, biotinylated miRNA (biotin-miRNA) with the same sequence as that of target miRNA was captured by the sensor electrode. The biotin tags on electrode surface allowed for the attachment of tetrameric streptavidin (SA) protein through the biotin-SA interaction. Meanwhile, biotinylated phenylalanine nanoparticles (biotin-FNPs) in solution triggered the assembly of more SA molecules on electrode surface through the same interaction. The circular recruitment of SA and biotin-FNPs from solution led to the in situ formation of SA-biotin-FNPs networks on electrode surface. The networks created an insulating layer to hamper the electron transfer, thus amplifying the impedance response. The competitive hybridization between target miRNA and biotin-miRNA with the capture probe prevented the attachment of biotin-miRNA by the sensor electrode, thus preventing the in situ formation of SA-biotin-FNPs networks and leading to the decrease in impedance signal. The method was applied to determine miRNA-21 in cell lysates with satisfactory results. The signal amplification strategy by in situ formation of nanoparticle networks can potentially be applied to develop novel affinity biosensors for detection of various biomolecules [ABSTRACT FROM AUTHOR]