The aggregation of Au nanoparticles by an autonomous DNA machine detects viruses

An autonomous DNA-based machine that amplifies DNA biorecognition by the generation of a nucleic acid product that induces aggregation of Au nanoparticles (NPs) was analyzed. The colorimetric imaging of the DNA machine functions and the optical readout of the biosensing event was done by optical features of the Au NP aggregates. The DNA machine reveals an approach for the sensing of NP aggregates that include a controlled number of Au NPs in aggregated clusters. The results show that the time-dependent spectral changes of the DNA system upon the interaction of nucleic acid and primer decreases the absorbance of Au NPs at 25 nm. The spectral changes in the DNA system are intensified with the increase in the time interval for the operation of DNA machine. The results also show that the increase in concentration of nucleic acid template intensifies the spectral features that correspond to aggregated Au Nps.