DNA Nanotubes Coupled with Magnetic Nanoparticles as a Platform for Colorimetric Biosensors

This study describes the fabrication techniques for two forms of magnetic DNA nanotubes (MDNTs) and their applications as platforms for developing colorimetric assays. The first form of MDNTs was DNTs filled-up with magnetic nanoparticles (MNPs) and the second one was DNTs arayed with MNPs on their extrior surfaces. Then the both forms of MDNTs were employed as platforms for attaching a specific insulin aptamer. The sensitivity and accuracy of the insulin measurement using both platforms were studied and compared with enzyme-linked immunosorbent assay (ELISA) as the standard method for the measurement of insulin in cliniccal laboratories. Applying the magnetic field to MDNTs led to enhance the ability of insulin capturing by the aptamer array in serum and subsequently by removing unspecified contents led to precised detection. For specific detection of insulin and its measurement in this study, a G-rich DNA aptamer with HRP-mimicking activity was used that simulated the peroxidase performance when the insulin was trapped with the aptamer. The presence of MDNTs made a high flexibility, a greater convergence of the connectivity to superficial aptamers, and hence the availability of these aptamers to increase the target molecules and subsequently increased the sensitivity of the measurements. This colorimetric method can be used as a novel biosensores for detection of any target molecules.