Amplification yield enhancement of short DNA templates using bulk and surface-attached amine-functionalized single-wall carbon nanotubes

Abstract

In this report, water dispersions of pristine, amine-functionalized, and carboxyl-functionalized single-wall carbon nanotubes were introduced into model DNA amplification reactions in order to exploit the effects of surface charge, dispersion quality, and concentration of the carbon nanomaterials in the final amplification yield. The magnetic beads that were covalently modified with the functionalized carbon nanotubes were also evaluated under equal conditions to observe the difference between bulk and surface-attached nanotubes.The centrifugation and filtration steps applied to the bulk dispersions were found to be useful to eliminate aggregates, which ultimately enhanced the final amplification yields of the samples containing pristine and amine-functionalized carbon nanotubes. However, the carboxylated carbon nanotubes displayed an inhibitory action in all samples, regardless of the centrifugation and filtration, indicating a disfavored surface charge. The magnetic beads modified with the amine-functionalized carbon nanotubes also improved the amplification yield; besides, they greatly simplified the elimination of the nanotubes from reactions.Mechanism studies proved the preferential binding of the DNA templates onto the amine-functionalized nanotubes during amplification. Meanwhile, none of the DNA templates showed interaction with the carboxyl-functionalized carbon nanotubes, probably due to the electrostatic repulsion between the negative charges.