Stretching and Heating Single DNA Molecules with Optically Trapped Gold-Silica Janus Particles

Self-propelled micro- and nanoscale motors are capable of autonomous motion typically by inducing local concentration gradients or thermal gradients in their surrounding medium. This is a result of the heterogeneous surface of the self-propelled structures that consist of materials with different chemical or physical properties. Here we present a selfthermophoretically driven Au-silica Janus particle that can simultaneously stretch and partially melt a single double stranded DNA molecule. We show that the effective force acting on the DNA molecule is in the similar to pN range, well suited to probe the entropic stretching regime of DNA, and we demonstrate that the local temperature enhancement around the gold side of the particle produces partial DNA dehybridization.