Fig. 2. (a–e) Representative native 10% PAGE gel sections for the unlabeled nanomachine and linear probe after incubation in 70% human serum at 37 °C. Incubation times are indicated above each lane and were the same for the nanomachine states and the Dark linear probe. The incubation times for the Bright linear probe were shorter due to its considerably shorter lifetime. The nanomachine and Dark linear probe have bands visible even after 48 hours of incubation in human serum, while the Bright linear probe is completely degraded within 6 hours. For this figure, image contrast has been enhanced uniformly for individual gels to enhance the visibility of the faint bands. (f) Mean lifetimes (mean ± SE) from the DNA nanomachine and linear probe incubated in 70% human serum at 37 °C. Lifetimes were estimated based on normalized band intensities of native PAGE experiments, as described in ESI S4.† These data indicate considerable differences in degradation rates. No data is shown for the Cy5.5-IBRQ Dark linear probe (red asterisk) due to purification issues associated with Cy5.5-IBRQ interaction (see ESI S3†).