On January 22, 2025, a significant advancement in the realm of nanotechnology was reported regarding DNA-nanoparticle motors. A study published in Nature Communications examined how these artificial motors, which utilize the properties of DNA and RNA to convert chemical energy into mechanical motion, can be optimized to increase their efficiency, particularly in terms of speed.

Understanding DNA-Nanoparticle Motors

DNA-nanoparticle motors are innovative devices that leverage enzymatic processes to create motion. The functioning of these motors is grounded in the burnt-bridge Brownian ratchet mechanism, where chemical bonds (or bridges) are broken down, enabling the motors to move by biasing the natural Brownian motion (random motion of particles suspended in a fluid).

This mechanism presents unique opportunities, especially in applications like molecular computation, diagnostics, and molecular transport. However, a major challenge has been their inability to match the speed of biological motor proteins, which perform essential functions in cellular processes.

Challenge of Speed

According to Takanori Harashima, a leading researcher in the study, the speed of natural motor proteins ranges from 10 to 1,000 nm/s, while traditional DNA-nanoparticle motors have been restricted to much slower speeds of less than 1 nm/s. This disparity highlights a critical area for research and development.

Proposed Solutions

The research team conducted a series of experiments and simulations to identify the bottleneck in motor speed. The findings indicated that the binding of RNase H, an enzyme that degrades RNA in RNA/DNA hybrids within the motor, was a crucial factor in slowing down the entire process. Specifically, longer RNase H binding times resulted in extended pauses during motor activity.

By increasing the concentration of RNase H, they observed a significant improvement in speed, reducing pause lengths from 70 seconds to approximately 0.2 seconds.

Trade-offs in Performance

While increasing RNase H concentration enhanced speed, it also led to trade-offs concerning processivity (the number of steps before detachment) and run-length (the distance traveled before detachment). To mitigate these trade-offs, researchers focused on improving the hybridization rate of the DNA/RNA components. The engineering of DNA/RNA sequences resulted in a remarkable:

  • A 3.8-fold increase in hybridization rate.
  • A final motor speed of 30 nm/s.
  • 200 processivity and a run-length of 3 µm.

These modifications have brought the performance of DNA-nanoparticle motors closer to that of natural motor proteins.

Future Implications

Despite the inherent trade-offs, this research opens up exciting possibilities. Harashima articulated a vision of developing artificial molecular motors that might eventually surpass the performance characteristics of natural motor proteins. Applications for these enhanced motors are vast and could include roles in:

Application Description
Molecular Computation Utilizing motor motion for complex calculations and data processing.
Biomolecular Diagnostics Detecting disease-related molecules with high precision.
Therapeutic Delivery Systems Transporting drugs at the microscale within biological systems.

In summary, the study signifies a pivotal step towards optimizing DNA-nanoparticle motors, potentially enabling them to match or exceed the functionalities of their naturally occurring counterparts. This advancement not only furthers our understanding of artificial molecular systems but also paves the way for innovative applications in biotechnology and medical diagnostics.

References

[1] Harashima, T., et al. (2025). Rational engineering of DNA-nanoparticle motor with high speed and processivity comparable to motor proteins. Nature Communications.

[2] Lifespan.io