Nanomotors hold great promise as a new paradigm in drug delivery . The active delivery of drugs to a specific disease site would a) greatly diminish the therapeutic dosage and b) reduce collateral cytotoxicity. However, there are several challenges to achieving this goal. In many in vivo applications, the nanomotors need to be powerful enough to move against fluid flow, such as in circulatory systems . This remains to be demonstrated. However, the observation of rheotaxis by active nanomotors enabling them to move near walls against fluid flow is a useful development . One alternative is to deploy the nanomotors locally, in confined spaces, where diffusion is limited, and traditional drugs cannot easily reach the target.