This study investigates the effects of shape on the transport and trafficking of micelles compared to spherical particles in biological systems. The researchers used highly stable polymer micelle assemblies called filomicelles, which persisted in the circulation of rodents for up to one week after intravenous injection, significantly longer than spherical particles. Under fluid flow conditions, shorter filomicelles were more readily taken up by cells than longer filaments due to the extension of the latter by the flow. Preliminary results also showed that filomicelles loaded with the anticancer drug paclitaxel effectively shrank human-derived tumors in mice. The findings suggest that long-circulating vehicles need not be spherical and provide insights into the possible shape effects of natural filamentous viruses. The study highlights the importance of shape in biological systems at the nanoscale and the potential of filamentous carrier systems for drug delivery.This study investigates the effects of shape on the transport and trafficking of micelles compared to spherical particles in biological systems. The researchers used highly stable polymer micelle assemblies called filomicelles, which persisted in the circulation of rodents for up to one week after intravenous injection, significantly longer than spherical particles. Under fluid flow conditions, shorter filomicelles were more readily taken up by cells than longer filaments due to the extension of the latter by the flow. Preliminary results also showed that filomicelles loaded with the anticancer drug paclitaxel effectively shrank human-derived tumors in mice. The findings suggest that long-circulating vehicles need not be spherical and provide insights into the possible shape effects of natural filamentous viruses. The study highlights the importance of shape in biological systems at the nanoscale and the potential of filamentous carrier systems for drug delivery.