When tackling the challenges of drug delivery, new tools are always welcome. And in certain special cases, nature has already solved some of the problems encountered... “We considered sperm a potential candidate to carry drugs, especially in female reproductive tracts, because of their adapted ability to swim in,” says Mariana Medina-Sánchez leader of the Micro and Nanobiomedical Engineering Group at IFW Dresden and coauthor of the study uploaded to pre-print server arXiv (1). “Additionally, sperm have the ability to encapsulate hydrophilic drugs [...] their bodies protect the drugs from body dilution, immunoreactions, and enzyme degradation. And with their somatic cell-fusion ability and such a compact membrane system, sperm can release drugs inside cancer cells while efficiently avoiding dose dumping.”
The project started out as a proposal from Oliver Schmidt, Head of the Institute for Integrative Nanoscience at Leibniz IFW Dresden, who was interested in novel micro-swimmers for biomedical applications – so the sperm-hybrid actually began life as a fertility-booster concept. Says Medina-Sánchez, “To tackle sperm with motility problems but still the ability to fertilize, Schmidt proposed an artificial flagellum to help transport the sperm cell to the oocyte. But inspired by the work of others (we were intrigued by the idea of microorganisms or bacteria carrying drugs) and given the external control we had over the artificial flagella, we thought sperm cells could work as potential therapeutics for female reproductive tract diseases.” The single sperm cell’s swimming action acts as the driving force of motion, but the external control system that guides the mecha-sperm to the desired site – a tumor, for example – uses magnetic fields; the micromotor ‘harness’ is coated with a layer of nanolayer of iron. Buoyed by early results, Medina-Sánchez says, “We are currently working on improving the coupling efficiency of the sperm and micromotors, as well as developing new platforms to carry and deliver multiple sperm at once. We’re also planning to further delve into research to determine the required drug dose, the penetration capability of the sperm, and biodegradation of the complete platform.”
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References
- Haifeng Xu et al, “Sperm-hybrid micromotor for drug delivery in the female reproductive tract” arXiv:1703.08510 (2017). Available at: http://arxiv.org/abs/1703.08510. Accessed May 11, 2017.
