A team of scientists from the Institute for Integrative Nanosciences in Dresden has developed what it is calling a "spermbot," which it claims could provide a more effective treatment for male infertility than other available options. Artificial insemination, for instance, involves inserting sperm directly into a woman’s womb, yet yields success rates of only 30 percent, while in vitro fertilization (IVF), whereby eggs are removed from the ovaries and injected with sperm in a laboratory, can be more effective but also considerably more expensive.
Moreover, neither of these techniques address one of the major causes of male infertility: immotile sperm – in other words, sperm that are unable to swim well. Often, these gametes are in fact fertile, and just as capable of reproduction as those that do swim well, yet their immobility prevents them from ever reaching the egg.
To address this, the team behind the invention created a miniature polymer helix, which they then coated in nickel and titanium so that it could be controlled magnetically. In the laboratory, they propelled the helix through a solution using a rotating magnetic field, and were able to guide it towards bovine sperm placed in a petri dish. By coiling around the flagellum – or tail – of the sperm, the helix was then able to carry it, driving it forwards and delivering it to the wall of a bovine oocyte, or egg.
Having reached its destination, the helix was then propelled in reverse, as can be seen in the video below, thereby releasing the sperm and allowing it to fertilize the egg.
Publishing a report of their study in the American Chemical Society’s journal Nano Letters, the researchers note that the motorization of sperm may prove preferable to IVF, since it allows fertilization to take place in vivo – meaning inside the body – rather than in a laboratory. However, they concede that they are still a long way from being able to begin trialing this new technology in humans, and several complications still have to be overcome in order to ensure the safety and efficacy of these spermbots.
For instance, while the researchers were able to guide the helixes towards their intended target in a petri dish, doing so in the body presents a much more daunting challenge. Furthermore, the team reports that they often had difficulty getting the spermbots to dislodge from the sperm once the oocyte wall had been reached, and this stage of the process will have to be perfected before any in vivo tests can be conducted.