Spermbots: potential impact for drug delivery and assisted reproductive technologies

Abstract

Micromotors and nanomotors are an emerging research field that aims at achieving locomotion on the microscale for a variety of applications such as drug delivery, single cell manipulation, microsensors and lab-on-achip devices, just to point out a few. The enthusiastic development of hybrid micromotors harnessing biological power sources for physiologically compatible nano/microdevices has recently brought a lot of attention to the international research community that is looking for a solution for the actuation and locomotion on the microscale. This article describes the potential of spermdriven micro-bio-robots in the biomedical field such as drug delivery or single cell manipulation. Herein, a specific potential of the sperm-driven micro-biorobot is described that might have impact on the development of assisted reproductive technologies.

Biohybrid and Bioinspired Magnetic Microswimmers

“…This technology has mainly been used for sperm cells, but has lately also been applied to bacteria . Sperm cells are studied to solve fertilization problems or for anticancer drug delivery in the female reproductive apparatus, exploiting the natural configuration of sperms that are optimized for swimming in this environment, including viscous media, acidic pH, vaginal flowback, and cervical crypts . One of the major problems to successfully achieve fertilization consists in the release of the cell.…”

“…[88,89] Sperm cells are studied to solve fertilization problems or for anticancer drug delivery in the female reproductive apparatus, exploiting the natural configuration of sperms that are optimized for swimming in this environment, including viscous media, acidic pH, vaginal flowback, and cervical crypts. [114] One of the major problems to successfully achieve fertilization consists in the release of the cell. To address this feature, the simple tube geometry can be updated to include four flexible arms that can bend at contact with surfaces/other cells, and thus release the sperms.…”

Chemotactic Micro‐ and Nanodevices

“…[26] Thus,the affinity of neutrophils to E. coli was employed in af abrication of ah ybrid cargo carrier designed for targeted doxorubicin delivery. These hybrids link the ability of aliving cell, such as,t he neutrophil or sperm cell, to both autonomously move and detect the target they move towards.O nly af ew examples of such biohybrid micromachines utilizing the intrinsic chemotactic abilities of the living cells have been reported so far.The specific design of these hybrid "cyborgs" consists,m ore or less,o fformation of ac argo that will not damage or kill the host, at least until its job is finished, and simultaneously will efficiently fulfil its task in the target area.…”

“…Thea pplication field of these micromachines is predestined by the restrictions of the biological part of these hybrid machines.T he neutrophils will follow the gradient of ac hemoattractant toward the pathogen, thus primarily becoming suitable carriers for specific drug delivery;t he spermatozoa follow the gradients of chemicals produced by the respective gametes,w hich makes them ideal carriers for fertilization-related problems. [26] Thus,the affinity of neutrophils to E. coli was employed in af abrication of ah ybrid cargo carrier designed for targeted doxorubicin delivery. [27] In this experiment the affinity towards E. coli was employed twice-first to mask the cargo and make it suitable for the neutrophil to "load" it and survive and, second in the search for the target (living E. coli) to which the drug was to be delivered.…”

Tubular micromotors: from microjets to spermbots

“…In addition, a proper cell release mechanism needs to be applied to deliver the sperm cell to the fertilization site as well as suitable imaging and control techniques. There are several challenges that must be addressed in future studies when harnessing spermatozoa as transporters, some of which were discussed in a recent editorial [66]. One of the challenges that spermbots will be facing when used as drug delivery vehicles is the immune response of the host organism.…”