Gelatin Microcartridges for Onboard Activation and Antioxidant Protection of Sperm

Abstract

Sperm-driven micromotors are promising devices for developing autonomous, noninvasive diagnostic and therapeutic tools, specifically in reproductive biology and medicine. In this article, we present template-based microstructures fabricated from gelatin for sperm capture, activation, and antioxidant protection. The cartridge-like structures with one closed end-capture single bovine sperm cells and are propelled by the sperm's flagellum. We demonstrate the pH-dependent release of heparin from the gelatin microcartridges to induce capacitation, a crucial maturation process prior to fertilization. Further, the gelatin cartridges exhibit a protection against oxidative stress, one of the main causes for sperm damage. Finally, we investigate the stability and degradability of the microstructures in various physiological environments, such as endometrial cell culture, different pH, and in the presence of proteases. Overall, we prove that these gelatin spermbots display great potential for the development of noninvasive theranostic tools in reproductive biology and medicine for the protection and activation of sperm, especially useful for studying sperm migration. We present their beneficial features which comprise not only biocompatibility and biodegradability but also pH response, loading stability, and antioxidant protection.

Vitamin E Delivery Systems Increase Resistance to Oxidative Stress in Red Deer Sperm Cells: Hydrogel and Nanoemulsion Carriers

“…Recently, Ridzewski et al (2020) proved that gelatin spermbots, using a polycarbonate template, have great potential for the development of noninvasive theranostic tools in reproductive biology and medicine for the protection and activation of sperm, which is especially useful when studying sperm migration. Their beneficial features include biocompatibility and biodegradability, as well as pH response, loading stability, and antioxidant protection [ 29 ]. Keeping all these results in mind, we propose the use of hydrogels for the controlled release of VE to prevent oxidate stress in spermatology.…”

Hydrogel-Based Stimuli-Responsive Micromotors for Biomedicine

“…The variations in pH are ubiquitous in certain body sites (such as vagina, gastrointestinal tract, and blood vessels), which provides a natural initiator to trigger the swelling/deswelling action of hydrogel-based pH-responsive micromotors. Scientists have successfully enhanced the sperm motion capacity and triggered sperm capacitation, which is a crucial maturation process before fertilization, by releasing heparin from HBSR micromotors containing pH-responsive gelatin hydrogels at pH 8 [ 63 ]. Based on the correlation between the pH value and the velocity of the bubble-propelled micromotor, pH-responsive HBSR micromotor containing gelatin hydrogels can be applied for motion-based pH sensing [ 64 ].…”

Nano/Micromotors in Active Matter

“…Biocompatibility, efficient locomotion in the low Reynolds number flow and manipulability make sperm cells become an ideal power source for NMMs [70]. The most common sperm-based NMMs are composed of well-designed microcap and the sperm cell [13,[71][72][73][74] (Figure 6). The microcap provides the object for functionalizing the NMM, while the sperm cell serves as the motor for the power.…”

“…The high propulsion force enables sperm cells to power NMMs to swim against flowing blood and to deliver cargos [13] (Figure 6b). In various physiological environments, microcaps can protect against oxidative stress that may damage sperm cells [74]. Together, NMMs driven by sperm cells have a good prospect in cargo delivery and targeted therapy and have become a potential treatment for gynecological diseases and cancer.…”