Make it spin: individual trapping of sperm for analysis and recovery using micro-contact printing

Abstract

In this article, we describe the development of a high throughput platform to spatially manipulate viable sperm for motility measurements and recovery of the best single sperm for fertilization purposes. Micro-contact printing was used to pattern islands of adhesive proteins (fibronectin) separated by sperm repellent species (Pluronic acid F-127) on commercially available polystyrene substrates. Following washing, arrays of viable single sperm were captured onto the islands demonstrating for the first time that sperm can be trapped by micro-contact printing with patterning efficiency of 90% while retaining 100% viability. These were then subjected to motility analysis whilst remaining spatially confined to the islands. Single sperm motility was assessed (n = 37) by software analysis measuring the number of rotations per second (degrees s⁻¹). The assignment of array coordinates allows the more active single sperm to be easily identified and recovered by a simple micromanipulator pipette aspiration step with automated possibility for assisted reproductive technologies or further quality correlation analysis. Taken together, we show for the first time a technique to simultaneously screen thousands of viable single sperm for motility assessment while retaining the ability for single species recovery for enhanced fertilization purposes.

Disrupting the wall accumulation of human sperm cells by artificial corrugation

“…This effect may be of minor importance in typical mL volume chambers, but will certainly become a dominant issue in the miniaturized micro or nanoliter volume chambers used in microfluidic lab-on-chip devices (platforms all-in-one). 4,5,[20][21][22] In other words, it would be highly desirable to find a way to counteract the material-independent and ubiquitous cell accumulation at the chamber boundaries with a mechanism leading to the formation of a more uniform density distribution of microswimmers.…”

How to Improve Spermbot Performance

“…In addition to the physical trapping of the cell inside the microtube, the cell‐tube binding is supported by attaching biomolecules on the inner tube surface that interact with the sperm cell membrane during the coupling. There are several candidates that are able to bind to sperm cells such as Fn, hyaluronic acid, and others . The glycoprotein Fn is a component of the extracellular matrix which is also present in the surroundings of the oocyte .…”

“…The integrins connect the external environment with the interior cytoskeleton of the cell and act as mediators . Fn was recently utilized in a high throughput platform to attach and analyze single spermatozoa to a planar surface . One of the goals in this work was to attach Fn on the inner tube lining.…”

“…This technique involves the printing of the target protein directly on the nanomembranes before the roll‐up of the microtubes. This method is a form of soft‐lithography, which was introduced in 1996 by Whitesides and co‐workers at Harvard University and was also applied for binding sperm cells onto glass or polystyrene surfaces printed with Fn . Polydimethylsiloxane (PDMS) stamps with squared pillars (with geometries of 20 × 20 μm 2 and 50 × 50 μm 2 , height 10 μm) were prepared by using a soft‐lithography technique.…”

Spermometer: electrical characterization of single boar sperm motility

“…Nascimento et al (18) showed the potential to entrap single sperm cells using laser tweezers and to measure their motility optically. In previous work from our group, we used microcontact printed fibronectin spots to entrap single sperm cells, after which their motility was analyzed using image analysis (19). With a different approach, we used a hydrodynamic trapping procedure to entrap single sperm cells in small microfluidic channels to study their viability, acrosome integrity, and sex chromosome content using fluorescent analysis (20).…”