Analytical Sciences

Separation of Progressive Motile Sperm from Mouse Semen Using On-chip Chemotaxis

Yong-Jun KO,*1 Joon-Ho MAENG,*2 Byung-Chul LEE,*2 Seungwoo LEE,*1 Seung Yong HWANG,*3 and Yoomin AHN*4

*1 Department of Mechanical Engineering, Graduate School, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea
*2 Department of Biochemistry, Graduate School, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan Kyeonggi-do 426-791, Korea
*3 Division of Molecular and Life Science, Hanyang University and GenoCheck Co. Ltd., 55 Hanyangdaehak-ro, Sangnok-gu, Ansan Kyeonggi-do 426-791, Korea
*4 Department of Mechanical Engineering, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan Kyeonggi-do 426-791, Korea

We present a novel method for the separation of progressive motile sperm from non-progressive motile and immotile sperm. This separation was accomplished by inducing chemotaxis along a longitudinal chemical gradient in a microchip composed of a biocompatible polydimethysiloxane layer and a glass substrate. In a preliminary experiment using fluorescent rhodamine B as a marker, we verified that a chemical gradient was generated by diffusion within the microchannel. We used acetylcholine as a chemoattractant to evaluate the chemotactic response of sperm. We tested the response to a 1/2 to 1/64 dilution series of acetylcholine. The results of a mouse sperm chemotaxis assay showed that progressive motile sperm swam predominantly toward the outlet at an optimal chemical gradient of 0.625 (mg/ml)/mm of acetylcholine. This device provides a convenient, disposable, and high-throughput platform that could function as a progressive motile sperm sorter for potential use in intracytoplasmic sperm injection.

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