- 學位論文
帶電性磁性奈米粒子應用於精子移動控制
Sperm Movement Control Utilizing Surface Charged Modified Magnetic Nanoparticles
摘要
弱精症或寡精症為導致男性不育的重要因素。為了提高受孕機率，針對治療男性不孕症最有效且直接的方法多採單精子卵漿內注射(ICSI)，但此方法經費昂貴、成功率僅約六七成且無法直接於體內執行。2015年由Nasr-Esfahani及Marziyeh提出精子表面整體呈負電性，愈強的負電荷值可能表明精子有更完整的細胞膜，故若能將精子表面與帶電性磁性奈米粒子結合，並通過磁場梯度作用以磁控技術操控精子的移動速度與位置，應可直接提升精子與卵子的接觸機會。 近十幾年來，磁控磁性奈米粒子在生物技術中的應用已經相當廣泛，如傳遞藥物、去除血栓等，由於四氧化三鐵(Fe3O4)磁性奈米粒子具有很高的生物相容性與超順磁特性，因此本研究建構一套磁控精子移動之系統，透過靜電力使帶正電之Fe3O4磁性奈米粒子吸附精子，採用靜態磁場並改變磁場強度及距離，即可誘發磁性材料產生動能，進而帶動精子而達到操控精子移動之目的；若使用帶負電Fe3O4磁性奈米粒子時，透過磁流體之運動亦可間接推動精子移動，但其速度會較慢。 實驗結果顯示透過永久磁鐵產生靜態磁場及磁場梯度後，帶正電Fe3O4磁性奈米粒子與精子細胞膜上負電荷相互吸引而可控制精子移動速度與位置。在磁場強度1.48T時，附著帶正電奈米粒子的精子平移速度約40μm/s，但若使用帶負電之磁性奈米粒子時，因無奈米粒子吸附於精子上，精子不受磁場約束而自由運動；當精子在磁流體溶液中，無論帶正電或帶負電磁性奈米粒子均可藉由磁流體運動帶動精子移動，當磁場強度1.48T時，精子平移速度分別約為100μm/s與80μm/s。而移動速度對磁場強度和磁場梯度呈線性依賴性，與永久磁鐵和精子之間的距離呈二次依賴型。顯示本研究成果已初步驗證精子移動磁控技術是可實現的。
並列摘要
Oligozoospermia or especially asthenospermia is the significant issue related to males for infertility. A popular method to increase the chance of pregnancy is intracytoplasmic sperm injection (ICSI). However, the process is complicated, expensive and can not be implemented in vivo. As shown from previous research, the surface membrane of the sperm is negatively charged. The stronger the negative charge may indicate that the sperm has a more complete cell membrane. (M.H Nasr-Esfahani and T. Marziyeh, 2015). The objective of this research is to establish a system to enhance the movement of sperm by using a combination of oscillating and static magnetic field, thus improving the probability of pregnancy. The goal for this research is to augment the velocity of inactive sperm with magnetically controlled nanoparticles within a variying magnetic field. With very high biocompatibility and super magnetic characteristics, iron oxide(Fe3O4) magnetic nanoparticles(MNPs) are used in this research. Based on Coulomb's law, positively charged MNPs are attracted to the negativly charged cell membrane and attach to help guide it’s movment when placed in a magnetic field. Negatively charged MNPs will repel the sperm cell’s negativly charged surface through the magnetic fluid can therefore be used to direct their movement when introduced to a magnetic field. The permanent magnet in the system is to produce a static magnetic field and gradient and then magnetize the MNPs. Experimental results show that positively charged MNPs were attracted to the negatively charged cell membrane of sperms and the movement speed of the sperms was about 40μm/s at a magnetic field strength of 1.48T. As negatively charged MNPs weren’t attracted to the sperm cell’s negatively charged surface, the sperms would move by themselves without magnetic control. When sperms move in a ferrofluid, no matter the ferrofluid was modified by positively or negatively charged MNPs, sperms would move with the movement of the magnetic fluid, and the maximum moving speed were about 100μm/s and 80μm/s under the magnetic field strength of 1.48T, respectively. The motion velocity of sperms reveals a linear dependence to the magnetic field strength and the field gradient and quadratic dependence with the distance between permanent magnet and the sperm. Our research has verified that the proposed sperm-magnetic controlling technology with MNPs is possible to improve the activity of sperms.
參考文獻
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