Unfertilised eggs (oocytes) release chemical biomarkers into the medium surrounding them. This provides an opportunity to monitor cell health and development during assisted reproductive processes if detected in a non‐invasive manner. Here we report the measurement of pH using an optical fibre probe, OFP1, in 5 μL drops of culture medium containing single mouse cumulus oocyte complexes (COCs). This allowed for the detection of statistically significant differences in pH between COCs in culture medium with no additives and those incubated with either a chemical (cobalt chloride) or hormonal treatment (follicle stimulating hormone); both of which serve to induce the release of lactic acid into the medium immediately surrounding the COC. Importantly, OFP1 was shown to be cell‐safe with no inherent cell toxicity or light‐induced phototoxicity indicated by negative DNA damage staining. Pre‐measurement photobleaching of the probe reduced fluorescence signal variability, providing improved measurement precision (0.01‐0.05 pH units) compared to previous studies. This optical technology presents a promising platform for the measurement of pH and the detection of other extracellular biomarkers to assess cell health during assisted reproduction.

中文翻译：

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一种在体外测量小体积pH值的生物光子方法：卵-卵母细胞复合体（COC）周围代谢通量的可量化差异。

未受精卵（卵母细胞）将化学生物标志物释放到它们周围的培养基中。如果以非侵入性方式检测到，这将提供机会在辅助生殖过程中监测细胞健康和发育。在这里，我们报告使用光纤探针OFP1在5μL含有单个小鼠卵丘卵母细胞复合物（COC）的培养基滴中测量pH值。这样就可以检测出无添加剂的培养基中的COC与经过化学处理（氯化钴）或激素处理（促卵泡激素）的COC之间pH值之间的统计学差异。两者都有助于诱导乳酸释放到紧邻COC的培养基中。重要的，OFP1被证明是对细胞安全的，没有DNA阴性染色指示的固有细胞毒性或光诱导的光毒性。与以前的研究相比，探针的预测量光漂白减少了荧光信号的变异性，提供了更高的测量精度（0.01-0.05 pH单位）。这项光学技术提供了一个有前途的平台，可用于测量pH值和检测其他细胞外生物标志物，以评估辅助生殖过程中的细胞健康状况。