In vitro fertilization (IVF) is the most common assisted reproductive technology used to treat infertility. Embryo selection for transfer in IVF cycles relies on the morphological evaluation by embryologists, either by conventional microscopic assessment or more recently by time-lapse imaging systems. Despite the introduction of time-lapse imaging improvements in IVF success rates have failed to materialize, therefore alternative approaches are needed. Recent studies have shown that embryos resulting in successful pregnancy differ in their secretome and metabolism compared to embryos that fail to implant, suggesting that the molecular analysis of the culture medium could assist in non-invasive single embryo selection. However, this approach has yet to be adopted clinically due to the lack of appropriate highly sensitive screening technologies needed to assess volume-limited samples. Here we report the detection of hCGβ, IL-8 and TNFα from conditioned culture media of single human embryos using electrochemical impedance spectroscopy. The impedimetric immunosensors revealed that morphologically non-viable embryos produce higher concentrations of IL-8 and TNFα, associated with abnormal cell division and cell death, respectively. More importantly, hCGβ detection was able to discriminate apparent morphologically identical viable embryos. This work brings an objective dimension to embryo selection, which could overcome the major limitations of morphology-based embryo selection for implantation. Future work should include the validation of these biomarkers in a large patient cohort.

体外受精（IVF）是用于治疗不育症的最常见辅助生殖技术。在IVF周期中转移的胚胎选择取决于胚胎学家的形态学评估，或者通过常规显微镜评估，或者最近通过延时成像系统进行。尽管引入了延时成像技术，但IVF成功率的改善未能实现，因此需要替代方法。最近的研究表明，与未能植入的胚胎相比，导致成功妊娠的胚胎在分泌组和代谢方面存在差异，这表明对培养基进行分子分析可以帮助非侵入性选择单个胚胎。然而，由于缺乏评估体积受限样品所需的适当高灵敏度筛选技术，因此该方法尚未在临床上采用。在这里，我们报告使用电化学阻抗谱从单个人类胚胎的条件培养基中检测到hCGβ，IL-8和TNFα。阻抗免疫传感器显示，形态学上不可行的胚胎产生更高浓度的IL-8和TNFα，分别与异常的细胞分裂和细胞死亡有关。更重要的是，hCGβ检测能够区分明显的形态相同的存活胚胎。这项工作为胚胎选择带来了一个客观的维度，可以克服基于形态学的胚胎选择的主要局限性。