Petkowski Janusz Jurand, Bains William, Seager Sara
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Mass. Ave., Cambridge, MA 02139, USA.
Department of Physics, Massachusetts Institute of Technology, 77 Mass. Ave., Cambridge, MA 02139, USA.
Life (Basel). 2020 Jun 10;10(6):84. doi: 10.3390/life10060084.
Despite more than one hundred years of work on organosilicon chemistry, the basis for the plausibility of silicon-based life has never been systematically addressed nor objectively reviewed. We provide a comprehensive assessment of the possibility of silicon-based biochemistry, based on a review of what is known and what has been modeled, even including speculative work. We assess whether or not silicon chemistry meets the requirements for chemical diversity and reactivity as compared to carbon. To expand the possibility of plausible silicon biochemistry, we explore silicon's chemical complexity in diverse solvents found in planetary environments, including water, cryosolvents, and sulfuric acid. In no environment is a life based primarily around silicon chemistry a plausible option. We find that in a water-rich environment silicon's chemical capacity is highly limited due to ubiquitous silica formation; silicon can likely only be used as a rare and specialized heteroatom. Cryosolvents (e.g., liquid N) provide extremely low solubility of all molecules, including organosilicons. Sulfuric acid, surprisingly, appears to be able to support a much larger diversity of organosilicon chemistry than water.
尽管有机硅化学已有一百多年的研究历史，但硅基生命合理性的依据从未得到系统探讨或客观审视。我们基于对已知内容和已建模内容（甚至包括推测性工作）的回顾，对硅基生物化学的可能性进行了全面评估。我们评估了与碳相比，硅化学是否满足化学多样性和反应性的要求。为了拓展合理的硅基生物化学的可能性，我们探索了硅在行星环境中发现的各种溶剂（包括水、低温溶剂和硫酸）中的化学复杂性。在任何环境中，以硅化学为主的生命都不是一个合理的选择。我们发现，在富水环境中，由于普遍形成二氧化硅，硅的化学能力受到极大限制；硅可能只能用作稀有且特殊的杂原子。低温溶剂（如液氮）对所有分子（包括有机硅）的溶解度极低。令人惊讶的是，硫酸似乎比水能够支持更多样化的有机硅化学。
