Quantum Dynamics of Radical Pairs Reactions in Membranes: Elucidating Magnetic Field Effects in Lipid Autoxidation

自由基是普遍存在的短寿命反应中间体，其包含单个未配对电子，并且通常以明确定义的电子自旋状态成对产生，单重态（“反平行自旋”）或三重态（“平行自旋”）。对于涉及这种自由基对的化学反应，量子效应可以引起对与地球磁场一样弱的外部静磁场的强度和/或方向的显着敏感性。潜在的机制，所谓的自由基对机制，吸引了科学界和普通观众的广泛兴趣，由于其推定的相关性，动物磁感受和弱电磁场对人类健康的可能不利影响。事实上，大量研究表明弱磁场暴露与氧化应激水平增加、遗传毒性效应和细胞凋亡/坏死之间存在关联。虽然详细的相互作用模型仍然缺乏-一个因素，严重阻碍了部分有争议的文献对这个问题的评估和磁场暴露的指导方针的进步-磷脂的氧化降解出现在许多暴露研究的首要主题。事实上，已知活性氧及其诱导的自由基攻击磷脂膜中的多不饱和脂肪酸，从而引发脂质过氧化反应，这改变了膜特性并诱导细胞损伤。通过这种自由基链反应的终止和简并链支化步骤，磁敏性被可行地赋予。不幸的是，仍然缺乏对这些效应的机理细节和合理的理论理解：自由基对机理还没有被开发用于局限于二维的系统，例如脂质双层，并且所涉及的自由基的性质还没有关于磁敏路径和自旋弛豫来表征。这里，我提出了一个理论和计算调查的复杂性的自由基对机制在两个-三维界面和探索相关的放大机制超越了标准的自由基对机制，我最近在磁感受领域提出，但在这方面完全未被探索。特别是，我将集中在：a）限制的耦合自由基对的扩散到两个维度的效果，B）的潜在的分子运动，导致噪声增强的磁场效应（MFEs），和c）所谓的化学芝诺效应，其中MFEs被放大的清除反应与自旋携带的反应partners.I设想找到支持的假设，意想不到的大MFEs可以随之而来，在这些封闭的系统，内在的和上述二级放大效应的结果。除了提供对MFE更好，更完整的理解外，我们的工作还将揭示如何在嘈杂的环境中维持和放大微妙的量子效应。这些见解对于新兴的量子生物学领域至关重要，可以为增强量子设备和传感器铺平道路，提高对环境噪声的适应能力。此外，如果发现这种扩增方案适用于生物学相关反应，则可能会促使人们重新评估弱磁场暴露的健康风险，并在未来研究使用MFE作为疗法，通过自由基对机制增强免疫反应。缩写：MFE =磁场效应; RPM =自由基对机制。

Radicals are ubiquitous short-lived reaction intermediates that contain a single unpaired electron and are usually created in pairs in a well-defined electronic spin state, either singlet ("anti-parallel spins") or triplet ("parallel spins"). For chemical reactions involving such pairs of radicals, quantum effects can induce a remarkable sensitivity to the intensity and/or orientation of external static magnetic fields as weak as the Earth's magnetic field. The underlying mechanism, the so-called Radical Pair Mechanism, has attracted widespread interest from the scientific community and general audiences owing to its putative relevance to animal magnetoreception and possibly adverse effects of weak electromagnetic fields on human health. Indeed, a multitude of studies have suggested an association between weak magnetic field exposure and increased levels of oxidative stress, genotoxic effects and apoptosis/necrosis. While detailed interaction models are still lacking - a factor that severely impedes the assessment of partly controversial literature on this subject and the advancement of guidelines for magnetic field exposure - the oxidative degradation of phospholipids appears as an overarching motif in many exposure studies. Indeed, reactive oxygen species and the free radicals they induce are known to attack polyunsaturated fatty acids in phospholipid membranes, thereby initiating lipid peroxidation reactions, which alter membrane characteristics and induce cell damage. Through termination and degenerate chain branching steps of this free-radical chain reaction, magnetosensitivity is feasibly imparted. Unfortunately, mechanistic details and a sound theoretical understanding of these effects are still lacking: the Radical Pair Mechanism has not yet been developed for systems confined to two dimensions, such as lipid bilayers, and the properties of the involved radicals have not been characterized with respect to magnetosensitive pathways and spin relaxation.Here, I propose a theoretical and computational investigation of intricacies of the radical pair mechanism at two-dimensional interfaces and the exploration of related amplification mechanisms beyond the standard Radical Pair Mechanism that I have recently suggested in the field of magnetoreception, but which are utterly unexplored in this context. In particular, I will focus on:a) the effect of confining the diffusion of coupled radical pairs to two dimensions,b) the potential for molecular motion to result in noise-enhanced magnetic field effects (MFEs), andc) the so-called chemical Zeno effect, by which MFEs are amplified by scavenging reactions with spin-carrying reaction partners.I envisage to find support for the hypothesis that unexpectedly large MFEs could ensue in these confined systems, intrinsically and as a consequence of the abovementioned secondary amplification effects. In addition to providing a better, more complete understanding of MFEs, our work will also reveal how subtle quantum effects can be sustained and amplified in noisy environments. These insights are essential to the emerging field of Quantum Biology and could pave the way to enhanced quantum devices and sensors with improved resilience to environmental noise. Furthermore, if such amplification schemes are found to apply to biologically relevant reactions, it could prompt a reassessment of the health risks of weak magnetic field exposure and future research into the use of MFEs as therapeutics to boost the immune response via the radical pair mechanism.Abbreviations: MFE = Magnetic Field Effect; RPM = Radical Pair Mechanism.