用二维晶体增强散射信号，让高背景下的X射线成像成为可能
High-background X-ray single particle imaging enabled by holographic enhancement with 2D crystals
- 在目标物旁加二维晶体，利用其布拉格峰增强信号
- 可在背景比信号高10万倍的环境下实现结构重建
- 适合同步辐射源，支持固定靶样品，接近真实生物环境
X射线单颗粒成像（SPI）有望实现近原子分辨率的生物分子结构解析。然而，目前在X射线自由电子激光（XFEL）上达到的结构分辨率仍受限于背景散射。本文通过计算模拟，提出一种基于强散射二维晶体晶格的全息增强型改进SPI方法。该晶体产生的布拉格峰可使结构重构在背景信号高达目标信号10⁵倍的情况下依然可行。该方法有望使SPI在更易获取的同步辐射光源中实现，当前在此类光源下甚至难以检测到样品，且支持固定靶样品输送，可在接近天然条件下实现高分辨率成像。通过自研重建算法进行数值模拟，验证了该方法在提升分辨率和扩大应用范围方面的潜力。
原文摘要 · Abstract (English)
X-ray single particle imaging (SPI) has offered the potential to visualize structures of biomolecules at near-atomic resolution. However, state-of-the-art structures at X-ray free electron lasers (XFELs) are limited to moderate resolution, primarily due to background scattering. We computationally explore a modified SPI technique based on holographic enhancement from a strongly scattering 2D crystal lattice placed near the object. The Bragg peaks from the crystal enable structure retrieval even for background levels up to 10$^{5}$ times higher than the object signal. This method could enable SPI at more widely accessible synchrotron sources, where even detection of objects before radiation damage is nearly impossible currently, supports practical fixed-target sample delivery, and enables high-resolution imaging under near-native conditions. Numerical simulations with a custom reconstruction algorithm to recover the latent parameters show the potential to improve the achievable resolution while also expanding the accessibility to the technique.
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