Fixed Path Length Sample Holders Enable Robust Cryosaxs Measurements from Sub-Microliter Sample Volumes

Small angle x-ray scattering (SAXS) gives structural information about biological molecules in solution. However, large (∼30 microliter) sample volumes are needed to mitigate radiation damage, limiting the use of SAXS in studying rare molecules. By cryocooling SAXS samples, radiation damage and required sample volumes are reduced by orders of magnitude [1], but challenges in creating identically-sized frozen samples complicate background subtraction. Here we present microfabricated silicon sample holders for cryoSAXS. These rigid sample holders have a fixed x-ray path length, simplifying background subtraction. Less than 800 nL of sample are required, facilitating measurements on expensive or hard-to-express molecules. These fixed path length, low volume sample holders make cryoSAXS a more accessible technique capable of probing a wide range of biological molecules.1. S. P. Meisburger et al. Biophys. J. 104, 227 (2013).