[Sensors] Innovative High-Throughput SAXS Methodologies Based on Photonic Lab-on-a-Chip Sensors: App
The relevance of coupling droplet-based Photonic Lab-on-a-Chip (PhLoC) platforms and Small-Angle X-Ray Scattering (SAXS) technique is here highlighted for the performance of high throughput investigations, related to the study of protein macromolecular interactions. With this configuration, minute amounts of sample are required to obtain reliable statistical data. The PhLoC platforms presented in this work are designed to allow and control an effective mixing of precise amounts of proteins, crystallization reagents and buffer in nanoliter volumes, and the subsequent generation of nanodroplets by means of a two-phase flow. Spectrophotometric sensing permits a fine control on droplet generation frequency and stability as well as on concentration conditions, and finally the droplet flow is synchronized to perform synchrotron radiation SAXS measurements in individual droplets (each one acting as an isolated microreactor) to probe protein interactions. With this configuration, droplet physic-chemical conditions can be reproducibly and finely tuned, and monitored without cross-contamination, allowing for the screening of a substantial number of saturation conditions with a small amount of biological material. The setup was tested and validated using lysozyme as a model of study. By means of SAXS experiments, the proteins gyration radius and structure envelope were calculated as a function of protein concentration. The obtained values were found to be in good agreement with previously reported data, but with a dramatic reduction of sample volume requirements compared to studies reported in the literature.
Isaac Rodríguez-Ruiz 1, Dimitri Radajewski 2, Sophie Charton 1, Nhat Phamvan 2, Martha Brennich 3, Petra Pernot 3, Françoise Bonneté 4 and Sébastien Teychené 2,* 1 CEA, DEN, DMRC, SA2I, 30207 Bagnols-sur-Cèze, France 2 Laboratoire de Génie Chimique, UMR 5503, 4 allée Emile Monso, 31432 Toulouse, France 3 European Molecular Biology Laboratory, 71 avenue des Martyrs, 38000 Grenoble, France 4 Institut des Biomolécules Max-Mousseron, UMR 5247, Université d’Avignon, 33 rue Louis Pasteur, 84000 Avignon, France * Author to whom correspondence should be addressed. Academic Editors: Remco J. Wiegerink and Luis J. Fernandez Received: 19 April 2017 / Revised: 17 May 2017 / Accepted: 31 May 2017 / Published: 2 June 2017 (This article belongs to the Special Issue Microfluidic Sensors and Control Devices)