2018 - Quantifying Permeation of Small Charged Molecules across Channels: Electrophysiology in Small Volumes
Port-a-Patch and 
Vesicle Prep Pro publication in ACS Omega (2018)
Authors:
Wang J., Benier L., Winterhalter M.
Journal:
ACS Omega (2018) doi: 10.1021/acsomega.8b01611
Abstract:
A major bottleneck in the development of small molecule antibiotics is to achieve good permeability across the outer membrane in Gram-negative bacteria. Optimization with respect to permeability surprisingly lacks appropriate methods. Recently we proposed to use the diffusion potential for charged molecules created by their difference in electrophoretic mobility while crossing the outer membrane channel under a concentration gradient. The latter provides semi-quantitative values but the current available setups require large volumes and thus exclude several classes of molecules. Here we propose a simple approach capturing proteoliposomes at aperture of glass surface (planar aperture or conical glass capillary) decreasing the necessary volume below 50 µL. We measured the transport of two charged molecules sulbactam and ceftazidime across the two major porins in E.coli. Both molecules permeate through these porins were observed with sulbactam owes higher permeability.