| Active transport of ions across membranes and against thermodynamic gradients is essential for many cellular functions such as energy storage, excitability, or volume control. The active transport of calcium ions can be divided into two broad classes: primary pumps that utilize an energy source directly, and secondary transport mechanisms which exchanges a concentration gradient of ions such as Na+, K+, or H+, for a Ca2+ gradient. Synthetic approaches to Ca2+ transport often use a chemical potential gradient to carry ions across phase boundaries. In this work a secondary transport system using the poly-ether antibiotic ionomycin which exchanges a proton gradient, developed by an artificial photosynthetic membrane, for a Ca2+ gradient has been explored. In addition, a primary pump that directly utilizes the redox potential generated by an artificial photosynthetic membrane has been developed. The system transports calcium ions across the bilayer of a liposome to develop both a calcium ion concentration gradient and a membrane potential. |
