Membrane potential, photoresponsive

PhotocontroUed Transport Phenomenon in Lipid Bilayer Membranes. Photocontrolled ion transport across lipid bilayer membranes using photoresponsive compounds such as azobenzene derivatives has been of great interest for potential applications in optoelectronic devices and optical transducers. Most research has exploited membrane capacitance change because of the disruption of membrane structures resulting from photoisomerization of azoben-zene-containing compounds incorporated into the lipid bilayers. Others have used the volumetric change of azobenzene moieties associated with photoisomerization. 

Moreover, a low molar mass spiropyran compound entrapped in a membrane consisting of plasticized poly(vinyl chloride) rendered the latter photoresponsive. A membrane potential change of more than 100 mV was induced by irradiation with light [27]. For further details and additional references, the reader is referred to the relevant reviews [11, 28]. 

Fig. 5.5 Photoresponsive behavior of membranes of an azo-modified poly(L-glutamic acid) containing 12-14 mol% azobenzene groups at 60°C. (a) Membrane potential,...

Fig. 2. Upper portion A record of potential difference across a chloroplast extract BLM exposed on both sides to 0.1 M potassium acetate buffer pH 5.0, containing 1 mMFeCls and 0.5 mM FeCla. Membrane potential, was varied by applying various currents through another pair of electrodes. Ascorbic acid was added to outside solution at time indicated. Polarity refers to inside solution. Lower portion Analysis of photoresponse, JK, as a function of membrane potential, Vm, before (curve I) and after (curve II) addition of ascorbic acid to outside solution. The points in the lower portion of the figure are calculated from the record shown in the upper portion. The labels a, b, c, etc., indicate the corresponding points on record trace in the upper portion of the figure. (Reprinted from reference [9], by courtesy of Springer-Verlag, Inc.).

S. Shinkai, K. Shigematsu, M. Sato and O. Manabe, Photoresponsible crown ethers. Part 6. Ion transport mediated by photoinduced cis-trans interconversion of azobis-(benzocrown ether), J. Chem. Soc., Perkin Trans. I, 1982, 2735-2739 J. Anzai, H. Sasaki, A. Ueno and T. Osa, Photo-induced potential changes across poly(vinyl chloride)-crown ether membranes, J. Chem. Soc., Chem. Commun., 1983, 1045 J. Anzai, H. Sasaki, K. Shimokawa, A. Ueno and T. Osa, Photocontrol of alkali metal ion permeability through the poly(vinyl chloride)/crown ether membranes, Nippon Kagaku Zasshi, 1984, 338. 

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