A. Zheliaskova et al., Photoconductance effects in bilayer lipid membranes, containing amphiphilic hexadecylbenzospiropyrane derivative, MOLEC CRYST, 352, 2000, pp. 471-477
The effect of photoinduced conformational transitions between closed and op
en form of an alkyl-substituted spiropyrane derivative upon the conductance
of bilayer lipid membranes (BLM) was investigated. BLM were self-assembled
and investigated by the tip-dip patch clamp method from natural soybean le
cithin (SoyL) or from synthetic diphytanoyl lecithin (DPhL) mixed with 10%
wt hexadecylbenzospiropyrane (SP). Photoisomerization (closed-open) of spir
opyrane was effected by repetitive UV light pulses. The reverse isomerizati
on (open-closed) was achieved by continuous illumination with white light.
Current vs. voltage measurements were performed in dark, after termination
of UV or visible light irradiation.
Experimental results with SoyL displayed a reversible increase of the dark
BLM conductivity upon UV illumination. However, results with DPhL showed th
e opposite, although weaker, overal tendency: a visible light-induced incre
ase and a UV-induced decrease. This demonstrated the crucial role of lipid
matrix steric asymmetry in the observed photoconductance effects and eventu
ally suggested a different structure of the conducting pores.