BEHAVIOR OF THE RATE-CONSTANT FOR REACTIONS IN RESTRICTED SPACES - FLUORESCENCE PROBING OF LIPID VESICLES

The bimolecular reaction A + B --> products, where [A] < [B], was studied by fluorescence probing of small unilamellar vesicles of dipalmitoylphosphatidylglycerol with pyrene, and by computer simulation on a square lattice containing nonpercolating clusters. The decay curves of the minority species were fitted with an equation obtained from the theory of random walks in fractal domains. The analysis of the data has allowed redefinition of the reaction rate in restricted geometries, which is now time dependent, and sets the basis for simple treatment of bimolecular reactions in organized assemblies. The values of the spectral dimension calculated from this work are in the range 0.35-0.66, where the upper limit reflects the Alexander-Orbach conjecture, and the lower values are used to monitor the solubilizate aggegation in vesicles.