Oscillation of membrane potential in immobilized DNA membranes

Immobilized DNA membranes prepared by binding between DNA and poly(γ-methyl-L-glutamate) membranes having a cis-diaminedichloro platinum group-generated oscillation of the membrane potential under a concentration gradient of several salts at frequencies between 0 and 5 Hertz at pH 7.0, although nonmodified poly(γ-methyl-L-glutamate) membranes showed a constant potential. The amplitude of oscillation depended on the length of the joint segments between the DNA and poly(γ-methyl-L-glutamate) membranes; the immobilized DNA membranes modified with diaminopropane and diaminobutane showed a high oscillation amplitude (e.g., 4-5 mV). It was also influenced by the salts used, and the highest oscillation amplitude in the membrane potential across the immobilized DNA membranes modified with diaminobutane was observed when NaCl was used as the salt solution. Fast Fourier transport analysis revealed that the oscillation of the membrane potential had several specific frequencies depending on the salt solution and the immobilized DNA membranes used. Recognition of the model endocrine disrupters (i.e., dibenzo-p-dioxin and biphenyl) from the oscillation of the membrane potential was performed in the immobilized DNA membranes. The drastic decrease in the membrane potential and the decrease in magnitude of the power spectra were observed in the immobilized DNA membranes modified with hexamethylenediamine after the immobilized DNA membranes were immersed in the saturated solution of dibenzo-p-dioxin. It was qualitatively possible to recognize intercalating molecules of DNA including the endocrine disruptors from the membrane potential oscillation data of the immobilized DNA membranes.