Blockage of action potential-like spiking in D2O-suspended proteinoid microspheres

This study investigates the effects of heavy water (D${}_2$O) on action potential-like electrical activity in proteinoid microspheres. We demonstrate that D${}_2$O completely suppresses spontaneous electrical spiking, contrasting with the robust spiking patterns observed in deionized water (mean amplitude 5.39–9.81 mV, period 2489–2826 s). Electrochemical impedance spectroscopy shows that charge transport differs between the two environments: deionized water has charge transfer behavior ($Z_{max}^{\prime }\approx 8$ k$\Omega$), while D₂O exhibits diffusion-dominated responses ($Z_{max}^{\prime }\approx 120$ k$\Omega$). Cyclic voltammetry measurements show different behaviors for D₂O and H₂O. D₂O has stable current responses up to 900 mV/s. Then, at 1000 mV/s, there is a sharp rise (I_a = $22.71\mu A$, I_c = $-22.19\mu A$). H₂O, on the other hand, shows gradual current increases as the scan rate rises. Statistical analysis shows significant differences ($p<0.0001$) in membrane potential dynamics between the two conditions, with D${}_2$O showing reduced variability (${\sigma }_{D_{2}O}=1.70-15.08$ mV vs ${\sigma }_{DI}=12.01-22.40$ mV). Using an R(CW)RO topology for equivalent circuit modeling shows enhanced diffusion limits in D${}_2$O. This suggests changes in charge transport mechanisms. The model has a ${\chi }^2$ of 0.0736. These findings show how cellular bioelectricity works. They highlight the important role of proton dynamics in creating the basic membrane potential.