Study of effect of silver nanoparticles on the electrical excitability of hippocampal neuronal network based on “Voltage Threshold Measurement Method”

The purpose of this study is to investigate the effect of silver nanoparticles (SNPs) on the electrical excitability of hippocampal neuronal networks by using the voltage threshold measurement method (VTMM) based on micro-electrode array (MEA). First, SNPs were prepared and characterized, and then, the hippocampal neuronal network was prepared on an MEA, and the normal voltage threshold $\left(V_{\mathrm{Th}}\right)$ of the hippocampal neuronal network (control group) was measured by VTMM. After that, 5 $\mu \mathrm{M}$ and $100-\mu \mathrm{M}$ SNPs were added and the $V_{\text {Th}}$ of the hippocampal neuronal networks were measured. The results showed that the normal $V_{\text {Th}}$ of the hippocampal neuronal network in the control group were 55.14,55.00,54.71,54.85 and 55.00 mV after 4,12,24, 48 and 72 h culture, respectively; The V
Th
of the hippocampal neuronal networks after treated by $5-\mu \mathrm{M}$ SNPs for 4,12,24,48 and 72 h were 51.71,52.57,53.14,53.42 and 53.85 mV, respectively, which were all lower than the normal $V_{\mathrm{Th}}$, Thus, it proved the effect of 5-$\mu \mathrm{M}$ SNPs on the electrical activity of the hippocampal neuronal network was excitatory; The $V_{\text {Th}}$ of the hippocampal neuronal network treated by $100-\mu \mathrm{M}$ SNPs for 4,12,24,48 and 72 h were 51.57,52.14,53.85,56.57 and 57.57 mV, respectively, which were lower than the normal $V_{\text {Th}}$ after 4,12 and 24 h treatment and higher than the normal $V_{\text {Th}}$ after 48 and 72 h treatment. This proved the effect of $100-\mu \mathrm{M}$ SNPs on the electrical activity of the hippocampal neuronal network was first excitatory and then inhibitory with the increase of action time. The study proved that the effects of 5 and $100-\mu \mathrm{M}$ SNPs on the electrical activity of hippocampal neuronal networks.