Inverted Ion Current Rectification-Based Chemical Delivery Probes for Stimulation of Neurons

Abstract

Ion current rectification (ICR), diodelike behavior in surface-charged nanopores, shows promise in the design of delivery probes for manipulation of neural networks as it can solve diffusive leakages that might be critical in clinical and research applications. However, it has not been achieved because ICR has restrictions in nanosized dimension and low electrolyte concentration, and rectification direction is inappropriate for delivery. Herein, we present a polyelectrolyte gel-filled (PGF) micropipette harnessing inverted ICR as a delivery probe, which quantitatively transports glutamate to stimulate primary cultured neurons with high efficiency while minimizing leakages. Since the gel works as an ensemble of numerous surface-charged nanopores, the current is rectified in the micro-opening and physiological environment. By extending the charge-selective region using the gel, inverted ICR is generated, which drives outward deliveries of major charge carriers. This study will help in exploring new aspects of ICR and broaden its applications for advanced chemical delivery.

Accurate delivery of chemicals to a small target using a pressure-driven valved micropipette

“…However, the pressure-driven technique introduced here diers from these in that we focus on the discharge of a very small amount of chemicals rapidly, which is crucial for impulse stimulation studies. One method that can potentially be used for a similar application is an innovative delivery system using an inverted-ion-current-rectication technique [3]. This method was shown to minimize chemical exchange near the mouth of a micropipette in the rest state and to selectively eject major ion carriers when a small electrical potential is applied to the micropipette.…”

“…This method was shown to minimize chemical exchange near the mouth of a micropipette in the rest state and to selectively eject major ion carriers when a small electrical potential is applied to the micropipette. In particular, it can be used to load and unload neuron transmitters at synapses of a cultured neuronal network by stimulation using glutamate [3]. However, the inverted-ion-current-rectication delivery system has several limitations:…”

“…A systematic study of this kind allows extraction of useful information such as response times and response thresholds. Examples include studies of immuno-response of human cells [1], synapses of neurons [2,3], and bacterial chemotaxis [4,5].…”

Nanoionics from Biological to Artificial Systems: An Alternative Beyond Nanoelectronics

“…The nanofluidic system with an ionic rectification property can also be used for the unidirectional transport of several charged drugs or cell messengers, which can then be used for smart drug delivery or to study cell commination by avoiding diffusive leakages. [ 95 ]…”

“…The nanofluidic system with an ionic rectification property can also be used for the unidirectional transport of several charged drugs or cell messengers, which can then be used for smart drug delivery or to study cell commination by avoiding diffusive leakages. [95] Ion pumping means that ions can transport against a concentration gradient by consuming external energy. In biological systems, ion pumping is used to pump protons from low to high concentration to create an electrochemical potential difference, which can be then used to drive an ATPase to produce ATP.…”