Probing electrical signals in the retina via graphene-integrated microfluidic platforms

Abstract

Graphene has attracted extensive attention in biological and biomedical fields due to its unique physical properties and excellent biocompatibility. We combine graphene field-effect transistors and scanning photocurrent microscopy with microfluidic platforms to investigate electrical signals in mouse retina. Remarkable photocurrent signals were detected from the graphene underneath optic nerve head (ONH) of the retina, where the electrical activity from this region can modulate the carrier concentration of the graphene and induce local potential gradients. These built-in electrical potential gradients can efficiently separate photo-excited electron-hole pairs, leading to strong photocurrent responses in the graphene underneath the ONH. We also show that no significant photocurrent signal was observed in the graphene underneath either dehydrated or fixed retinal tissues, verifying that the photocurrent responses generated in the graphene underneath the ONH were indeed induced by the electrical activity in living retina. This method not only provides a way to investigate electrical processes in living retinal tissues, but also offers opportunities to study many other cellular systems involving cell-cell interactions through electrical signaling.

Membrane cholesterol mediates the cellular effects of monolayer graphene substrates

“…Furthermore, its superior carrier mobility enables graphene-based electrodes to detect electrochemical changes associated with a variety of cellular activities or to deliver optical or electrical stimuli. For example, graphene electrodes have been used as voltage sensors to measure membrane potential changes at the single-cell level and to record electrical activity in neuronal networks in vitro and in vivo 7 , 8 . However, a significant drawback to the use of graphene-based devices remains, in that detection efficiency exponentially decreases as the distance from the cells or tissue increases.…”

“…However, a significant drawback to the use of graphene-based devices remains, in that detection efficiency exponentially decreases as the distance from the cells or tissue increases. Therefore, graphene needs to be close to cell or tissue surfaces 8 in order to maximize its utility in bioapplications. This then raises a fundamental question: how graphene affects the plasma membrane and related cellular functions.…”

In situ monitoring of electrical and optoelectronic properties of suspended graphene ribbons during laser-induced morphological changes

“…1b), suggesting p-type characteristics at a zero gate voltage. 25,26 In order to manipulate and monitor the optoelectronic properties of the suspended graphene, two lasers were used in this experiment (details provided in Materials and methods). Electrical and optoelectronic properties were examined before altering the morphology of the suspended graphene ribbon.…”

Impact of Graphene on the Efficacy of Neuron Culture Substrates

“…Significant research endeavors are ongoing to explore its potential applications for imaging, biosensing, drug delivery, and tissue engineering. [18–22] While great progresses have been made on almost all fronts, many fundamental questions pertaining to biomedical applications of graphene still remain unanswered.…”

“…This includes neurobiological studies, for which graphene is of particular interest as a biosensor for electro-physiological assays. [18–22] Over the century long in vitro cell culture practice, many standard protocols have been developed for optimal cell culture. For neuronal cultures, the culture substrate is of primary importance for cell survival, differentiation and functionality; and the needs of a specific neuronal subtype or cell line dictate the optimal culture substrate.…”