Characterization of the Coupling between Out‐of‐Plane Graphene and Electrogenic Cells

AbstractThe cell‐chip coupling is in general regulated by the interplay between cells and the material surface at the interface. Electroactive planar materials have shown limited crosstalk with cells, whereas pseudo 3D patterned materials promote a more intimate contact with the biological system. Here, unprecedented physical properties of a carbon‐based material, i.e., graphene, to engineer out‐of‐plane morphologies are exploited: 1) 3D single‐ to few‐layer fuzzy graphene morphology (3DFG), 2) 3DFG on a collapsed Si nanowire mesh template, and 3) 3DFG on a noncollapsed Si nanowire mesh template. These materials are synthesized and interfaced with cardiomyocyte‐like cells focusing on the characterization of the cytoskeletal arrangement as well as membrane wrapping processes yet regulated by endocytic proteins. Finally, some major conditions to promote tight coupling to the device and eventually spontaneous intracellular penetration are found

Synthetically Encoded Ultrashort-Channel Nanowire Transistors for Fast, Pointlike Cellular Signal Detection

Nanostructures, which have sizes comparable to biological functional units involved in cellular communication, offer the potential for enhanced sensitivity and spatial resolution compared to planar metal and semiconductor structures. Silicon nanowire (SiNW) field-effect transistors (FETs) have been used as a platform for biomolecular sensors, which maintain excellent signal-to-noise ratios while operating on lengths scales that enable efficient extra- and intracellular integration with living cells. Although the NWs are tens of nanometers in diameter, the active region of the NW FET devices typically spans micrometers, limiting both the length and time scales of detection achievable with these nanodevices. Here, we report a new synthetic method that combines gold-nanocluster-catalyzed vapor–liquid–solid (VLS) and vapor–solid–solid (VSS) NW growth modes to produce synthetically encoded NW devices with ultrasharp (<5 nm) n-type highly doped $(n^{++})$ to lightly doped (n) transitions along the NW growth direction, where $n^{++}$ regions serve as source/drain (S/D) electrodes and the n-region functions as an active FET channel. Using this method, we synthesized short-channel $n^{++}/n/n^{++}$ SiNW FET devices with independently controllable diameters and channel lengths. SiNW devices with channel lengths of 50, 80, and 150 nm interfaced with spontaneously beating cardiomyocytes exhibited well-defined extracellular field potential signals with signal-to-noise values of ca. 4 independent of device size. Significantly, these “pointlike” devices yield peak widths of $\sim 500 \mu s$, which is comparable to the reported time constant for individual sodium ion channels. Multiple FET devices with device separations smaller than $2 \mu m$ were also encoded on single SiNWs, thus enabling multiplexed recording from single cells and cell networks with device-to-device time resolution on the order of a few microseconds. These short-channel SiNW FET devices provide a new opportunity to create nanoscale biomolecular sensors that operate on the length and time scales previously inaccessible by other techniques but necessary to investigate fundamental, subcellular biological processes.Chemistry and Chemical BiologyEngineering and Applied Science

Outside Looking In: Nanotube Transistor Intracellular Sensors

Nanowire-based field-effect transistors, including devices with planar and three-dimensional configurations, are being actively explored as detectors for extra- and intracellular recording due to their small size and high sensitivities. Here we report the synthesis, fabrication, and characterization of a new needle-shaped nanoprobe based on an active silicon nanotube transistor, ANTT, that enables high-resolution intracellular recording. In the ANTT probe, the source/drain contacts to the silicon nanotube are fabricated on one end, passivated from external solution, and then time-dependent changes in potential can be recorded from the opposite nanotube end via the solution filling the tube. Measurements of conductance versus water-gate potential in aqueous solution show that the ANTT probe is selectively gated by potential changes within the nanotube, thus demonstrating the basic operating principle of the ANTT device. Studies interfacing the ANTT probe with spontaneously beating cardiomyocytes yielded stable intracellular action potentials similar to those reported by other electrophysiological techniques. In addition, the straightforward fabrication of ANTT devices was exploited to prepare multiple ANTT structures at the end of single probes, which enabled multiplexed recording of intracellular action potentials from single cells and multiplexed arrays of single ANTT device probes. These studies open up unique opportunities for multisite recordings from individual cells through cellular networks.Chemistry and Chemical Biolog

Intracellular Recordings of Action Potentials by an Extracellular Nanoscale Field-Effect Transistor

The ability to make electrical measurements inside cells has led to many important advances in electrophysiology. The patch clamp technique, in which a glass micropipette filled with electrolyte is inserted into a cell, offers both high signal-to-noise ratio and temporal resolution. Ideally, the micropipette should be as small as possible to increase the spatial resolution and reduce the invasiveness of the measurement, but the overall performance of the technique depends on the impedance of the interface between the micropipette and the cell interior, which limits how small the micropipette can be. Techniques that involve inserting metal or carbon microelectrodes into cells are subject to similar constraints. Field-effect transistors (FETs) can also record electric potentials inside cells, and because their performance does not depend on impedance, they can be made much smaller than micropipettes and microelectrodes. Moreover, FET arrays are better suited for multiplexed measurements. Previously, we have demonstrated FET-based intracellular recording with kinked nanowire structures, but the kink configuration and device design places limits on the probe size and the potential for multiplexing. Here, we report a new approach in which a $SiO_2$ nanotube is synthetically integrated on top of a nanoscale FET. This nanotube penetrates the cell membrane, bringing the cell cytosol into contact with the FET, which is then able to record the intracellular transmembrane potential. Simulations show that the bandwidth of this branched intracellular nanotube FET (BIT-FET) is high enough for it to record fast action potentials even when the nanotube diameter is decreased to 3 nm, a length scale well below that accessible with other methods. Studies of cardiomyocyte cells demonstrate that when phospholipid-modified BIT-FETs are brought close to cells, the nanotubes can spontaneously penetrate the cell membrane to allow the full-amplitude intracellular action potential to be recorded, thus showing that a stable and tight seal forms between the nanotube and cell membrane. We also show that multiple BIT-FETs can record multiplexed intracellular signals from both single cells and networks of cells.Chemistry and Chemical BiologyEngineering and Applied SciencesPhysic

The Baltimore declaration toward the exploration of organoid intelligence

We, the participants of the First Organoid Intelligence Workshop - "Forming an OI Community" (22-24 February 2022), call on the international scientific community to explore the potential of human brain-based organoid cell cultures to advance our understanding of the brain and unleash new forms of biocomputing while recognizing and addressing the associated ethical implications. The term "organoid intelligence" (OI) has been coined to describe this research and development approach (1) in a manner consistent with the term "artificial intelligence" (AI) - used to describe the enablement of computers to perform tasks normally requiring human intelligence. OI has the potential for diverse and far-reaching applications that could benefit humankind and our planet, and which urge the strategic development of OI as a collaborative scientific discipline. OI holds promise to elucidate the physiology of human cognitive functions such as memory and learning. It presents game-changing opportunities in biological and hybrid computing that could overcome significant limitations in silicon-based computing. It offers the prospect of unparalleled advances in interfaces between brains and machines. Finally, OI could allow breakthroughs in modeling and treating dementias and other neurogenerative disorders that cause an immense and growing disease burden globally. Realizing the world-changing potential of OI will require scientific breakthroughs. We need advances in human stem cell technology and bioengineering to recreate brain architectures and to model their potential for pseudo-cognitive capabilities. We need interface breakthroughs to allow us to deliver input signals to organoids, measure output signals, and employ feedback mechanisms to model learning processes. We also need novel machine learning, big data, and AI technologies to allow us to understand brain organoids

Nanowire nanoelectronics: Building interfaces with tissue and cells at the natural scale of biology

The interface between nanoscale electronic devices and biological systems enables interactions at length scales natural to biology, and thus should maximize communication between these two diverse yet complementary systems. Moreover, nanostructures and nano - structured substrates show enhanced coupling to artificial membranes, cells, and tissue. Such nano–bio interfaces offer better sensitivity and spatial resolution as compared to conventional planar structures. In this work, we will report the electrical properties of silicon nanowires (SiNWs) interfaced with embryonic chicken hearts and cultured cardiomyocytes. We developed a scheme that allowed us to manipulate the nanoelectronic to tissue/cell interfaces while monitoring their electrical activity. In addition, by utilizing the bottom-up approach, we extended our work to the subcellular regime, and interfaced cells with the smallest reported device ever and thus exceeded the spatial and temporal resolution limits of other electrical recording techniques. The exceptional synthetic control and flexible assembly of nanowires (NWs) provides powerful tools for fundamental studies and applications in life science, and opens up the potential of merging active transistors with cells such that the distinction between nonliving and living systems is blurred.Chemistry and Chemical Biolog