Bio-inspired Two-dimensional Nanofluidic Ionic Transistor for Neuromorphic Signal Processing

Voltage-gated ion channels prevalent in neurons play important roles in generating action potential and information transmission by responding to transmembrane potential. Fabricating bio-inspired ionic transistors with ions as charge carriers will be crucial for realizing neuro-inspired devices and brain-liking computing. Here, we reported a two-dimensional nanofluidic ionic transistor based on a MXene membrane with sub-1 nm interlayer channels. By applying a gating voltage on the MXene nanofluidic, a transmembrane potential will be generated to active the ionic transistor, which is similar to the transmembrane potential of neuron cells and can be effectively regulated by changing membrane parameters, e.g., thickness, composition, and interlayer spacing. For the symmetric MXene nanofluidic, a high on/off ratio of ~2000 can be achieved by forming an ionic depletion or accumulation zone, contingent on the sign of the gating potential. An asymmetric PET/MXene-composited nanofluidic transitioned the ionic transistor from ambipolar to unipolar, resulting in a more sensitive gate voltage characteristic with a low subthreshold swing of 560 mV/decade. Furthermore, ionic logic gate circuits, including the "NOT", "NAND", and "NOR" gate, were implemented for neuromorphic signal processing successfully, which provides a promising pathway towards highly parallel, low energy consumption, and ion-based brain-like computing.

Mitochondrial Artificial K+ Channel Construction Using MPTPP@5F8 Nanoparticles for Overcoming Cancer Drug Resistance via Disrupting Cellular Ion Homeostasis

Mitochondrial potassium ion channels have become a promising target for cancer therapy. However, in malignant tumors, their low expression or inhibitory regulation typically leads to undesired cancer therapy, or even induces drug resistance. Herein, this work develops an in situ mitochondria-targeted artificial K+ channel construction strategy, with the purpose to trigger cancer cell apoptosis by impairing mitochondrial ion homeostasis. Considering the fact that cancer cells have a lower membrane potential than that of normal cells, this strategy can selectively deliver artificial K+ channel molecule 5F8 to the mitochondria of cancer cells, by using a mitochondria-targeting triphenylphosphine (TPP) modified block polymer (MPTPP) as a carrier. More importantly, 5F8 can further specifically form a K+ -selective ion channel through the directional assembly of crown ethers on the mitochondrial membrane, thereby inducing mitochondrial K+ influx and disrupting ions homeostasis. Thanks to this design, mitochondrial dysfunction, including decreased mitochondrial membrane potential, reduced adenosine triphosphate (ATP) synthesis, downregulated antiapoptotic BCL-2 and MCL-1 protein levels, and increased reactive oxygen species (ROS) levels, can further effectively induce the programmed apoptosis of multidrug-resistant cancer cells, no matter in case of pump or nonpump dependent drug resistance. In short, this mitochondria-targeted artificial K+ -selective ion channel construction strategy may be beneficial for potential drug resistance cancer therapy.

Ferroptosis MRI for early detection of anticancer drug-induced acute cardiac/kidney injuries

Ferroptosis has been realized in anticancer drug-induced acute cardiac/kidney injuries (ACI/AKI); however, molecular imaging approach to detect ferroptosis in ACI/AKI is a challenge. We report an artemisinin-based probe (Art-Gd) for contrast-enhanced magnetic resonance imaging of ferroptosis (feMRI) by exploiting the redox-active Fe(II) as a vivid chemical target. In vivo, the Art-Gd probe showed great feasibility in early diagnosis of anticancer drug-induced ACI/AKI, which was at least 24 and 48 hours earlier than the standard clinical assays for assessing ACI and AKI, respectively. Furthermore, the feMRI was able to provide imaging evidence for the different mechanisms of action of ferroptosis-targeted agents, either by blocking lipid peroxidation or depleting iron ions. This study presents a feMRI strategy with simple chemistry and robust efficacy for early evaluation of anticancer drug-induced ACI/AKI, which may shed light on the theranostics of a variety of ferroptosis-related diseases.