Artificial optoelectronic synapses with both electrical and light‐induced synaptic behaviors have recently been studied for applications in neuromorphic computing and artificial vision systems. However, the combination of visual perception and high‐performance information processing capabilities still faces challenges. In this work, the authors demonstrate a memristor based on 2D bismuth oxyiodide (BiOI) nanosheets that can exhibit bipolar resistive switching (RS) performance as well as electrical and light‐induced synaptic plasticity eminently suitable for low‐power optoelectronic synapses. The fabricated memristor exhibits high‐performance RS behaviors with a high ON/OFF ratio up to 105, an ultralow SET voltage of ≈0.05 V which is one order of magnitude lower than that of most reported memristors based on 2D materials, and low power consumption. Furthermore, the memristor demonstrates not only electrical voltage‐driven long‐term potentiation, depression plasticity, and paired‐pulse facilitation, but also light‐induced short‐ and long‐term plasticity. Moreover, the photonic synapse can be used to simulate the “learning experience” behaviors of human brain. Consequently, not only the memristor based on BiOI nanosheets shows ultra‐low SET voltage and low‐power consumption, but also the optoelectronic synapse provides new material and strategy to construct low‐power retina‐like vision sensors with functions of perceiving and processing information.

Although ultrasound-based therapeutic strategies have achieved great success in the battle against antibiotic-resistant bacterial infections, various sonodynamic treatments still suffer from poor therapeutic efficiency, failing to completely eradicate infections. Thus, more potent strategies are urgently required. Herein, a novel ultrasound-driven treatment modality, sonoactivated chemodynamic therapy (SCDT), is proposed, which shows a robust generation of superoxide anion and destructive hydroxyl radical via sonotriggered catalytic reactions. This SCDT platform is prepared by grafting Fe 3+ onto polyethylenimine-modified bismuth oxybromide (BiOBr) nanoplates. During sonocatalysis, the introduction of Fe 3+ can effectively separate the holes (h +) and electrons (e-) of BiOBr NPs and shorten their transport path of valence electrons, resulting in the activation of multioxygen reduction and Fenton reaction to generate abundant reactive oxygen species against methicillin-resistant Staphylococcus aureus (MRSA) infection. More importantly, Fe 3+ can also serve as a magnetic resonance imaging (MRI) contrast agent to achieve the accurate diagnosis of bacterial infection. The SCDT-mediated bactericidal outcome can be monitored by in situ monitoring through MRI technique, revealing a complete elimination of MRSA myositis in mice. Collectively, its deep tissue penetration, high therapeutic efficacy, and noninvasive properties make SCDT a promising therapeutic modality for combating multidrug-resistant bacterial infection.

The development of optoelectronic synapses can provide an important breakthrough toward creating a sophisticated and adaptable artificial visual system analogous to that of humans. However, it remains a great challenge to implement the various functions of the biological visual neuromorphic system at the single device level. Intriguingly, 2D van der Waals (vdW) heterostructure may offer a platform to address the issue. Here, a novel multifunctional synaptic device based on ferroelectric α-In 2 Se 3 /GaSe vdW heterojunction is proposed to emulate the entire biological visual system. Essential synaptic behaviors are observed in response to light and electrical stimuli; additionally, the retina-like selectivity for light wavelengths and the achievement of Pavlov's dog experiment demonstrate the device's capacity for processing complex electrical and optical inputs. Beyond the optoelectronic synaptic behaviors, the device incorporates memory and logic functions analogous to those in the brain's visual cortex. The results of artificial neural network simulations show that the vdW heterojunction-based device is completely capable of performing logic operations and recognizing images with a high degree of accuracy. The study indicates that versatile devices with a rationally designed construction have great potential for efficiently processing complex visual information and may simplify the design of artificial visual systems.

No abstract

Recently, 2D niobium carbide MXene has drawn vast attention due to its merits of large surface area, good metallic conductivity, and tunable band gap, making it desirable for various applications. However, the usage of highly toxic fluoride-containing etchant and quite long etching time in the conventional synthesis route has greatly hindered further exploration of MXene, especially restricting its biomedical application. Herein, novel fluoride-free Nb 2 CT x nanosheets are prepared by a facile strategy of electrochemical etching (E-etching) exfoliation. Taking advantage of rapid aluminum clearance, excellent chemical stability, and biocompatibility from the MXene by E-etching, fluoride-free Nb 2 CT x /acetylcholinesterase-based biosensors are constructed for phosmet detection with the limit of detection down to 0.046 ng mL −1. The fabricated Nb 2 CT x-based biosensor is superior to the counterpart from hydrofluoric acid-etched Nb 2 CT x , indicating that fluoride-free MXene can enhance the enzyme activity and electron transfer in the biosensor. The results prove that the fluorine-free MXene shows promise for developing biosensors with high performance of ultrahigh sensitivity and selectivity. It is highly expected that the fluoride-free MXene as a stable and biocompatible nanoplatform has great potential to be expanded to many other biomedical fields. MXenes as an emerging class of 2D materials are composed of layered transition metal carbides or nitrides with high conductivity, good hydrophilicity, superior optical, and mechanical properties. [1] MXenes have been developed in various applications, such as electrochemical catalysis, [2] medical devices, [3] energy conversion, and storage. [4] MXenes can be generally classified as M n+1 X n T x (n = 1, 2, or 3) where n + 1 layers of transition metals M (e.g., Sc, Ti, V, and Nb) are interleaved with n