Tiny 2D silicon quantum sheets: a brain photonic nanoagent for orthotopic glioma theranostics.

We report that atomically thin two-dimensional silicon quantum sheets (2D Si QSs), prepared by a scalable approach coupling chemical delithiation and cryo-assisted exfoliation, can serve as a high-performance brain photonic nanoagent for orthotopic glioma theranostics. With the lateral size of approximately 14.0 nm and thickness of about 1.6 nm, tiny Si QSs possess high mass extinction coefficient of 27.5 L g-1 cm-1 and photothermal conversion efficiency of 47.2% at 808 nm, respectively, concurrently contributing to the best photothermal performance among the reported 2D mono-elemental materials (Xenes). More importantly, Si QSs with low toxicity maintain the trade-off between stability and degradability, paving the way for practical clinical translation in consideration of both storage and action of nanoagents. In vitro Transwell filter experiment reveals that Si QSs could effectively go across the bEnd.3 cells monolayer. Upon the intravenous injection of Si QSs, orthotopic brain tumors are effectively inhibited under the precise guidance of photoacoustic imaging, and the survival lifetime of brain tumor-bearing mice is increased by two fold. Atomically thin Si QSs with strong light-harvesting capability are expected to provide an effective and robust 2D photonic nanoplatform for the management of brain diseases.

Biodegradable Nickel Disulfide Nanozymes with GSH-Depleting Function for High-Efficiency Photothermal-Catalytic Antibacterial Therapy.

Bacterial infections caused by pathogens have always been a thorny issue that threatens human health, and there is urgent need to develop a new generation of antimicrobial nano-agents and treatments. Herein, biodegradable nickel disulfide (ND) nanozymes as excellent antibacterial agents that integrate excellent photothermal performance, nano-catalysis property, and glutathione (GSH)-depleting function have been successfully constructed. The ND nanozymes can effectively catalyze the decomposition of H2O2 to produce ⋅OH, and the hyperthermia of ND nanozymes generated by photothermal therapy (PTT) can further increase its catalytic activity, which provides rapid and effective bacterial killing effect compared with nano-catalytic treatment or PTT alone. Surprisingly, the ND nanozymes have the ability of GSH consumption, thus enhancing its sterilization effect. Moreover, the ND nanozymes are biodegradable nanomaterials that do not cause any significant toxicity in vivo. Collectively, the ND nanozymes with excellent photothermal performance, catalytic activity, and GSH-depleting function are used for high-efficiency sterilization.

Facile synthesis of monodisperse chromogenic amylose-iodine nanoparticles as an efficient broad-spectrum antibacterial agent.

The famous chromogenic reaction between starch and iodine has been widely used for chemical analysis since its first discovery in the year of 1814 while it is seldom utilized in biomedical applications. Inspired by their high iodine content and strong optical absorbance in the near infrared (NIR) region, monodisperse amylose-iodine nanoparticles (AM-I NPs), synthesized by simple mixing of amylose NPs and KI-I2 solutions, were explored as a new class of high-performance antibacterial agent. Benefiting from the broad-spectrum antibacterial property of iodine and photothermal effect of the amylose-iodine complex, the obtained AM-I NPs exhibited an excellent photothermal-enhanced sterilization effect for both Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). For instance, upon incubation with AM-I NP suspensions (30 µg mL-1) plus NIR laser irradiation (808 nm, 1.33 W cm-2, 5 min), the relative survival rates of E. coli and MRSA were only 1.2% and 1.7%, respectively. In addition, the AM-I NPs depicted better biocompatibility in vitro than that of KI-I2 solution, indicating their safety for potential biomedical applications in vivo. This proof-of-concept study revealed the antibacterial applications of a traditional starch-iodine complex and is expected to provide insights into the design and development of efficient broad-spectrum antibacterial agents.

Liquid Exfoliation of Atomically Thin Antimony Selenide as an Efficient Two-Dimensional Antibacterial Nanoagent.

The ever-growing global crisis of multidrug-resistant bacteria has triggered a tumult of activity in the design and development of antibacterial formulations. Here, atomically thin antimony selenide nanosheets (Sb2Se3 NSs), a minimal-toxic and low-cost semiconductor material, were explored as a high-performance two-dimensional (2D) antibacterial nanoagent via a liquid exfoliation strategy integrating cryo-pretreatment and polyvinyl pyrrolidone (PVP)-assisted exfoliation. When cultured with bacteria, the obtained PVP-capped Sb2Se3 NSs exhibited intrinsic long-term antibacterial capability, probably due to the reactive oxygen species generation and sharp edge-induced membrane cutting during physical contact between bacteria and nanosheets. Upon near-infrared laser irradiation, Sb2Se3 NSs achieved short-time hyperthermia sterilization because of strong optical absorption and high photothermal conversion efficiency. By virtue of the synergistic effects of these two broad-spectrum antibacterial mechanisms, Sb2Se3 NSs exhibited high-efficiency inhibition of conventional Gram-negative Escherichia coli, Gram-positive methicillin-resistant Staphylococcus aureus, and wild bacteria from a natural water pool. Particularly, these three categories of bacteria were completely eradicated after being treated with Sb2Se3 NSs (300 µM) plus laser irradiation for only 5 min. In vivo wound healing experiment further demonstrated the high-performance antibacterial effect. In addition, Sb2Se3 NSs depicted excellent biocompatibility due to the biocompatible element constitute and bioinert PVP modification. This work enlightened that atomically thin Sb2Se3 NSs hold great promise as a broad-spectrum 2D antibacterial nanoagent for various pathogenic bacterial infections.

Cryo-assisted exfoliation of atomically thin 2D Sb2Se3 nanosheets for photo-induced theranostics.

A liquid-phase exfoliation approach, combined with cryogenic fracturing and bath/probe sonication, is developed to prepare atomically thin 2D anisotropic Sb2Se3 nanosheets for simultaneous photoacoustic imaging and photothermal therapy.