Quantum dots, derived from two-dimensional (2D) materials, have shown promise in bioimaging, sensing and photothermal applications, and in white light emitting devices (WLEDs).

Here, two dimensional Nb2C quantum dots with green fluorescence were fabricated for the first time with a quantum yield (QY) of up to 19%, the highest reported for Nb2C dots so far with good photostability and pH stability.

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Recently, we developed highly fluorescent Ti3C2 and Nb2C Mxene quantum dots (QDs) for labeling of in vitro models. However, the mechanism of the toxicity of the prepared QDs was not explored before. In this study, we addressed the possible mechanism associated with cytotoxicity of the QDs to human umbilical vein endothelial cells (HUVECs). Exposure to up to 100 μg/ml Ti3C2 but not Nb2C QDs for 24 h significantly induced cytotoxicity. The exposure also increased intracellular Ti and Nb elements, indicating the internalization of both types of QDs. None of the QDs promoted interleukin 6 (IL‐6) and IL‐8 releases. Rather, Ti3C2 QDs significantly reduced IL‐6 and IL‐8 release, indicating that the toxicity of Ti3C2 QDs was not due to elevated inflammatory responses. Exposure to Ti3C2 but not Nb2C QDs resulted in increased LC3B‐II/I ratio and beclin‐1 proteins, biomarkers of autophagy, as well as the accumulation of autophagic substance p62. Ti3C2 QDs also more effectively promoted pro‐caspase 3 but not pro‐caspase 8 compared with Nb2C QDs. Furthermore, pre‐treatment with autophagic modulators altered the cytotoxicity of Ti3C2 QDs, which further confirmed the role of autophagic dysfunction in Ti3C2 QD‐induced toxicity to HUVECs. In conclusion, the results from this study suggested that high levels of Ti3C2 QDs could induce cytotoxicity to HUVECs by inducing the dysfunction of autophagy. Nb2C QDs appeared to be more biocompatible to HUVECs compared with Ti3C2 QDs at the same mass concentrations, which suggested a role of composition of Mxene QDs to determine their toxicity to human endothelial cells.

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Infectious diseases and the deaths caused due to contact with germ-contaminated surfaces are severe problems worldwide. Antibacterial materials based on silver nanowires (AgNWs) have a structural advantage when addressing this issue; this is because agglomeration is minimized when nanowires are fabricated into a film. Therefore, employing AgNWs for antimicrobial applications has garnered continuous interest, and increased research for further improvements has been observed. In this study, a AgNW film was fabricated onto glass by spin-coating and then subjected to surface irradiation up to a dose of 1200 kGy, using a low-energy electron beam (e-beam). This “e-beam” irradiation changed the surface morphology and chemical composition; consequently, this improved the performance of the film. The generation of a silver oxide (Ag2O and AgO) outer layer was identified over the AgNWs by X-ray photoelectron spectroscopy (XPS). The antibacterial test corresponding to a contact time of 1 h revealed that the e-beam irradiation increased the antibacterial activity in the log reduction from 1.2 to 1.4 for Staphylococcus aureus and from 1.5 to 3.7 for Escherichia coli. Based on the experimental results and the known antibacterial mechanisms of silver (Ag) nanospecies, we discuss the method by which the antibacterial performance of the AgNW film was improved via the e-beam irradiation. This work provides a simple and swift method to functionally enhance the AgNW antibacterial film via e-beam irradiation.

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