RESUMO
Fluorine-doped tin oxide (FTO) is one of the most studied and established materials for transparent electrode applications. However, the syntheses for FTO nanocrystals are currently very limited, especially for stable and well-dispersed colloids. Here, we present the synthesis and detailed characterization of FTO nanocrystals using a colloidal heat-up reaction. High-quality SnO2 quantum dots are synthesized with a tuneable fluorine amount up to ~10% atomic, and their structural, morphological and optical properties are fully characterized. These colloids show composition-dependent optical properties, including the rise of a dopant-induced surface plasmon resonance in the near infrared.
RESUMO
The fabrication of antimicrobial surfaces that exhibit enhanced activity toward a large variety of microbial species is one of the major challenges of our time. In fact, the negative effects associated with both bacterial and fungal infections are enormous, especially considering that many microbial species are developing resistance to known antibiotics. In this work, we show how a combination of a specific surface morphology and surface chemistry can create a surface that exhibits nearly 100% antimicrobial activity toward both Gram-negative and Gram-positive bacteria and fungal cells. Arrays of vertically aligned, oxygen-deficient zinc oxide (ZnO) nanowires grown on a substrate exhibit enhanced antimicrobial activity compared with surfaces containing either less defective nanowires or highly oxygen-deficient flat films. This synergistic effect between physical activity (morphology) and chemical activity (surface composition) has been shown to be responsible for the outstanding antimicrobial activity of our surfaces, especially toward notoriously resilient bacterial or fungal species. These findings provide a series of design rules for tuning the activities of antibacterial and antifungal nanomaterials. These rules constitute an excellent platform for the development of next-generation antimicrobial surfaces.
