LMNT Research Highlights


Polyethylene Glycol-Mediated Switchable Blue-Green Emissions in Sulfur Nanostructures Controlled through the Surface Chemistry

chem mater 2023The design of efficient and highly durable photoelectrodes requires innovative solutions that can be integrated into thin-film-based technologies. Mesoporous ordered titania, which is characterized by an organized porosity in the 2−10 nm range, represents an ideal matrix for such a purpose. One of the main challenges is the homogeneous and controlled incorporation of photoactive nanoparticles inside the matrix. Titania-carbon dots (C-dots) heterostructures represent promising candidates, but a method to homogeneously introduce C-dots in mesoporous films is still missing. In the present work, C-dots have been nucleated and grown within a mesoporous titania film through in situ solvothermal synthesis. The process
promotes the crystallization of titania anatase at low temperatures and at the same time allows the formation of carbon dots without disruption of the porous ordered structure. The process allows building a high-performance
nanocomposite as an electrode for oxygen evolution reactions. Photocurrent production under different illumination conditions was measured by linear sweep voltammetry and chronoamperometry. When exposed to a solar simulator, the nanocomposite electrodes yield an increase in photocurrent compared to bare TiO2 matrices. The
better performance has been associated with the presence of C-dots acting as active light-harvesting sites and as charge donors to the photoactive centers of the titania film (Chem. Mater. 2023 Open Acces



Photobleaching and Recovery Kinetics of a Palette of Carbon Nanodots Probed by In Situ Optical Spectroscopy

Carbon dots (CDs) are a family of fluorescent nanoparticles displaying a wide range of interesting properties, which make them attractive for potential applications in different fields like bioimaging, photocatalysis, and many others. However, despite many years of dedicated studies, wide variations exist in the literature concerning the reported photostability of CDs, and even the photoluminescence mechanism is still unclear. Furthermore, an increasing number of recent studies have highlighted the photobleaching (PB) of CDs under intense UV or visible light beams. PB phenomena need to be fully addressed to optimize practical uses of CDs and can also provide information on the fundamental mechanism underlying their fluorescence. Moreover, the lack of systematic studies comparing several types of CDs displaying different fluorescence properties represents another gap in the literature. In this study, we explored the optical properties of a full palette of CDs displaying a range from blue to red emissions, synthesized using different routes and varying precursors. We investigated the photostability of different CDs by observing in situ their time-resolved fluorescence degradation or optical absorption changes under equivalent experimental conditions and laser irradiation. The results about different PB kinetics clearly indicate that even CDs showing comparable emission properties may exhibit radically different resistances to PB, suggesting systematic connections between the resistance to PB, the characteristic spectral range of emission, and CD quantum yields. To exploit the PB dynamics as a powerful tool to investigate CD photophysics, we also carried out dedicated experiments in a partial illumination geometry, allowing us to analyze the recovery of the fluorescence due to diffusion. Based on the experimental results, we conclude that the nature of the CD fluorescence cannot be solely ascribable to small optically active molecules free diffusing in solution, contributing to shed light on one of the most debated issues in the photophysics of CDs. (ACS applied materials & interfaces 14 (31), 36038-36051)




Effective SARS-CoV-2 antiviral activity of hyperbranched polylysine nanopolymers

The coronavirus pandemic (COVID-19) had spread rapidly since December 2019, when it was first identified in Wuhan, China. As of April 2021, more than 130 million cases have been confirmed, with more than 3 million deaths, making it one of the deadliest pandemics in history. Different approaches must be put in place to confront a new pandemic: community-based behaviours (i.e., isolation and social distancing), antiviral treatments, and vaccines. Although behaviour-based actions have produced significant benefits and several efficacious vaccines are now available, there is still an urgent need for treatment options. Remdesivir represents the first antiviral drug approved by the Food and Drug Administration for COVID-19 but has several limitations in terms of safety and treatment benefits. There is still a strong request for other effective, safe, and broad-spectrum antiviral systems in light of future emergent coronaviruses. Here, we describe a polymeric nanomaterial derived from L-lysine, with an antiviral activity against SARS-CoV-2 associated with a good safety profile in vitro. Nanoparticles of hyperbranched polylysine, synthesized by L-lysine's thermal polymerization catalyzed by boric acid, effectively inhibit the SARS-CoV-2 replication. The virucidal activity is associated with the charge and dimension of the nanomaterial, favouring the electrostatic interaction with the viral surface being only slightly larger than the virions’ dimensions. Low-cost production and easiness of synthesis strongly support the further development of such innovative nanomaterials as a tool for potential treatments of COVID-19 and, in general, as broad-spectrum antivirals. (Nanoscale, 2021, 13, 16465-16476).




Hydrophobic Thin Films from Sol–Gel Processing: A Critical Review

Fabrication of hydrophobic thin films from a liquid phase is a hot topic with critical technological issues. Interest in the production of hydrophobic surfaces is growing steadily due to their wide applications in several industrial fields. Thin films from liquid phases can be deposited on different types of surfaces using a wide variety of techniques, while the design of the precursor solution offers the possibility of fine-tuning the properties of the hydrophobic coating layers. A general trend is the design of multifunctional films, which have different properties besides being hydrophobic. In the present review, we have described the synthesis through sol–gel processing of hydrophobic films enlightening the main achievements obtained in the field (Materials 2021, 14(22), 6799).



BOOK: Water Droplets to Nanotechnology: A Journey Through Self-Assembly

The ability of nanostructures to organize into complex arrangements leads to unique materials with valuable applications. Self-assembly is therefore a key concept for nanotechnology, but it can be quite a complex and difficult subject to approach. Water Droplets to Nanotechnology gives a simple and general overview of the different self-assembly processes which are at the basis of recent developments in nanotechnology. The book shows how simple phenomenon from everyday examples can become sophisticated tools for self-assembly and the fabrication of nanomaterials. By exploring the coffee stain and tears of wine phenomena, the first part looks at how the evaporation of a droplet of colloidal solution can be used in designing organized structures. This leads onto more complex systems such as templated porous materials, photonic crystals, colloidal nanocrystals and quasi-crystals through to bottom-up systems for designing hierarchal materials. By taking the reader on a journey from everyday life to the secrets of nanotechnology, the book is suitable for a nonspecialist audience interested in self-assembly as well as the wider perspectives and latest developments of nanoscience.





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Updated 24 July 2023

LMNT Laboratory of Materials Science and NanoTechnology - Department of Biomedical Sciences, University of Sassari.
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