Search results for "Carbon dot"
showing 10 items of 29 documents
Carbon based nanomaterials for tissue engineering of bone: Building new bone on small black scaffolds: A review.
2019
Graphical abstract
Highly Efficient Electron Transfer in a Carbon Dot–Polyoxometalate Nanohybrid
2020
Using solar radiation to fuel catalytic processes is often regarded as the solution to our energy needs. However, developing effective photocatalysts that are active under visible light has proven to be difficult, often due to the toxicity, instability, and high cost of suitable catalysts. We engineered a novel photoactive nanomaterial obtained by the spontaneous electrostatic coupling of carbon nanodots with [P2W18O62]6-, a molecular catalyst belonging to the class of polyoxometalates. While the former are used as photosensitizers, the latter was chosen for its ability to catalyze reductive reactions such as dye decomposition and water splitting. We find the electron transfer within the na…
Functionalization of Metal and Carbon Nanoparticles with Potential in Cancer Theranostics
2021
Cancer theranostics is a new concept of medical approach that attempts to combine in a unique nanoplatform diagnosis, monitoring and therapy so as to provide eradication of a solid tumor in a non-invasive fashion. There are many available solutions to tackle cancer using theranostic agents such as photothermal therapy (PTT) and photodynamic therapy (PDT) under the guidance of imaging techniques (e.g., magnetic resonance—MRI, photoacoustic—PA or computed tomography—CT imaging). Additionally, there are several potential theranostic nanoplatforms able to combine diagnosis and therapy at once, such as gold nanoparticles (GNPs), graphene oxide (GO), superparamagnetic iron oxide nanoparticles (SP…
Halloysite nanotubes-carbon dots hybrids multifunctional nanocarrier with positive cell target ability as a potential non-viral vector for oral gene …
2019
Abstract Hypothesis The use of non-viral vectors for gene therapy is hindered by their lower transfection efficiency and their lacking of self-track ability. Experiments This study aims to investigate the biological properties of halloysite nanotubes-carbon dots hybrid and its potential use as non-viral vector for oral gene therapy. The morphology and the chemical composition of the halloysite hybrid were investigated by means of high angle annular dark field scanning TEM and electron energy loss spectroscopy techniques, respectively. The cytotoxicity and the antioxidant activity were investigated by standard methods (MTS, DPPH and H2O2, respectively) using human cervical cancer HeLa cells …
Electron transfer between carbon dots and tetranuclear Dawson-derived sandwich polyanions
2022
Among the photocatalysts which could be used for converting solar energy, polyoxometalates are often regarded as ideal candidates because of their remarkable performances in photocatalytic water splitting and photodegradation of pollutants. Nonetheless, these polyanions are only capable of absorbing UV light, unless coupled to a visible-light photosensitizer. Carbon nanodots are especially promising for this purpose because of their strong visible-light absorption, photostability, non-toxicity, and very low production costs. In this work we demonstrate the possibility of coupling carbon dots to polyoxometalates with different structures, by a simple self-assembly approach based on electrost…
Photoinduced charge transfer from Carbon Dots to Graphene in solid composite
2019
Abstract The emission in solid phase of Carbon Dots (CDs) deposited by drop-casting technique is investigated by means of micro-photoluminescence. Graphene and SiO2 are used as substrates, and the influence of their different nature – conductive or insulating – on the emission of CDs is highlighed. In particular, a systematic loss of efficiency in the emission of CDs on graphene is found, suggesting a CD-graphene interaction possibly due to a photoinduced electron transfer between the surface states of CDs and the conduction band of graphene. Finally, thanks to the negligible influence on CDs emission, SiO2 substrate is used as support to perform thermal processing of CDs in solid phase, sh…
Ultrafast spectroscopic investigation on fluorescent carbon nanodots: the role of passivation.
2019
Disentangling the respective roles of the surface and core structures in the photocycle of carbon nanodots is a critical open problem in carbon nanoscience. While the need of passivating carbon dot surfaces to obtain efficiently emitting nanoparticles is very well-known in the literature, it is unclear if passivation introduces entirely new surface emitting states, or if it stabilizes existing states making them fluorescent. In this multi-technique femtosecond spectroscopy study, the relaxation dynamics of non-luminescent (non-passivated) carbon dots are directly compared with their luminescent (passivated) counterparts. Non-passivated dots are found to host emissive states, albeit very sho…
Multiband light emission and nanoscale chemical analyses of carbonized fumed silica
2018
Fumed silica with a specific area of 295 m2/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 °C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible em…
UV photobleaching of carbon nanodots investigated by in situ optical methods.
2020
Carbon dots are a family of optically-active nanoparticles displaying a combination of useful properties that make them attractive for many applications in photonics and photochemistry. Despite the initial claims of high photostability of carbon dots even under prolonged illuminations, several recent studies have evidenced their photobleaching (PB) under UV light, detrimental for some applications. A study of the mechanism and dynamics of carbon dot PB can be considered a useful route to gather relevant information on the underlying photophysics of these nanoparticles, which is still widely debated. Here we report a study of the PB of carbon dots under UV light, conducted through optical ex…
Hybrid Inorganic‐Organic White Light Emitting Diodes
2020
This chapter reviews the state of the art of materials, technologies, characterizations, process and challenges concerning hybrid white light‐emitting diodes (LEDs). Here, for a “hybrid LED” we mean a device based on a layer of organic phosphors (or a mix of inorganic and organic ones) pumped by a high‐energy inorganic LED. Light is emitted by a frequency down‐conversion (sometimes simply named color‐conversion) process. Benefits and weak spots of this technology are investigated with a special attention for the materials involved into the process of frequency down‐conversion, in order to envisage the future impact of the hybrid lighting technology among the well‐established inorganic ones.