Carbon nanodot cellular uptake and modulation of Tumor necrosis factor-alpha-induced endothelial dysfunction

In the past forty years, we have advanced our understanding of cardiovascular pathology through epidemiological and molecular studies. Atherosclerosis is one of the main cardiovascular diseases, which is also an underlying cause of more severe cardiovascular pathologies. Atherosclerosis is the chronic inflammatory response initiated by the damage to the endothelium caused by an imbalance of reactive oxygen species (ROS). This chronic inflammation causes the accumulation of plaque in arterial walls. Due to the widespread of cardiovascular disease, finding better treatment options is of importance. The interdisciplinary field of nanomedicine has been studying the application of various nanoparticles for future treatment options. A new class of nanoparticles that has promising features for medical application is carbon nanodots (CND). The citric acid-ethylenediamine synthesized CNDs used in this study have antioxidant properties making them candidates for quenching ROS and decreasing cardiovascular inflammation. Previous studies have shown that carbon nanodots have low toxicity in numerous cell lines, but CND exposure to endothelial cells has not been explored. The main goal of this study is to analyze in vitro and in vivo the effect of CNDs on endothelial dysfunction. Our in vitro results showed that the uptake of carbon nanodots by EA.hy926 endothelial cells is both time and dose-dependent. Our experiments showed cell-viability consistent with previous studies showing that nanodots have low cytotoxicity after 24 hr exposure with lower CND concentrations up to 0.3 mg/mL. However, we also found that higher concentrations affect metabolic activity via MTT assay after 6 hr exposure. CNDs significantly inhibited TNF-a-mediated expression of intracellular adhesion molecule-1 (ICAM-1), and interleukin 8, two key molecules that are responsible for the activation and the firm adhesion of monocytes to activated endothelial cells for the initiation of atherosclerosis, while the mRNA levels increased for monocyte chemoattractant protein-1 (MCP-1/CCL2). Similarly to the previously mentioned results, the gene expression of pro-inflammatory genes in cells that were treated with carbon nanodots alone showed a change in gene expression. Additional data showed that NQO1 activity is increased by nanodots after 24 hr treatment, this phase II cytoprotective enzyme is known to maintain homeostasis in the vasculature. Histology of samples from our 8-week animal study in apolipoprotein E knockout mice (Apo E -/-) suggest that plaque formation in the aorta is decreased in animals dosed with CNDs. Tissue samples from the liver of mice dosed with CNDs appear to have a decrease in hepatic lipidosis, while the kidney which is also an important detoxifying organ seems to have no significant change in histology. In conclusion, this study explored the bioapplication of carbon nanodots in endothelial cell dysfunction, and our results showed that carbon nanodots could be promising nanoparticles that may decrease cardiovascular inflammation. Future studies need to explore the role of the NF-?B pathway and the Nrf2 pathway activation to understand the underlying mode of action by which pro-inflammatory gene expression changes, and NQO1 enzymatic activity increases

Cytotoxicity Screening Matrix Assisted Laser Desorption Ionization Mass Spectrometery for nanoparticle biomarker detection

Toxicology is a broad topic that aims to assess the risk of chemicals on living organisms. It has been acknowledged that everything is toxic to a living organism. What distinguishes a toxin from a remedy depends on the dose 1. Presently, there are toxicity assays that are implemented for human risk assessment studies such as, 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) assay; however, it has been shown that some toxins interfere with these assays. Carbon nanodots, an unknown toxicant has shown to interfere with the LDH assay. Therefore proper methods and techniques must be devised for the analysis of these unknown toxicants to enable the reliable risk assessment for humans. In this study a new method was devised using, hydrogen peroxide and aflatoxin b1 as the known toxicants. The Cytotoxicity Screening Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (cs-MALDI-TOF-MS) technique was implemented as a viable approach to studying nanoparticle toxicity. Previously, Human liver (HepG2) cells were dosed with varying concentrations of these known toxicants and analyzed using cs-MALDI. In this study, Human monocyte (THP-1) cells were dosed with the same concentrations of these known toxicants as the HepG2 and analyzed. This study demonstrates that the two toxicants can be distinguished through the presence and absence of certain peaks using the cs-MALDI method. This method has been developed as a high throughput screening method that can lead to the future identification of biomarkers associated to each toxicant independently

Nanopuntos de carbono : composición, estructura y fotofísica

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 16-12-2022The main part of this thesis focuses on the production and characterisation of carbon nanodots. Regarding the production methods of the CNDs chosen in this work, CNDs produced by two clearly different bottom-up methods have been studied in detail. On the one hand, the solvothermal method has been used. This method consists of heating a liquid, in a closed container, above its boiling point, generating a pressure higher than atmospheric pressure, and thus inducing the condensation of CNDs. The obvious advantages of this synthetic method are: it is easy, cheap and environmentally friendly (provided that the solvent used in the solvothermal method is an environmentally friendly solvent, in our case we used water and ethanol). All these advantages provided a great opportunity to easily prepare and investigate CNDs, which, when prepared by this method, were found to have promising properties such as solubility in aqueous media, biocompatibility, photocatalytic activity in heterostructures with TiO2 and biocidal properties that can be employed to prepare biocidal polymer surfaces. The combination of the advantages proposed by the synthetic method and the promising properties of the products obtained have made this method the most common synthetic procedure for the production of CNDs...La parte principal de esta tesis se centra en la producción y caracterización de los nanopuntos de carbono. En cuanto a los métodos de producción de los CNDs elegidos en este trabajo, se han estudiado en detalle los CNDs producidos por dos métodos ascendentes claramente diferentes. Por un lado, se ha utilizado el método solvotérmico. Este método consiste en calentar un líquido, en un recipiente cerrado, por encima de su punto de ebullición, generando una presión superior a la atmosférica, e induciendo así la condensación delos CNDs. Las ventajas evidentes de este método sintético son: es fácil, barato y respetuoso con el medio ambiente (siempre que el disolvente utilizado en el método solvotérmico sea un disolvente respetuoso con el medio ambiente, en nuestro caso hemos utilizado agua y etanol). Todas estas ventajas proporcionaron una gran oportunidad para preparar e investigar fácilmente los CNDs, los cuales, al ser preparados por este método, resultaron tener propiedades prometedoras como la solubilidad en medios acuosos, la biocompatibilidad, la actividad fotocatalítica en heteroestructuras con TiO2 y propiedades biocidas que pueden ser empleadas para preparar superficies poliméricas biocidas. La combinación de las ventajas propuestas por el método sintético y las prometedoras propiedades de los productos obtenidos han hecho de este método el procedimiento sintético más común para la producción de CNDs...Fac. de Ciencias QuímicasTRUEunpu

ブロックコーポリマーを用いた自己組織化法による5 nm 径ドット形成とその応用に関する研究

学位記番号：工博甲47

Extremely sharp carbon nanocone probes for atomic force microscopy imaging

A simple and reliable catalyst patterning technique combined with electric-field-guided growth is utilized to synthesize a sharp and high-aspect-ratio carbon nanocone probe on a tipless cantilever for atomic force microscopy. A single carbon nanodot produced by an electron-beam-induced deposition serves as a convenient chemical etch mask for catalyst patterning, thus eliminating the need for complicated, resist-based, electron-beam lithography for a nanoprobe fabrication. A gradual, sputtering-induced size reduction and eventual removal of the catalyst particle at the probe tip during electric-field-guided growth creates a sharp probe with a tip radius of only a few nanometers. These fabrication processes are amenable for the wafer-scale synthesis of multiple probes. High resolution imaging of three-dimensional features and deep trenches, and mechanical durability enabling continuous operation for many hours without noticeable image deterioration have been demonstrated

Quantum-Dot Light-Emitting Diodes with Nitrogen-Doped Carbon Nanodot Hole Transport and Electronic Energy Transfer Layer

Electroluminescence efficiency is crucial for the application of quantum-dot light-emitting diodes (QD-LEDs) in practical devices. We demonstrate that nitrogen-doped carbon nanodot (N-CD) interlayer improves electrical and luminescent properties of QD-LEDs. The N-CDs were prepared by solution-based bottom up synthesis and were inserted as a hole transport layer (HTL) between other multilayer HTL heterojunction and the red-QD layer. The QD-LEDs with N-CD interlayer represented superior electrical rectification and electroluminescent efficiency than those without the N-CD interlayer. The insertion of N-CD layer was found to provoke the Forster resonance energy transfer (FRET) from N-CD to QD layer, as confirmed by time-integrated and - resolved photoluminescence spectroscopy. Moreover, hole-only devices (HODs) with N-CD interlayer presented high hole transport capability, and ultraviolet photoelectron spectroscopy also revealed that the N-CD interlayer reduced the highest hole barrier height. Thus, more balanced carrier injection with sufficient hole carrier transport feasibly lead to the superior electrical and electroluminescent properties of the QD-LEDs with N-CD interlayer. We further studied effect of N-CD interlayer thickness on electrical and luminescent performances for high-brightness QD-LEDs. The ability of the N-CD interlayer to improve both the electrical and luminescent characteristics of the QD-LEDs would be readily exploited as an emerging photoactive material for high-efficiency optoelectronic devices.ope

In-situ monitoring of photocatalytic reactions in optofluidic microreactors

To advance the state-of-the-art technology in photocatalysis, there is a growing need to develop optically efficient microreactors that allow rapid changes in reaction conditions for catalyst screening. In addition, such microreactors should offer strong light-matter interactions for the in-situ spectroscopic detection of chemical species. Motivated by these challenges, this thesis marries the fields of fibre-based optofluidics and photocatalysis to generate scientific insights into how promising new photocatalysts behave. Novel types of optical fibre were optimised and characterised for liquid phase spectroscopy on sub-microlitre samples; these fibres included kagomé-style and single-ring hollow-core photonic crystal fibres (HC-PCFs). New kinetic insights were obtained into the photoactivity of carbon nanodots (CDs) through systematic screening of a wide range of reaction conditions within kagomé-style HC-PCF microreactors. Spectrokinetic insights across twenty-nine reaction conditions were studied with a cumulative sample volume of < 1.5 mL, using viologen species as indicators of electron transfer from CDs. First, amorphous and graphitic CDs were benchmarked against the well-known photocatalyst [Ru(bpy)3]2+. This study was then extended to replace the viologen indicator with hydrogen-evolving cobaloxime electrocatalysts, to probe catalytic intermediate states. To give further insight into the electron transfer from carbon nanodots to viologens, transient absorption spectroscopy was then performed to probe changes on timescales of 1 nanosecond to 1 millisecond. Finally, a new ultralow volume fibre-based fluorescence spectroscopy method was realised. As a proof of principle, the photoredox catalyst 4CzIPN was combined with the fluorescence quenchers tetrabutylammonium azide and cyclohexylamine. The extracted bimolecular Stern-Volmer quenching coefficients were compared with conventional fluorimeter-based approaches, which were taken on much larger sample volumes. This thesis provides a foundation for developing continuous-flow photocatalytic screening systems based on HC-PCFs, which minimise the consumption of precious reagents