Immunomodulatory Potential of Differently-Terminated Ultra-Small Silicon Carbide Nanoparticles

Ultra-small nanoparticles with sizes comparable to those of pores in the cellular membrane possess significant potential for application in the field of biomedicine. Silicon carbide ultra-small nanoparticles with varying surface termination were tested for the biological system represented by different human cells (using a human osteoblastic cell line as the reference system and a monocyte/macrophage cell line as immune cells). The three tested nanoparticle surface terminations resulted in the observation of different effects on cell metabolic activity. These effects were mostly noticeable in cases of monocytic cells, where each type of particle caused a completely different response (‘as-prepared’ particles, i.e., were highly cytotoxic, –OH terminated particles slightly increased the metabolic activity, while –NH2 terminated particles caused an almost doubled metabolic activity) after 24 h of incubation. Subsequently, the release of cytokines from such treated monocytes and their differentiation into activated cells was determined. The results revealed the potential modulation of immune cell behavior following stimulation with particular ultra-small nanoparticles, thus opening up new fields for novel silicon carbide nanoparticle biomedical applications

Direct Observation of Transition from Solid-State to Molecular-Like Optical Properties in Ultrasmall Silicon Carbide Nanoparticles

We employ time-dependent photoluminescence (PL) and steady-state PL excitation (PLE) measurements to study the size dependent optical properties of ultrasmall silicon carbide (SiC) nanoparticles (NP). We find that the nature of the optical transition transforms from solid-state indirect gap to molecular-like as the diameter of spherical SiC NPs is reduced from 4-6 nm to 1-3 nm with a smooth transition in between. We deduce the radiative lifetimes of SiC NPs that are well supported by ab initio time-dependent density functional theory calculations on realistically large SiC NPs with realistic surface terminations, including the solvation effects

Studies of nanocrystalline silicon colloidal suspensions

Práce se věnuje optickým a biofyzikálním vlastnostem koloidních suspenzí nanokrystalů porézního křemíku (dále jen por-Si) v různých rozpouštědlech, podmínkám vzniku por-Si s různými maximy luminiscence a jejich optické charakterizaci (emisní a excitační spektra). Pro oranžový por-Si je změřena doba života excitovaného stavu = (28,6±0,9) us na emisní vlnové délce 600 nm pomocí časově rozlišené fluorescence. Chování por-Si a drceného křemíku (krystaly o velikosti 1um) v biologickém prostředí je studováno na buněčné linii L929 (myší fibroblasty) pomocí transmisní mikroskopie, časosběrného mikrofotografování vývoje buněčné kultury, fluorescenční mikroskopie a skanovací elektronové mikroskopie (SEM). Transmisní snímky dokazují vznik agregátu v médiu za přítomnosti por-Si nebo drceného křemíku, tyto agregáty se dostávají do vnitřního prostředí buněk. Při velkých koncentracích drceného křemíku je pozorováno odumírání buněk. Por-Si měl mírně negativní vliv na vývoj buněčné kultury při velkých koncentracích, ale buňky byly životaschopné a docházelo k jejich dělení, následující generace vykazovala normální vývoj. Pomocí fluorescenční mikroskopie je studován oranžově emitující por-Si, který se zřejmě koncentruje na buněčných membránách, jeho přítomnost je prokázána i ve vnitřním prostředí buňky. SEM prokázala...This diploma thesis deals with optical and biophysical properties of colloidal suspensions of porous nanocrystalline silicon (por-Si) in different media, conditions necessary to create por-Si with different luminescence peaks and their optical characterization (emission and excitation spectra). The lifetime excited state = (28,6±0,9) us on emission wavelength 600 nm for orange emitting por-Si is measured by the time resolved fluorescence. The behaviour of por-Si and grinded silicon (crystals of size about 1um) in biological environment (L929 mouse fibroblast) is studied with optical transmission microscopy, time-lapse microphotography of cell culture evolution, fluorescent microscopy, and scanning electron microscopy (SEM). Transmission pictures prove an aggregation in presence of por-Si in media. This aggregates are going to internal environment of cells. At high concentration of grinded silicon we see meronecrosis. Por-Si has had also mildly negative effect on evolution of cell culture at very high concentrations, but cells are viable and cell division proceeds normally - next cell generation shows normal behaviour. Fluorescence microscopy used on orange emitting por-Si shows that por-Si is concentrated probably on cell membranes and its presence in internal cell environment is also proved. SEM proved...Department of Chemical Physics and OpticsKatedra chemické fyziky a optikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Bioapplications of novel nanostructured materials

Title: Bioapplications of novel nanostructured materials Author: Anna Fučíková Department / Institute: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. RNDr. Jan Valenta, Ph.D., Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This work is aimed at development of new fluorescent labels based on silicon nanocrystals. Nanodiamonds and commercial CdSe quantum dots have been used as comparative materials. Silicon nanocrystals are relatively small (1-4 nm) compared to other studied nanomaterials. They are prepared by electro-chemical etching and their surface can be activated by various molecules which strongly influences luminescence properties. Luminescence quantum efficiency can be as high as 30 % and perfectly photostable even in biological environment. Si nanocrystals are biodegradable in a living organism within reasonable time scale and non-toxic. We are able to detect luminescence of single nanocrystals, even inside living cells, with use of our micro-spectroscopy apparatus. Nanodiamonds have weak luminescence; they are toxic at higher dosages and very stable in living bodies (without available technique how to remove them). Studied CdSe..

Studies of nanocrystalline silicon colloidal suspensions

This diploma thesis deals with optical and biophysical properties of colloidal suspensions of porous nanocrystalline silicon (por-Si) in different media, conditions necessary to create por-Si with different luminescence peaks and their optical characterization (emission and excitation spectra). The lifetime excited state = (28,6±0,9) us on emission wavelength 600 nm for orange emitting por-Si is measured by the time resolved fluorescence. The behaviour of por-Si and grinded silicon (crystals of size about 1um) in biological environment (L929 mouse fibroblast) is studied with optical transmission microscopy, time-lapse microphotography of cell culture evolution, fluorescent microscopy, and scanning electron microscopy (SEM). Transmission pictures prove an aggregation in presence of por-Si in media. This aggregates are going to internal environment of cells. At high concentration of grinded silicon we see meronecrosis. Por-Si has had also mildly negative effect on evolution of cell culture at very high concentrations, but cells are viable and cell division proceeds normally - next cell generation shows normal behaviour. Fluorescence microscopy used on orange emitting por-Si shows that por-Si is concentrated probably on cell membranes and its presence in internal cell environment is also proved. SEM proved..

Studies of nanocrystalline silicon colloidal suspensions

This diploma thesis deals with optical and biophysical properties of colloidal suspensions of porous nanocrystalline silicon (por-Si) in different media, conditions necessary to create por-Si with different luminescence peaks and their optical characterization (emission and excitation spectra). The lifetime excited state = (28,6±0,9) us on emission wavelength 600 nm for orange emitting por-Si is measured by the time resolved fluorescence. The behaviour of por-Si and grinded silicon (crystals of size about 1um) in biological environment (L929 mouse fibroblast) is studied with optical transmission microscopy, time-lapse microphotography of cell culture evolution, fluorescent microscopy, and scanning electron microscopy (SEM). Transmission pictures prove an aggregation in presence of por-Si in media. This aggregates are going to internal environment of cells. At high concentration of grinded silicon we see meronecrosis. Por-Si has had also mildly negative effect on evolution of cell culture at very high concentrations, but cells are viable and cell division proceeds normally - next cell generation shows normal behaviour. Fluorescence microscopy used on orange emitting por-Si shows that por-Si is concentrated probably on cell membranes and its presence in internal cell environment is also proved. SEM proved..

Bioapplications of novel nanostructured materials

Title: Bioapplications of novel nanostructured materials Author: Anna Fučíková Department / Institute: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. RNDr. Jan Valenta, Ph.D., Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This work is aimed at development of new fluorescent labels based on silicon nanocrystals. Nanodiamonds and commercial CdSe quantum dots have been used as comparative materials. Silicon nanocrystals are relatively small (1-4 nm) compared to other studied nanomaterials. They are prepared by electro-chemical etching and their surface can be activated by various molecules which strongly influences luminescence properties. Luminescence quantum efficiency can be as high as 30 % and perfectly photostable even in biological environment. Si nanocrystals are biodegradable in a living organism within reasonable time scale and non-toxic. We are able to detect luminescence of single nanocrystals, even inside living cells, with use of our micro-spectroscopy apparatus. Nanodiamonds have weak luminescence; they are toxic at higher dosages and very stable in living bodies (without available technique how to remove them). Studied CdSe..

Bioaplikace nových nanostrukturních materiálů

Title: Bioapplications of novel nanostructured materials Author: Anna Fučíková Department / Institute: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. RNDr. Jan Valenta, Ph.D., Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This work is aimed at development of new fluorescent labels based on silicon nanocrystals. Nanodiamonds and commercial CdSe quantum dots have been used as comparative materials. Silicon nanocrystals are relatively small (1-4 nm) compared to other studied nanomaterials. They are prepared by electro-chemical etching and their surface can be activated by various molecules which strongly influences luminescence properties. Luminescence quantum efficiency can be as high as 30 % and perfectly photostable even in biological environment. Si nanocrystals are biodegradable in a living organism within reasonable time scale and non-toxic. We are able to detect luminescence of single nanocrystals, even inside living cells, with use of our micro-spectroscopy apparatus. Nanodiamonds have weak luminescence; they are toxic at higher dosages and very stable in living bodies (without available technique how to remove them). Studied CdSe...Název práce: Bioaplikace nových nanostrukturních materiálů Autor: Anna Fučíková Katedra: Katedra chemické fyziky a optiky, Matematicko-fyzikální fakulta Univerzity Karlovy v Praze Vedoucí doktorské práce: Doc. RNDr. Jan Valenta, Ph.D. Katedra chemické fyziky a optiky, Matematicko-fyzikální fakulta Univerzity Karlovy v Praze Abstrakt: Tato práce se zabývá vývojem nových fluorescenčních značek na bázi křemíkových nanokrystalů. Pro srovnání jsou zkoumány také nanodiamanty a komerční kvantové tečky na bázi CdSe. Křemíkové nanokrystaly jsou malé (1-4 nm) ve srovnání s ostatními testovanými nanočasticemi; připravujeme je pomocí elektro-chemického leptání v roztoku HF. Povrch Si nanokrystalů lze aktivovat různými molekulami a tím modifikovat jejich luminiscenční vlastnosti. Luminiscence má kvantovou účinnost až 30 % a je relativně fotostabilní (na rozdíl od ostatních fluorescenčních značek, které vybělují) Si nanočástice jsou poměrně stabilní v biologickém prostředí, z dlouhodobého hlediska ovšem biodegradabilní a netoxické. Pomocí mikro-spektroskopie jsme schopni pozorovat jednotlivé luminiskující Si nanokrystaly a to i uvnitř živých buněk. Studované nanodiamanty vykazují pouze slabou luminiscenci, jsou velmi stabilní v biologickém prostředí, ale neodbouratelné a při větších koncentracích značně toxické. Komerční...Katedra chemické fyziky a optikyDepartment of Chemical Physics and OpticsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult