Sodium yttrium fluoride based upconversion nano phosphors for biosensing

In the present study, NaYF4-Yb3+/Er3+ having the composition NaYF4-18%Yb3+/2%Er3+ and NaYF4-20%Yb3+/2%Er3+ with and without the addition of PVP (polyvinyl pyrolidone) have been synthesised by a solution method using NaF, yttrium nitrate, ytterbium nitrate and erbium nitrate as precursors. Upconversion spectra of prepared nanomaterial under 980 nm laser excitation have been studied. The variation in upconversion spectra with new born calf serum and myoglobin has been studied. Myoglobin (Mb) may be helpful when used in conjunction with other cardiac markers for rapid determination of acute myocardial ischemia, especially in patients with a typical chest pain or nonspecific ECG changes. The variation of UC fluorescence with addition of Mb indicates the suitability of using NaYF4 based UC nanoparticles in cardiac marker detection. The detailed study is currently under progress

High performance magneto-fluorescent nanoparticles assembled from terbium and gadolinium 1,3-diketones

Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted. The core composition was optimized for the longitudinal relaxivity to be greater than that of the commercial magnetic resonance imaging (MRI) contrast agents together with high level of Tb(III)-centered luminescence. The tuning of both magnetic and luminescent output of nanoparticles is obtained via the simple variation of lanthanide chelates concentrations in the initial synthetic solution. The exposure of the pheochromocytoma 12 (PC 12) tumor cells and periphery human blood lymphocytes to nanoparticles results in negligible effect on cell viability, decreased platelet aggregation and bright coloring, indicating the nanoparticles as promising candidates for dual magneto-fluorescent bioimaging

Developing a multifunctional nanocomposite using albumin-encapsulated rare-earth doped nanoparticles for tumor targeting

Optically guided imaging of diseases and surgical procedures is challenged by the lack of photoluminescent probes that can be sensitively detected within living tissues and tracked in real-time. The use of visible light for the detection of conventional probes suffers from poor tissue penetration and non-specific fluorescence. Emerging probes excited using near infrared light (NIR) reduce undesired tissue absorbance, however light scattering resulting from the complex heterogeneity of biological tissues limits the penetration depth of light propagation. Optical probes that emit over a new window of electromagnetic radiation in the short wavelength infrared (SWIR) region can significantly improve in vivo imaging sensitivity compared to NIR. However, current SWIR-detectable probes lack the optical tunability and biocompatibility requisite for biological implantation in vivo. This doctoral dissertation is focused on investigating albumin-derived, biologically interactive nanoparticles as a platform system that can be designed with distinct multifunctional properties, particularly, SWIR imaging and the delivery of therapeutic cargo. The bulk of the thesis is focused on conceptualizing and developing a new class of SWIR-detectable nanomaterials for targeted imaging of cancerous tissues. Conventionally fabricated rare-earth doped nanoprobes (REs) are weakly bioavailable, lack functional surface groups for tissue targeting and exhibit potential cytotoxicity. A major research effort of this thesis was to develop albumin nanoshells around rare-earth nanoprobes for establishing highly biocompatible and biologically targetable RE nanocomposites with controlled sizes and pharmacodynamic behaviors. This study also produced the first evidence reported to date of multi-spectral, real-time SWIR imaging at anatomical resolution in vivo and demonstrated the prospects of REs for targeted molecular imaging. The albumin-encapsulated, inorganic-organic nanocomposite of REs showed enhanced SWIR signal intensity in diseased tissue through accumulation of REs at tumor sites and extended the in vivo retention of REs. Further modifications were made to the albumin coating to create a multifunctional nanoparticle with tumor-penetrating and therapeutic delivery properties for both imaging and drug delivery applications. The cumulative findings of this thesis lay the groundwork for the design of new biomedical probes and imaging methods that have the potential to significantly advance surveillance of a range of diseases with complex molecular etiologies, from cancers to heart disease.Ph. D.Includes bibliographical referencesIncludes vitaby Dominik Jan Naczynsk

The role of capital structure management (elements of the theory, experience, practice)

W strategii finansowej przedsiębiorstwa struktura kapitału odgrywa szczególną rolę, wpływając na stopień podejmowanego ryzyka finansowego. Poszukiwanie najlepszych źródeł finansowania, najbardziej efektywnych możliwości inwestowania, to podstawowe decyzje uczestników rynku finansowego. Stąd ważne jest pytanie, w jakim stopniu zmiany struktury kapitału decydują o wyborach inwestorów i związanej z tym wartości rynkowej spółek. W artykule zaprezentowano podstawowe elementy teorii struktury kapitału z próbą oceny jej wpływu na wartość rynkową przedsiębiorstw na polskim rynku kapitałowym.In the company’s financial strategy the capital structure plays a special role influencing the degree of financial risk taken. The search for the best sources of financing, the most effective investment opportunities are the basic decisions of financial market participants. Therefore, it is important to find the answer to the question how the changes of capital structure influence the investors’ choices and the company’s market valuation. The article presents basic elements of the theory of capital structure with an attempt to assess its impact on the market value of companies on Polish capital market

Dimeric Gold Nanoparticle Assemblies as Tags for SERS- Based Cancer Detection

Herein, a new class of multifunctional materials combining a clustered nanoparticle-based probe is presented for surface enhanced Raman scattering (SERS)-based microscopy and surface functionalization for tissue targeting. Controlled assembly of spherical gold nanoparticles into dimers (DNP-REP) is engineered using a small, rigid Raman-active dithiolated linking reporter (REP) to yield narrow internanoparticle gaps and to strategically generate the “hot spot” while concurrently placing the reporter within the region of highest SERS enhancement. Peptide functionalized DNP-REP materials are highly stable even upon incubation with living cells and show controlled levels of binding and intracellular endocytosis. To demonstrate the functionality of such probes for disease detection, differentially targeted DNP-REPs are incubated over various time points with cultured human glioblastoma cells. Using human glioblastoma cells, the SERS maps of targeted tumor cells show the markedly enhanced signals of the DNP-REP, compared to conventional confocal fluorescence based approaches, especially at low incubation times. Even with as few as 40 internalized DNP-REP, a relatively intense SERS signal is measured, demonstrating the high signal to noise ratio and inherent biocompatibility of the materials. Thus, these Raman reporter-based nanoparticle cluster probes present a promising and versatile optical imaging tool for fast, reliable, selective, and ultrasensitive tissue targeting and disease detection and screening