163 research outputs found
Studies on Bodipy-platinum(Ii/Iv) Conjugates for Cellular Imaging and Photodynamic Therapy
No full textCancer emerges from the abnormal proliferation of aberrant cells. Amidst a multitude of treatment options, chemotherapy is widely used as a viable methodology. Despite its widespread use, it is encumbered with significant limitations due to drug related side-effects. Consequently, in recent times, photodynamic therapy (PDT) and photoactivated chemotherapy (PACT) have emerged as highly promising alternatives to traditional chemotherapy. This thesis aims to conceive and synthesize new platinum(II/IV) complexes using ligands as multifunctional agents for effective phototherapy and photochemotherapy applications. In the initial phase, a series of mono-functional platinum(II) complexes [Pt(L1-3)Cl]Cl (1-3) were synthesized having BODIPY (boron-dipyrromethene)-tagged dipicolylamine (dpa) ligands (L2 and L3) as green and red light emitting photosensitizers along with a benzyl derivative of dpa (L1). These mono-functional complexes exhibit remarkable affinity for DNA binding, as evidenced from a study employing the model nucleobase 9-EtG, while also displaying the ability to generate singlet oxygen upon photoactivation of the BODIPY photosensitizer. In subsequent investigations, we synthesized a novel platinum(IV)-BODIPY conjugate, named Oxoplatin-B (4), derived from cisplatin. The prodrug exhibited photo-induced ligand release, accompanied by the simultaneous formation of the cisplatin core through a two-electron Pt(IV)-Pt(II) reduction process. Encouraged from the results obtained with the green light Pt(IV) prodrug, we embarked on investigating the possibilities of a clinically applicable platinum(IV) prodrug with the formulation [Pt(NH3)2Cl2(OH)(L6)] (6), having a red light active BODIPY ligand (HL6). Upon red light irradiation, the complex exhibited significant PDT activity with sub-micromolar IC50 values in cancer cells such as HeLa and MCF-7. Moving forward, we introduced a novel prodrug (7) formulation that combines a platinum(IV) core with a bioactive biotin (vitamin B7) moiety, covalently linked to a PEGylated BODIPY ligand (HL7) designed to respond to red light stimulation and for enhanced bioavailability. Notably, the complex displays remarkable stability in solution in dark, but rapidly activates upon red light exposure without any need for external reducing agents. Finally, we made a comprehensive study on the synthesis and characterization of a hetero-bimetallic Ru(II)-Pt(IV) conjugate (9). This conjugate presents a dual-action Pt(IV) complex with a chemo-active unit and a BODIPY-Ru(II)-bis-terpyridine dyad complex as a photosensitizer. This prodrug induced significant photocytotoxicity with remarkably high phototherapeutic index (PI) value of >4500 in A549 cancer cells. The findings of this thesis work pave the way for innovative approaches in the design and development of new generation of platinum(II/IV) complexes having BODIPY-based photosensitizers, offering exciting prospects in PDT and cellular imaging applications
Optimization of down-conversion phosphor films for high efficiency white organic light-emitting diodes
No full textArc-discharge In Solution: A Novel Synthesis Method For Carbon Nanotubes And In Situ Decoration Of Carbon Nanotubes With Nanoparticles
Get PDFNanotechnology has reached the status of the 21st century\u27s leading science and technology based on fundamental and applied research during the last two decades. An important feature of nanotechnology is to bridge the crucial dimensional gap between the atomic and molecular fundamental sciences and microstructural scale of engineering. Accordingly, it is very important to have an in-depth understanding of the synthesis of nanomaterials for the use of state-of-the-art high technological devices with enhanced properties. Recently, the \u27bottom-up\u27 approach for the fabrication of nanomaterials has received a great deal of attention for its simplicity and cost effectiveness. Tailoring the various parameters during synthesis of selected nanoparticles can be used to fabricate technologically important components. During the last decade, carbon nanotubes (CNTs) have been envisioned for a host of different new applications. Although carbon nanotubes can be synthesized using a variety of techniques, large-scale synthesis is still a great challenge to the researchers. Three methods are commonly used for commercial and bulk productions of carbon nanotubes: arc-discharge, chemical vapor deposition and laser ablation. However, low-cost, large-scale production of high-quality carbon nanotubes is yet to be reported. One of the objectives of the present research is to develop a simplified synthesis method for the production of large-scale, low-cost carbon nanotubes with functionality. Herein, a unique, simple, inexpensive and one-step synthesis route of CNTs and CNTs decorated with nanoparticles is reported. The method is simple arc-discharge in solution (ADS). For this new method, a full-fledged optoelectronically controlled instrumen is reported here to achieve high efficiency and continuous bulk production of CNTs. In this system, a constant gap between the two electrodes is maintained using a photosensor which allows a continuous synthesis of the carbon nanostructures. The system operates in a feedback loop consisting of an electrode-gap detector and an analogue electronic unit, as controller. This computerized feed system was also used in single process step to produce in situ-decorated CNTs with a variety of industrially important nanoparticles. To name a few, we have successfully synthesized CNTs decorated with 3-4 nm ceria, silica and palladium nanoparticles for many industrially relevant applications. This process can be extended to synthesize decorated CNTs with other oxide and metallic nanoparticles. Sixty experimental runs were carried out for parametric analysis varying process parameters including voltage, current and precursors. The amount of yield with time, rate of erosion of the anode, and rate of deposition of carbonaceous materials on the cathode electrode were investigated. Normalized kinetic parameters were evaluated for different amperes from the sets of runs. The production rate of pristine CNT at 75 A is as high as 5.89 ± 0.28 g.min-1. In this study, major emphasis was given on the characterizations of CNTs with and without nanoparticles using various techniques for surface and bulk analysis of the nanostructures. The nanostructures were characterized using transmission electron microscopy, high resolution transmission electron microscopy, scanning transmission electron microscopy, energy dispersive spectroscopy and scanning electron microscopy, x-ray photo electron spectroscopy, x-ray diffraction studies, and surface area analysis. Electron microscopy investigations show that the CNTs, collected from the water and solutions, are highly pure except the presence of some amorphous carbon. Thermogravimetric analysis and chemical oxidation data of CNTs show the good agreement with electron microscopy analysis. The surface area analysis depicts very high surface area. For pristine multi-walled carbon nanotubes, the BET surface area is approximately 80 m2.g-1. X-ray diffraction studies on carbon nanotubes shows that the products are clean. Nano-sized palladium decorated carbon nanotubes are supposed to be very efficient for hydrogen storage. The synthesis for in-situ decoration of palladium nanoparticles on carbon nanotubes using the arc discharge in solution process has been extensively carried out for possible hydrogen storage applications and electronic device fabrication. Palladium nanoparticles were found to form during the reduction of palladium tetra-chloro-square planar complex. The formation of such a complex was investigated using ultraviolet-visible spectroscopic method. Pd-nanoparticles were simultaneously decorated on carbon nanotubes during the rolling of graphene sheets in the arc-discharge process. Zero-loss energy filtered transmission electron microscopy and scanning transmission electron microscopy confirm the presence of 3 nm palladium nanoparticles. The deconvoluted X-ray photoelectron spectroscopy envelope shows the presence of palladium. Surface area measurements using BET method show a surface area of 28 m2.g-1. The discrepancy with pristine CNTs can be explained considering the density of palladium (12023 kg.m-3). Energy dispersive spectroscopy suggests no functionalization of chlorine to the sidewall of carbon nanotubes. The presence of dislodged graphene sheets with wavy morphology as observed with high-resolution transmission electron microscopy supports the formation of CNTs through the \u27scroll mechanism\u27
Importance of Information Product for Economic Development
Get PDFThe collection of information and the construction of knowledge has become an inevitable part for the economic growth and development. Now we are living in an advanced world where information is becoming important for every human to upgrade as technical development. The present information age is running to face many more challenges to achieve these much-needed goals. That is rapid technological advancement, which also creates new opportunities for using information virtually in all human pursuits. The extensive development of informational technologies, the emergence of information networks, the increasing reliance of the contemporary society on collecting, processing and distribution of information for its economic health, a paradigm shift to information work as a predominant occupation have led to the conception of information as a primary source of income. This paper attempt to highlight how information product affects the economic development through different medium of collecting information
Structural characterization of spray-dried microgranules by spin-echo small-angle neutron scattering
No full textSpray-drying is a widely used industrial technique and has shown an immense potential in the fields of nanoscience and technology. This is due to its ability to synthesize microgranules consisting of correlated nanostructures using evaporation induced assembly through bottom-up approach. Although the nature of correlation among the constituent nanoparticles and their size distribution could earlier be obtained by conventional Small-angle Scattering (SAS) technique, a statistically averaged quantitative measure of the shell thickness and hollowness of the formed granules remained a challenge. In this work, we have used Spin-echo Small-angle Neutron Scattering (SESANS) technique to characterize spray-dried nanostructured microgranules having different hollowness. It is shown that this non-destructive technique provided precise quantification of the granular sizes and hollowness by utilizing polarization property of neutrons in real space directly.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Neutron and Positron Methods in Material
Nickel-Catalyzed Alkylation of Oxindoles with Secondary Alcohols
No full textHerein,
we have demonstrated a simple nickel-catalyzed C-3-selective
alkylation of 2-oxindoles using a wide variety of secondary alkyl
alcohols. As a special highlight, functionalization of the cholesterol
derivative was reported. Control experiments, initial mechanistic
studies, and deuterium-labeling experiments were performed for the alkylation process
Hybrid polymer-CdSe solar cells with a ZnO nanoparticle buffer layer for improved efficiency and lifetime
No full textWe report the use of a solution-processed ZnO nanoparticle buffer layer in hybrid solar cells based on blends of poly(3-hexylthiophene)(P3HT) and CdSe quantum dots. Depending on the size of the CdSe nanocrystal, these devices exhibit20-70% higher photocurrent output than similar devices without the ZnO nanoparticle layer, which is attributed to a combination of electronic and optical effects. With negligible change in open-circuit voltage and a small increase in the fill factor, the power conversion efficiency of these P3HT:CdSe hybrid solar cells was increased by30-80% with incorporation of the ZnO nanoparticle layer. The presence of the ZnO nanoparticle layer also drastically improves the stability of these hybrid solar cells. Less than40% loss in efficiency was observed for such devices after70 days of exposure to the laboratory ambient without any type of encapsulation.? The Royal Society of Chemistry2011
White light emission from single layer poly (n-vinylcarbazole) polymeric light-emitting devices by mixing singlet and triplet excimer emissions
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