The preparation of magnetic nanoparticle assemblies for biomedical applications

Magnetic nanoparticles and their assemblies are subjects of considerable scientific interest for basic research, but also for applications as contrast agents in magnetic resonance imaging (MRI) and for hyperthermia. Such applications depend on the production of stable suspensions of the particles, it is important therefore to characterise the particles in suspension. In this work photon correlation spectroscopy was used to measure of the hydrodynamic size of the particles. NMR techniques were used to determine the stability and to quantify the contrast efficiency (relaxivity) of the suspensions. This work has also provided insight into the nature of the nanoclusters in suspension and into the mechanisms of their growth. In the first part of this thesis the synthesis, stabilisation and magnetic properties of aqueous magnetite nanocomposite suspensions which are formed in the presence of fatty acids or DNA are presented. For fatty-acid stabilised nanocomposites the NMR response is sensitively dependent on the method of preparation, which cab result in magnetically blocked or superparamagnetic nanoclusters. In the case of the DNA nanocomposites, the biomolecule acts as a template for the preparation of low dimensional assemblies, or magnetic nanowires, whose suspensions exhibit high relaxivity at low magnetic field. In this second part the synthesis, stabilisation and magnetic properties of magnetite nanoparticle suspensions formed in organic solvents in the presence of long chain surfactants are presented. The influence of nanoparticle size on the magnetic properties is discussed in detail. The NMR response of the particles in non-aqueous suspension is shown to conform to a model previously developed for aqueous suspensions of magnetite. Studies of the controlled clustering of the nanoparticles in organic solvents are presented. The mechanism and kinetics of nanocluster growth are discussed

Size-tunable hydrophilic cerium oxide nanoparticles as a `turn-on' fluorescence sensor for the rapid detection of ultralow concentrations of vitamin C

The novel perspective of cerium dioxide as a fluorescence sensor has been demonstrated in the present study. The green coloured emission associated with the nano-dimensions of ceria has been adopted as an analytical tool to sense vitamin C, which is a biologically important molecule, in dilute concentrations. Ultrafine ceria nanoparticles of average size 2.2 nm have been fabricated by a surfactant assisted thermal decomposition strategy. The particular fashion of attachment of the oleic acid surfactant with ceria resulted in the surface hydrophobicity of the nanoparticles which in turn prevents their interaction with a hydrophilic molecule like vitamin C in the reaction media. In order to tackle the incompatibility of the nanoparticles with water, a hydrophilic surfactant coating has been grafted over their surface via bilayer surface functionalisation. The success of the accomplished strategy has been confirmed by thermogravimetric analyses, zeta potential and contact angle measurements. The redox properties of ceria and its optical properties served as a probe to quantify vitamin C in the concentration range 10(-7) to 10(-4) M with a very low limit of detection (LoD) of 500 nM. The designed sensor exhibits a rapid `turn on' fluorescence response within 30 seconds and the reversibility of its fluorescence even after 5 cycles of vitamin C addition corroborates its reusability. The high selectivity of the sensor to detect vitamin C again highlights its suitability as an analytical tool. The realistic application of the sensor has also been displayed by the quantification of vitamin C in pharmaceutical formulations within acceptable error limits

Land Use/Land Cover Change and Environmental Impact Analysis of Ramgarh-Naudiha Region in Uttar Pradesh, India through Geospatial Technology

Rapidly changing LULC scenario with growing population is of great concern in the modern world. The present study was undertaken to evaluate the changes in LULC pattern in Ramgarh-Naudiha region of Sonbhadra district, UP, over 20 years during 1998-2018 using datasets from the Landsat Thematic Mapper (TM) 5 and Landsat 8 (OLI/TIRS) satellites. LULC map for the chosen period has been generated by unsupervised classification with maximum likelihood algorithm. Results indicate that the study area is vulnerable to such LULC changes due to its sensitive geographic location. It is found that the major changes did happen in agriculture, forest, wasteland and water bodies. Agriculture and Forest areas have decreased by similar to 2 and 6.56% respectively in the study period. The wastelands had increased fast from 5.08% in 1998 to 18.87% in 2018 at the cost of the forest cover and agricultural land respectively. In 1998, water bodies were 7.49%, whereas, it has decreased to 2.04% in 2018. On the contrary, urban fringe area has grown from 0.33% in 1998 to 0.49% in 2018 especially due to population growth. The present study concludes that this LULC analysis will increase awareness and help in taking necessary action in appropriate land use planning and management

pH dependent chemical stability and release of methotrexate from a novel nanoceramic carrier

Considering the pH dependent chemical stability of anticancer drug methotrexate (MTX), the present communication reports a new approach for intercalation of the same in a nanoceramic vehicle, magnesium aluminium layered double hydroxide (LDH), by ex situ anion exchange method at pH 7.00, using 0.3 M ammonium acetate solution for dissolution of the drug. This simple method ensures maximum stability of the drug at the above said pH, with no degradation byproduct (e.g., N-10-methyl folic acid formed due to alkaline hydrolysis) under the given experimental conditions, compared to the similar approach, using 0.1 M sodium hydroxide solution, reported in our earlier work. Importantly, the above method leads to an enhanced drug loading of 32.3 wt%, compared to our previous reports. The cumulative release profile of MTX from LDH-MTX formulation in phosphate buffer saline (PBS) at pH 7.4 exhibited burst release initially which was taken care of by imparting a unique coating of poly(D,L-lactideco-glycolide, PLGA) on the LDH-MTX nanostructure that reduces the toxicity due to local accumulation. Hence, the superiority of the above for use in cancer chemotherapy, over the conventional drug-polymer system has been established w.r.t the drug release profile and a possible hypothesis of the same has been suggested. The half maximal inhibitory concentration (IC50) of the MTX drug used in this study has been determined and the same has been used to estimate the time dependent (24, 48, 72 and 96 h) efficacy of the MTX loaded samples with/without polymer coating, on human colon tumour cells (HCT-116)

Land Use/Land Cover Change and Environmental Impact Analysis of Ramgarh-Naudiha Region in Uttar Pradesh, India through Geospatial Technology

Rapidly changing LULC scenario with growing population is of great concern in the modern world. The present study was undertaken to evaluate the changes in LULC pattern in Ramgarh-Naudiha region of Sonbhadra district, UP, over 20 years during 1998-2018 using datasets from the Landsat Thematic Mapper (TM) 5 and Landsat 8 (OLI/TIRS) satellites. LULC map for the chosen period has been generated by unsupervised classification with maximum likelihood algorithm. Results indicate that the study area is vulnerable to such LULC changes due to its sensitive geographic location. It is found that the major changes did happen in agriculture, forest, wasteland and water bodies. Agriculture and Forest areas have decreased by ~2 and 6.56% respectively in the study period. The wastelands had increased fast from 5.08% in 1998 to 18.87% in 2018 at the cost of the forest cover and agricultural land respectively. In 1998, water bodies were 7.49%, whereas, it has decreased to 2.04% in 2018. On the contrary, urban fringe area has grown from 0.33% in 1998 to 0.49% in 2018 especially due to population growth. The present study concludes that this LULC analysis will increase awareness and help in taking necessary action in appropriate land use planning and management

Fabrication of magnetite nanocrystals in alcohol/water mixed solvents: catalytic and colloid property evaluation

In this work, Fe3O4 nanocrystals have been synthesized by homogeneous precipitation in different alcohol/water (1 : 1) solvent mixtures at two different temperatures to elucidate the role of the dielectric constant (ε) of the reaction medium. The effects of different solvents on the catalytic activity of precipitated NPs in carbon combustion were examined. HRTEM images, SAED and XRD confirmed that the nanocrystals are of pure fcc inverse spinel Fe3O4 phase with narrow size distribution, and the crystals are completely dispersible in water. The morphological features of the nanocrystals, such as their surface termination and shape of the Fe3O4 NPs, were analyzed by HR-TEM. As ε decreases, the crystal size decreases for mono-ol systems compared to ∼13 nm size in water, whereas ethylene glycol/water yields finer ∼8.2 nm crystals although it has the highest ε among the mono-/poly-ols. A soot combustion study demonstrates that the catalytic activity is mainly due to the available surface area along with the exposure of active crystallographic facets. A study of the colloids by light scattering shows that the alcohol mediated process produces 16 to 33 nm MNP clusters composed of 2 to 3 particles in highly stable aqueous magnetic fluids. The relatively high temperature process favors higher crystallinity and particle size with reduced colloidal stability in the aqueous phase. The nanocrystalline powders and the dispersed colloids have excellent potential applications in biotechnology and selective catalysis and also as ferrofluids

Concentration quenching in cerium oxide dispersions via a Forster resonance energy transfer mechanism facilitates the identification of fatty acids

The energy exchange phenomena of cerium oxide based nanoparticles in a medium have been studied by means of a meticulous approach. A concentration dependent non-radiative pathway has been revealed for the particles due to the close proximity between them which causes the extinction of fluorescence. The calibration plot, according to the Stern-Volmer equation, showed a good linear relationship within the acceptable error limit, and the value of Q, denoting the exchange interaction, was close to 6, implying dipolar coupling between particles. Theoretical analysis of spectroscopic data showed that Forster resonance energy transfer (FRET) is the dominant mechanism responsible for the interparticle excitation transfer and the Forster radius (R-0) calculated was 68.6 A degrees. The distance dependence of FRET has been utilized to analyse the conformation and chain length of fatty acids by interrupting the energy transfer efficiency among the particles, and thus a simple analytical tool based on FRET for the qualitative as well as quantitative assessment of fatty acids has been projected

Beneficiation of Clays from Ramgarh-Naudiha Region of Sonbhadra District Uttar Pradesh, Impart Improved Properties for Ceramic Industries

Chemical and physical properties of clay samples collected from the deposits in the Ramgarh-Naudiha of Sonbhadra district, Uttar Pradesh were examined for their utilisation in ceramic industry. The raw clays from the deposits were found to be siliceous ball clays, contained less kaolinite, non-plastic and were unsuitable for making ceramic items. These clays have been subjected to standard beneficiation techniques which removed the free quartz. The beneficiated clays were less siliceous, had improved properties that can be used as partial replacement material in making ceramic items

Spectroscopic investigation confirms retaining the pristine nature of single-walled carbon nanotubes on dissolution in aniline

Carbon nanotubes in all forms are very much insoluble in both organic and inorganic solvents due to its high agglomeration and entangled morphology. General methods for dissolution of single-walled carbon nanotubes (SWNTs) are mostly associated with complexation or polymerization or addition of macromolecules which change the physical or chemical properties of SWNTs and the pristine nature of SWNTs is lost. Dissolution of SWNTs in a solvent like aniline is practiced here which is a very simple reaction method. Here aniline is capable to form a SWNT-aniline charge transfer complex without attachment of macromolecules or polymer which is also soluble in other organic solvents. Solvation of SWNTs by this method is also capable of maintaining the similarity between the structure of SWNTs before and after the dissolution, which means that the pristine nature of SWNTs is preserved. Formation of charge transfer complex in this reaction has been proven by UV-Vis/NIR absorption and photoluminescence spectroscopy. Raman spectroscopy and electron microscopy (FESEM and TEM) are the evidences for protection of the pristine nature of SWNTs even after high-temperature complexation reaction with aniline and also after solubilization in organic solvents

Morphologically Diverse Cerium Oxide Nanostructures and Nanofields for Multi functional applications.

The prospective impact of nanomaterials in science and technology has followed an increasing trend due to their unique chemical and physical properties compared to bulk. Significant advances in current technologies in areas such as clean energy production, electronics, medicine, and environment have fuelled major research and development efforts in nanotechnology around the world. This leads to the opportunity to use such nanostructured materials in novel applications and devices. Ceria, zirconia, alumina and titania are some of the major oxides which find vast applications as a nanomaterial on a wider side