Quantum Dots: An Emerging Approach for Cancer Therapy

Nanotechnology is indisputably a scientific technique that offers the prospect of new therapies, and hope, for the treatment of malignant illnesses. It is a novel technology that offers new approaches for the diagnosis and management of diverse diseases. Although the discovery of Quantum dots (QD) nano-transporters has already led to a few positive developments, QD nano-transporters are still at their initial stage, though have yet proven valuable to society. The excertion of QD indicates conversion in natural imaging along with photograph have established incredible suitability in bio-imaging, new drug development, targeted gene deliverance, biosensing, photodynamic treatment as well as diagnosis. The present review aimed to confer the significance of QD in diagnosis as well as in management of cancer. This review aims to impart fundamental insight as well as conception of QD its merits, properties, utilization as well as mode of action. This review highlight of different designing schemes of QD like hydrothermal, drop-casting, ultrasonic, solvothermal, spin-coating, atomic layer desorption, layer by layer, polymethylmethacrylate aided-transfer, electrochemical, ion beam sputtering deposition. Moreover, we have elaborated on the diverse researches related to cytotoxic examination to reveal that QDs are harmless. Concisely, the present review summarizes the fabrication schemes, current research and utilization of QD in cancer treatment.

Probing the Miscibility Gap of the Pt–Pd Binary System by Atom Probe Tomography

To solve the uncertainty of the platinum (Pt)–palladium (Pd) phase diagram, especially the existence of a suggested miscibility gap, atom probe tomography (APT) was used to determine the time evolution of the composition after heat treatment. Due to the extraordinarily slow diffusion in the temperature range of the controversial phase separation, the investigated volume was limited to nano-sized multiple layers deposited by ion beam sputtering (IBS). The evaporated volume was reconstructed from the obtained datasets and the respective diffusion coefficients were determined using the Fourier series solution of the diffusion equation. Beginning with pure Pt and Pd layers annealed at 673, 773, 873, and 973 K, the mixing appears to be purely diffusion controlled in the chosen annealing times, but the state of complete mixing was still not observed. Therefore, extended isothermal annealing sequences at 673 and 773 K with pre-alloyed layers have been carried out. They clearly suggest complete mixing even at the lowest investigated temperatures.

Systematic study of the synthesis of nanostructured multiferroic films and their structural, electronic and magnetic properties

<p>Multiferroics are unique materials that display multiple ferroic properties (ferroelectricity, ferromagnetism and ferroelasticity) simultaneously. A number of materials containing bismuth have intrinsic multiferroic properties, including BiFeO₃ and BiCrO₃. Among them, BiFeO₃ has attracted widespread attention because BiFeO₃ was the first material to display multiferroic behaviour at ambient temperature. A weak ferromagnetism occurs only at low temperatures depending on synthesis conditions. This thesis reports the structural, magnetic and optical properties of nanostructured BiFeO₃ thin films prepared by two novel approaches of ion beam sputtering and ion implantation techniques. Nanocrystalline BiFeO₃ films were prepared at ambient temperature by sputtering and thermal annealing at 500 °C in an oxygen atmosphere. The annealing resulted in the formation of multiferroic BiFeO₃ phase with a reduction of iron oxide and bismuth phases. Superparamagnetism was observed and could be attributed to magnetite and maghemite nanoparticles. The magnetic properties were mainly due to magnetite and maghemite nanoparticles. The saturation magnetic moment was 60% lower after annealing, which was due to Fe in phases of iron oxide being incorporated into BiFeO₃ nanoparticles. An exchange bias was observed before and after annealing. The exchange bias cannot be attributed to BiFeO₃ structure. Instead, the exchange has likely arisen from magnetite and maghemite cores with spin-disordered shells. Piezoelectric responses measured by piezoelectric force microscopy confirmed the presence of BiFeO₃ ferroelectric material. The Magneto-optical Kerr effect (MOKE) and optical studies were used to calculate an anomalously high Verdet constant. The MOKE and magnetic circular dichroism (MCD) displayed a significant modification in function of the wavelength. Further increasing the annealing temperature lead to an increase in iron oxide phases, while increasing the annealing duration reduced the iron oxide phases, however this increases the fraction of Bi₂Fe₄O₉ and Bi₂O₃. Another approach to synthesise BiFeO₃ thin film was investigated by bismuth ion implantation into iron oxide thin film. An as-made iron oxide film subsequently implanted with bismuth and annealed showed a 6.5% reduction of the ferromagnetic phase fraction. An annealed iron oxide film subsequently implanted with bismuth and annealed show that the ferromagnetic phase was present at less than 4% while Fe₃O₄ and γ-Fe₂O₃ increased to 7%. The coercive field is affected by annealing. However, this field is not affected by the bismuth implantation. For the first-time, a preliminary investigation reporting the implantation of Bi then Fe then O into SiO₂:Si was made with the aim to synthesise BiFeO₃ films and magnetic nanoparticles. The implantation of Fe then O then Bi into SiO₂:Si contained a mix of iron oxides: α-Fe₂O₃ and Fe₃O₄, as confirmed by Raman spectroscopy and X-ray diffraction, while γ-Fe₂O₃ was most likely also present in the film. The as-implanted sample displayed a sign of a superparamagnetic phase that was lost with annealing the sample. Preliminary investigations of another multiferroic material, BiCrO₃, were carried out. Thin films of BiCrO₃ were prepared by ion beam sputtering and annealing the sample in an oxygen atmosphere which lead to BiCrxOy with chromium oxides and bismuth oxide phases. Magnetic enhancement was observed when annealing above 700 °C. Annealing in an oxygen atmosphere followed by an argon atmosphere created a superparamagnetic phase that was not visible under other annealing conditions.</p>

Systematic study of the synthesis of nanostructured multiferroic films and their structural, electronic and magnetic properties

<p>Multiferroics are unique materials that display multiple ferroic properties (ferroelectricity, ferromagnetism and ferroelasticity) simultaneously. A number of materials containing bismuth have intrinsic multiferroic properties, including BiFeO₃ and BiCrO₃. Among them, BiFeO₃ has attracted widespread attention because BiFeO₃ was the first material to display multiferroic behaviour at ambient temperature. A weak ferromagnetism occurs only at low temperatures depending on synthesis conditions. This thesis reports the structural, magnetic and optical properties of nanostructured BiFeO₃ thin films prepared by two novel approaches of ion beam sputtering and ion implantation techniques. Nanocrystalline BiFeO₃ films were prepared at ambient temperature by sputtering and thermal annealing at 500 °C in an oxygen atmosphere. The annealing resulted in the formation of multiferroic BiFeO₃ phase with a reduction of iron oxide and bismuth phases. Superparamagnetism was observed and could be attributed to magnetite and maghemite nanoparticles. The magnetic properties were mainly due to magnetite and maghemite nanoparticles. The saturation magnetic moment was 60% lower after annealing, which was due to Fe in phases of iron oxide being incorporated into BiFeO₃ nanoparticles. An exchange bias was observed before and after annealing. The exchange bias cannot be attributed to BiFeO₃ structure. Instead, the exchange has likely arisen from magnetite and maghemite cores with spin-disordered shells. Piezoelectric responses measured by piezoelectric force microscopy confirmed the presence of BiFeO₃ ferroelectric material. The Magneto-optical Kerr effect (MOKE) and optical studies were used to calculate an anomalously high Verdet constant. The MOKE and magnetic circular dichroism (MCD) displayed a significant modification in function of the wavelength. Further increasing the annealing temperature lead to an increase in iron oxide phases, while increasing the annealing duration reduced the iron oxide phases, however this increases the fraction of Bi₂Fe₄O₉ and Bi₂O₃. Another approach to synthesise BiFeO₃ thin film was investigated by bismuth ion implantation into iron oxide thin film. An as-made iron oxide film subsequently implanted with bismuth and annealed showed a 6.5% reduction of the ferromagnetic phase fraction. An annealed iron oxide film subsequently implanted with bismuth and annealed show that the ferromagnetic phase was present at less than 4% while Fe₃O₄ and γ-Fe₂O₃ increased to 7%. The coercive field is affected by annealing. However, this field is not affected by the bismuth implantation. For the first-time, a preliminary investigation reporting the implantation of Bi then Fe then O into SiO₂:Si was made with the aim to synthesise BiFeO₃ films and magnetic nanoparticles. The implantation of Fe then O then Bi into SiO₂:Si contained a mix of iron oxides: α-Fe₂O₃ and Fe₃O₄, as confirmed by Raman spectroscopy and X-ray diffraction, while γ-Fe₂O₃ was most likely also present in the film. The as-implanted sample displayed a sign of a superparamagnetic phase that was lost with annealing the sample. Preliminary investigations of another multiferroic material, BiCrO₃, were carried out. Thin films of BiCrO₃ were prepared by ion beam sputtering and annealing the sample in an oxygen atmosphere which lead to BiCrxOy with chromium oxides and bismuth oxide phases. Magnetic enhancement was observed when annealing above 700 °C. Annealing in an oxygen atmosphere followed by an argon atmosphere created a superparamagnetic phase that was not visible under other annealing conditions.</p>

Atom Probe Study of the Miscibility Gap in CuNi Thin Films and Microstructure Development

The unclear miscibility of CuNi alloys was investigated with atom probe tomography (APT). Multilayered thin film samples were prepared by ion beam sputtering (IBS) and focused ion beam (FIB) shaping. Long-term isothermal annealing treatments in a UHV furnace were conducted at temperatures of 573, 623, and 673 K to investigate the mixing process. The effective interdiffusion coefficient of the nanocrystalline microstructure (including defect diffusion) was determined to be Deff = 1.86 × 10−10 m2/s × exp(−164 kJ/mol/RT) by fitting periodic composition profiles through a Fourier series. In nonequilibrium states, microstructural defects like grain boundaries and precipitates were observed. While at the two higher temperatures total mixing is observed, a clear experimental evidence is found for a miscibility gap at 573 K with the boundary concentrations of 26 and 66 at%. These two compositions are used in a subregular solution model to reconstruct the phase miscibility gap. So, the critical temperature TC of the miscibility gap is found to be 608 K at a concentration of 45 at% Ni.