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Photonic and electronic properties exist inherently in ferroelectric barium titanate (BaTiO3); severe luminescence quenching also exists due to the insufficient confinement of excitons. In this sense, high optical emission can only be achieved by its chemical and structural modification. Thin BaTiO3 and Er:BaTiO3 films were grown by the spin coating method on a glass substrate at room temperature. Self-trapping of excitons in the thin BaTiO3 film and its structural modification due to the doping with Er3+ ions (Er:BaTiO3) are verified using scanning confocal fluorescence microscopy (SCFM), where self-trapping excitons never occured in its pure state. By thermal treatment and doping (BaTiO3 and Er:BaTiO3) we obtained localization of the excitons, which would further induce lattice strain around the surface defects, to accommodate the self-trapped excitons. With such a self-trapped state, the structure of BaTiO3 generates broadband emission of several overlapping bands between 1.95 and 2.65 eV at room temperature, while the structure Er:BaTiO3 showed defined emission bands at 2.24 and 2.35 eV, with very weak contributions of the emission due to the self-trapping state. The influence of the variation of the excitation wavelength using 1PE and 2PE on the emission bands of BaTiO3 and Er:BaTiO3 is also investigated. The results of enhanced emission bands suggest a clear dependence of the emission intensity on the excitation energy, where a ∼3 fold enhancement in emission has been demonstrated under Er3+ (1.55 eV) excitation, which can be attributed to effective energy transfer between the Er3+ ions. As a result, it is concluded that the developed BaTiO3 and Er:BaTiO3 can pave the way for future photonic devices.

The study of density of grain boundary defects and grain shape was conducted for Erbium doped Barium Titanate (BTE) thin films, which were deposited on Si(100) and Si(100)-Au substrates by electron beam physical vapor deposition (EB-PVD). The crystallite as well as grain size show strong dependence on thermal annealing. Analysis of surface morphologies revealed variations of growth, after thermal annealing process, in films deposited on Si(100) and Si(100)-Au. In films deposited on Si(100) and Si(100)-Au, the root mean square (RMS) roughness value increased from 1.95 to 6.33 nm and 1.73 to 12.9 nm, respectively. These values correspond to 3.2% and 3.7% of the deposited thickness, which is quite low in comparison to the film thickness. Diameters of cavities are observed more significant in films deposited on Si(100)-Au, which increased from 35 to 250 nm. Moreover, the evolution of growth also revealed changes in the surface morphology via surface energy analysis. The results also revealed that chemisorption and physisorption by grain boundary in Si(100)-Au substrate, makes the cavities hydrophilic. These observations are fundamentally important for understating the mechanism of formations of hydrophilic surfaces and changes in their properties owing to the interdiffusion and diffusion effects by the grain boundary. Furthermore, shape of the grains on the surface and the effects of density of grain boundary defects are discussed.

Biosensors can be fabricated using nanomaterials in a certain way, which provides inexpensive, quick, and efficient systems as compared to the heavy traditional instruments used for the early cancer diagnosis. There are ways to prove the credibility, efficiency, and selectivity of such sensors for certain cancer types. Each biosensor serves for only one cancer type and doesn’t serve for more, for example, the biosensor for the pancreatic cancer is different than that for the breast cancer. Once cancer is diagnosed, many kinds of nanoparticles have been known for transporting appropriate anticancer agents to the point of action, based on their chemical modifications and the ligands attached, which facilitate the drug delivery in certain ways. Various factors such as compatibility, bio-distribution, circulation time, degradation, and conditions for bioavailability of drugs are essential in the investigation of the drug delivery process. The selectivity of chemotherapeutics is of great importance and has been achieved through various biological weapons such as monoclonal antibodies specifically designed to recognize and bind certain organic molecules like protein and DNA in cancer cells and hence detected, destroyed, and/or growth inhibited by the immune system. Another approach is to transport the anticancer drugs to the point of activity by conjugating them with the monoclonal antibodies or by incorporation into nanocarriers. Various inhibitors such as tyrosine kinase can inhibit abnormal growth characteristic of cancer and can be used to prevent unwanted growth. Some coordination metal complexes have been known to inhibit cancer growth as well which will also be discussed in the chapter.

Barium titanate (BaTiO3) is well-known for its variety of macroscopic properties, however, the mechanism of formation of this oxide in microscale remains poorly understood. We prepared the BaTiO3 nanoparticles and studied them as a function of milling time and temperature. A systematic study was performed to understand the reaction mechanism of undissociated and dissociated 2-propanol molecules on TiO2 and BaCO3 particles. Structural evolution and thermal decomposition of surface particles were carried out and studied by X-ray diffraction, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy analysis. Structural parameters refined by Rietveld analysis using X-ray diffraction data revealed a tetragonal structure with P4/mm space group, which was due to the dependence of functional groups on the milling time and thermal treatment. The divergence of tetragonality as a function of thermal treatment was identified for particles of size

Accepted Manuscript, The challenge of the early diagnosis of pancreatic cancer in routine clinical practice requires low-cost means of detection, and this may be achieved with immunosensors based on electrical or electrochemical principles. In this paper, we report a potentially low-cost immunosensor built with interdigitated gold electrodes coated with a self-assembled monolayer and a layer of anti-CA19-9 antibodies, which is capable of detecting the pancreatic cancer biomarker CA19-9 using electrical impedance spectroscopy. Due to specific, irreversible adsorption of CA19-9 onto its corresponding antibody, according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), the immunosensor is highly sensitive and selective. It could detect CA19-9 in commercial samples with a limit of detection of 0.68 U mL−1, in addition to distinguishing between blood serum samples from patients with different concentrations of CA19-9. Furthermore, by treating the capacitance data with information visualization methods, we were able to verify the selectivity and robustness of the immunosensor with regard to false positives, as the samples containing higher CA19-9 concentrations, including those from tumor cells, could be distinguished from those with possible interferents., CAPES, FAPESP (Grant 2013/14262-7 and 2012/15543-7), CNPq (150985/2017-7), nBioNet network and Barretos Cancer Hospital for financial support, info:eu-repo/semantics/publishedVersion

Biosensors fabricated with nanomaterials promise faster, cheaper, and more efficient alternatives to traditional, often bulky devices for early cancer diagnosis. In this study, we fabricated a thin film sensing unit on interdigitated gold electrodes combining polyethyleneimine and carbon nanotubes in a layer by layer fashion, onto which antibodies anti-CA19-9 were adsorbed with a supporting layer of N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide solution. By use of impedance spectroscopy, the pancreatic cancer biomarker CA19-9 was detected in a buffer with limit of detection of 0.35 U/mL. This high sensitivity allowed for distinction between samples of blood serum from patients with distinct probabilities to develop pancreatic cancer. The selectivity of the biosensor was confirmed in subsidiary experiments with HT-29 and SW-620 cell lines and possible interferents, e.g., p53 protein, ascorbic acid, and glucose, where significant changes in capacitance could only be measured with HT-29 that contained the CA19-9 biomarker. Chemisorption of CA19-9 molecules onto the layer of anti-CA19-9 antibodies was the mechanism responsible for sensing while electrostatic interactions drove the adsorption of carbon nanotubes, according to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The adsorption behavior was successfully described by the Langmuir-Freundlich isotherm.

We report on the chemiresistive gas sensing characteristics of ZnO nanorods (NRs) modified by a thin layer of nickel phthalocyanine (NiPc). Ozone detection was carried out through electrical measurements with an optimized performance at 250°C, good reproducibility and suitable concentration range (from 80 to 890 ppb) for technological applications. The hybrid NiPc:ZnO films had superior performance to pure ZnO nanorods in terms of response time and sensitivity. The response times were 22 s and 26 s, respectively, whereas the ratio of resistances under ozone and air was 3.27 for NiPc:ZnO films and 2.56 for the pure ZnO NRs. The improvement in response time is attributed to the large surface area generated with the coating of the ZnO nanorods with the NiPc layer. Significantly, images taken with field-emission scanning electron microscopy (FE-SEM) indicated that the ZnO nanorods were fully covered with NiPc. X-ray diffraction measurements (XRD) revealed a preferential growth of the nanorod-like structures along the [100] direction. In summary, a successful approach has been developed to functionalize ZnO nanorods, which is promising for detection of ppb levels of ozone gas.

In this paper, we have investigated the effect of Be acceptors on the electroluminescence and the spin polarization in GaAs/AlAs p-i-n resonant tunneling diodes. The quantum well emission comprise two main lines separated by ∼20 meV attributed to excitonic and Be-related transitions, which intensities show remarkably abrupt variations at critical voltages, particularly at the electron resonant peak where it shows a high-frequency bistability. The circular-polarization degree of the quantum-well electroluminescence also shows strong and abrupt variations at the critical bias voltages and it attains relatively large values (of ∼−75% at 15 T). These effects may be explored to design novel devices for spintronic applications such as a high-frequency spin-oscillators.