Advances of nanotechnology in agro-environmental studies

With the increase in the world population and the demand for food, new agricultural practices have been developed to improve food production through the use of more effective pesticides and fertilisers. These technologies can lead to an uncontrolled release of undesired substances into the environment, with the potential to contaminate soil and groundwater. Today, nanotechnology represents a promising approach to improve agricultural production and remediate polluted sites. This paper reviews the recent applications of nanotechnologies in agro-environmental studies with particular attention to the fate of nanomaterials once introduced in water and soil, to the advantages of their use and their possible toxicology. Findings show that the use of nanomaterials can improve the quality of the environment and help detect and remediate polluted sites. Only a small number of nanomaterials demonstrated potential toxic effects. These are discussed in detail

Nanostructured luminescently labeled nucleic acids

Important and emerging trends at the interface of luminescence, nucleic acids and nanotechnology are: (i) the conventional luminescence labeling of nucleic acid nanostructures (e.g. DNA tetrahedron); (ii) the labeling of bulk nucleic acids (e.g. single‐stranded DNA, double‐stranded DNA) with nanostructured luminescent labels (e.g. copper nanoclusters); and (iii) the labeling of nucleic acid nanostructures (e.g. origami DNA) with nanostructured luminescent labels (e.g. silver nanoclusters). This review surveys recent advances in these three different approaches to the generation of nanostructured luminescently labeled nucleic acids, and includes both direct and indirect labeling methods

Strategies for inorganic incorporation using neat block copolymer thin films for etch mask function and nanotechnological application

Block copolymers (BCPs) and their directed self-assembly (DSA) has emerged as a realizable complementary tool to aid optical patterning of device elements for future integrated circuit advancements. Methods to enhance BCP etch contrast for DSA application and further potential applications of inorganic nanomaterial features (e.g., semiconductor, dielectric, metal and metal oxide) are examined. Strategies to modify, infiltrate and controllably deposit inorganic materials by utilizing neat self-assembled BCP thin films open a rich design space to fabricate functional features in the nanoscale regime. An understanding and overview on innovative ways for the selective inclusion/infiltration or deposition of inorganic moieties in microphase separated BCP nanopatterns is provided. Early initial inclusion methods in the field and exciting contemporary reports to further augment etch contrast in BCPs for pattern transfer application are described. Specifically, the use of evaporation and sputtering methods, atomic layer deposition, sequential infiltration synthesis, metal-salt inclusion and aqueous metal reduction methodologies forming isolated nanofeatures are highlighted in di-BCP systems. Functionalities and newly reported uses for electronic and non-electronic technologies based on the inherent properties of incorporated inorganic nanostructures using di-BCP templates are highlighted. We outline the potential for extension of incorporation methods to triblock copolymer features for more diverse applications. Challenges and emerging areas of interest for inorganic infiltration of BCPs are also discussed

Fabrication of 2D materials via novel laser treatment processes and their implementation in optoelectronic applications

Pulsed laser treatment of 2D materials is becoming increasingly popular due to the simple and efficient nature of the treatment process. In this thesis, the femtosecond laser treatment methods of 2D materials to fabricate functionalized particles and nanorods are proposed to deepen the understanding of how the femtosecond laser and the process parameters can be tuned to yield different chemical compositions and shapes, which in turn can fit different applications and devices. A femtosecond laser process was developed to treat flakes of 2D materials (molybdenum disulfide (MoS2), tungsten disulfide (WS2), and boron nitride (BN) flakes) in an ethanol-containing solvent. The highly energetic laser pulses exfoliate and cleave the flakes into nanosheets with diameters of ≈3 nm and simultaneously dissociate the solvent molecules. The dissociated carbon and oxygen atoms from the solvent bond with the freshly cleaved 2D nanoparticles to satisfy edge sites, resulting in the formation of hybrid 2D nanoparticles that contain graphene-like carbon domains as well as the host material. Contrary to the current state of the art, where functionalization techniques can take several days to achieve, the hybrid nanoparticles are formed in as little as 20 min without toxic or corrosive chemicals and are multifunctional. Photoluminescence and absorption owing to both the carbon domains and the host 2D material (MoS2, WS2, or BN) are observed. This novel hybrid optical behavior makes these materials promising for emerging optoelectronic applications. An adaptive recipe was consequently developed to fabricate halogenated graphene particles, aiming to address the main challenge facing large-scale commercialization of perovskite solar cells: their instability and degradation from humidity. The current state of the art studies discussing the implementation of 2D materials in perovskite solar cells to enhance their stability are limited and lack discussion about long-term degradation and efficiency retention. Highly hydrophobic iodinated and chlorinated graphene particles were fabricated using femtosecond laser and incorporated into the hole transport layer and as an encapsulating layer. While the power conversion efficiency (PCE) was retained, the long-term stability was significantly enhanced for the cells containing the graphene in both ambient conditions and highly humid conditions, in test spans of 2200 hrs and 50 hrs, respectively. The previously unrealized ability to grow nanorods and nanotubes of 2D materials using femtosecond laser irradiation is demonstrated. In as little as 20 min, nanorods of tungsten disulfide, molybdenum disulfide, graphene, and boron nitride are grown in solutions. The technique fragments nanoparticles of the 2D materials from bulk flakes and leverages molecular-scale alignment by nonresonant intense laser pulses to direct their assembly into nanorods up to several micrometers in length. The laser treatment process is found to induce phase transformations in some of the materials, and also results in the modification of the nanorods with functional groups from the solvent atoms. Notably, the WS2 nanoparticles, which are ablated from semiconducting 2H WS2 crystallographic phase flakes, reassemble into nanorods consisting of the 1T metallic phase. Due to this transition, and the 1D nature of the fabricated nanorods, the WS2 nanorods display substantial improvements in electrical conductivity and optical transparency when employed as transparent conductors

Nanoscale Polymeric Particles via Aerosol-Photopolymerization

This PhD thesis focuses on the process of aerosol-photopolymerization for the generation of various polymeric particles. Such structures are most often prepared by liquid-based methods via the well-established thermal initiation step, and aerosol-photopolymerization is presented as an alternative, aerosol-based technique which employs photoinitiated polymerization. Discussed within this thesis are the advantages and broad aspects of the process

21st Century Nanostructured Materials

Nanostructured materials (NMs) are attracting interest as low-dimensional materials in the high-tech era of the 21st century. Recently, nanomaterials have experienced breakthroughs in synthesis and industrial and biomedical applications. This book presents recent achievements related to NMs such as graphene, carbon nanotubes, plasmonic materials, metal nanowires, metal oxides, nanoparticles, metamaterials, nanofibers, and nanocomposites, along with their physical and chemical aspects. Additionally, the book discusses the potential uses of these nanomaterials in photodetectors, transistors, quantum technology, chemical sensors, energy storage, silk fibroin, composites, drug delivery, tissue engineering, and sustainable agriculture and environmental applications

Nanopartículas de óxido de zinco sub-tóxicas modulam os níveis das proteínas PSD-95 e shank 3

The effect of zinc on neuronal systems is growing interest in scientific research due to a possible role as a modulator of synaptic activity. Additionally, recent research points to the therapeutic potential of zinc oxide nanoparticles (ZnO NPs) on neuronal cells. These nanoparticles are excellent drug carriers to the brain because, besides having positive characteristics for the protection of cellular homeostasis, they are small, allowing them to pass the blood brain barrier and interact directly within these cells. In this sense, the present thesis explored the effect of sub-toxic ZnO NP concentrations on cell viability and ROS production in SH-SY5Y cells, as well as their impact on the expression levels of PSD-95, SHANK 3 and β-actin proteins. The results showed increases in PSD-95 and SHANK 3 protein expression without variations in β-actin expression after neuronal cell exposure to sub-toxic concentrations and at reduced exposure times to ZnO NPs. Future efforts should be implemented to investigate how this increase may reduce brain impairment associated with neurodegenerative diseases. However, the results here presented have clearly identified some of the synaptic molecular targets of ZnO NPs and that these NPs are worthwhile exploring for their therapeutic potential.O efeito do zinco nos sistemas neuronais está a aumentar o seu interesse na pesquisa científica devido a um possível papel como modulador da atividade sináptica. Além disso, pesquisas recentes apontam para o potencial terapêutico de nanopartículas de óxido de zinco (ZnO NPs) em células neuronais. Essas nanopartículas são excelentes transportadoras de fármacos para o cérebro porque, além de terem características positivas para a proteção da homeostase celular, são pequenas, permitindo que elas ultrapassem a barreira hematoencefálica e interajam diretamente dentro dessas células. Nesse sentido, a presente tese explorou o efeito de concentrações sub-tóxicas de ZnO NPs na viabilidade celular e produção de ROS em células SH-SY5Y, bem como seu impacto nos níveis de expressão das proteínas PSD-95, SHANK 3 e β-actina. Os resultados mostraram aumentos na expressão das proteínas PSD-95 e SHANK 3, sem variações na expressão da β-actina após a exposição das células neuronais a concentrações sub-tóxicas e em tempos de exposição reduzidos aos ZnO NPs. Esforços futuros devem ser implementados para investigar como esse aumento pode reduzir o comprometimento cerebral associado a doenças neurodegenerativas. No entanto, os resultados aqui apresentados identificaram claramente alguns dos alvos moleculares sinápticos das ZnO NPs e que vale a pena explorar o seu potencial terapêutico.Mestrado em Biomedicina Molecula

Nanoscale Self-Assembly: Nanopatterning and Metrology

The self-assembly process underlies a plethora of natural phenomena from the macro to the nano scale. Often, technological development has found great inspiration in the natural world, as evidenced by numerous fabrication techniques based on self-assembly (SA). One striking example is given by epitaxial growths, in which atoms represent the building blocks. In lithography, the use of self-assembling materials is considered an extremely promising patterning option to overcome the size scale limitations imposed by the conventional photolithographic methods. To this purpose, in the last two decades several supramolecular self-assembling materials have been investigated and successfully applied to create patterns at a nanometric scale. Although considerable progress has been made so far in the control of self-assembly processes applied to nanolithography, a number of unresolved problems related to the reproducibility and metrology of the self-assembled features are still open. Addressing these issues is mandatory in order to allow the widespread diffusion of SA materials for applications such as microelectronics, photonics, or biology. In this context, the aim of the present Special Issue is to gather original research papers and comprehensive reviews covering various aspects of the self-assembly processes applied to nanopatterning. Topics include the development of novel SA methods, the realization of nanometric structures and devices, and the improvement of their long-range order. Moreover, metrology issues related to the nanoscale characterization of self-assembled structures are addressed