Advancing AFM Nanometrology Through Experimental FSI Quantification, Novel Sensor Design, and Fractional ODE-based Material Models

Nanometrology, which is the study of materials at the nanoscale, has been an important topic for the material science community at large. Atomic Force Microscopy (AFM) has become an indispensable tool to perform nanometrology. Especially, contact resonance (CR) AFM has been used to perform accurate nanomaterial characterization due to its advantage over other similar modes. While performing CR-AFM, the material is brought into an intimate net-repulsive contact with a cantilever tip to estimate material properties. However, CR-AFM faces challenges while estimating material properties in a few specific cases. This dissertation will mainly ask three different questions related to CR-AFM. The first topic is to predict the fluid forces around a dynamic cantilever to characterize materials in a fluidic environment. Next, a novel AFM cantilever sensor will be designed to tune the stiffness of the sensor according to the sample of interest. This dissertation will also focus on updating the current material models to characterize materials for a wide range of frequencies. Solving the aforementioned issues will improve the CR-AFM method, thus improving the nanoscale material characterization. Historically, CR-AFM has been developed to be operated in a vacuum environment. So, the question becomes what if the cantilever is operated in an environment other than a vacuum? How can a material be characterized inside a fluidic environment? We successfully show that predicting the fluid forces will enable us to estimate the material properties immersed in a liquid environment. Then, the cantilever beam sensor has its bandwidth limitations while probing different sample properties. We have to design a novel sensor that will enable us to probe different samples without replacing the sensor according to the sample. The solution lies in the curvature-induced cantilever plate geometry design as an AFM sensor. The induced curvature in a plate structure enables us to control the inherent stiffness of the plate sensor. This tunability is essential while performing CR-AFM for vastly different sample properties. The third part talks about the material modeling. Classical material models are used to quantify viscoelastic materials. For a few frequency-dependent materials, these classical models do not predict well for a wide range of frequency. We have utilized fractional models to predict material properties for a wide range of frequencies. These fractional models show drastic improvements over the classical integer order models

Imaging and engineering optical localized modes at the nanoscale

In this thesis we experimentally developed high-resolution groundbreaking imaging techniques and novel methods suitable for nanophotonics materials. The experimental results are carefully supported by theory and numerical calculations. We engineered the propagation of light by exploiting devices that strongly localize electromagnetic fields at the nanoscale. The proposed techniques have a large field of application. We deeply investigated ordered and disordered based single and coupled nano-resonators, called photonicmolecules, and develop a laser-assisted local oxidation of the dielectric environment. These results put the basis for an unprecedented investigation of light behaviour in optical nano-resonators. Therefore, they would pave the way for novel devices that exploit the strong coupling regime between single light emitters and localized optical modes

A High-Q AFM Sensor Using a Balanced Trolling Quartz Tuning Fork in the Liquid

A quartz tuning fork (QTF) has been widely used as a force sensor of the frequency modulation atomic force microscope due to its ultrahigh stiffness, high quality factor and self-sensing nature. However, due to the bulky structure and exposed surface electrode arrangement, its application is limited, especially in liquid imaging of in situ biological samples, ionic liquids, electrochemical reaction, etc. Although the complication can be resolved by coating insulating materials on the QTF surface and then immersing the whole QTF into the liquid, it would result in a sharp drop of the quality factor, which will reduce the sensitivity of the QTF. To solve the problem, a novel method, called the balanced trolling quartz tuning fork (BT-QTF), is introduced here. In this method, two same probes are glued on both prongs of the QTF separately while only one probe immersed in the liquid. With the method, the hydrodynamic interaction can be reduced, thus the BT-QTF can retain a high quality factor and constant resonance frequency. The stable small vibration of the BT-QTF can be achieved in the liquid. Initially, a theoretical model is presented to analyze the sensing performance of the BT-QTF in the liquid. Then, the sensing performance analysis experiments of the BT-QTF have been performed. At last, the proposed method is applied to atomic force microscope imaging different samples in the liquid, which proves its feasibility

Integrated AFM-Raman for molecular characterization of peptide nano- and micro-tubes

This work is focused on exploring a unique integration of techniques, Raman micro-spectroscopy and atomic force microscopy (AFM), which when combined offer more than the sum of their respective parts. The non-invasive chemical specificity afforded by Raman spectroscopy, combined with the nanoscale-resolution topographic imaging of AFM offer much individually. The physics underlying the practical application of each technique is very general; Raman spectroscopy detects molecular vibrational shifts using light, and AFM uses a physical probe to interact with a surface to provide topographic (and mechanical) information. As a result, there are few restrictions to the possible samples that can be studied with these techniques, from semiconductors and geological crystals, through to simple organic chemical structures all the way to complex biological molecules and systems such as cells and tissue. In this work, a synthetic biomaterial composed of diphenylalanine (FF) peptide units which self-assemble into strong tubular structures is used as a sample of interest when exploring the different possibilities available from a combined Raman-AFM instrument. First, the combined system was set up in order to perform tip-enhanced Raman spectroscopy (TERS), a technique promising Raman spectroscopic imaging at the resolution of AFM imaging. A relatively young technique, TERS has huge potential in extending the reach of Raman spectroscopic imaging to the nanoscale, at a regime where a great deal of structure exists, but is usually blurred by conventional diffraction-limited Raman microspectroscopy. A major focus in this work is addressing a current problem with TERS: the fabrication of suitable probes. TERS typically utilizes AFM tips modified to have a silver nanoparticle, capable of locally enhancing the Raman signal, attached at the probe apex. A new method is presented here that promises several improvements over existing approaches, as the entire fabrication can be performed in-situ on the instrument. Tips produced in this way are then characterized by electron microscopy and tested on FF nanotubes. Following this, several techniques for the synthesis of silver nanoparticles are explored for use in TERS. Here, the focus is particularly on decahedral nanoparticles, which can be grown into rod shaped particles with well- defined shapes and sizes. These are important considerations for obtaining the desired enhancing properties for TERS probes. Finally, the AFM-Raman instrument is used to investigate the mechanical properties of FF tubes using several methods. AFM force spectroscopy of tubes suspended across a gap can be used in conjunction with a bending beam theory to measure the Young's modulus of individual tubes. A new type of co-localized experiment using polarized Raman spectroscopy on a suspended tube under various forces from the AFM is tested, and subsequently information relating to the hydrogen bonding network is used, in conjunction with existing X-ray data, to determine the molecular contributions to the modulus using a simple model for amyloid fibrils. Each experiment operates at the single fibril level, with the same fibrils being used, such that different methods can be compared for a single FF tube

Integrated AFM-Raman for molecular characterization of peptide nano- and micro-tubes

This work is focused on exploring a unique integration of techniques, Raman micro-spectroscopy and atomic force microscopy (AFM), which when combined offer more than the sum of their respective parts. The non-invasive chemical specificity afforded by Raman spectroscopy, combined with the nanoscale-resolution topographic imaging of AFM offer much individually. The physics underlying the practical application of each technique is very general; Raman spectroscopy detects molecular vibrational shifts using light, and AFM uses a physical probe to interact with a surface to provide topographic (and mechanical) information. As a result, there are few restrictions to the possible samples that can be studied with these techniques, from semiconductors and geological crystals, through to simple organic chemical structures all the way to complex biological molecules and systems such as cells and tissue. In this work, a synthetic biomaterial composed of diphenylalanine (FF) peptide units which self-assemble into strong tubular structures is used as a sample of interest when exploring the different possibilities available from a combined Raman-AFM instrument. First, the combined system was set up in order to perform tip-enhanced Raman spectroscopy (TERS), a technique promising Raman spectroscopic imaging at the resolution of AFM imaging. A relatively young technique, TERS has huge potential in extending the reach of Raman spectroscopic imaging to the nanoscale, at a regime where a great deal of structure exists, but is usually blurred by conventional diffraction-limited Raman microspectroscopy. A major focus in this work is addressing a current problem with TERS: the fabrication of suitable probes. TERS typically utilizes AFM tips modified to have a silver nanoparticle, capable of locally enhancing the Raman signal, attached at the probe apex. A new method is presented here that promises several improvements over existing approaches, as the entire fabrication can be performed in-situ on the instrument. Tips produced in this way are then characterized by electron microscopy and tested on FF nanotubes. Following this, several techniques for the synthesis of silver nanoparticles are explored for use in TERS. Here, the focus is particularly on decahedral nanoparticles, which can be grown into rod shaped particles with well- defined shapes and sizes. These are important considerations for obtaining the desired enhancing properties for TERS probes. Finally, the AFM-Raman instrument is used to investigate the mechanical properties of FF tubes using several methods. AFM force spectroscopy of tubes suspended across a gap can be used in conjunction with a bending beam theory to measure the Young's modulus of individual tubes. A new type of co-localized experiment using polarized Raman spectroscopy on a suspended tube under various forces from the AFM is tested, and subsequently information relating to the hydrogen bonding network is used, in conjunction with existing X-ray data, to determine the molecular contributions to the modulus using a simple model for amyloid fibrils. Each experiment operates at the single fibril level, with the same fibrils being used, such that different methods can be compared for a single FF tube

Cancer theranostics: multifunctional gold nanoparticles for diagnostics and therapy

Doctorate in Biology, Specialty in BiotechnologyThe use of gold nanoparticles (AuNPs) has been gaining momentum in molecular diagnostics due to their unique physico-chemical properties these systems present huge advantages, such as increased sensitivity, reduced cost and potential for single-molecule characterisation. Because of their versatility and easy of functionalisation, multifunctional AuNPs have also been proposed as optimal delivery systems for therapy (nanovectors). Being able to produce such systems would mean the dawn of a new age in theranostics (diagnostics and therapy)driven by nanotechnology vehicles. Nanotechnology can be exploit for cancer theranostics via the development of diagnostics systems such as colorimetric and imunoassays, and in therapy approaches through gene therapy, drug delivery and tumour targeting systems. The unique characteristics of nanoparticles in the nanometre range, such as high surface-tovolume ratio or shape/size-dependent optical properties, are drastically different from those of their bulk materials and hold pledge in the clinical field for disease therapeutics This PhD project intends to optimise a gold-nanoparticle based technique for the detection of oncogenes’ transcripts (c-Myc and BCR-ABL) that can be used for the evaluation of the expression profile in cancer cells, while simultaneously developing an innovative platform of multifunctional gold nanoparticles (tumour markers, cell penetrating peptides, fluorescent dyes) loaded with siRNA capable of silencing the selected proto-oncogenes, which can be used to evaluate the level of expression and determine the efficiency of silencing. This work is a part of an ongoing collaboration between Research Centre for Human Molecular Genetics, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal and Biofunctional Nanoparticles and Surfaces Group, Instituto de Nanociencia de Aragón, Spain within a European project [NanoScieE+ - NANOTRUCK]. In order to achieve this goal we developed effective conjugation strategies to combine, in a highly controlled way, biomolecules to the surface of AuNPs with specific functions such as: ssDNA oligos to detect specific sequences and for mRNA quantification; Biofunctional spacers: Poly(ethylene glycol) (PEG) spacers used to increase solubility and biocompatibility and confer chemical functionality; Cell penetrating peptides: to overcome the lipophilic barrier of the cellular membranes and deliver molecules into cells using TAT peptide to achieve cytoplasm and nucleus; Quaternary ammonium: to introduce stable positively charged in gold nanoparticles surface; and RNA interference: siRNA complementary to a master regulator gene, the proto-oncogene c-Myc, that is implicated in cell growth, proliferation, loss of differentiation, and cell death. In order to establish that they are viable alternatives to the available methods, these innovative nanoparticles were extensively characterized on their chemical functionalization, ease of uptake, cellular toxicity and inflammation, and knockdown of MYC protein expression in several cancer cell lines and in in vivo models.Fundação para a Ciência e Tecnologia - (SFRH/BD/62957/2009); PTDC/BIO/66514/2006; NANOLIGHT-PTDC/QUI-QUI/112597/2009; Silencing the silencers via multifunctional gold nanoconjugates towards cancer therapy - PTDC/BBB-NAN/1812/201

Combustion generated fine carbonaceous particles

Soot is of importance for its contribution to atmospheric particles with their adverse health impacts and for its contributions to heat transfer in furnaces and combustors, to luminosity from candles, and to smoke that hinders escape from buildings during fires and that impacts global warming or cooling. The different chapters of the book adress comprehensively the different aspects from fundamental approaches to applications in technical combustion devices

Argonne National Laboratory Reports

This sixth symposium covers process control processes and issues involved in the conversion of fossil fuels into synthetic fuels