Progress in synthesis technologies and advances in fundamental understanding of materials with low dimensionality has led to the birth of a new scientific field, nanoscience, and to strong expectations of multiple applications of nanomaterials. The physical properties of small particles are unique, bridging the gap between atoms and molecules, on one side, and bulk materials on the other side. The work presented in this thesis investigates the potential of using magnetic nanoparticles as the next generation of contrast agents for biomedical imaging. The focus is on gadolinium-based nanoparticles and cellular activity including the uptake, morphology and production of reactive oxygen species.

Gd ion complexes, like Gd chelates, are used today in the clinic, world-wide. However, there is a need for novel agents, with improved contrast capabilities and increased biocompatibility. One avenue in their design is based on crystalline nanoparticles. It allows to reduce the total number of Gd ions needed for an examination. This can be done by nanotechnology, which allows one to improve and fine tune the physico- chemical properties on the nanomaterial in use, and to increase the number of Gd atoms at a specific site that interact with protons and thereby locally increase the signal. In the present work, synthesis, purification and surface modification of crystalline Gd2O3-based nanoparticles have been performed. The nanoparticles are selected on the basis of their physical properties, that is they show enhanced magnetic properties and therefore may be of high potential interest for applications as contrast agents.

The main synthesis method of Gd₂O₃ nanoparticles in this work was the modified “polyol” route, followed by purification of as-synthesized DEG-Gd2O3 nanoparticles suspensions. In most cases the purification step involved dialysis of the nanoparticle samples. In this thesis, organosilane were chosen as an exchange agent for further functionalization. Moreover, several paths have been explored for modification of the nanoparticles, including Tb³⁺ doping and capping with sorbitol.

Biocompatibility of the newly designed nanoparticles is a prerequisite for their use in medical applications. Its evaluation is a complex process involving a wide range of biological phenomena. A promising path adopted in this work is to study of nanoparticle interactions with isolated blood cells. In this way one could screen nanomaterial prior to animal studies.

The primary cell type considered in the thesis are polymorphonuclear neutrophils (PMN) which represent a type of the cells of human blood belonging to the granulocyte family of leukocytes. PMNs act as the first defense of the immune system against invading pathogens, which makes them valuable for studies of biocompatibility of newly synthesized nanoparticles. In addition, an immortalized murine alveolar macrophage cell line (MH-S), THP-1 cell line, and Ba/F3 murine bone marrow-derived cell line were considered to investigate the optimization of the cell uptake and to examine the potential of new intracellular contrast agent for magnetic resonance imaging.

In paper I, the nanoparticles were investigated in a cellular system, as potential probes for visualization and targeting intended for bioimaging applications. The production of reactive oxygen species (ROS) by means of luminol-dependent chemiluminescence from human neutrophils was studied in presence of Gd₂O₃ nanoparticles. In paper II, a new design of functionalized ultra-small rare earth-based nanoparticles was reported. The synthesis was done using polyol method followed by PEGylation, and dialysis. Supersmall gadolinium oxide (DEG-Gd2O3) nanoparticles, in the range of 3-5 nm were obtained and carefully characterized. Neutrophil activation after exposure to this nanomaterial was studied by means of fluorescence microscopy. In paper III, cell labeling with Gd₂O₃ nanoparticles in hematopoietic cells was monitored by magnetic resonance imaging (MRI). In paper IV, ultra-small gadolinium oxide nanoparticles doped with terbium ions were synthesized as a potentially bifunctional material with both fluorescent and magnetic contrast agent properties. Paramagnetic behavior was studied. MRI contrast enhancement was received, and the luminescent/ fluorescent property of the particles was attributable to the Tb³⁺ ion located on the crystal lattice of the Gd₂O₃ host. Fluorescent labeling of living cells was obtained. In manuscript V, neutrophil granulocytes were investigated with rapid cell signaling communicative processes in time frame of minutes, and their response to cerium-oxide based nanoparticles were monitored using capacitive sensors based on Lab-on-a-chip technology. This showed the potential of label free method used to measure oxidative stress of neutrophil granulocytes. In manuscript VI, investigations of cell-(DEGGd₂O₃) nanoparticle interactions were carried out. Plain (DEG-Gd₂O₃) nanoparticles, (DEG-Gd₂O₃) nanoparticles in presence of sorbitol and (DEG-Gd₂O₃) nanoparticles capped with sorbitol were studied. Relaxation studies and measurements of the reactive oxygen species production by neutrophils were based on chemiluminescence. Cell morphology was evaluated as a parameter of the nanoparticle induced inflammatory response by means of the fluorescence microscopy.

The thesis demonstrates high potential of novel Gd₂O₃-based nanoparticles for development of the next generation contrast agents, that is to find biocompatible compounds with high relaxivity that can be detected at lower doses, and in the future enable targeting to provide great local contrast.

We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

This thesis work focuses on the design and production of nanoparticle based contrast agents for signal enhancement in magnetic resonance imaging (MRI). Three different synthesis routes are explored, primarily to produce crystalline gadolinium oxide (Gd2O3) nanoparticles, and surface modification is done to obtain stable, dispersible, biocompatible probes inducing high proton relaxivities.

In Paper I and II we utilized the polyol synthesis method and nanoparticle purification was performed with dialysis. Active surface functionalization was achieved by an innermost layer of 3-mercaptopropyl trimetoxy silanes (MPTS) and an outer layer of bifunctional PEG. Surface capping was shown to greatly affect the water proton relaxation to a degree which is strongly dependent on the purification time. PEGylation also induced stabilizing effects and the ability to provide the nanoparticles with luminescent properties was proven by linking the fluorescent dye Rhodamine to the bifunctional PEG.

In Paper III the magnetic behavior of yttrium (Y) alloyed Gd₂O₃ nanoparticles was investigated as a function of Y concentration. This was done by performing magnetic measurements and by studying the signal line width in electron paramagnetic resonance spectroscopy for Gd₂O₃, Y₂O₃ and a series of (Gd_xY_1-x)₂O₃ samples produced using the combustion synthesis. The results verified that the signal line width is dependent on the percent of yttrium dilution. This is considered as an indication of that yttrium dilution changes the electron spin relaxation time in Gd₂O₃.

Paper IV and V present a novel precipitation synthesis method for Gd₂O₃ nanoparticles. Acetate molecular groups were found to coordinate the nanoparticle surface increasing the water dispersability. The Gd₂O₃ nanoparticles induce a twice as high relaxivity per gadolinium atom, as compared to the commercially available contrast agent Magnevist. Incorporation of luminescent europium (Eu³⁺) ions into the Gd₂O₃ nanoparticles in combination with surface modification with a fluorescent branched carboxyl terminated TEG, produced dual probes with tunable luminescence, maintained relaxivity and thus a bright contrast in MRI.

In Paper VI, a new approach to accomplish a dual probe was investigated. Luminescent ZnO nanoparticles decorated with Gd ions bound in an organic matrix were evaluated for MR signal enhancement and ability to function as fluorescent probes. Interestingly, these nanoprobes did show an enhanced capability to both strengthen the MR signal and increase the fluorescent quantum yield, as compared to the pure oxides.

In Paper VII we investigate sub 5 nm crystalline manganese based nanoparticles produced by the precipitation synthesis used for Gd₂O₃ nanoparticles. Manganese oxide was chosen as another candidate for MRI contrast enhancement as it is expected to have a straight forward surface coupling chemistry. Characterization of the crystal structure and chemical composition indicated nanoparticles with a MnO core and presence of manganese species of higher valences at the nanoparticle surface. The MnO nanomaterial showed a superparamagnetic behavior and less capability to increase the MR signal as compared to Gd₂O₃.

Characterization of the nanoparticle crystal structure and size is, throughout the work, performed by means of transmission electron microscopy, X-ray diffraction and dynamic light scattering. The chemical composition is studied with X-ray photoelectron spectroscopy, infrared spectroscopy and near edge X-ray absorption fine structure spectroscopy and the fluorescence characteristics are evaluated with fluorescence spectroscopy. In addition, theoretical models and calculated IR spectroscopy and near edge X-ray absorption fine structure spectroscopy data have been used for evaluation of experimental results.

To conclude, the aim of this work is the design, production and characterization of ultrasmall rare earth based nanoparticles for signal enhancement in biomedical imaging. Surface modification clearly increases the colloidal stability and biocompatibility of the nanoparticles. Compared to the agents in clinical use today, these nanoprobes have a higher capability to enhance the MR-signal, and they will in the near future be equipped with tags for specific targeting.

Recently, much attention has been given to the development of biofunctionalized nanoparticles with magnetic properties for novel biomedical imaging. Guided, smart, targeting nanoparticulate magnetic resonance imaging (MRI) contrast agents inducing high MRI signal will be valuable tools for future tissue specific imaging and investigation of molecular and cellular events. In this study, we report a new design of functionalized ultrasmall rare earth based nanoparticles to be used as a positive contrast agent in MRI. The relaxivity is compared to commercially available Gd based chelates. The synthesis, PEGylation, and dialysis of small (3−5 nm) gadolinium oxide (DEG-Gd₂O₃) nanoparticles are presented. The chemical and physical properties of the nanomaterial were investigated with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and dynamic light scattering. Neutrophil activation after exposure to this nanomaterial was studied by means of fluorescence microscopy. The proton relaxation times as a function of dialysis time and functionalization were measured at 1.5 T. A capping procedure introducing stabilizing properties was designed and verified, and the dialysis effects were evaluated. A higher proton relaxivity was obtained for as-synthesized diethylene glycol (DEG)-Gd₂O₃ nanoparticles compared to commercial Gd-DTPA. A slight decrease of the relaxivity for as-synthesized DEG-Gd₂O₃ nanoparticles as a function of dialysis time was observed. The results for functionalized nanoparticles showed a considerable relaxivity increase for particles dialyzed extensively with r₁ and r₂ values approximately 4 times the corresponding values for Gd-DTPA. The microscopy study showed that PEGylated nanoparticles do not activate neutrophils in contrast to uncapped Gd₂O₃. Finally, the nanoparticles are equipped with Rhodamine to show that our PEGylated nanoparticles are available for further coupling chemistry, and thus prepared for targeting purposes. The long term goal is to design a powerful, directed contrast agent for MRI examinations with specific targeting possibilities and with properties inducing local contrast, that is, an extremely high MR signal at the cellular and molecular level.

Chelated gadolinium ions, e. g., GdDTPA, are today used clinically as contrast agents for magnetic resonance imaging (MRI). An attractive alternative contrast agent is composed of gadolinium oxide nanoparticles as they have shown to provide enhanced contrast and, in principle, more straightforward molecular capping possibilities. In this study, we report a new, simple, and polyol-free way of synthesizing 4-5-nm-sized Gd2O3 nanoparticles at room temperature, with high stability and water solubility. The nanoparticles induce high-proton relaxivity compared to Gd-DTPA showing r(1) and r(2) values almost as high as those for free Gd3+ ions in water. The Gd2O3 nanoparticles are capped with acetate and carbonate groups, as shown with infrared spectroscopy, near-edge X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and combined thermogravimetric and mass spectroscopy analysis. Interpretation of infrared spectroscopy data is corroborated by extensive quantum chemical calculations. This nanomaterial is easily prepared and has promising properties to function as a core in a future contrast agent for MRI.

Sub 5 nm sized manganese oxide nanoparticles; MnOx (1 ≤ x ≤ 2), were synthesized via a short time room temperature synthesis route. The nanoparticles are crystalline, spherically shaped and in the size range of 2-4 nm as shown by transmission electron microscopy studies. Selected area electron diffraction patterns were collected and their appearance indicated that the nanoparticle cores are composed of MnO. Also, co-existence of the (II) and (III) oxidation states at the nanoparticle surface was verified by results achieved from infrared spectroscopy and X-ray photoelectron spectroscopy. These measurements also supported presence of a minor amount of acetate groups as well as a negligible fraction of carbonate groups at the nanoparticle surfaces. The interpretation of the IR spectra was confirmed by quantum chemical calculations using the high spin manganese nanoparticle Mn₁₂O₁₂(OAc)₁₆(H₂O)₄, as a model system for the MnO_x nanoparticle surface. Bulk MnO and Mn2O3 are known to be antiferromagnetic. The magnetic properties are however somewhat dependent of the crystallite size and changes when scaling down to the nanoregion. The MnO_x (1 ≤ x ≤ 2) nanoparticles investigated in this work show a superparamagnetic behavior with a blocking temperature of approximately 12 K proven by means of SQUID measurements. The relaxivities of the nanoparticles and the Mn(OAc)2 precursors were studied with a bench top NMR analyzer verifying nanoparticle r1 and r2 of 0.5 and 6 mMs^-1 respectively. The r1 relaxivity is lower than what is earlier reported for Gd based contrast agent, but improvements are expected by further surface modification, due to increased rotational time and higher water dispersability.

A method to prepare amyloid-like fibrils functionalized with magnetic nanoparticles has been developed. The amyloid-like fibrils are prepared in a two step procedure, where insulin and magnetic nanoparticles are mixed simply by grinding in the solid state, resulting in a water soluble hybrid material. When the hybrid material is heated in aqueous acid, the insulin/nanoparticle hybrid material self assembles to form amyloid-like fibrils incorporating the magnetic nanoparticles. This results in magnetically labeled amyloid-like fibrils which has been characterized by Transmission Electron Microscopy (TEM) and electron tomography. The influence of the aggregation process on proton relaxivity is investigated. The prepared materials have potential uses in a range of bio-imaging applications.

Metal oxide nanoparticles are widely used in both consumer products and medical applications, but the knowledge regarding exposure-related health effects is limited. However, it is challenging to investigate nanoparticle interaction processes with biological systems. The overall aim of this project was to improve the possibility to predict exposure-related health effects of metal oxide nanoparticles through interdisciplinary collaboration by combining workflows from the pharmaceutical industry, nanomaterial sciences, and occupational medicine. Specific aims were to investigate nanoparticle-protein interactions and possible adverse immune reactions. Four different metal oxide nanoparticles; CeOx nanocrystals with 5% or 14% Gd, Co3O4, and Fe2O3, were characterized by dynamic light scattering and high-resolution transmission electron microscopy. Nanoparticle-binding proteins were identified and screened for HLA-binding peptides in silico. Monocyte interaction with nanoparticle-protein complexes was assessed in vitro. Herein, for the first time, immunogenic properties of nanoparticle-binding proteins have been characterized. The present study indicates that especially Co3O4-protein complexes can induce both danger signals, verified by the production of inflammatory cytokines and simultaneously bind autologous proteins, which can be presented as immunogenic epitopes by MHC class II. The clinical relevance of these findings should be further evaluated to investigate the role of metal oxide nanoparticles in the development of autoimmune disease. The general workflow identified experimental difficulties, such as nanoparticle aggregate formation and a lack of protein-free buffers suitable for particle characterization, protein analyses, as well as for cell studies. This confirms the importance of future interdisciplinary collaborations.

Nucleases are a class of enzymes that break down nucleic acids by catalyzing the hydrolysis of the phosphodiester bonds that link the ribose sugars. Nucleases display a variety of vital physiological roles in prokaryotic and eukaryotic organisms, ranging from maintaining genome stability to providing protection against pathogens. Altered nuclease activity has been associated with several pathological conditions including bacterial infections and cancer. To this end, nuclease activity has shown great potential to be exploited as a specific biomarker. However, a robust and reproducible screening method based on this activity remains highly desirable. Herein, we introduce a method that enables screening for nuclease activity using nucleic acid probes as substrates, with the scope of differentiating between pathological and healthy conditions. This method offers the possibility of designing new probe libraries, with increasing specificity, in an iterative manner. Thus, multiple rounds of screening are necessary to refine the probes design with enhanced features, taking advantage of the availability of chemically modified nucleic acids. The considerable potential of the proposed technology lies in its flexibility, high reproducibility, and versatility for the screening of nuclease activity associated with disease conditions. It is expected that this technology will allow the development of promising diagnostic tools with a great potential in the clinic.

Early cancer diagnosis is a crucial element to improved treatment options and survival. Great research efforts have been made in the search for better performing cancer diagnostic biomarkers. However, the quest continues as novel biomarkers with high accuracy for an early diagnosis remain an unmet clinical need. Nucleases, which are enzymes capable of cleaving nucleic acids, have been long considered as potential cancer biomarkers. The implications of nucleases are key for biological functions, their presence in different cellular counterparts and catalytic activity led the enthusiasm towards investigating the role of nucleases as promising cancer biomarkers. However, the most essential feature of these proteins, which is their enzymatic activity, has not been fully exploited. This review discusses nucleases interrogated as cancer biomarkers, providing a glimpse of their physiological roles. Moreover, it highlights the potential of harnessing the enzymatic activity of cancer-associated nucleases as a novel diagnostic biomarker using nucleic acid probes as substrates.

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Electrochemical impedance spectroscopy was employed to explore the possibility of relating the permeation of electrolyte ions in ?-functionalized self-assembled monolayers to structural or polarity changes induced by interaction with metal ions. The monolayers were based on alkanethiols modified with a phosphorylated tyrosine analogue, which from previous work are known to drastically change their organization on gold surfaces upon interaction with aluminum and magnesium ions. The ion permeation was evaluated by using relatively low excitation frequencies, 1000 to 2 Hz, and quantified by an extra resistive component in the equivalent circuit (R SAM). The extent of ion permeation influenced by the dc potential, the electrolyte concentration, the functional group, and the thiol length were also investigated. It was, for example, found that RSAM decreased ~20% when the thiol organization collapsed and that RSAM increased ~4-5 times when the electrolyte concentration was decreased by 1 order of magnitude. Interesting observations were also made regarding the potential dependence of RSAM and the double layer capacitance. The evaluation of the ion permeation can be used to indirectly detect whether the organization of a SAM is influenced by, for example, electric fields or chemical and biological interactions. This analysis can be performed without addition of redox species, but is on the other hand complicated by the fact that other factors also influence the presence of ions within the monolayer. In addition, a second parallel RC process was obtained in some of the impedance spectra when using even lower frequencies, and its resistive component revealed different results compared to RSAM. Such data may be useful for the understanding of complex double layer phenomena at modified electrodes. © 2007 American Chemical Society.

We present PLIS, a publicly available, open-source software for the determination of protein-ligand dissociation constants that can be used to characterize biological processes or to shed light on biophysical aspects of interactions. PLIS can analyze data from titration experiments monitored by for instance fluorescence spectroscopy or from nuclear magnetic resonance relaxation dispersion experiments. In addition to analysis of experimental data, PLIS includes functionality for generation of synthetic data, useful for understanding how different parameters effect the data in order to better analyze experiments.

For decades, hexavalent chromium has been used in the surface treatment of aluminum alloys in the aerospace industry. In the sealing process of anodic coatings, hexavalent chromium provides surface protection with excellent corrosion resistance. However, the toxicity and carcinogenity of chromium substances signify the need for more sustainable alternatives. Herein, the more environmentally friendly rare earth metal cerium is investigated as potential candidate to replace chromium to seal the pores of anodized Al alloy 2024-T3 sample surfaces. Sealing was performed in cerium chloride solution with the addition of hydrogen peroxide as accelerant to form cerium oxide nanoparticles. Several sealing conditions were investigated: i) sealing immersion time, ii) ratio of CeCl3:H2O2, iii) CeCl3 concentration, iv) addition of surfactant, v) stirring conditions and vi) hydrothermal sealing. Results were evaluated using contact angle measurements (CAMs), scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed increased number and size of cerium oxide nanoparticle clusters as a function of immersion time under stirred conditions. CAM and XRD results indicated changes in surface characteristics with the addition of surfactants and altered CeCl3:H2O2 ratio. The findings in this thesis supports the earlier proposed theory that cerium could be used as an environmentally friendly alternative to hexavalent chromium. The thesis work clearly shows that it was possible to control some surface characteristics of the Al alloy samples, such as the number of cerium oxide nanoparticles and the morphology of nanoparticle clusters.

Antibiotic therapy comes with disturbances on human microbiota, resulting in changes of bacterial communities and thus leading to well-established health problems. In this study, we demonstrated that targeted teicoplanin administration maintains the faecal microbiota composition undisturbed in a mouse model while reaching therapeutic improvements for S. aureus infection.

Imaging and visualization of cell activity when exposed to nanomaterial are of main importance, when investigating biological response to a wide range of biomaterials from medical implants to smart nanoprobes. The ability to provide molecular and chemical information with spatial resolution in the region of sub-µm leads to increased insight and understanding of these biological challenges. Interdisciplinary collaborative effort may contribute and help solving urgent matters related to the challenges that we globally share. It is necessary to develop powerful tools such as analytical imaging techniques for addressing these urgent issues. This will increase our knowledge from the visualization on the cellular and subcellular level and help designing sustainable, personalized medical nanoprobes. In this thesis, the focus is to investigate the possibilities using the fluorescence microscopy, combined with surface analytical techniques delivering element specific information. 

Neutrophils are the most abundant immune cell in our bodies. They scavenge the body for threats and are usually among the first ones to find intruders and start the inflammation process. They have several ways of handling a threat, the main three being degranulation, phagocytosis, and neutrophil extracellular traps (NETs). In short, degranulation where granules are released into the extracellular matrix, phagocytosis is the process when for example the bacteria in engulfed by the neutrophil and neutralized. The NETs are when the neutrophil decondense their DNA and throw it out as a net to physically trap the invader and together with reactive oxygen species, proteases, and other antimicrobial molecules. It has been observed that nanoparticles (NP) can trigger NETs and there have been some comparisons between different parameters such as size, geometry, and functionalization. 

In this thesis we have explored how to measure neutrophil activity by a novel label free and noninvasive method (Paper 1). The NanoEsca, a combined XPS and PEEM instrument, is used to chemically map the neutrophils and NETs. We could clearly observe the NETs in PEEM and XPS mode. Quantum Dots (QDots, CdSe based) was used to trigger NETs. We track down the Quantum Dots with the element specific mapping. In the next paper we further explored how to extract new information with this advanced instrument that is traditionally is used for material- and surface science, and just recently deliver results in imaging and visualization within life sciences. Ultrathin slices of neutrophils where made special focus was given to the research work developing strategies to obtain and extract additional information from inside the neutrophils. These are pilot studies and show great potential to get chemical information in a label free way and is a good complement to fluorescence, SEM and TEM. We then made an in-depth investigation on the mechanisms how nanoparticles interact with neutrophils, with special focus on processes triggering NETs formation. Using QDots as a model system we could show that the NETs release is strongly dependent on the uptake of the nanoparticles. We used fluorescence and TEM to investigate where the QDots uptake and to identify the pattern where they finally end up. We clearly observed them inside vesicles in the inner part of the cell and even within the NETs structure giving proof that the uptake of QDots play an important role of the NETs formation. In the last paper we expanded the study and exposed the cells to Iron Oxide NPs (FeNP) Here we developed a strategy how to alternate the magnetic field control the direction of the NETs. We could manipulate live NETs with a magnetic field and made observations that parts of the NETs are static and some clearly mobile, still with an internal memory to find its initial structure just after release. TEM studies revealed that, like the QDots, the FeNP end up inside the NETs. In conclusion in this thesis work, detailed processes are explored on neutrophils and their NETs formation with new unconventional methods and how neutrophils and nanoparticles interact with respect to NETs. 

Neutrophil granulocytes are the most abundant white blood cells in mammals and vital components of the immune system. They are involved in the early phase of inflammation and in generation of reactive oxygen species. These rapid cell-signaling communicative processes are performed in the time frame of minutes. In this work, the activity and the response of neutrophil granulocytes are monitored when triggered by cerium-oxide based nanoparticles, using capacitive sensors based on Lab-on-a-chip technology. The chip is designed to monitor activation processes of cells during nanoparticle exposure, which is for the first time recorded on-line as alteration of the capacitance. The complementary metal oxide semiconductor engineering chip design is combined with low temperature co-fired ceramic, LTCC, packaging technology. The method is label free and gently measures cells on top of an insulating surface in a weak electromagnetic field, as compared to commonly used four-point probes and impedance spectroscopy electric measurements where electrodes are in direct contact with the cells. In summary, this label free method is used to measure oxidative stress of neutrophil granulocytes in real time, minute by minute and visualize the difference in moderate and high cellular workload during exposure of external triggers. It clearly shows the capability of this method to detect cell response during exposure of external triggers. In this way, an informationally dense non-invasive method is obtained, to monitor cells at work.

Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

Transition-metal oxides (TMOs) are potential candidates for anode materials of lithium-ion batteries (LIBs) due to their high theoretical capacity (similar to 1000 mA h/g) and enhanced safety from suppressing the formation of lithium dendrites. However, the poor electron conductivity and the large volume expansion during lithiation/delithiation processes are still the main hurdles for the practical usage of TMOs as anode materials. In this work, the CoSnO3@NC@ MnO@NC hierarchical nanobox (CNMN) is then proposed and fabricated to solve those issues. The as-prepared nanobox contains hollow cubic CoSnO3 as a core and dual N-doped carbon-"sandwiched" MnO particles as a shell. As anode materials of LIBs, the hollow and carbon interlayer structures effectively accommodate the volume expansion while dual active TMOs of CoSnO3 and Notably, the dual-layer structure of N-doped carbons plays a critical functional role MnO efficiently increase the specific capacity. in the incorporated composites, where the inner layer serves as a reaction substrate and a spatial barrier and the outer layer offers electron conductivity, enabling more effective involvement of active anode materials in lithium storage, as well as maintaining their high activity during lithium cycling. Subsequently, the as-prepared CNMN exhibits a high specific capacity of 1195 mA h/g after the 200th cycle at 0.1C and an excellent stable reversible capacity of about 876 mA h/g after the 300th cycle at 0.5C with only 0.07 mA h/g fade per cycle after 300 cycles. Even after a 250 times fast charging/discharging cycle both at SC, it still retains a reversible capacity of 422.6 mA h/g. We ascribe the enhanced lithium storage performances to the novel hierarchical architectures achieved from the rational design.

Electrochemical splitting of water is one of the most reliable and effective ways for the sustainable production of pure hydrogen on a large scale, while the core of this technology lies in the development of highly active non-noble-metal-based electrocatalysts to lower the large dynamic overpotentials of electrode materials. Here, an interface engineering strategy is demonstrated to construct an efficient and stable catalyst based on NiS@MoS2 core-shell hierarchical microspheres for the hydrogen evolution reactions (HER). The ultrathin MoS2 nanosheets in-situ grow on the surface of NiS hierarchical micro-sized spheres constructed by porous nanoplates, endowing the composites with rich interfaces, well-exposed electroactive edges, high structural porosity and fast transport channels. These advantages are favorable for the improvement of catalytic sites and the transport of catalysis-relevant species. More importantly, the intimate contact between MoS2 nanosheets and NiS nanoplates synergistically favors the chemical sorption of hydrogen intermediates, thereby reducing the reaction barrier and accelerating the HER catalytic process. As a result, the optimized NiS@MoS2 catalyst manifests impressive HER activity and durability, with a low overpotential of 208 mV in 0.5 M H2SO4 and 146 mV in 1.0 M KOH at 10 mA cm(-2), respectively. This work not only provides an effective way to construct core-shell hierarchical microspheres but also a multiscale strategy to regulate the electronic structure of heterostructured materials for energy-related applications. (C) 2020 Elsevier B.V. All rights reserved.

Hollow heterostructures have tremendous advantages in electrochemical energy storage and conversion areas due to their unique structure and composition characteristics. Here, we report the controlled synthesis of hollow CoSe2 nanocubes decorated with ultrathin MoSe2 nanosheets (CoSe2@MoSe2) as an efficient and robust bifunctional electrocatalyst for overall water splitting in a wide pH range. It is found that integrating ultrathin MoS2 nanosheets with hollow CoSe2 nanocubes can provide abundant active sites, promote electron/mass transfer and bubble release and facilitate the migration of charge carriers. Additionally, the surface electron coupling in the heterostructures enables it to serve as a source of sites for H+ and/or OH- adsorption, thus reducing the activation barrier for water molecules adsorption and dissociation. As a result, the title compound, CoSe2@MoSe2 hollow heterostructures, exhibits an overpotential of 183 mV and 309 mV at a current density of 10 mA cm(-2) toward hydrogen evolution reactions and oxygen evolution reactions in 1.0 M KOH, respectively. When applied as both cathode and anode for overall water splitting, a low battery voltage of 1.524 V is achieved along with excellent stability for at least 12 h. This work provides a new idea for the design and synthesis of high-performance catalysts for electrochemical energy storage and conversion.

Metal oxides have a large storage capacity when employed as anode materials for lithium-ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge-discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal-organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N-doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as-prepared ZnO-Co3O4@N-C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO-Co3O4@N-C shows a discharge capacity of 2373 mAh g(-1) at the first cycle and exhibits a retention capacity of 1305 mAh g(-1) even after 300 cycles at 0.1 A g(-1). In addition, a reversible capacity of 948 mAh g(-1) is obtained at a current density of 2 A g(-1), which delivers an excellent high-rate cycle ability.

We describe a method for magnetic solid phase extraction of trace-levels of Hg(II) ions by using Fe3O4 nanoparticles (NPs) covered with a shell of silica and modified with the chelator N-(2-acetylaminoethyl)-N-(3-triethoxysilylpropyl)thiourea. The new magnetic NPs enable rapid magnetic separation, thus leading to higher efficiency and accuracy. The extracted Hg(II) ions on the NPs were directly quantified using a mercury analyzer. Possible interferents are widely eliminated in this highly selective extraction process, and the NPs are not exerting an interfering effect either. The method has an enrichment factor of 100, and extraction recoveries are between 95 and 107 % when using 10 mg of the extracting NPs. The method works over a wide range of pH values and can be applied to even complex natural samples. The effects of pH value, extraction time, sample volume and adsorbent amount on the extraction efficiency were optimized. Under the optimal conditions, the detection limit is as low as 17 ng L-1. The method was applied to the preconcentration and detection of Hg(II) in three natural water samples using the standard addition method.

Human papillomavirus (HPV) infection is the main cause of cervical cancer, but the risk is associated with the various HPV genotypes which may be found in women with or without clinical findings.

Amine-functionalized alpha-cyanostilbene derivatives (Z)-2-(4-aminophenyl)-3-(4-butoxyphenyl) acrylonitrile (ABA) and (Z)-3-(4-butoxyphenyl)-2-[4-(butylamino) phenyl] acrylonitrile (BBA) were designed for specific recognition of picric acid (PA), an environmental and biological pollutant. The 1:1 host-guest complexes formed between the chemosensors and PA enhanced fluorescence quenching, thus leading to sensitive and selective detection in aqueous media and the solid phase.

As one of the major causes of antimicrobial resistance, beta-lactamase develops rapidly among bacteria. Detection of beta-lactamase in an efficient and low-cost point-of-care testing (POCT) way is urgently needed. However, due to the volatile environmental factors, the quantitative measurement of current POCT is often inaccurate. Herein, we demonstrate an artificial intelligence (AI)-assisted mobile health system that consists of a paper-based beta-lactamase fluorogenic probe analytical device and a smartphone-based AI cloud. An ultrafast broad-spectrum fluorogenic probe (B1) that could respond to beta-lactamase within 20 s was first synthesized, and the detection limit was determined to be 0.13 nmol/L. Meanwhile, a three-dimensional microfluidic paper-based analytical device was fabricated for integration of B1. Also, a smartphone-based AI cloud was developed to correct errors automatically and output results intelligently. This smart system could calibrate the temperature and pH in the beta-lactamase level detection in complex samples and mice infected with various bacteria, which shows the problem-solving ability in interdisciplinary research, and demonstrates potential clinical benefits.

Functionalized computed tomography (CT) in combination with labelled cells is virtually non-existent due to the limited sensitivity of X-ray-absorption-based imaging, but would be highly desirable to realise cell tracking studies in entire organisms. In this study we applied in-line free propagation X-ray phase-contrast CT (XPCT) in an allergic asthma mouse model to assess structural changes as well as the biodistribution of barium-labelled macrophages in lung tissue. Alveolar macrophages that were barium-sulfate-loaded and fluorescent-labelled were instilled intratracheally into asthmatic and control mice. Mice were sacrificed after 24 h, lungs were kept in situ, inflated with air and scanned utilizing XPCT at the SYRMEP beamline (Elettra Synchrotron Light Source, Italy). Single-distance phase retrieval was used to generate data sets with ten times greater contrast-to-noise ratio than absorption-based CT (in our setup), thus allowing to depict and quantify structural hallmarks of asthmatic lungs such as reduced air volume, obstruction of airways and increased soft-tissue content. Furthermore, we found a higher concentration as well as a specific accumulation of the barium-labelled macrophages in asthmatic lung tissue. It is believe that XPCT will be beneficial in preclinical asthma research for both the assessment of therapeutic response as well as the analysis of the role of the recruitment of macrophages to inflammatory sites.

Lung imaging in mouse disease models is crucial for the assessment of the severity of airway disease but remains challenging due to the small size and the high porosity of the organ. Synchrotron inline free-propagation phase-contrast computed tomography (CT) with its intrinsic high soft-tissue contrast provides the necessary sensitivity and spatial resolution to analyse the mouse lung structure in great detail. Here, this technique has been applied in combination with single-distance phase retrieval to quantify alterations of the lung structure in experimental asthma mouse models of different severity. In order to mimic an in vivo situation as close as possible, the lungs were inflated with air at a constant physiological pressure. Entire mice were embedded in agarose gel and imaged using inline free-propagation phase-contrast CT at the SYRMEP beamline (Synchrotron Light Source, Elettra, Trieste, Italy). The quantification of the obtained phase-contrast CT data sets revealed an increasing lung soft-tissue content in mice correlating with the degree of the severity of experimental allergic airways disease. In this way, it was possible to successfully discriminate between healthy controls and mice with either mild or severe allergic airway disease. It is believed that this approach may have the potential to evaluate the efficacy of novel therapeutic strategies that target airway remodelling processes in asthma.

A Surface Plasmon Resonance (SPR) aptasensor was developed for the detection of Brucella melitensis (B. melitensis) in milk samples. Brucellosis is a bacterial zoonotic disease with global distribution caused mostly by contaminated milk or their products. Aptamers recognizing B. melitensis were selected following a whole bacteria-SELEX procedure. Two aptamers were chosen for high affinity and high specificity. The high affinity aptamer (B70 aptamer) was immobilized on the surface of magnetic silica core-shell nanoparticles for initial purification of the target bacteria cells from milk matrix. Another aptamer, highly specific for B. melitensis cells (B46 aptamer), was used to prepare SPR sensor chips for sensitive determination of Brucella in eluted samples from magnetic purification since direct injection of milk samples to SPR sensor chips is known for a high background unspecific signal. Thus, we integrated a quick and efficient magnetic isolation step for subsequent instant detection of B. melitensis contamination in one ml of milk sample by SPR with a LOD value as low as 27 ± 11 cells.

Two-dimensional materials offer a unique platform for sensing where extremely high sensitivity is a priority, since even minimal chemical interaction causes noticeable changes inelectrical conductivity, which can be used for the sensor readout. However, the sensitivity has to becomplemented with selectivity, and, for many applications, improved response- and recovery times are needed. This has been addressed, for example, by combining graphene (for sensitivity) with metal/oxides (for selectivity) nanoparticles (NP). On the other hand, functionalization or modification of the graphene often results in poor reproducibility. In this study, we investigate thegas sensing performance of epitaxial graphene on SiC (EG/SiC) decorated with nanostructured metallic layers as well as metal-oxide nanoparticles deposited using scalable thin-film depositiontechniques, like hollow-cathode pulsed plasma sputtering. Under the right modification conditions the electronic properties of the surface remain those of graphene, while the surface chemistry can betuned to improve sensitivity, selectivity and speed of response to several gases relevant for airquality monitoring and control, such as nitrogen dioxide, benzene, and formaldehyde.

A challenging task, in the area of magnetic resonance imaging is to develop contrast enhancers with built-in antioxidant properties. Oxidative stress is considered to be involved in the onset and progression of several serious conditions such as Alzheimer’s and Parkinson’s disease, and the possibility to use cerium-contained nanoparticles to modulate such inflammatory response has gained a lot of interest lately. The rare earth element gadolinium is, due to its seven unpaired f-electrons and high symmetry of the electronic state, a powerful element for contrast enhancement in magnetic resonance imaging. Chelates based on gadolinium are the most commonly used contrast agents worldwide. When introducing external contrast agents there is always a risk that it may trigger inflammatory responses, why there is an urgent need for new, tailor-made contrast agents.

Small sized cerium oxide nanoparticles have electronic structures that allows coexistence of oxidation states 3+ and 4+ of cerium, which correlates to applicable redox reactions in biomedicine. Such cerium oxide nanoparticles have recently shown to exhibit antioxidant properties both in vitro and in vivo, via the mechanisms involving enzyme mimicking activity.

This PhD project is a comprehensive investigation of cerium oxide nanoparticles as scaffold materials for gadolinium integration. Gadolinium is well adopted into the crystal structure of cerium oxide, enabling the combination of diagnostic and therapeutic properties into a single nanoparticle. The main focus of this thesis project is to design cerium oxide nanoparticles with gadolinium integration. A stepwise approach was employed as follows: 1) synthesis with controlled integration of gadolinium, 2) material characterization by means of composition crystal structure, size, and size distribution and 3) surface modification for stabilization. The obtained nanoparticles exhibit remarkable antioxidant capability in vitro and in vivo. They deliver strongly enhanced contrast per gadolinium in magnetic resonance imaging, compared to commercially available contrast agents.

A soft shell of dextran is introduced to encapsulate the cerium oxide nanoparticles with integrated gadolinium, which protects and stabilizes the hard core and to increases their biocompatibility. The dextran-coating is clearly shown to reduce formation of a protein corona and it improves the dispersibility of the nanoparticles in cell media. Functionalization strategies are currently being studied to endow these nanoparticles with specific tags for targeting purposes. This will enable guidance of the nanoparticles to a specific tissue, for high local magnetic resonance contrast complemented with properties for on-site reduced inflammation.

In conclusion, our cerium oxide nanoparticles with integrated gadolinium, exhibit combined therapeutic and diagnostic, i.e. theragnostic capabilities. This type of nanomaterial is highly promising for applications in the field of biomedical imaging.

The chelating gadolinium-complex is routinely used as magnetic resonance imaging (MRI) -contrast enhancer. However, several safety issues have recently been reported by FDA and PRAC. There is an urgent need for the next generation of safer MRI-contrast enhancers, with improved local contrast and targeting capabilities. Cerium oxide nanoparticles (CeNPs) are designed with fractions of up to 50% gadolinium to utilize the superior MRI-contrast properties of gadolinium. CeNPs are well-tolerated in vivo and have redox properties making them suitable for biomedical applications, for example scavenging purposes on the tissue-and cellular level and during tumor treatment to reduce in vivo inflammatory processes. Our near edge X-ray absorption fine structure (NEXAFS) studies show that implementation of gadolinium changes the initial co-existence of oxidation states Ce3+ and Ce4+ of cerium, thereby affecting the scavenging properties of the nanoparticles. Based on ab initio electronic structure calculations, we describe the most prominent spectral features for the respective oxidation states. The as-prepared gadolinium-implemented CeNPs are 3-5 nm in size, have r(1)-relaxivities between 7-13 mM(-1) s(-1) and show clear antioxidative properties, all of which means they are promising theranostic agents for use in future biomedical applications.

Gadolinium chelates are employed worldwide today as clinical contrast agents for magnetic resonance imaging. Until now, the commonly used linear contrast agents based on the rare-earth element gadolinium have been considered safe and well-tolerated. Recently, concerns regarding this type of contrast agent have been reported, which is why there is an urgent need to develop the next generation of stable contrast agents with enhanced spin-lattice relaxation, as measured by improved T-1 relaxivity at lower doses. Here, we show that by the integration of gadolinium ions in cerium oxide nanoparticles, a stable crystalline 5 nm sized nanoparticulate system with a homogeneous gadolinium ion distribution is obtained. These cerium oxide nanoparticles with entrapped gadolinium deliver strong T-1 relaxivity per gadolinium ion (T-1 relaxivity, r(1) = 12.0 mM(-1) s(-1)) with the potential to act as scavengers of reactive oxygen species (ROS). The presence of Ce3+ sites and oxygen vacancies at the surface plays a critical role in providing the antioxidant properties. The characterization of radial distribution of Ce3+ and Ce4+ oxidation states indicated a higher concentration of Ce3+ at the nanoparticle surfaces. Additionally, we investigated the ROS-scavenging capabilities of pure gadolinium-containing cerium oxide nanoparticles by bioluminescent imaging in vivo, where inhibitory effects on ROS activity are shown.

The size distribution and magnetic properties of ultra-small gadolinium oxide crystals (US-Gd₂O₃) were studied, and the impact of polyethylene glycol capping on the relaxivity constants (r₁, r₂) and signal intensity with this contrast agent was investigated. Size distribution and magnetic properties of US-Gd₂O₃ nanocrystals were measured with a TEM and PPMS magnetometer. For relaxation studies, diethylene glycol (DEG)-capped US-Gd₂O₃ nanocrystals were reacted with PEG-silane (MW 5000). Suspensions were adequately dialyzed in water to eliminate traces of Gd³⁺ and surfactants. The particle hydrodynamic radius was measured with dynamic light scattering (DLS) and the proton relaxation times were measured with a 1.5 T MRI scanner. Parallel studies were performed with DEG–Gd₂O₃ and PEG-silane–SPGO (Gd₂O₃,< 40 nm diameter). The small and narrow size distribution of US-Gd₂O₃ was confirmed with TEM (~3 nm) and DLS. PEG-silane–US-Gd₂O₃ relaxation parameters were twice as high as for Gd–DTPA and the r₂/r₁ ratio was 1.4. PEG-silane–SPGO gave low r₁ relaxivities and high r₂/r₁ ratios, less compatible with positive contrast agent requirements. Higher r₁ were obtained with PEG-silane in comparison to DEG–Gd₂O₃. Treatment of DEG–US-Gd₂O₃ with PEG-silane provides enhanced relaxivity while preventing aggregation of the oxide cores. This study confirms that PEG-covered Gd₂O₃ nanoparticles can be used for positively contrasted MR applications requiring stability, biocompatible coatings and nanocrystal functionalization.

The innovative construction of bifunctional non-noble electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative for electrochemical water splitting. Herein, we provide a collaborative self-templating method to prepare a hybrid catalyst of nanoporous CoP nanowire (NWs) arrays decorated with carbon-coated CoP nanoparticles (NPs). Its found that the unique structure and morphology of the resultant catalyst can provide abundant available active sites and faciliatate the rapid H-2/O-2 transmission. Additionally, the N-doped carbon improves the conductivity of the catalyst and prevents the aggregation and deactivation of CoP nanoparticles. Forthermore, the strong coupling and synergistic effects by interface engineering are also conducive to the electrochemical performance. Benefiting from these advantages, the CoP NWs/CoP NPs@NC/CC only needs a low overpotential of 103 mV to achieve 10 mA cm(-2) with a small Tafel slope of 87 mV dec(-1) for HER. When employed in an electrolytic cell as an electrocatalyst for overall water splitting, a low voltage of 1.60 V is required to drive 10 mA cm(-2). This study may provide a novel way to fabricate transitionmetal-based catalysts for water splitting.

Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with epsilon-poly-L-Lysine (epsilon-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight epsilon-PLL was crosslinked in pristine BC membranes and to carboxymethyl cellulose functionalized BC using carbodiimide chemistry. The functionalization of BC with epsilon-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with epsilon-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.

Introduction In the increasingly challenging field of clinical microbiology, diagnosis is a cornerstone whose accuracy and timing are crucial for the successful management, therapy, and outcome of infectious diseases. Currently employed biomarkers of infectious diseases define the scope and limitations of diagnostic techniques. As such, expanding the biomarker catalog is crucial to address unmet needs and bring about novel diagnostic functionalities and applications. Areas covered This review describes the extracellular nucleases of 15 relevant bacterial pathogens and discusses the potential use of nuclease activity as a diagnostic biomarker. Articles were searched for in PubMed using the terms: nuclease, bacteria, nuclease activity or biomarker. For overview sections, original and review articles between 2000 and 2019 were searched for using the terms: infections, diagnosis, bacterial, burden, challenges. Informative articles were selected. Expert opinion Using the catalytic activity of nucleases offers new possibilities compared to established biomarkers. Nucleic acid activatable reporters in combination with different transduction platforms and delivery methods can be used to detect disease-associated nuclease activity patterns in vitro and in vivo for prognostic and diagnostic applications. Even when these patterns are not obvious or of unknown etiology, screening platforms could be used to identify new disease reporters.