1,721,015 research outputs found
Plasmonic and Magnetic Nanostructures for Multiplexing Detection and Multiple Imaging Techniques in Bionanomed
Full text linkIn the last years nanotechnology is strongly influencing the progresses of medicine, in particular against cancer, both for diagnostic and therapeutic purposes. Nanostructures can be planned with properties useful for a specific application. However, the same nanostructure can be synthesized also for more diagnostic techniques. In addiction, one can also plan these nanostructures for what is called multiplexing, namely the presence in the same diagnostic signal of information related to many analytes at the same time. The nanostructures can be synthesized for obtaining targeting, which increases the ability of discriminating different type of tumour associated antigens or, in the case of therapeutic purposes, for the ability of being directed to a specific site.
In the present thesis, nanostructures have been synthesized for their applications in particular with two techniques like surface enhanced Raman spectroscopy (SERS) and magnetic resonance imaging (MRI), which are complementary techniques for imaging. The nanostructures have been functionalized also with antibodies for targeting antigens.
SERS exploits the huge enhancement of electromagnetic fields of plamonic nanostructures. It is shown that this technique can be used for quantitative measurements of clinically interesting anticancer drugs, with a linear range response in the order of nanomole per millimetre square of SERS active area, which is appropriate also for clinical purposes. It is also demonstrated how molecules with a poor Raman cross section could be revealed with the help of a protocol, called Reactive-SERS, which considers a simple photoactivated reaction.
Nanoparticles are obtained with laser ablation and they are found easy to functionalize due to their unique naked surface. It is shown that their properties are useful in laser desorption ionization mass spectrometry. Used as a matrix, they are compared with chemically produced particles and with a widely used organic matrix and they always show the lowest background especially in the low mass region under 500 Da, which is important for the identification of small molecules.
Multiplexing analysis are carried out with gold nanoparticles (AuNP) functionalized with different dyes, as SERS reporters, associated to different antibodies. The library of optimized thiolated reporters is increased and makes possible to investigate more complex biological samples. This application is also translated to the cultural heritage research field for the characterization of paint stratigraphic samples.
Multimodal contrast agents are developed, coupling the SERS activity, typical of dye functionalized gold nanoparticles, with magnetic sensitive moieties, like iron atoms in alloy nanoparticles or with Gd3+ ions linked to gold nanoparticles. A new polymer, called SuperDOTA, is synthetized for achieving high Gd3+ loadings on the surface of nanoparticles. Preliminary results show that AuNPs, functionalized with both a SERS reporter dye and SuperDOTA-Gd, have useful properties for in vivo MRI tumour analysis and ex-vivo SERS imaging
Microplastic pollution in the North-east Atlantic Ocean surface water: How the sampling approach influences the extent of the issue
Full text linkDetection of low-quantity anticancer drugs by surface-enhanced Raman scattering
No full textUltrasensitive detection of low-quantity drugs is important for personalized therapeutic approaches in several diseases and, in particular, for cancer treatment. In this field, surface-enhanced Raman scattering (SERS) can be very useful for its ability to precisely identify analytes from their unique vibrational spectra, with very high sensitivity. Here, we report a study about SERS detection of sunitinib, paclitaxel and irinotecan, i.e. three commonly used antineoplastic drugs, and of SN-38, i.e. the metabolite of irinotecan, dissolved in methanol solutions. By using commercial Klarite substrates, we found that sunitinib, irinotecan and SN-38 have detection limits of 20-70 ng, which is below the threshold for applications in cancer therapy. Conversely, the SERS signal was not appreciable with paclitaxel, and this is explained by the absence of optical resonances in the visible range. Overall, our results show that ultrasensitive SERS detection of sunitinib, irinotecan and SN-38 is feasible, encouraging further development of this technology also for other drugs with similar molecular structure especially for those analytes with absorption bands in the visible range
3D SERS and Raman imaging of protective microcapsules containing bio‐active terpenoids
Full text linkTerpenoids play a major role in agriculture, given their fungicidal and herbicidal actions, as well as their favorable toxicological, ecotoxicological, and environmental profiles. Despite all these advantages, terpenoids are reported to be unstable in direct sunlight and atmospheric conditions, so both commercial suppliers and scientific literature foresee their protection by encapsulation. The so-called microcapsules (mu Caps) are therefore of high relevance as drug-delivery vectors, but very few techniques focus on their surface as well as on their morphological characterization. Indeed, these aspects are of great importance, given that their surface chemistry governs both their colloidal stability and mechanism of action. Common analysis techniques, such as chromatographic and mass-spectrometric ones, are destructive, require sample preparation, and do not result in the complete morphological characterization of the microcapsules. Micro-Raman spectroscopy, in conjunction with the surface-enhanced Raman spectroscopy (SERS) effect, offers a valuable alternative method of investigation capable of achieving a complete and non-destructive morphological characterization of the terpenoid-encapsulating systems, the dimensions of which fall within the micrometric range. In addition, the SERS effect can be exploited by fabricating the microcapsules with gold nanostars (AuNSs) modified with chitosan and a SERS reporter (Nile Blue A). Thanks to the high contrast provided by the SERS signals of this tag, it was possible to localize and confirm the chitosan in the morphology of the microcapsules. The results of this study shed new light on the possibility of analyzing terpenoid-encapsulating microcapsules and possibly other kinds of encapsulates brought by using Raman spectroscopy and by exploiting the SERS effect
One-step laser ablation synthesis of magnetic nanoparticles with carbon coating for tribological applications
Full text linkAmong different materials able to reduce wear and friction in tribological couplings, there are lubricant nano -fluids obtained by dispersing suitable nanoparticles into a host fluid. Carbon-based nanomaterials are known to be effective additives, but their efficiency can be further improved by combination with magnetic compounds. Unfortunately, the preparation of such bifunctional materials often require complex syntheses or need post -synthesis functionalization processes, thus increasing costs and reducing reliability. Herein, a simple and cost-effective one-step synthesis method, based on laser ablation in solution, is used to produce magnetic respon-sive nanoparticles surrounded by a carbon matrix to be exploited as lubricating additives. The lubricating colloidal solutions are thus easily obtained without the use of surfactants nor multi-step processes, which can contaminate the final product or increase production costs. They exhibit a very good stability and reduce the wear coefficient of almost 50% in presence of an applied magnetic field in respect to the base fluid alone. The importance of the presence of the carbon matrix surrounding the magnetic core to develop a positive tribological behaviour has been proved
Synthesis of magnetic nanoparticles by laser ablation of strontium ferrite under water and their characterization by optically detected magnetophoresis supported by BEM calculations
No full textMeasurement of the properties of magnetic nanoparticles is mandatory for their application and usually this is accomplished using magnetometers, like SQUIDs or VSMs. However, these techniques require amounts of materials that are not always available and do not allow exploration of new syntheses with low production. The tiny quantity of nanoparticles obtained by laser ablation of strontium ferrite necessitated the characterization of their magnetic properties using an alternative technique, optically detected magnetophoresis, which exploits the motion of nanoparticles in a fluid under a magnetic field gradient. Time dependent optical extinction of a colloidal solution of magnetic nanoparticles can be used for recording the collective motion of the nanoparticles in a fluid. The optical extinction of nanoparticles, with absorption and scattering contributions, depends on the particle material and on their morphologies. We report a new implementation of a magnetophoretic model with the extinction properties of nanoparticles calculated using the Boundary Element Method. The model is applied to estimate the magnetic properties of a challenging sample of mixed ferrite nanoparticles. The results show that, especially for polydisperse samples, the explicit consideration of the size dependent extinction properties of the nanoparticles is needed to characterize magnetic nanoparticles by optically detected magnetophoresis. The motion of magnetic nanoparticles in a fluid, exploited in many applications, is provided with an appropriate description using the present approach
High performance multi-purpose nanostructured thin films by inkjet printing: Au micro-electrodes and SERS substrates
No full textA surface enhanced Raman scattering based colloid nanosensor for developing therapeutic drug monitoring
No full textChiroplasmonic DNA Scaffolded “Fusilli” Structures
Full text link: DNA is an ideal template for the design of nanoarchitectures with molecular-like features. Here, we present an optimized assembly strategy for the concatenation of DNA quasi-rings into long scaffolds. Ionic strength, which played a major role during self-assembly, produced the expected high quality only at 15 mM MgCl2. Atomic force microscopy (AFM) characterization showed several micrometer long tubular structures that were used as templates for the positioning of plasmonic nanoparticles (NPs) along a three-dimensional helical path using DNA tethers. As imaged by high-resolution scanning transmission electron microscopy (HR-STEM) and modeled by theoretical calculations, the NPs distributed into a "fusilli" fashion (i.e., a helical pasta shape), displaying chiroptical activity as revealed by a bisignated CD absorption, centered at the plasmon resonance wavelength. The present structures contribute to enrich the ever-developing arena of chiroplasmonic DNA-based nanomaterials and demonstrate that large assemblies are attainable for their future application to develop metamaterials
Reliable Methodology for Measuring SERS Enhancement Factor on Colloidal and Solid Substrates: A Practical Guide
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