1,721,011 research outputs found
Measuring oxidized DNA and RNA precursors by micro-Raman spectroscopy
No full textDNA/RNA synthesis precursors are especially vulnerable to damage induced by reactive oxygen species occurring during oxidative stress. 8-oxo-dGTP and 8-oxo-rGTP are the prevalent oxidized nucleotides which can be incorporated into DNA or RNA and lead to mutations and cell death. The MTH1 enzyme protects against these effects by hydrolysing oxidized nucleotides. Since MTH1 inhibition is currently under development as novel target in cancer therapy, measurements of cellular 8-oxo-dGTP or 8-oxo-rGTP concentration provide an important strategy to monitor the enzyme function.
Here we present a novel method based on Micro-Raman spectroscopy to reveal oxidative damage in the nucleotide pool. The analysis of d/rGTP and 8-oxo-d/rGTP Raman spectra with the support of ab initio calculations allowed us to identify specific and highly sensitive spectroscopic markers of oxidation. We developed a procedure to determine the concentration of 8-oxo-dGTP in dGTP, and their ribo counterpart, down to very low concentration. Present experiments pave the way for employing this procedure to identify the composition and quantitatively determine the oxidatively damaged nucleotide pool present in the cell
Spectroscopic study on accelerated ageing of materials used in contemporary art
No full textPictorial films in contemporary art represent a material matrix that can be really complex: for their works contemporary artists use fairly new material –from XIX and XX centuries- that derive from industrial productions and whose conservation characteristics are unknown. Artists often combine pigments and binders with other materials that do not belong to traditional chemical classes used in artistic field. In addiction, contemporary art can be subjected to less monitored or more aggressive environmental conditions, for example like in street art.
The aim of this study, part of a PhD project, is the characterization of pictorial films in synthetic organic pigments and acrylic binder in terms of stability and degradation products through accelerated ageing. For this reason, different accelerated ageing processes are used to consider influence of multiple factors – UV radiation, solar light, thermic stress- in monitoring of temperature and Relative Humidity.
The characterization of ageing is based on several spectroscopic techniques
Characterization of compounds present in the ammonia extract of Madder lake, using NMR, ESI-MS and HPTLC-SERS
No full textA multi-analytical approach for characterization of orcein dyes in historical textiles, extracted through a new alkaline extraction protocol
No full textSurface Enhanced Raman Spectroscopy for Biophysical Applications Using Plasmonic Nanoparticle Assemblies
No full textThe book explores the phenomenon of surface-enhanced Raman scattering (SERS), the huge amplification of Raman signal from molecules in the proximity of a metallic nanostructured surface, allowing readers to gain an in-depth understanding of the mechanisms affecting the spectroscopic response of SERS-active systems for effective applications. SERS spectroscopy is an ultrasensitive analytical technique with great potential for applications in the field of biophysics and nanomedicine. As examples, the author presents the design of nanocolloid-based SERS-active substrates for molecular sensing and of a folate-based SERS-active nanosensor capable of selectively interacting with cancer cells, enabling cancer diagnostics and therapy at the single-cell level. The author also suggests novel paths for the systematization of the SERS nanosystem design and experimental protocols to maximize sensitivity and reproducibility, which is essential when real-world biomedical applications are the goal of the study. With a combined approach, both fundamental and applied, and a detailed analysis of the state of the art, this book provides a valuable overview both for students new to SERS spectroscopy and for experts in the field
Folate conjugated gold nanoparticles for surface-enhanced Raman imaging and theranostics on healthy and cancer human cells selective targeting of human cancer cells
No full textSince its discovery, Surface Enhanced Raman Scattering (SERS) has been employed for the spectroscopic study and detection of molecules with a relevant role in biology [1,2]. More recently, the application of SERS-active nanostructures as spectroscopic “antennas” inside biological cells has proved to be a simple way to perform spectroscopic imaging of living tissues [3].
When dealing with biology, an interesting task for biophysics is to find ways to distinguish between healthy and cancer cells. Moreover, much interest has lately risen around the concept of “theranostics”, i.e. combining diagnostics with therapy, the latter to perform selectively on cancer cells without damaging the healthy ones [4]. When based on plasmonics, theranostics is often performed combining SERS and photothermal bleaching.
Here we will present a biocompatible system based on gold nanoparticles (Nps) functionalized with the Raman active bifunctional linker 4-aminothiophenol. This molecule bounds covalently to the gold Np via the S-H moiety, and exposes the amminic NH2 group for further conjugation. This functional group is exploited for the binding of folic acid, a biomolecule with an essential role in cell reproduction. Our system can be considered a nanobiovector, as it is capable of targeting a specific kind of cell and locate in its proximity and/or inside it. Since cancer cell show many more receptors for folic acid than healthy cells, as they reproduce more quickly, the nanovectors will target cancer cells much more efficiently [5].
We will present SERS and microscopic characterization of this system. The interaction of our nanobiovector with different cell cultures will be explained, and proofs of selective targeting and eventual internalization in cells will be shown. The presence of SERS-active Nps allows for performing Raman imaging witnessing the position of the nanovector with respect to the cell (see Fig.1). We will also illustrate a SERS-based screening method that allows for distinguishing sick and healthy cell with an easy and quick measurement
Addressing Crystal Structure in Semiconductor Nanowires by Polarized Raman Spectroscopy
No full textRaman scattering is a powerful inelastic light scattering technique able to probe the vibrational properties of materials. This technique has been successfully employed in semiconductor nanowires to provide information on their fundamental properties, such as the phononic properties, the crystal composition, and the electronic band structure. When performed in a polarization-resolved manner on a single nanowire, Raman spectroscopy can even allow addressing the nanowire's crystal structure. This is a fact of pivotal importance, as crystal phase is emerging as a novel degree of freedom in the bandgap engineering and phonon engineering of materials, and the control of the crystal phase is a possibility uniquely offered by nanowires. Indeed, recent advances in the synthetic growth of nanowires have given access to crystal phases (e.g., hexagonal phase in Si and Ge) that in the bulk can only be obtained under extreme pressure conditions, and it is possible to controllably switch between different crystal phases during the growth of nanowires. The realization and, even more, the interpretation of polarized Raman experiments on nanowires can be non-trivial, as several issues have to be considered. Therefore, in this chapter, we provide the basic theoretical background necessary to calculate Raman selection rules and interpret polarization-resolved Raman spectra of semiconductor nanowires. We also discuss the main ingredients of a Raman setup, with a focus on the scattering geometries typically used for nanowires. We highlight the main differences in the Raman spectra of nanowires with cubic and hexagonal crystal symmetries, and we treat also the case of the most challenging type of heterostructure: a nanoscale crystal-phase homostructure. Finally, we discuss resonant Raman experiments that allow the determination of the energy of some electronic transitions in nanowires. We focus mostly on a very new material system, namely Ge nanowires with controlled crystal phase, but the general procedure that we establish can be applied to several types of nanostructures
Monitoring DNA oxidative damage: pushing the limits of Raman spectroscopy
No full textWe propose an advanced Raman spectroscopy (RS) study of nucleic acids. As known, nondisruptive optical techniques can allow for a qualitative investigation and for monitoring
structural changes in molecules. These capabilities can also be improved, with the correlation of spectroscopic information with computational simulations.
Furthermore, this approach can lead to a semi-quantitative analysis, e.g. in terms of nucleotide composition, of DNA or RNA. An important possibility
is the employment of Surface- Enhanced Raman Spectroscopy (SERS) in enhancing the sensitivity of the technique
Folate conjugated, SERS-active gold nanoparticles for selective targeting of human cancer cells
No full textOne of the most interesting applications of Surface Enhanced Raman Scattering (SERS), ever since its discovery, has been the spectroscopic study and detection of biomolecules [1,2]. More recently, the application of SERS-active nanostructures as spectroscopic antennas inside biological cells has proved to be a simple way to perform spectroscopic imaging of both healthy and damaged living tissues [3]: an interesting task for biophysicists is indeed to find ways to distinguish between healthy and cancer cells. Moreover, much interest has lately risen around the concept of “theranostics”, i.e. combining diagnostics with therapy, the latter to perform selectively on cancer cells without damaging the healthy tissue [4]. Plasmonics-based theranostics is often performed combining SERS and photothermal bleaching.
We will here present a biocompatible system based on gold nanoparticles (Nps) functionalized with the Raman active bifunctional linker 4-aminothiophenol and further conjugated with folic acid, a biomolecule with an essential role in cell reproduction (see Fig. 1., (a)). Our system can be considered a nanobiovector, as it is capable of targeting a specific kind of cell and locate in its proximity and/or inside it. Folic acid receptors are more frequent in cancer cells, as they reproduce more quickly [5]. For this reason, our nanovector targets cancer cells much more efficiently (Fig. 1., (b)). After presenting the system characterization, we will illustrate the interaction of our nanobiovector with different cell cultures. Proofs of selective targeting and eventual internalization in cells will be shown. The presence of SERS-active Nps allows not only to perform Raman imaging, but also the implementation of a SERS-based screening method that allows for a precise single cell diagnosi
- …
