Pitfalls and promises in FTIR spectromicroscopy analyses to monitor iron-mediated DNA damage in sperm

FTIR microscopy evaluation of the immunogenicity of eco-friendly γFe2O3@Ag@Cs nanocomposite as a platform for the discovery and screening of vaccine adjuvants

Core-shell nanoparticles have been extensively researched, particularly as multimodal for medical applications. Scientists are interested in combining the optical properties of nano-plasmonic nanoparticles with the magnetic properties of super-paramagnetic nanoparticles. This combination is very important because it reduces metal toxicity and improves nanoparticle targeting. Tuning the shape and size of the nanoparticles significantly reflects their properties and applications. In previous study, we assessed the SPION@Ag@chitosan core-shell nanocomposite (γFe2O3@Ag@Cs NCs) toxicity both in vitro and preclinically in vivo, using traditional toxicological assessment and biochemical parameters. The results showed that up to100 ug/kg is a safe NP dose as evaluated by pathological and biochemical parameters. The aim of the present study was to gain insight into the effect of γFe2O3@Ag@Cs NC at sub-cytotoxic concentrations (100ug/ml) on the biochemical profile of immune organs (inguinal, axillary, spleen and thymus) by combining the investigation of cytokine secretion to ex vivo FTIR spectroscopy. The four immune organs were treated with 100 ug/kg NC and the time dependence of the effects produced by the treatment was analyzed. The Data shows that the used core-shell NC with the indicate dose have a stimulatory effect on the immune system, as evidenced by an increase in antibody secretion (IgG and IgM), lipid, nucleic acid, and protein synthesis after uptake time which depends on the specific immune organ.

Strategies and Perspectives for UV Resonance Raman Applicability in Clinical Analyses of Human Sperm RNA

Developing a deeper knowledge about the impact of DNA and RNA epigenetic mutations on sperm production and fertilization performance is essential for selecting best quality samples in Assisted Reproductive Technologies (ART). Indeed, sperm RNAs adenine and guanine are likely to be methylated in low quality RNA sperm samples and their study requires the employment of techniques able to isolate high quality nucleic acids. UV resonance Raman spectroscopy represents a valuable tool that is able to monitor peculiar molecular modifications occurring predominantly in nucleic acids, being less sensitive to the presence of other biological compounds. In this work, we used an UV Resonance Raman (UVRR) setup coupled to a synchrotron radiation source tuned at 250 nm, in order to enhance sperm RNAs adenine and guanine vibrational signals, reducing also the impact of a fluorescence background typically occurring at lower energies. Despite that our protocol should be further optimized and further analyses are requested, our results support the concept that UVRR can be applied for setting inexpensive tools to be employed for semen quality assessment in ART.

Infrared microspectroscopy studies on the protective effect of curcumin coated gold nanoparticles against H2O2-induced oxidative stress in human neuroblastoma SK-N-SH cells

The contribution of oxidative stress in several chronic and degenerative diseases suggests that antioxidant therapy can be a promising therapeutic strategy. However, in the case of many antioxidants, their biodistribution and bioactivity are restricted due to low water solubility. Curcumin is a powerful free radical scavenger that upon conjugation to gold nanoparticles results in the formation of stable gold nanoparticles that act as highly water-soluble carriers for the curcumin molecules. In the present study, the effect of curcumin-coated gold nanoparticles (Cur-GNPs) on the H₂O₂-treated human neuroblastoma (SK-N-SH) cell line was evaluated by using Fourier transform infrared (FTIR) microspectroscopy. Biochemical changes in cells resulting from exposure to reactive oxygen species (ROS) and antioxidant treatment on cells were investigated. Analyzing changes in PO₂^- bands and amide bands in the fingerprint region and also changes in the ratio of CH_2(asym) to CH_3(asym) bands in the lipid region revealed that post-treatment with Cur-GNPs could effectively decrease the damage on DNA caused by H₂O₂ treatment, whereas pre-treatment of cells with Cur-GNPs was found to be more effective at preventing lipid peroxidation than post-treatment. Further analysis of the CH_2(asym) to CH_3(asym) ratio provided information on not only the lipid peroxidation level in cells, but also the interaction of nanoparticles with the plasma membrane, as confirmed by lactate dehydrogenase assay.

Soft X-ray Microscopy Techniques for Medical and Biological Imaging at TwinMic—Elettra

Progress in nanotechnology calls for material probing techniques of high sensitivity and resolution. Such techniques are also used for high-impact studies of nanoscale materials in medicine and biology. Soft X-ray microscopy has been successfully used for investigating complex biological processes occurring at micrometric and sub-micrometric length scales and is one of the most powerful tools in medicine and the life sciences. Here, we present the capabilities of the TwinMic soft X-ray microscopy end-station at the Elettra synchrotron in the context of medical and biological imaging, while we also describe novel uses and developments.

Scanning Probe Microscopies: Imaging and Biomechanics in Reproductive Medicine Research

Basic and translational research in reproductive medicine can provide new insights with the application of scanning probe microscopies, such as atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). These microscopies, which provide images with spatial resolution well beyond the optical resolution limit, enable users to achieve detailed descriptions of cell topography, inner cellular structure organization, and arrangements of single or cluster membrane proteins. A peculiar characteristic of AFM operating in force spectroscopy mode is its inherent ability to measure the interaction forces between single proteins or cells, and to quantify the mechanical properties (i.e., elasticity, viscoelasticity, and viscosity) of cells and tissues. The knowledge of the cell ultrastructure, the macromolecule organization, the protein dynamics, the investigation of biological interaction forces, and the quantification of biomechanical features can be essential clues for identifying the molecular mechanisms that govern responses in living cells. This review highlights the main findings achieved by the use of AFM and SNOM in assisted reproductive research, such as the description of gamete morphology; the quantification of mechanical properties of gametes; the role of forces in embryo development; the significance of investigating single-molecule interaction forces; the characterization of disorders of the reproductive system; and the visualization of molecular organization. New perspectives of analysis opened up by applying these techniques and the translational impacts on reproductive medicine are discussed.

Spectroscopic assessment of oxidative damage in biomolecules and tissues

Oxidative damage is one of the main causes of cryopreservation injury compromising the use of cryopreserved biospecimens. The aim of this study was to evaluate the use of Fourier transform infrared spectroscopy (FTIR) as a non-invasive method to assess changes in biomolecular composition and structure, associated with oxidative stress in isolated biomolecules, acellular heart valve tissues, and ovarian cortex tissues. FTIR spectra of these specimens subjected to various treatments (H₂O₂- and Fenton-treatment or elevated temperatures) were vector normalized and selected spectral regions were analyzed by principal component analysis (PCA). Control and damaged biomolecules can easily be separated using PCA score plots. Acellular heart valve tissues that were subjected to different levels of oxidative damage formed separate cluster in PCA score plots. In hydrated ovarian tissue, large variation of the principal components was observed. Drying the ovarian tissues samples resulted in improved cluster separation of treatment groups. However, early signs of oxidative damage under mild stress conditions could not be detected by PCA of FTIR spectra. For the ovarian tissue samples, the standardly used nitro blue tetrazolium chloride (NBT) assay was used to monitor the amount of formazan production, reflecting reactive oxygen species (ROS) production at various temperatures. At 37 °C, formazan staining rapidly increased during the first 30 min, and then slowly reached a saturation level, but also at lower temperatures (i.e. 4 °C) formazan production was observed. In summary, we conclude that ATR-FTIR combined with PCA can be used to study oxidative damage in biomolecules as well as in tissues. In tissues, however, sample heterogeneity makes it difficult to detect early signs of oxidative damage.

Investigation of genomic DNA methylation by ultraviolet resonant Raman spectroscopy

Cytosine plays a preeminent role in DNA methylation, an epigenetic mechanism that regulates gene expression, the misregulation of which can lead to severe diseases. Several methods are nowadays employed for assessing the global DNA methylation levels, but none of them combines simplicity, high sensitivity, and low operating costs to be translated into clinical applications. Ultraviolet (UV) resonant Raman measurements at excitation wavelengths of 272 nm, 260 nm, 250 nm, and 228 nm have been carried out on isolated deoxynucleoside triphosphates (dNTPs), on a dNTP mixture as well as on genomic DNA (gDNA) samples, commercial from salmon sperm and non-commercial from B16 murine melanoma cell line. The 228 nm excitation wavelength was identified as the most suitable energy for enhancing cytosine signals over the other DNA bases. The UV Raman measurements performed at this excitation wavelength on hyper-methylated and hypo-methylated DNA from Jurkat leukemic T-cell line have revealed significant spectral differences with respect to gDNA isolated from salmon sperm and mouse melanoma B16 cells. This demonstrates how the proper choice of the excitation wavelength, combined with optimized extraction protocols, makes UV Raman spectroscopy a suitable technique for highlighting the chemical modifications undergone by cytosine nucleotides in gDNA upon hyper- and hypo-methylation events.

FTIR Spectroscopy to Reveal Lipid and Protein Changes Induced on Sperm by Capacitation: Bases for an Improvement of Sample Selection in ART

Although being a crucial step for Assisted Reproduction Technologies (ART) success, to date sperm selection is based only on morphology, motility and concentration characteristics. Considering the many possible alterations, there is a great need for analytical approaches allowing more effective sperm selections. The use of Fourier Transform Infrared (FTIR) may represent an interesting possibility, being able to reveal many macromolecular changes in a single measurement in a nondestructive way. As a proof of concept, in this observational study, we used a FTIR approach to reveal features related to sperm quality and chemical changes promoted by in vitro capacitation. We found indication that α-helix content is increased in capacitated sperm, while high percentages of the β-structures seem to correlate to poor-quality spermatozoa. The most interesting observation was related to the lipid composition, when measured as CH₂/CH₃ vibrations (ratio 2853/2870), which resulted in being strongly influenced by capacitation and well correlated with sperm motility. Interestingly, this ratio is higher than 1 in infertile samples, suggesting that motility is related to sperm membranes stiffness and lipid composition. Although further analyses are requested, our results support the concept that FTIR can be proposed as a new smart diagnostic tool for semen quality assessment in ART.

Synchrotron radiation soft X-ray microscopy and low energy X-ray fluorescence to reveal elemental changes in spermatozoa treated with photobiomodulation therapy

Male infertility is a worldwide clinical issue that increases the number of couples resorting to assisted reproductive technologies (ARTs) to achieve pregnancy. Photobiomodulation therapy (PBMT) is a promising technique that can biostimulate cells and tissues and it is currently successfully employed to enhance the sperm motility in vitro. Nevertheless, its use has been so far restricted to the research field. In the present work, we exploited two PBMT protocols at an 800 nm wavelength on sperm derived from infertile individuals, detecting an increase in sperm motility 1 hour after irradiation. Moreover, in order to add new information about the molecular effect of PBMT, the content of some light elements was evaluated using high resolution X-ray fluorescence imaging. Interestingly, an increase in Na content was detected in the irradiated samples, possibly suggesting a role of this element in sperm motility; indeed, a low Na content was previously correlated with a poor sperm quality, low semen volume, and modest fertilization rate. Amplifying the knowledge of PBMT in the ART field will expedite the translational potentiality of the PBMT use in clinical settings.

Spectral features of nuclear DNA in human sperm assessed by Raman Microspectroscopy: Effects of UV-irradiation and hydration

Raman Microspectroscopy represents an innovative tool for the assessment of sperm biochemical features otherwise undetectable by routine semen analysis. Previously, it was shown that induced DNA damage can be detected in smeared sperm by this technique. This novel readout may be of value for clinical settings especially if it can be transferred to living cells. Yet, starting with living sperms this study was carried-out using a variety of conditions to disclose the Raman features of sperm nuclei under different hydration conditions and UV exposure. Human sperm were immobilized and Raman spectra were obtained from individual sperm as repeated measurements. To create conditions with controlled DNA damage, sperm samples were exposed to ultraviolet light. Several media were used to evaluate their effect on Raman spectra in aqueous conditions. To substantiate differences between the experimental conditions, the spectra were analyzed by Principal Component Analysis. We observed that spectra of sperm nuclei obtained in different solutions showed a qualitatively unchanged spectral pattern showing the principal signals related to DNA. Evaluating the effect of ultraviolet light generated the finding that spectra representing DNA damage were only observed in dry conditions but not in aqueous medium. Thus, Raman microspectroscopy was successfully applied for sperm analysis in different conditions, among them in live spermatozoa in aqueous solution during the initial measurement, revealing the principle use of this technique. However, implementation of Raman spectroscopy as a technique for clinical sperm analysis and selection may be especially relevant when DNA evaluation can be established using live sperm.

Contribution of Ribonucleic Acid (RNA) to the Fourier Transform Infrared (FTIR) Spectrum of Eukaryotic Cells

We report on an optimized protocol for the digestion of cellular RNA, which minimally affects the cell membrane integrity, maintaining substantially unaltered the vibrational contributions of the other cellular macromolecules. The design of this protocol allowed us to collect the first Fourier transform infrared (FTIR) spectra of intact hydrated B16 mouse melanoma cells deprived of RNA and to highlight the in-cell diagnostic spectral features of it. Complementing the cellular results with the FTIR analysis of extracted RNA, ds-DNA, ss-cDNA and isolated nuclei, we verified that the spectral component centered at ∼1220 cm^-1 is a good qualitative and semiquantitative marker of cellular DNA, since it is minimally affected by cellular RNA removal. Conversely, the band centered at ∼1240 cm^-1, conventionally attributed to RNA, is only a qualitative marker of it, since its intensity is majorly influenced by other macromolecules containing diverse phosphate groups, such as phospholipids and phosphorylated proteins. On the other hand, we proved that the spectral contribution centered at ∼1120 cm^-1 is the most reliable indicator of variations in cellular RNA levels, that better correlates with cellular metabolic activity. The achievement of these results have been made possible also by the implementation of new methods for baseline correction and automated peak fitting, presented in this paper.