Wild-Type and SOD1-G93A SH-SY5Y under oxidative stress: EVs characterization and topographical distribution of budding vesicles

Extracellular vesicles (EVs) are important mediators of intercellular communication in several physiopathological conditions. Oxidative stress alters EVs release and cargo composition depending on the cell type and stimulus. Recently, most of the EVs studies have focused on the characterization of their cargo, rather than on the morphological features (i.e., size distribution, shape, and localization on the cell surface). Due to their high heterogeneity, to fully characterize EVs both the functional and morphological characterization are required. Atomic force microscopy (AFM), introduced for cell morphological studies at the nanoscale, represents a promising method to characterize in detail EVs morphology, dynamics along the cell surface, and its variations reflecting the cell physiological status. In the present study, untreated or H2O2-treated wild-type and SOD1-G93A SH-SY5Y cells have been compared performing a transmission electron microscopy (TEM) and AFM morpho-quantitative analysis of budding and released vesicles. Intriguingly, our analysis revealed a differential EVs profiling, with an opposite behavior and implying different cell areas between WT and SOD1-G93A cells, on both physiological conditions and after H2O2 exposure. Our results empower the relationship between the morphological features and functional role, further proving the efficacy of EM/AFM in giving an overview of the cell physiology related to EVs trafficking

Upscaling of Electrospinning Technology and the Application of Functionalized PVDF-HFP@TiO2 Electrospun Nanofibers for the Rapid Photocatalytic Deactivation of Bacteria on Advanced Face Masks

In recent years, Electrospinning (ES) has been revealed to be a straightforward and innovative approach to manufacture functionalized nanofiber-based membranes with high filtering performance against fine Particulate Matter (PM) and proper bioactive properties. These qualities are useful for tackling current issues from bacterial contamination on Personal Protective Equipment (PPE) surfaces to the reusability of both disposable single-use face masks and respirator filters. Despite the fact that the conventional ES process can be upscaled to promote a high-rate nanofiber production, the number of research works on the design of hybrid materials embedded in electrospun membranes for face mask application is still low and has mainly been carried out at the laboratory scale. In this work, a multi-needle ES was employed in a continuous processing for the manufacturing of both pristine Poly (Vinylidene Fluoride-co-Hexafluoropropylene) (PVDF-HFP) nanofibers and functionalized membrane ones embedded with TiO2 Nanoparticles (NPs) (PVDF-HFP@TiO2). The nanofibers were collected on Polyethylene Terephthalate (PET) nonwoven spunbond fabric and characterized by using Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Raman spectroscopy, and Atomic Force Microscopy (AFM) analysis. The photocatalytic study performed on the electrospun membranes proved that the PVDF-HFP@TiO2 nanofibers provide a significant antibacterial activity for both Staphylococcus aureus (~94%) and Pseudomonas aeruginosa (~85%), after only 5 min of exposure to a UV-A light source. In addition, the PVDF-HFP@TiO2 nanofibers exhibit high filtration efficiency against submicron particles (~99%) and a low pressure drop (~3 mbar), in accordance with the standard required for Filtering Face Piece masks (FFPs). Therefore, these results aim to provide a real perspective on producing electrospun polymer-based nanotextiles with self-sterilizing properties for the implementation of advanced face masks on a large scale

Advancing Raman Spectroscopy Resolution towards the Nanoscale: Fundamentals, Advantages, and Applications of Tip-Enhanced Raman Spectroscopy

Raman spectroscopy has long been a powerful analytical technique for studying molecular interactions and chemical properties of materials. However, its limited spatial resolution has posed a challenge in observing nanoscale phenomena. In response to this challenge, the field of Tip-Enhanced Raman Spectroscopy (TERS) has emerged as a revolutionary approach, pushing the boundaries of Raman spectroscopy resolution down to the nanoscale. This presentation delves into the fundamentals of TERS, highlighting its advantages over traditional Raman spectroscopy, and explores its diverse applications across various scientific disciplines (electronics, green transitions, biology, ....)

Strain characterization in SiGe epitaxial samples by Tip Enhanced Raman Spectroscopy

The progressive downsizing of semiconductors is driving information processing technology into a broader spectrum of new applications and capabilities. Strained silicon has become one of the best solutions for integrated circuits thanks to the advantages in terms of miniaturization. Indeed, a biaxial tensile stress applied to the silicon in the channel region of a MOSFET increases the mobility of carriers. This stress can be imposed by doping the silicon underneath with germanium, causing a mismatch between the lattice constant thus improving the electrons’ mobility [1]. Over the years, there has been an increasing need, especially in the industrial sector, to develop faster and non-destructive characterization techniques to monitor strain during the manufacturing phases of semiconductor devices. Currently, Tip-Enhanced Raman Spectroscopy (TERS) is one of most powerful methods for strain characterization, as it is a non-contact and non-destructive technique with a lateral resolution of a few nanometers and the capability of analyzing and collecting signals from the most superficial layer of a sample. The enhanced field is strongly restricted to the surface plasmons region, just a few nanometers deep [2], thanks to the simultaneous use of a nanometric tip of an Atomic Force Microscope (AFM) and a laser from a Raman spectrometer [3]. The analyzed sample was provided by CEA-Leti (Laboratoire d'électronique des technologies de l'information, Grenoble) and consists of a (001) silicon substrate where an epitaxial layer of Si0.7Ge0.3 with thickness of 17 nm is grown following several patterns. The AFM probe employed is characterized by an innovative coating which enables its implementation in the clean room for in-line characterization. TERS is used to map the variation in the position of the silicon peak in the local Raman spectrum (≈520.5 cm-1) along the sample pattern in order to identify the strain profile with a resolution of a few nanometers. The results confirm that TERS represents a powerful tool in monitoring the quality of production lines in the semiconductor industry and currently provides the best resolution among the Raman techniques for the strain characterization. References [1] P. Dobrosz et all, Surface and Coatings Technology, 2005, 200, 1755–1760. [2] F. Shao, R. Zenobi, Analytical and Bioanalytical Chemistry, 2019, 411, 37–61. [3] N.Hayazawa et al., Nanosensing Materials Devices, and Systems III, 2007, Proc. of SPIE Vol. 6769, 67690P

Electrospinning technology to upscale the production of low-cost and high-filtering functionalized polymer-based nanofibers providing photocatalytic activity for bacterial inactivation in advanced face mask

The importance to produce polymer-based membranes with suitable self-cleanable properties in preventing high risk of contamination on the fabric for long time usage has been becoming a relevant issues, especially in the last years when the pandemic outbreak of the Coronavirus disease (COVID-19) have brought to a mass consumption of personal protective equipment (PPE), such as face mask/respirators, which resulted in a potential source of further contamination from bacteria or virus. Modified electrospinning set-ups combined with modern textile techniques turned out to be an innovative way to manufacture nanofiber-based membrane showing high filtering performance against submicron pollution particles and suitable bioactive properties for tackling the current issues from bacterial contamination on PPE surfaces to the reusability of both disposable single use facemask and respirator’s filters [1]. With this paper we aim to provide further insight about the development of advanced electrospun nanofibrous photocatalytic membranes for large scale production. Investigation on the effects of processing variables on the fabrication of functionalized electrospun nanofibers embedded with active NPs for the scale-up line have been carried out by using Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Atomic Force Microscopy (AFM), and Raman spectroscopy analysis. In addition, photocatalytic disinfection for some bacteria strains, were conducted on the hybrid polymer-based membranes under UV-A light exposition by using the pristine electrospun membranes as control in the colony count method [2]. Finally, to provide a real perspective for the application of nanotextile in the manufacturing of advanced face mask on large-scale, both particle filtration and breathability test were also conducted on the nanofiber mats, in accordance with the standard required for Filtering Face Piece masks (FFP). [1] Cimini A., E. Imperi, A. Picano, M. Rossi. Electrospun nanofibers for medical face mask with protection capabilities against viruses: State of the art and perspective for industrial scale-up. Applied Materials Today, 2023, (32) 101833. [2] Q. Li, Y. Yin, D. Cao, Y. Wang, P. Luan, X. Sun, W. Liang, H. Zhu, Photocatalytic rejuvenation enabled self-sanitizing, reusable, and biodegradable masks against COVID-19, ACS Nano, 2021, 15 (7), 11992–12005