Silvia Caponi - Academia.edu (original) (raw)

Papers by Silvia Caponi

Light-Science & Applications, Oct 12, 2017

Innovative label-free microspectroscopy, which can simultaneously collect Brillouin and Raman sig... more Innovative label-free microspectroscopy, which can simultaneously collect Brillouin and Raman signals, is used to characterize the viscoelastic properties and chemical composition of living cells with sub-micrometric resolution. The unprecedented statistical accuracy of the data combined with the high-frequency resolution and the high contrast of the recently built experimental setup permits the study of single living cells immersed in their buffer solution by contactless measurements. The Brillouin signal is deconvoluted in the buffer and the cell components, thereby revealing the mechanical heterogeneity inside the cell. In particular, a 20% increase is observed in the elastic modulus passing from the plasmatic membrane to the nucleus as distinguished by comparison with the Raman spectroscopic marker. Brillouin line shape analysis is even more relevant for the comparison of cells under physiological and pathological conditions. Following oncogene expression, cells show an overall reduction in the elastic modulus (15%) and apparent viscosity (50%). In a proof-of-principle experiment, the ability of this spectroscopic technique to characterize subcellular compartments and distinguish cell status was successfully tested. The results strongly support the future application of this technique for fundamental issues in the biomedical field.

Biophysical Chemistry, Dec 1, 2013

Cellular imaging techniques have become powerful tools in cell biology. With respect to others, t... more Cellular imaging techniques have become powerful tools in cell biology. With respect to others, the techniques based on vibrational spectroscopy present a clear advantage: the molecular composition and the modification of subcellular compartments can be obtained in label-free conditions. In fact, from the evolution of positions, intensities and line widths of Raman and infrared bands in the cell spectra, characteristic information on cellular activities can be achieved, and particularly, cellular death can be investigated. In this work we present the time evolution of the Raman spectra of single live Jurkat cells (T-lymphocyte) by looking at the high frequency part of their Raman spectra, that is the CH stretching region, around 3000 cm −1. In particular, investigation into the composition or rearrangement of CH bounds, markers of cellular membrane fatty acids, can represent an important method to study and to recognize cell death. The experimental procedure we used, together with the analysis of these high frequency vibrational bands, may represent a new, improved and advantageous approach to this kind of study.

Nature Materials

The process in which locally confined epithelial malignancies progressively evolve into invasive ... more The process in which locally confined epithelial malignancies progressively evolve into invasive cancers is often promoted by unjamming, a phase transition from a solid-like to a liquid-like state, which occurs in various tissues. Whether this tissue-level mechanical transition impacts phenotypes during carcinoma progression remains unclear. Here we report that the large fluctuations in cell density that accompany unjamming result in repeated mechanical deformations of cells and nuclei. This triggers a cellular mechano-protective mechanism involving an increase in nuclear size and rigidity, heterochromatin redistribution and remodelling of the perinuclear actin architecture into actin rings. The chronic strains and stresses associated with unjamming together with the reduction of Lamin B1 levels eventually result in DNA damage and nuclear envelope ruptures, with the release of cytosolic DNA that activates a cGAS–STING (cyclic GMP-AMP synthase–signalling adaptor stimulator of interfe...

Nanomaterials

Mechanotransduction refers to the cellular ability to sense mechanical stimuli from the surroundi... more Mechanotransduction refers to the cellular ability to sense mechanical stimuli from the surrounding environment and convert them into biochemical signals that regulate cellular physiology and homeostasis. Mechanosensitive ion channels (MSCs), especially ones of Piezo family (Piezo1 and Piezo2), play a crucial role in mechanotransduction. These transmembrane proteins directly react to mechanical cues by triggering the onset of an ionic current. The relevance of this mechanism in driving physiology and pathology is emerging, and there is a growing need for the identification of an affordable and reliable assay to measure it. Setting up a mechanosensitivity assay requires exerting a mechanical stimulus on single cells while observing the downstream effects of channels opening. We propose an open-hardware approach to stimulate single adherent cells through controlled microindentation, using a 3D-printed actuation platform. We validated the device by measuring the mechanosensitivity of a...

ACS Photonics

We provide a new analytic expression and an innovative experimental method to isolate the effect ... more We provide a new analytic expression and an innovative experimental method to isolate the effect of multiple scattering (MS) in Brillouin investigation of highly turbid media. On the one hand, an analytic model is given to describe the spectrum in case of ill-defined exchanged wave-vector. On the other hand, a new experimental method, named Polarization Gated Brillouin Spectroscopy (PG-BS), is proposed for selecting the MS contribution through light polarization. Both experimental and analytic methods are tested against a benchmark material, milk, demonstrating their capability to extract reliable micromechanical parameters even in highly turbid materials till now inaccessible to in-depth Brillouin scattering investigation.

Smart Materials and Structures, 2018

Electret based smart materials have been attracting increasing attention for their versatility co... more Electret based smart materials have been attracting increasing attention for their versatility combined with easy fabrication. In particular, electret microparticles can be embedded in micro- and nano-electronic devices, enabling applications such as sensing, actuating, biological transducers and energy harvesting. In this work, silica micro-electrets are charged by electron injection in a SEM environment. The particle charge distribution is precisely controlled adjusting the energy of the primary beam. The surface potential, measured in the SEM chamber by the shift of the Duane–Hunt limit and by secondary electron spectroscopy reaches up to 200 V for 1 micron particles. The increase of the particle surface potential with the electron penetration depth is explained by a theoretical model, which also provides the value of about 0.1 C cm−3 for the charge concentration. The charge decay is studied in time monitoring the secondary electron emission by an in–lens SEM detector, showing that most of the charge injected deeper than 200 nm is retained in the particles for several months after the charging process. The capability to reach high values of surface potential stable over time on micrometric scale makes these materials as ideal candidates for applicative purposes and strategic elements in nanotechnology.

This folder contains all the raw datasets obtained by using Brillouin and Raman microscopy applie... more This folder contains all the raw datasets obtained by using Brillouin and Raman microscopy applied to bone imaging.

Nanotechnology Characterization Tools for Tissue Engineering and Medical Therapy, 2019

The possibility to fully heal damaged or failing tissues and organs is one of the major challenge... more The possibility to fully heal damaged or failing tissues and organs is one of the major challenges of modern medicine. Several approaches have been proposed, either using tissue engineered functional substitutes or inducing the body to self-repair, exploiting its innate regenerative potential. In any case, a crucial step for the success of therapy is provided by the design of a suitable scaffold, capable to sustain cellular growth and induce the differentiation towards the lineage of interest. A growing body of evidence suggests that the most affordable way to design an effective scaffold is to exploit a biomimetic approach, trying to emulate the characteristics of the natural environment. Moreover, it has been pointed out that not only the chemical nature of the material is relevant to this process but also its physical and, in particular, mechanical properties. Mapping the elasticity of a living tissue is becoming more and more relevant in the rational design of next generation biomimetic scaffolds, and the exploitation of advanced tools is required to achieve sub-μm resolution, comparable to the length scale probed by a single living cell.

Applied Nanoscience, 2020

Determining the thickness of a few-layer 2D material is a tough task that often involves complex ... more Determining the thickness of a few-layer 2D material is a tough task that often involves complex and time consuming measurements. Here we discuss a rapid method for determining the number of layers of molybdenum disulfide, MoS$$_2$$ 2 , flakes based on microscopic transmission imaging. By analyzing the contrast of the red, blue and green channels of the flake image against the background, we show that it is possible to unequivocally determine the number of layers. The presented method is based on the light absorption properties of MoS$$_2$$ 2 and its validity is confirmed by micro-Raman measurements. The main advantage of this method against traditional methods is to quickly determine the thickness of the material in the early stages of the experimental process with low cost apparatus.

European Biophysics Journal, 2022

European Biophysics Journal, 2021

In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biom... more In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biomedical research. It is now widely recognized that living cells respond not only to chemical stimuli (for example drugs), but they are also able to decipher mechanical cues, such as the rigidity of the underlying matrix or the presence of shear forces. Probing the viscoelastic properties of cells and their local microenvironment with sub-micrometer resolution is required to study this complex interplay and dig deeper into the mechanobiology of single cells. Current approaches to measure mechanical properties of adherent cells mainly rely on the exploitation of miniaturized indenters, to poke single cells while measuring the corresponding deformation. This method provides a neat implementation of the everyday approach to measure mechanical properties of a material, but it typically results in a very low throughput and invasive experimental protocol, poorly translatable towards three-dimens...

Catalysts, 2021

The recovery of the protein component and its transformation into protein hydrolysates, generally... more The recovery of the protein component and its transformation into protein hydrolysates, generally carried out chemically, gives great added value to waste biomasses. The production of protein hydrolysates through enzymatic catalysis would guarantee to lower the environmental impact of the process and raise product quality, due to the reproducible formation of low molecular weight peptides, with interesting and often unexplored biological activities. The immobilization of the enzymes represents a good choice in terms of stability, recyclability and reduction of costs. In this context, we covalently linked proteases from Aspergillus oryzae to polylactic acid an eco-friendly biopolymer. The hydrolytic efficiency of immobilized enzymes was assessed testing their stability to temperature and over time, and checking the hydrolysis of model biomasses (casein and bovine serum albumin). Soybean waste extracts were also used as proof of principle.

$Research paper thumbnail of Predicting the Refractive Index of Tissue Models Using Light Scattering Spectroscopy$

Applied Spectroscopy, 2021

In this work, we report the application of Raman microspectroscopy for analysis of the refractive... more In this work, we report the application of Raman microspectroscopy for analysis of the refractive index of a range of tissue phantoms. Using both a custom-developed setup with visible laser source and a commercial microspectrometer with near infrared laser, we measured the Raman spectra of gelatin hydrogels at various concentrations. By building a calibration curve from measured refractometry data and Raman scattering intensity for different vibrational modes of the hydrogel, we were able to predict the refractive indices of the gels from their Raman spectra. This work highlights the importance of a correlative approach through Brillouin–Raman microspectroscopy for the mechano–chemical analysis of biologically relevant samples.

Label-free Biomedical Imaging and Sensing (LBIS) 2020, 2020

Tissue morpho-mechanics is gaining an increasing relevance in various fields, including biology, ... more Tissue morpho-mechanics is gaining an increasing relevance in various fields, including biology, medicine, pathology, tissue engineering, and regenerative medicine, since it targets the relationship between morphological features and mechanical properties in biological tissues, which plays an important role in various biological processes including metastasis, wound healing and tissue regeneration. In particular, in every biological tissue, morphological, biochemical and mechanical properties are tightly connected and they influence each other in a correlative manner. For this reason, a correlative approach employing multiple techniques is ideal for targeting tissue morpho-mechanics with an optical approach. Here we report a correlative study performed by optical microscopies, disclosing the supramolecular collagen morphology correlated with its biomechanical and biochemical analyses. In particular, using human corneal tissue as a benchmark, we correlate Second-Harmonic Generation maps with mechanical and biochemical imaging obtained by Brillouin and Raman micro-spectroscopy, demonstrating that the peculiar mechanical functionality of so-called sutural lamellae originates from their distinctive supramolecular organization. A theoretical model based on the ultrastructural symmetry of corneal lamellar domains provides the interpretation of the experimental data at the molecular scale. The proposed methodology opens the way to the non-invasive assessment of tissue morpho-mechanics and holds the potential to be applicable to a broad range of biological and synthetic materials.

ACS Biomaterials Science & Engineering, 2021

This work is focused on the preparation and multi-technique characterization of potentially bioco... more This work is focused on the preparation and multi-technique characterization of potentially biocompatible reactive interfaces obtained by combining layered double hydroxides (LDHs) and hydroxyapatite (HA). Antimicrobial and osteoinductive metallic ions as Zn2+ and Ga3+ were chosen as intralayer constituents of LDH to obtain ZnAl and ZnAlGa systems. These LDHs, exchanged with dihydrogenphosphate anions, promoted the precipitation of HA on the LDH surface yielding HA@LDH composites. X-ray diffraction quantitative analysis, through the Rietveld refinement method, coupled with elemental analysis and micro-Raman spectroscopy showed the formation of a mixed Ca-Zn HA phase. Scanning electron microscopy revealed that HA, in the presence of LDH, grew preferentially along its a-axis, thus crystallizing mainly in the form of flake crystals. LDH and HA@LDH composites showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at not cytotoxic concentrations for human osteoblasts (hFob 1.19), especially when Ga cations were present in the LDH structure. The effect of the presence of HA in the composites on the bone-bonding ability and on human osteoblast proliferation was also investigated. The HA seemed to reduce the toxicity of the LDH toward human osteoblast while did not affect the bone-bonding ability. This multidisciplinary study provides the bio-chemical, structural characterization of new LDH and HA@LDH composites, evaluating also their bioactivity to be potentially applicable to titanium-based prostheses.

Tissue morpho-mechanics is gaining increasing in various fields, because it targets the relations... more Tissue morpho-mechanics is gaining increasing in various fields, because it targets the relationship between morphological features and mechanical properties in biological tissues, which plays an important role in various fields including biology, medicine, pathology, tissue engineering, and regenerative medicine. The intimate connection between morphological, biochemical and mechanical properties in biological tissues requires a multimodal correlative approach for their exhaustive investigation. In this study, we used Second-Harmonic Generation in combination with Brillouin and Raman micro-spectroscopy in order to correlate collagen morphology at the ultrastructural level with its biomechanical and biochemical features. In particular, by imaging human corneal tissue samples with our multimodal approach, we demonstrated that the peculiar mechanical properties of corneal lamellae in the anterior portion of the corneal stroma are due to a different supramolecular organization, rather ...