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1.
Biomater Adv ; 147: 213341, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36827851

ABSTRACT

Specifically designed samples have been analyzed to test the ability of Brillouin spectroscopy to provide reliable mechanical characterization of micro and nano-objects. The selected samples are polymeric films, whose transversal sizes from hundreds of nano- to some micro-meters cover the entire range of length-scales relevant in Brillouin scattering process. The experimental data highlight how, the size of the extended collective oscillation (acoustic phonons, in brief) is the lowest spatial resolution reachable in Brillouin mechanical characterization. Conversely, in the limit condition of phonon confinement, the technique provides the mechanical properties of nano-objects whose characteristic size is comparable with the phonon wavelength (⁓300 nm). Investigating acoustically heterogeneous materials, both size of heterogeneity and acoustic mismatch between adjacent regions are shown to be relevant in shaping the Brillouin response. In particular, a transition from a confined to a non-confined condition is obtained modulating the acoustic mismatch between the micro-objects and their local environment. The provided results and the derived analytic models for the data analysis will guide the interpretation of Brillouin spectra acquired in complex nano-structured samples such as cells, tissues or biomimetic materials. Our analysis can therefore generate new insights to tackle fundamental problems in mechanobiology or to characterize new bioengineered materials.


Subject(s)
Diagnostic Imaging , Phonons , Spectrum Analysis , Polymers
2.
J R Soc Interface ; 19(187): 20210642, 2022 02.
Article in English | MEDLINE | ID: mdl-35104431

ABSTRACT

Bone has a sophisticated architecture characterized by a hierarchical organization, starting at the sub-micrometre level. Thus, the analysis of the mechanical and structural properties of bone at this scale is essential to understand the relationship between its physiology, physical properties and chemical composition. Here, we unveil the potential of Brillouin-Raman microspectroscopy (BRaMS), an emerging correlative optical approach that can simultaneously assess bone mechanics and chemistry with micrometric resolution. Correlative hyperspectral imaging, performed on a human diaphyseal ring, reveals a complex microarchitecture that is reflected in extremely rich and informative spectra. An innovative method for mechanical properties analysis is proposed, mapping the intermixing of soft and hard tissue areas and revealing the coexistence of regions involved in remodelling processes, nutrient transportation and structural support. The mineralized regions appear elastically inhomogeneous, resembling the pattern of the osteons' lamellae, while Raman and energy-dispersive X-ray images through scanning electron microscopy show an overall uniform distribution of the mineral content, suggesting that other structural factors are responsible for lamellar micromechanical heterogeneity. These results, besides giving an important insight into cortical bone tissue properties, highlight the potential of BRaMS to access the origin of anisotropic mechanical properties, which are almost ubiquitous in other biological tissues.


Subject(s)
Bone and Bones , Haversian System , Anisotropy , Bone and Bones/diagnostic imaging , Cortical Bone , Haversian System/physiology , Humans , Microscopy, Electron, Scanning , Spectrum Analysis, Raman/methods
3.
Sci Rep ; 10(1): 17341, 2020 10 15.
Article in English | MEDLINE | ID: mdl-33060731

ABSTRACT

Brillouin-Raman microspectroscopy is presented as an innovative label-free all-optical investigation approachable to characterize the chemical composition and the mechanical properties of human tissues at micrometric resolution. Brillouin maps unveil mechanical heterogeneities in a human femoral diaphysis, showing a ubiquitous co-existence of hard and soft components, even in the most compact sections. The novel correlative analysis of Brillouin and Raman maps shows that the relative intensity of Brillouin peaks is a good proxy for the fraction of mineralized fibers and that the stiffness (longitudinal elastic modulus) of the hard component is linearly dependent on the hydroxyapatite concentration. For the soft component, a gradient of composition is found, ranging from an abundance of proteins in the more compact, external, bone to abundance of lipids, carotenoids, and heme groups approaching the trabecular, inner, part of the diaphysis. This work unveils the strong potential of correlative mechano-chemical characterization of human tissues at a micrometric resolution for both fundamental and translational research.


Subject(s)
Diaphyses/chemistry , Femur/chemistry , Spectrum Analysis, Raman/methods , Biomechanical Phenomena , Elastic Modulus , Humans , Translational Research, Biomedical
4.
Opt Lett ; 45(5): 1063-1066, 2020 Mar 01.
Article in English | MEDLINE | ID: mdl-32108770

ABSTRACT

Brillouin imaging is an emerging optical elastography technique that is able to generate maps of the mechanical properties at microscale with great potential in biophysical and biomedical fields. A key parameter is its spatial resolution, which is usually identified with that of the confocal microscope coupled to the Brillouin interferometer. Conversely, here we demonstrate that the mean free path of acoustic phonons plays a major role in defining the resolution, especially for high numerical aperture confocal setups. Surprisingly, the resolution of elastography maps may even deteriorate when decreasing the scattering volume.

5.
Biophys Chem ; 229: 123-129, 2017 10.
Article in English | MEDLINE | ID: mdl-28684254

ABSTRACT

Mechanical mapping with chemical specificity of biological samples is now made possible by joint micro-Brillouin and micro-Raman measurements. In this work, thanks to the unprecedented contrast of a new tandem Fabry-Perot interferometer, we demonstrate simultaneous detection of Brillouin and Raman spectra from different Candida biofilms. Our proof-of-concept study reveals the potential of this label-free joint micro-spectroscopy technique in challenging microbiological issues. In particular, heterogeneous chemo-mechanical maps of Candida biofilms are obtained, without the need for staining or touching the sample. The correlative Raman and Brillouin investigation evidences the role of both extracellular polymeric substances and of hydration water in inducing a marked local softening of the biofilm.


Subject(s)
Biofilms , Candida/chemistry , Microbiological Techniques/methods , Microspectrophotometry , Spectrum Analysis, Raman , Candida/physiology , Elastic Modulus , Microbiological Techniques/instrumentation , Viscosity
6.
Biophys Chem ; 208: 34-9, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26282883

ABSTRACT

In the present study, FTIR spectroscopy was used to monitor the freeze-thaw cycle of two cellular lines (HuDe and Jurkat) suspended in three different media: phosphate buffer solution (PBS); dimethylsulfoxide (DMSO)/PBS solution at 0.1 DMSO molar fraction; and CryoSure (0.1 DMSO molar fraction PBS solution+dextran 5% w/v) solution. The Trypan Blue test was also applied before freezing and after thawing each cell sample to estimate the recovery of membrane integrity after thermal treatment, and correlate this datum with spectroscopic results. By following the temperature evolution of two different spectral components (the libration and bending combination mode νc(H2O) at 2000-2500 cm(-1), and the methylene symmetric stretching vibration νsym(CH2) at about 2850 cm(-1)) in the -120÷28°C range, we evidenced the main transition of lipid membrane in connection with cell dehydration, as induced by ice formation in the extracellular medium. In particular, in DMSO/PBS and CryoSure samples we observed a transition to a more rigid state of the lipid membrane together with an increased amount of non-freezable water in the extracellular medium; these results are connected to the role of DMSO as a cryoprotective agent irrespective of the nature of cell type.


Subject(s)
Cell Membrane/chemistry , Cryopreservation , Cryoprotective Agents/chemistry , Fibroblasts/cytology , Freezing , Membrane Lipids/chemistry , Buffers , Cell Line , Dextrans/chemistry , Dimethyl Sulfoxide/chemistry , Humans , Jurkat Cells , Phosphates/chemistry , Spectroscopy, Fourier Transform Infrared , Temperature
7.
Biophys Chem ; 208: 48-53, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26256426

ABSTRACT

In this paper we test the ability of Raman micro-spectroscopy and Raman mapping to investigate the status of cells grown in adhesion on different substrates. The spectra of immortalized SH-SY5Y cells, grown on silicon and on metallic substrates are compared with those obtained for the same type of cells adhering on organic polyaniline (PANI), a memristive substrate chosen to achieve a living bio-hybrid system. Raman spectra give information on the status of the single cell, its local biochemical composition, and on the modifications induced by the substrate interaction. The good agreement between Raman spectra collected from cells adhering on different substrates confirms that the PANI, besides allowing the cell growth, doesn't strongly affect the general biochemical properties of the cell. The investigation of the cellular state in a label free condition is challenging and the obtained results confirm the Raman ability to achieve this information.


Subject(s)
Aniline Compounds/chemistry , Silicon/chemistry , Cell Adhesion , Cell Proliferation , Cell Survival , Humans , Spectrum Analysis, Raman , Tumor Cells, Cultured
8.
J Chem Phys ; 141(21): 214901, 2014 Dec 07.
Article in English | MEDLINE | ID: mdl-25481163

ABSTRACT

Brillouin light scattering measurements have been used to study the stress induced modification in the elastic properties of two glass forming polymers: polybutadiene and epoxy-amine resin, prototypes of linear and network polymers, respectively. Following the usual thermodynamic path to the glass transition, polybutadiene has been studied as a function of temperature from the liquid well into the glassy phase. In the epoxy resin, the experiments took advantage of the system ability to reach the glass both via the chemical vitrification route, i.e., by increasing the number of covalent bonds among the constituent molecules, as well as via the physical thermal route, i.e., by decreasing the temperature. Independently from the particular way chosen to reach the glassy phase, the measurements reveal the signature of long range tensile stresses development in the glass. The stress presence modifies both the value of the sound velocities and their mutual relationship, so as to break the generalized Cauchy-like relation. In particular, when long range stresses, by improvise sample cracking, are released, the frequency of longitudinal acoustic modes increases more than 10% in polybutadiene and ∼4% in the epoxy resin. The data analysis suggests the presence of at least two different mechanisms acting on different length scales which strongly affect the overall elastic behaviour of the systems: (i) the development of tensile stress acting as a negative pressure and (ii) the development of anisotropy which increases its importance deeper and deeper in the glassy state.

10.
J Phys Chem B ; 117(13): 3613-23, 2013 Apr 04.
Article in English | MEDLINE | ID: mdl-23343421

ABSTRACT

An aqueous self-assembled micellar system (sodium dodecyl sulfate, SDS, decorated with various adhesive sites, cryptand Kryptofix 222 and crown ether 18-Crown-6 molecules) has been investigated by dynamic light scattering (DLS) and small angle x-ray scattering (SAXS) to have insights into the micellar structure, the micellar interactions, and the aggregation properties of the system. DLS demonstrates the existence of populations of aggregates in the submicrometer/micrometer range, while the Guinier analysis of the SAXS curves helps in detailing objects smaller than 30 nm. The aggregates of micelles are here named cluster phases of micelles (CPMs). Considering that SDS micelles in water do not aggregate at low concentration, it is shown that macrocyclic ligands induce the SDS micelle aggregation as a function of the concentration (i.e., investigated ligand/SDS molar ratios are 5.0, 1.5, 1.0, and 0.5) and hydrophobicity of the adhesive sites. The sizes and the percentages of the micelles and the CPMs have been monitored to test the stability and reversibility of the system. DLS results clearly show that the aggregation processes of the decorated micelles are reproducible at time intervals of the order of 1 month, while the stability may not be entirely maintained after a year. As an issue of particular relevance, the higher the ligand/surfactant molar ratio, the larger are the CPMs induced. The K222 ligand results in being more effective in promoting the micellar aggregation than 18C6 as a consequence of the different hydrophobicity.


Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/chemistry , Crown Ethers/chemistry , Macrocyclic Compounds/chemistry , Sodium Dodecyl Sulfate/chemistry , Ligands , Micelles , Solutions
11.
Eur J Surg Oncol ; 39(4): 396-403, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23290583

ABSTRACT

AIMS: The incidence of intraductal papillary mucinous neoplasm (IPMN) is rising and these neoplasms now represent up to 25% of resected pancreatic neoplasms. The optimal postoperative management of resected invasive IPMN is still debated in the absence of large prospective clinical trials and of validated prognostic factors in this setting. The objective of our study was to identify potential prognostic factors and to investigate the role of adjuvant therapies for patients radically resected for invasive IPMN. METHODS: We retrospectively reviewed clinical and pathological data regarding a large series of patients with invasive IPMN who underwent surgical resection in the last six years at University Hospital of Pisa. RESULTS: Sixty-four patients were considered for the analysis, thirty-three of whom received adjuvant chemotherapy with gemcitabine. In our series node involvement and high tumoral grade emerged as the major pathologic prognostic factors. Patients treated with adjuvant chemotherapy with gemcitabine experienced a longer disease-free survival than those who received surgery alone. CONCLUSIONS: Gemcitabine-based chemotherapy seems beneficial as adjuvant treatment for patients with resected invasive IPMN.


Subject(s)
Adenocarcinoma, Mucinous/drug therapy , Antimetabolites, Antineoplastic/therapeutic use , Carcinoma, Pancreatic Ductal/drug therapy , Carcinoma, Papillary/drug therapy , Deoxycytidine/analogs & derivatives , Pancreatic Neoplasms/drug therapy , Adenocarcinoma, Mucinous/pathology , Adenocarcinoma, Mucinous/surgery , Adult , Aged , Aged, 80 and over , Carcinoma, Pancreatic Ductal/pathology , Carcinoma, Pancreatic Ductal/surgery , Carcinoma, Papillary/pathology , Carcinoma, Papillary/surgery , Chemotherapy, Adjuvant , Deoxycytidine/therapeutic use , Disease-Free Survival , Female , Humans , Italy , Male , Middle Aged , Multivariate Analysis , Neoplasm Invasiveness , Pancreatic Neoplasms/pathology , Pancreatic Neoplasms/surgery , Prognosis , Retrospective Studies , Survival Analysis , Gemcitabine
12.
Ann Oncol ; 24(3): 734-41, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23139258

ABSTRACT

BACKGROUND: This multicenter study evaluated three candidate microRNAs (miRNAs) (miR-21, miR-155 and miR-101) as potential biomarkers in intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. PATIENTS AND METHODS: miRNA expression was quantified by quantitative RT-PCR in 86 laser-microdissected specimens, including 65 invasive IPMNs, 16 non-invasive IPMNs and 5 normal pancreatic ductal tissues. Univariate and multivariate analyses compared miRNAs and clinical parameters with overall (OS) and disease-free survival (DFS). RESULTS: miR-21 and miR-155 were up-regulated in invasive IPMNs compared with non-invasive IPMNs, as well as in non-invasive IPMNs compared with normal tissues. Conversely, miR-101 levels were significantly higher in non-invasive IPMNs and normal tissues compared with invasive IPMNs. High levels of miR-21 were associated with worse OS [hazard ratio (HR) = 2.47, 95% confidence interval (CI) = 1.37-5.65, P = 0.0047]. Patients with high-miR-21 expression also had a shorter median DFS (10.9 versus 29.9 months, P = 0.01). Multivariate analysis confirmed miR-21 as independently prognostic for mortality and disease progression (death risk: HR = 3.3, 95% CI = 1.5-7.0, P = 0.02; progression risk: HR = 2.3, 95% CI = 1.2-4.8, P = 0.02), as well as positive lymph-node status (death risk: HR = 2.6, 95% CI = 1.1-6.3, P = 0.03; progression risk: HR = 2.2, 95% CI = 1.0-4.8, P = 0.04). CONCLUSIONS: miR-21, miR-155 and miR-101 showed significant differences in invasive versus non-invasive IPMNs. miR-21 emerged as an independent prognostic biomarker in invasive IPMNs and should be validated in prospective studies.


Subject(s)
Adenocarcinoma, Mucinous/metabolism , Adenocarcinoma, Papillary/metabolism , Carcinoma, Pancreatic Ductal/metabolism , MicroRNAs/metabolism , Pancreatic Neoplasms/metabolism , Adenocarcinoma, Mucinous/mortality , Adenocarcinoma, Mucinous/secondary , Adenocarcinoma, Papillary/mortality , Adenocarcinoma, Papillary/secondary , Adult , Aged , Aged, 80 and over , Carcinoma, Pancreatic Ductal/mortality , Carcinoma, Pancreatic Ductal/secondary , Disease-Free Survival , Female , Humans , Kaplan-Meier Estimate , Lymphatic Metastasis , Male , MicroRNAs/genetics , Middle Aged , Multivariate Analysis , Neoplasm Invasiveness , Pancreatic Neoplasms/mortality , Pancreatic Neoplasms/pathology , Proportional Hazards Models
13.
J Chem Phys ; 135(17): 174506, 2011 Nov 07.
Article in English | MEDLINE | ID: mdl-22070305

ABSTRACT

We report on the observation of a significant softening of the Boson peak (BP) frequency of vitreous GeO(2) above the glass transition temperature. The softening reminds a critical trend, with a transition temperature intermediate between the glass transition temperature, T(g), and the melting point. The softening of the BP frequency corresponds to a transition from a region dominated by Debye scaling to a non-Debye one. Below T(g) the density of vibrational states varies according to the modification of the elastic continuum medium. Above T(g) the relevant softening of the BP modes can be explained by a broadening of the distribution of elastic constants between neighboring atoms, induced by the structural rearrangement. These findings are discussed together with recent experimental and theoretical results on the low frequency vibrations in glasses.

15.
Phys Rev Lett ; 102(2): 027402, 2009 Jan 16.
Article in English | MEDLINE | ID: mdl-19257317

ABSTRACT

Raman-scattering measurements are used to follow the modification of the vibrational density of states in a reactive epoxy-amine mixture during isothermal polymerization. Combining them with Brillouin light and inelastic x-ray scattering measurements, we analyze the variations of the boson peak and of the Debye level while the system changes from liquid to glass upon increasing the number of covalent bonds among the constituent molecules. The shift and intensity variation of the boson peak are explained by the modification of the elastic properties throughout the reaction, and a master curve for the boson peak can therefore be obtained. Surprisingly, bond-induced modifications of the structure do not affect this master curve.

16.
Phys Rev Lett ; 97(3): 035501, 2006 Jul 21.
Article in English | MEDLINE | ID: mdl-16907508

ABSTRACT

We report measurements of the sound attenuation coefficient in vitreous silica, for sound waves of wavelength between 50 and 80 nm, performed with the new inelastic UV light scattering technique. These data indicate that in silica glass a crossover between a temperature-dependent (at low frequency) and a temperature-independent (at high frequency) acoustic attenuation mechanism occurs at Q approximately equal to 0.15 nm(-1). The absence of any signature in the static structure factor at this Q value suggests that the observed crossover should be associated with local elastic constant fluctuations.

17.
Parassitologia ; 47(3-4): 259-64, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16866030

ABSTRACT

The publication of Boudin's Traité de Geographie et de Statistique médicale (1857) and the creation in 1908 of the Institut de Pathologie Exotique by Laveran, correspond to two entirely different manners of considering tropical diseases and adaptability (or acclimatation) to the Tropics, directly associated with the idea of capability or incapability of Europeans to resist tropical diseases. We analyse the way perspectives have changed with respect to the influence that climate, particularly tropical, exert on the body of individuals and on populations used to live under temperate climatic conditions. The manner the concepts of medical geography, climatic pessimism and individual acclimatation get articulated with the discovery of tropical diseases, their aetiological agents and their localisation, particularly malaria, can only be understood by also analysing how the problems generated by the diversity of races and migration phenomena have been envisaged.


Subject(s)
Geography/history , Malaria/history , Tropical Climate/adverse effects , Tropical Medicine/history , Adaptation, Physiological , Animals , Anopheles/parasitology , Colonialism/history , History, 19th Century , History, 20th Century , Humans , Insect Vectors/parasitology , Malaria/transmission , Plasmodium/isolation & purification , Plasmodium/physiology , Racial Groups
18.
Article in English | MEDLINE | ID: mdl-11138109

ABSTRACT

The Brillouin light scattering spectra of the o-terphenyl single crystal are compared with those of the liquid and the glass phases. This shows (i) the direct evidence of a fast relaxation at frequencies nu approximately 5 GHz in both the single crystal and the glass; (ii) a similar temperature dependence for the attenuation of the longitudinal sound waves in the single crystal and the glass; and (iii) the absence of coupling between the fast relaxation and the transverse acoustic waves. These results allow us to assign such a relaxation to the coupling between the longitudinal acoustic waves and intramolecular vibrations, and therefore to exclude any relationship between it and the glass transition.

19.
Hist Cienc Saude Manguinhos ; 7(2): 250-82, 2000.
Article in Portuguese | MEDLINE | ID: mdl-16680885

ABSTRACT

The strategies against yellow fever developed by Argentina and Brazil were discussed at the Second Medical Congress of Latin America which was held in Buenos Aires in 1904. The study of the controversy between physicians from Argentina and Brazil around the existing explanatory models of this illness and the international prophylactic strategies in use at the time enables an epistemological understanding of the breakthrough brought about by the emergence of medicine of vectors. This chapter of Latin American medicine history constitutes a unique opportunity to analyze that reorganization of knowledge, which permitted the inclusion of intermediary living beings into the medical and epidemiological discourse.


Subject(s)
Congresses as Topic , Disease Vectors , Yellow Fever , Animals , Argentina , Brazil , Congresses as Topic/history , Culicidae , History, 20th Century , Research/history , Yellow Fever/etiology , Yellow Fever/history , Yellow Fever/prevention & control
20.
Hist Cienc Saude Manguinhos ; 6(1): 7-28, 1999.
Article in Spanish | MEDLINE | ID: mdl-11625537

ABSTRACT

The paper explores how Hannah Arendt's oppositions public-private and intimate-social can be used as an analytical tool to better understand a very concrete, extreme situation: the state of emergency triggered when an epidemiological outbreak hits a city, totally altering its inhabitants lives. Studied observation of what specific individuals (be they imagined or real) feel and think during times of epidemic is an underutilized tool that may prove helpful in studying epidemics themselves. Focusing on Camus' "The pest" and events in the city of Oran, the article looks at how victims of the plague felt about their public or private lives and their intimate and social ties.


Subject(s)
Disease Outbreaks/history , Literature/history , Philosophy/history , Plague/history , Algeria , France , History, 20th Century , Humans , Public Health/history , Public Opinion
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