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1.
Acta Biomater ; 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31988041

RESUMO

The structure of teeth can be altered by diet, age or diseases such as caries and sclerosis. It is very important to characterize their mechanical properties to predict and understand tooth decay, design restorative dental procedures, and investigate their tribological behavior. However, existing imaging techniques are not well suited to investigating the micromechanics of teeth, in particular at tissue interfaces. Here, we describe a microscope based on Brillouin light scattering (BLS) developed to probe the spectrum of the light scattered from tooth tissues, from which the mechanical properties (sound velocity, viscosity) can be inferred with a priori knowledge of the refractive index. BLS is an inelastic process that uses the scattering of light by acoustic waves in the GHz range. Our microscope thus reveals the mechanical properties at the micrometer scale without contact with the sample. BLS signals show significant differences between sound tissues and pathological lesions, and can be used to precisely delineate carious dentin. We also show maps of the sagittal and transversal planes of sound tubular dentin that reveal its anisotropic microstructure at 1 µm resolution. Our observations indicate that the collagen-based matrix of dentine is the main load-bearing structure, which can be considered as a fiber-reinforced composite. In the vicinity of polymeric tooth-filling materials, we observed the infiltration of the adhesive complex into the opened tubules of sound dentine. The ability to probe the quality of this interfacial layer could lead to innovative designs of biomaterials used for dental restorations in contemporary adhesive dentistry, with possible direct repercussions on decision-making during clinical work. STATEMENT OF SIGNIFICANCE: Mechanical properties of teeth can be altered by diet, age or diseases. Yet existing imaging modalities cannot reveal the micromechanics of the tooth. Here we developed a new type of microscope that uses the scattering of a laser light by naturally-occurring acoustic waves to probe mechanical changes in tooth tissues at a sub-micrometer scale without contact to the sample. We observe significant mechanical differences between healthy tissues and pathological lesions. The contrast in mechanical properties also reveals the microstructure of the polymer-dentin interfaces. We believe that this new development of laser spectroscopy is very important because it should lead to innovative designs of biomaterials used for dental restoration, and allow delineating precisely destructed dentin for minimally-invasive strategies.

2.
J Biophotonics ; 12(12): e201900218, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31452335

RESUMO

Modern document protection relies on the simultaneous combination of many optical features with micron and submicron structures, whose complexity is the main obstacle for unauthorized copying. In that sense, documents are best protected by the diffractive optical elements generated lithographically and mass-produced by embossing. The problem is that the resulting security elements are identical, facilitating mass-production of both original and counterfeited documents. Here, we prove that each butterfly wing-scale is structurally and optically unique and can be used as an inimitable optical memory tag and applied for document security. Wing-scales, exhibiting angular variability of their color, were laser-cut and bleached to imprint cryptographic information of an authorized issuer. The resulting optical memory tag is extremely durable, as verified by several century-old insect specimens still retaining their coloration. The described technique is simple, amenable to mass-production, low cost and easy to integrate within the existing security infrastructure.

3.
J Synchrotron Radiat ; 26(Pt 3): 700-707, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31074433

RESUMO

The THz beamline at FLASH, DESY, provides both tunable (1-300 THz) narrow-bandwidth (∼10%) and broad-bandwidth intense (up to 150 uJ) THz pulses delivered in 1 MHz bursts and naturally synchronized with free-electron laser X-ray pulses. Combination of these pulses, along with the auxiliary NIR and VIS ultrashort lasers, supports a plethora of dynamic investigations in physics, material science and biology. The unique features of the FLASH THz pulses and the accelerator source, however, bring along a set of challenges in the diagnostics of their key parameters: pulse energy, spectral, temporal and spatial profiles. Here, these challenges are discussed and the pulse diagnostic tools developed at FLASH are presented. In particular, a radiometric power measurement is presented that enables the derivation of the average pulse energy within a pulse burst across the spectral range, jitter-corrected electro-optical sampling for the full spectro-temporal pulse characterization, spatial beam profiling along the beam transport line and at the sample, and a lamellar grating based Fourier transform infrared spectrometer for the on-line assessment of the average THz pulse spectra. Corresponding measurement results provide a comprehensive insight into the THz beamline capabilities.

4.
Mater Sci Eng C Mater Biol Appl ; 91: 597-605, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30033292

RESUMO

Lanthanide-doped fluoride up-converting nanoparticles (UCNPs) represent the new class of imaging contrast agents which hold great potential for overcoming existing problems associated with traditionally used dyes, proteins and quantum dots. In this study, a new kind of hybrid NaYF4:Yb,Er/PLGA nanoparticles for efficient biolabeling were prepared through one-pot solvothermal synthesis route. Morphological and structural characteristics of the as-designed particles were obtained using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (SEM/TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy, while their cytotoxicity as well as up-conversion (UC) labeling capability were tested in vitro toward human gingival cells (HGC) and oral squamous cell carcinoma (OSCC). The results revealed coexistence of the cubic (Fm-3m) and hexagonal (P63/m) phase in spherical and irregularly shaped nanoparticles, respectively. PLGA [Poly(lactic-co-glycolic acid)] ligands attached at the surface of UCNPs particles provide their enhanced cellular uptake and enable high-quality cells imaging through a near-infrared (NIR) laser scanning microscopy (λex = 980 nm). Moreover, the fact that NaYF4:Yb,Er/PLGA UCNPs show low cytotoxicity against HGC over the whole concentration range (10-50 µg/mL) while a dose dependent viability of OSCC is obtained indicates that these might be a promising candidates for targeted cancer cell therapy.


Assuntos
Diagnóstico por Imagem , Érbio/química , Ácido Láctico/química , Neoplasias Bucais/diagnóstico por imagem , Neoplasias de Células Escamosas/diagnóstico por imagem , Ácido Poliglicólico/química , Espectroscopia de Luz Próxima ao Infravermelho , Itérbio/química , Adulto , Morte Celular , Linhagem Celular Tumoral , Gengiva/patologia , Humanos , Neoplasias Bucais/patologia , Nanopartículas/química , Nanopartículas/ultraestrutura , Neoplasias de Células Escamosas/patologia , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Adulto Jovem
5.
Tumour Biol ; 39(7): 1010428317711654, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28718368

RESUMO

In recent years, it has been demonstrated that malignancy arises and advances through the molecular interplay between tumor cells and non-malignant elements of the tumor stroma, that is, fibroblasts and extracellular matrix. However, in contrast to the mounting evidence about the role of tumor stroma in the genesis and progression of the malignant disease, there are very few data regarding the uninvolved stromal tissue in the remote surrounding of the tumor. Using the objective morphometric approach in patients with adenocarcinoma, we demonstrate the remodeling of extracellular matrix of the lamina propria in the uninvolved rectal mucosa 10 and 20 cm away from the neoplasm. We show that the representation of basic extracellular matrix constituents (reticular and collagen fibers and ground substance) is decreased. Also, the diameter of empty spaces that appear within the extracellular matrix of the lamina propria is increased. These spaces do not represent the blood or lymphatic vessel elements. Very likely, they reflect the development of tissue edema in the remote, uninvolved lamina propria of the mucosa in patients with the malignant tumor of the rectum. We hypothesize that the remodeling of extracellular matrix in lamina propria of the rectal mucosa may increase its stiffness, modulating the mechano-signal transduction, and thus promote the progression of the malignant disease.


Assuntos
Adenocarcinoma/patologia , Matriz Extracelular/patologia , Membrana Mucosa/patologia , Neoplasias Retais/patologia , Idoso , Vasos Sanguíneos/patologia , Carcinogênese/patologia , Progressão da Doença , Feminino , Humanos , Mucosa Intestinal , Masculino
6.
J Biomed Opt ; 22(2): 26003, 2017 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-28301654

RESUMO

The present study describes utilization of two photon excitation fluorescence (2PE) microscopy for visualization of the hemoglobin in human and porcine erythrocytes and their empty membranes (i.e., ghosts). High-quality, label- and fixation-free visualization of hemoglobin was achieved at excitation wavelength 730 nm by detecting visible autofluorescence. Localization in the suspension and spatial distribution (i.e., mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by 2PE. Prior to the 2PE mapping, the presence of residual hemoglobin in the bulk suspension of erythrocyte ghosts was confirmed by cyanmethemoglobin assay. 2PE analysis revealed that the distribution of hemoglobin in intact erythrocytes follows the cells' shape. Two types of erythrocytes, human and porcine, characterized with discocyte and echinocyte morphology, respectively, showed significant differences in hemoglobin distribution. The 2PE images have revealed that despite an extensive washing out procedure after gradual hypotonic hemolysis, a certain amount of hemoglobin localized on the intracellular side always remains bound to the membrane and cannot be eliminated. The obtained results open the possibility to use 2PE microscopy to examine hemoglobin distribution in erythrocytes and estimate the purity level of erythrocyte ghosts in biotechnological processes.


Assuntos
Eritrócitos/química , Eritrócitos/citologia , Hemoglobinas/análise , Microscopia de Fluorescência , Animais , Membrana Eritrocítica/química , Hemoglobinas/metabolismo , Humanos , Suínos
7.
J Biomed Opt ; 20(1): 016010, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25574994

RESUMO

We performed a study of the nonlinear optical properties of chemically purified chitin and insect cuticle using two-photon excited autofluorescence (TPEF) and second-harmonic generation (SHG) microscopy. Excitation spectrum, fluorescence time, polarization sensitivity, and bleaching speed were measured. We have found that the maximum autofluorescence signal requires an excitation wavelength below 850 nm. At longer wavelengths, we were able to penetrate more than 150-um deep into the sample through the chitinous structures. The excitation power was kept below 10 mW (at the sample) in order to diminish bleaching. The SHG from the purified chitin was confirmed by spectral- and time-resolved measurements. Two cave-dwelling, depigmented, insect species were analyzed and three-dimensional images of the cuticular structures were obtained.


Assuntos
Quitina/química , Besouros/química , Microscopia de Fluorescência por Excitação Multifotônica/instrumentação , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Animais , Artrópodes/química , Cavernas , Desenho de Equipamento , Imagem Tridimensional/métodos , Dinâmica não Linear
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