Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 15.344
Filtrar
1.
Anal Chem ; 93(9): 4154-4159, 2021 03 09.
Artículo en Inglés | MEDLINE | ID: mdl-33645217

RESUMEN

Chip-scale SARS-CoV-2 testing was demonstrated using silicon nitride (Si3N4) nanoslot fluidic waveguides to detect a tagged oligonucleotide with a coronavirus DNA sequence. The slot waveguides were fabricated using complementary metal-oxide-semiconductor (CMOS) fabrication processes, including multiscale lithography and selective reactive ion etching (RIE), forming femtoliter fluidic channels. Finite difference method (FDM) simulation was used to calculate the optical field distribution of the waveguide mode when the waveguide sensor was excited by transverse electric (TE) and transverse magnetic (TM) polarized light. For the TE polarization, a strong optical field was created in the slot region and its field intensity was 14× stronger than the evanescent sensing field from the TM polarization. The nanoscale confinement of the optical sensing field significantly enhanced the light-analyte interaction and improved the optical sensitivity. The sensitivity enhancement was experimentally demonstrated by measuring the polarization-dependent fluorescence emission from the tagged oligonucleotide. The photonic chips consisting of femtoliter Si3N4 waveguides provide a low-cost and high throughput platform for real-time virus identification, which is critical for point-of-care (PoC) diagnostic applications.


Asunto(s)
/métodos , /virología , ADN Viral/análisis , Nanopartículas/química , /aislamiento & purificación , Compuestos de Silicona/química , Humanos , Óptica y Fotónica , Sistemas de Atención de Punto , Refractometría , Semiconductores , Sensibilidad y Especificidad
2.
Nat Commun ; 12(1): 1744, 2021 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-33741998

RESUMEN

Interferometric scattering microscopy is increasingly employed in biomedical research owing to its extraordinary capability of detecting nano-objects individually through their intrinsic elastic scattering. To significantly improve the signal-to-noise ratio without increasing illumination intensity, we developed photonic resonator interferometric scattering microscopy (PRISM) in which a dielectric photonic crystal (PC) resonator is utilized as the sample substrate. The scattered light is amplified by the PC through resonant near-field enhancement, which then interferes with the <1% transmitted light to create a large intensity contrast. Importantly, the scattered photons assume the wavevectors delineated by PC's photonic band structure, resulting in the ability to utilize a non-immersion objective without significant loss at illumination density as low as 25 W cm-2. An analytical model of the scattering process is discussed, followed by demonstration of virus and protein detection. The results showcase the promise of nanophotonic surfaces in the development of resonance-enhanced interferometric microscopies.


Asunto(s)
Microscopía de Interferencia/instrumentación , Microscopía de Interferencia/métodos , Óptica y Fotónica/instrumentación , Óptica y Fotónica/métodos , Cristalización , Diseño de Equipo , Oro , Procesamiento de Imagen Asistido por Computador , Nanopartículas del Metal , Nanoestructuras , Fotones , Proteínas/aislamiento & purificación , Virión/aislamiento & purificación , Virus/aislamiento & purificación
3.
Molecules ; 26(4)2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33670175

RESUMEN

A range of solution-processed organic and hybrid organic-inorganic solar cells, such as dye-sensitized and bulk heterojunction organic solar cells have been intensely developed recently. TiO2 is widely employed as electron transporting material in nanostructured TiO2 perovskite-sensitized solar cells and semiconductor in dye-sensitized solar cells. Understanding the optical and electronic mechanisms that govern charge separation, transport and recombination in these devices will enhance their current conversion efficiencies under illumination to sunlight. In this work, density functional theory with Perdew-Burke Ernzerhof (PBE) functional approach was used to explore the optical and electronic properties of three modeled TiO2 brookite clusters, (TiO2)n=5,8,68. The simulated optical absorption spectra for (TiO2)5 and (TiO2)8 clusters show excitation around 200-400 nm, with (TiO2)8 cluster showing higher absorbance than the corresponding (TiO2)5 cluster. The density of states and the projected density of states of the clusters were computed using Grid-base Projector Augmented Wave (GPAW) and PBE exchange correlation functional in a bid to further understand their electronic structure. The density of states spectra reveal surface valence and conduction bands separated by a band gap of 1.10, 2.31, and 1.37 eV for (TiO2)5, (TiO2)8, and (TiO2)68 clusters, respectively. Adsorption of croconate dyes onto the cluster shifted the absorption peaks to higher wavelengths.


Asunto(s)
Teoría Funcional de la Densidad , Nanoestructuras/química , Energía Solar , Titanio/química , Adsorción , Compuestos de Calcio/química , Suministros de Energía Eléctrica , Electrónica , Electrones , Óptica y Fotónica/tendencias , Óxidos/química , Luz Solar
5.
J Vis Exp ; (167)2021 01 28.
Artículo en Inglés | MEDLINE | ID: mdl-33586701

RESUMEN

Myofibroblasts can spontaneously internalize silicon nanowires (SiNWs), making them an attractive target for bioelectronic applications. These cell-silicon hybrids offer leadless optical modulation capabilities with minimal perturbation to normal cell behavior. The optical capabilities are obtained by the photothermal and photoelectric properties of SiNWs. These hybrids can be harvested using standard tissue culture techniques and then applied to different biological scenarios. We demonstrate here how these hybrids can be used to study the electrical coupling of cardiac cells and compare how myofibroblasts couple to one another or to cardiomyocytes. This process can be accomplished without special equipment beyond a fluorescent microscope with coupled laser line. Also shown is the use of a custom-built MATLAB routine that allows the quantification of calcium propagation within and between the different cells in the culture. Myofibroblasts are shown to have a slower electrical response than that of cardiomyocytes. Moreover, the myofibroblast intercellular propagation shows slightly slower, though comparable velocities to their intracellular velocities, suggesting passive propagation through gap junctions or nanotubes. This technique is highly adaptable and can be easily applied to other cellular arenas, for in vitro as well as in vivo or ex vivo investigations.


Asunto(s)
Células/metabolismo , Fenómenos Electrofisiológicos , Nanocables/química , Óptica y Fotónica , Silicio/química , Animales , Calcio/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Miofibroblastos/citología , Miofibroblastos/metabolismo , Imagen Óptica , Grabación en Video
6.
Molecules ; 26(3)2021 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-33572957

RESUMEN

Lead halide perovskites are currently widely investigated as active materials in photonic and optoelectronic devices. While the lack of long term stability actually limits their application to commercial devices, several experiments demonstrated that beyond the irreversible variation of the material properties due to degradation, several possibilities exist to reversibly modulate the perovskite characteristics by acting on the environmental conditions. These results clear the way to possible applications of lead halide perovskites to resistive and optical sensors. In this review we will describe the current state of the art of the comprehension of the environmental effects on the optical and electronic properties of lead halide perovskites, and of the exploitation of these results for the development of perovskite-based sensors.


Asunto(s)
Técnicas Biosensibles , Compuestos de Calcio/química , Plomo/química , Óptica y Fotónica/métodos , Óxidos/química , Titanio/química , Clima , Electrónica , Monitoreo del Ambiente , Humanos , Compuestos Inorgánicos/química , Compuestos Inorgánicos/aislamiento & purificación , Plomo/aislamiento & purificación
7.
Nature ; 590(7847): 556-557, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33627804
8.
Nature ; 589(7840): 25-26, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33408372
9.
Adv Exp Med Biol ; 1293: 565-583, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33398843

RESUMEN

Although multiphoton microscopy enables optical control and monitoring of neural activity with single cells resolution over a depth of several hundreds of micrometers, the scattering nature of the brain tissue requires implantable optical neural interfaces to access subcortical structures. If micro light-emitting devices (µLEDs) and solid-state waveguides represent important technological advancements for the field, multimodal optical fibers (MMFs) are still the most diffused tool in neuroscience labs to interface with deep regions of the brain. At a first glance, MMFs can be seen as very limited systems. However, new studies and discoveries in optics, photonics, and technological solutions for their application to neuroscience research have enabled applications of MMF where competing technologies fail. In this framework, the chapter starts with a description of optical neural interfaces based on MMF, with specific reference on recent works analyzing the performances of this approach to deliver and collect light from scattering tissue. The discussion then focuses on how peculiar features of MMFs can be exploited to obtain unconventional applications, including brain imaging through a single multimode fiber, multifunctional neural interfaces, and depth-resolved light delivery and functional fluorescence collection.


Asunto(s)
Neurociencias , Fibras Ópticas , Diagnóstico por Imagen , Fluorescencia , Óptica y Fotónica
10.
Anal Chem ; 93(2): 828-833, 2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33319993

RESUMEN

A variety of surface plasmon resonance (SPR) sensing devices have been extensively used in biochemical detection for their characteristics of label-free, highly sensitive, and faster detecting. Among them, the spectrum-based SPR sensing devices have offered us great advantages in high-throughput sensing due to their large dynamic range and the possibility of detection resolution similar to that offered by angle interrogation. This paper demonstrates a spectrum-based SPR imaging sensing system with fast wavelength scanning capability achieved by an acousto-optic tunable filter (AOTF) and a low-cost and speckle-free halogen lamp implemented as the SPR excitation source. Especially, we developed a novel four-parameter-based spectral curve readjusting (4-PSCR) method for data processing, which offered us a faster and more accurate spectral data curve fitting process than the traditional polynomial fitting method. With the configuration, we have also conducted an SPR high-throughput detection of the novel coronavirus (COVID-19) spike protein, proving its application possibility in the screening of COVID-19 with high accuracy. We believe that the higher sensitivity and accuracy of the system have made it readily used in biochemical imaging and detecting applications.


Asunto(s)
Glicoproteína de la Espiga del Coronavirus/análisis , Resonancia por Plasmón de Superficie/métodos , Algoritmos , /virología , Humanos , Límite de Detección , Óptica y Fotónica , /metabolismo , Glicoproteína de la Espiga del Coronavirus/metabolismo , Resonancia por Plasmón de Superficie/instrumentación , Temperatura
11.
Curr Opin Ophthalmol ; 32(1): 31-44, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33165018

RESUMEN

PURPOSE OF REVIEW: Phacoemulsification cataract surgery is one of the most commonly performed surgical procedure worldwide. In the majority of cases, intraocular lenses (IOLs) are implanted. Due to the increasing life expectancy and the fact that cataract surgery is performed in earlier stages, the anticipated IOL duration in the eye has increased over the last decades. The aim of this study was to review the types and describe the characteristics of late intraocular lens opacifications. RECENT FINDINGS: Calcification was the most commonly reported type of opacification in hydrophilic IOLs; it usually negatively impacted the visual function and required IOL explantation. Glistening manifested in hydrophobic acrylic lenses and was frequent in some IOL models. In most cases glistening and subsurface nanoglistenigs do not lead to a decline in visual acuity or require IOL exchange. Current studies indicate that fluid-related phenomena may induce straylight, leading to a decrease of comfort and quality of vision. SUMMARY: Several reports on late IOL opacifications have been published in recent years. In some cases, particularly in glistening, the development of the opacifications might be related to IOL aging. The influence of the fluid-related microvacuoles on the quality of vision requires further research.


Asunto(s)
Calcinosis/patología , Implantación de Lentes Intraoculares , Lentes Intraoculares , Óptica y Fotónica , Facoemulsificación , Falla de Prótesis , Humanos
12.
Opt Lett ; 45(19): 5428-5431, 2020 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-33001920

RESUMEN

We show that waveguide sensors can enable a quantitative characterization of coronavirus spike glycoprotein-host-receptor binding-the process whereby coronaviruses enter human cells, causing disease. We demonstrate that such sensors can help quantify and eventually understand kinetic and thermodynamic properties of viruses that control their affinity to targeted cells, which is known to significantly vary in the course of virus evolution, e.g., from SARS-CoV to SARS-CoV-2, making the development of virus-specific drugs and vaccine difficult. With the binding rate constants and thermodynamic parameters as suggested by the latest SARS-CoV-2 research, optical sensors of SARS-CoV-2 spike protein-receptor binding may be within sight.


Asunto(s)
Betacoronavirus , Técnicas Biosensibles , Infecciones por Coronavirus , Óptica y Fotónica/instrumentación , Pandemias , Peptidil-Dipeptidasa A/metabolismo , Neumonía Viral , Receptores Virales/metabolismo , Glicoproteína de la Espiga del Coronavirus/metabolismo , Sitios de Unión , Humanos , Unión Proteica/fisiología
13.
Vestn Oftalmol ; 136(5. Vyp. 2): 237-240, 2020.
Artículo en Ruso | MEDLINE | ID: mdl-33063971

RESUMEN

The authors present a clinical case of central opacification of the intraocular lens (IOL) optic associated with a significant uncorrectable visual acuity decrease. Due to high surgical risks of IOL exchange, corectopia was achieved through sectoral laser photomydriasis. Stable dilation of the lower nasal sector of the pupil enabled the optical zone to be shifted outside the opaque area of the IOL. As shown by the perimetry results, the visual field borders enlarged through sectoral laser photomydriasis were comparable with the topography of the asymmetrically dilated pupil.


Asunto(s)
Lentes Intraoculares , Falla de Prótesis , Ojo Artificial , Humanos , Óptica y Fotónica , Agudeza Visual
14.
Vestn Oftalmol ; 136(5. Vyp. 2): 296-300, 2020.
Artículo en Ruso | MEDLINE | ID: mdl-33063980

RESUMEN

The review summarizes the results of surgical treatment of cataracts in patients with keratoconus. The major challenges of phacosurgery in keratoconus are associated with intraocular lens (IOL) power calculation, choice of the most appropriate IOL model and additional interventions required to stabilize keratectasia and reduce corneal irregularity.


Asunto(s)
Catarata , Queratocono , Lentes Intraoculares , Catarata/complicaciones , Catarata/diagnóstico , Humanos , Queratocono/diagnóstico , Queratocono/cirugía , Óptica y Fotónica , Refracción Ocular
15.
Surg Clin North Am ; 100(6): 971-992, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33128891

RESUMEN

Surgeons have been involved, since the beginning, in the development and evolution of endoscopy. They have been instrumental in developing new methods and have been actively involved in most of the therapeutic applications. The continued evolution of endoscopic technique is inevitable and will involve the integration of new technology with innovative thinking.


Asunto(s)
Endoscopios Gastrointestinales/historia , Endoscopía Gastrointestinal/historia , Tecnología de Fibra Óptica/historia , Endoscopía Gastrointestinal/instrumentación , Endoscopía Gastrointestinal/tendencias , Europa (Continente) , Tecnología de Fibra Óptica/instrumentación , Historia del Siglo XIX , Historia del Siglo XX , Historia Antigua , Humanos , Óptica y Fotónica/historia , Óptica y Fotónica/tendencias , Estados Unidos
16.
Neuron ; 108(1): 66-92, 2020 10 14.
Artículo en Inglés | MEDLINE | ID: mdl-33058767

RESUMEN

We propose a new paradigm for dense functional imaging of brain activity to surmount the limitations of present methodologies. We term this approach "integrated neurophotonics"; it combines recent advances in microchip-based integrated photonic and electronic circuitry with those from optogenetics. This approach has the potential to enable lens-less functional imaging from within the brain itself to achieve dense, large-scale stimulation and recording of brain activity with cellular resolution at arbitrary depths. We perform a computational study of several prototype 3D architectures for implantable probe-array modules that are designed to provide fast and dense single-cell resolution (e.g., within a 1-mm3 volume of mouse cortex comprising ∼100,000 neurons). We describe progress toward realizing integrated neurophotonic imaging modules, which can be produced en masse with current semiconductor foundry protocols for chip manufacturing. Implantation of multiple modules can cover extended brain regions.


Asunto(s)
Encéfalo/diagnóstico por imagen , Neuroimagen Funcional/métodos , Neuronas/patología , Imagen Óptica/métodos , Animales , Encéfalo/patología , Encéfalo/fisiología , Simulación por Computador , Sistemas de Computación , Neuroimagen Funcional/instrumentación , Procedimientos Analíticos en Microchip , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/patología , Vías Nerviosas/fisiología , Neuronas/fisiología , Imagen Óptica/instrumentación , Óptica y Fotónica , Optogenética
17.
Nature ; 585(7826): 506-507, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32968262
18.
J Breath Res ; 14(4): 043001, 2020 09 24.
Artículo en Inglés | MEDLINE | ID: mdl-32969348

RESUMEN

Cavity-enhanced absorption spectroscopies (CEAS) have gained importance in a wide range of applications in molecular spectroscopy. The development of optical sensors based on the CEAS techniques coupled with the continuous wave or pulsed laser sources operating in the mid-infrared or near-infrared spectral regime uniquely offers molecularly selective and ultra-sensitive detection of trace species in complex matrices including exhaled human breath. In this review, we discussed recent applications of CEAS for analyzing trace constituents within the exhaled breath matrix facilitating the non-invasive assessment of human health status. Next to a brief discussion on the mechanisms of formation of trace components found in the exhaled breath matrix related to particular disease states, existing challenges in CEAS and future development towards non-invasive clinical diagnostics will be discussed.


Asunto(s)
Pruebas Respiratorias/métodos , Espiración , Óptica y Fotónica/métodos , Animales , Humanos , Óxido Nítrico/análisis , Consumo de Oxígeno , Espectroscopía Infrarroja Corta
19.
Nat Commun ; 11(1): 4108, 2020 08 14.
Artículo en Inglés | MEDLINE | ID: mdl-32796840

RESUMEN

Replicating biological patterns is promising for designing materials with multifaceted properties. Twisted cholesteric liquid crystal patterns are found in the iridescent tessellated cuticles of many insects and a few fruits. Their accurate replication is extremely difficult since discontinuous patterns and colors must coexist in a single layer without discontinuity of the structures. Here, a solution is demonstrated by addressing striped insect cuticles with a complex twisted organization. Geometric constraints are met by controlling the thermal diffusion in a cholesteric oligomer bilayer subjected to local changes in the molecular anchoring conditions. A multicriterion comparison reveals a very high level of biomimicry. Proof-of-concept prototypes of anti-counterfeiting tags are presented. The present design involves an economy of resources and a high versatility of chiral patterns unreached by the current manufacturing techniques such as metallic layer vacuum deposition, template embossing and various forms of lithography which are limited and often prohibitively expensive.


Asunto(s)
Biomimética/métodos , Biofisica/métodos , Cristales Líquidos/química , Óptica y Fotónica/métodos , Animales , Insectos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...