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1.
Analyst ; 146(18): 5619-5630, 2021 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-34378560

RESUMEN

In response to the world's medical community's need for accurate and immediate infectious pathogen detection, many researchers have focused on adapting the standard molecular diagnostic method of polymerase chain reaction (PCR) for point-of-care (POC) applications. PCR technology is not without its shortcomings; current platforms can be bulky, slow, and power-intensive. Although there have been some advances in microfluidic PCR devices, a simple-to-operate and fabricate PCR device is still lacking. In the first part of this paper, we introduce a compact plasmonic PCR thermocycler in which fast DNA amplification is derived from efficient photothermal heating of a colloidal reaction mixture containing gold nanorods (AuNRs) using a small-scale vertical-cavity surface-emitting laser (VCSEL). Using this method, we demonstrate 30 cycle-assay time of sub-ten minutes for successful Chlamydia trachomatis DNA amplification in 20 µL total PCR sample volume. In the second part, we report an ultrasensitive real-time amplicon detection strategy which is based on cycle-by-cycle monitoring of 260 nm absorption of the PCR sample. This was accomplished by irradiating the PCR sample using a UV LED and collecting the transmitted optical power with a photodetector. The UV absorption dependency on the nucleotides' structural degree of freedom gives rise to distinctive features in the shape of UV amplification curves for the determination of PCR results, thus circumventing the need for the complicated design of target-specific probes or intercalating fluorophores. This amplicon quantification method has a high detection sensitivity of one DNA copy. This is the first demonstration of a compact plasmonic thermocycler combined with a real-time fluorophore-free quantitative amplicon detection system. The small footprint of our PCR device stems from hardware miniaturization, while abundant sample volume facilitates highly sensitive detection and fluid handling required for in-field sample analysis, thereby making it an excellent candidate for POC molecular diagnostics.


Asunto(s)
ADN , Técnicas de Amplificación de Ácido Nucleico , Técnicas de Diagnóstico Molecular , Sistemas de Atención de Punto , Pruebas en el Punto de Atención , Reacción en Cadena en Tiempo Real de la Polimerasa
2.
Opt Express ; 25(20): 24803-24815, 2017 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-29041293

RESUMEN

We present a novel approach to improve self-referenced sensing based on multiple-resonance nanorod structures. The method employs the maximum likelihood estimation (MLE) alongside a linear response model (LM), relating the sensor response (shifts in resonance wavelengths) to the changes due to surface binding and bulk refractive index. We also provide a solution to avoid repetitive simulations, that have been previously needed to determine the adlayer thickness sensitivity when measuring biological samples of different refractive indices. The finite element method (FEM) was used to model the nanorod structure, and the nanoimprint lithography was employed to fabricate them. The standard deviation of the results based on the MLE method is lower than that associated with the LM results. The method can be applied to an extended number of resonances to achieve a higher accuracy and precision.

3.
Analyst ; 142(13): 2386-2394, 2017 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-28555681

RESUMEN

Bacterial biofilms are a leading cause of infection in health-care settings. Surface plasmon resonance (SPR) biosensors stand as valuable tools not only for the detection of biological entities and the characterisation of biomaterials but also as a suitable means to monitor bacterial film formation. This article reports on a proof-of-concept study for the use of an angular-based SPR biosensor for the monitoring of bacterial cell growth and biofilm formation and removal under the effect of different cleaning agents. The benefit of this custom-made SPR instrument is that it records simultaneously both the critical and resonant angles. This provides unique information on the growth of bacterial cells which is otherwise not obtainable with commonly used intensity-based SPR systems. The results clearly showed that a multilayer biofilm can be formed in 48 hours and the steps involved can be monitored in real-time with the SPR instrument through the measurement of the refractive index change and following the evolution in the shape of the SPR curve. The number, the depth and the sharpness of the reflection ripples varied as the film became thicker. Simulation results confirmed that the number of layers of bacteria affected the number of ripples at the critical angle. Real-time monitoring of the film breakdown with three cleaning agents indicated that bleach solution at 4.5% was the most effective in disrupting the biofilm from the gold sensor. Our overall findings suggest that the SPR biosensor with angular modulation presented in this article can perform real-time monitoring of biofilm formation and has the potential to be used as a platform to test the efficiency of disinfectants.


Asunto(s)
Bacterias/crecimiento & desarrollo , Biopelículas/crecimiento & desarrollo , Técnicas Biosensibles , Resonancia por Plasmón de Superficie , Diseño de Equipo , Oro , Refractometría
4.
Analyst ; 142(10): 1746-1755, 2017 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-28443837

RESUMEN

Polymerase Chain Reaction (PCR) is a critical tool for biological research investigators but recently it also has been making a significant impact in clinical, veterinary and agricultural applications. Plasmonic PCR, which employs the very efficient heat transfer of optically irradiated metallic nanoparticles, is a simple and powerful methodology to drive PCR reactions. The scalability of next generation plasmonic PCR technology will introduce various forms of PCR applications ranging from small footprint portable point of care diagnostic devices to large footprint central laboratory multiplexing devices. In a significant advance, we have introduced a real time plasmonic PCR and explored the ability of ultra-fast cycling compatible with both label-free and fluorescence-based monitoring of amplicon production. Furthermore, plasmonic PCR has been substantially optimized to now deliver a 30 cycle PCR in 54 seconds, with a detectable product. The advances described here will have an immediate impact on the further development of the use of plasmonic PCR playing a critical role in rapid point of care diagnostics.

5.
Diagnostics (Basel) ; 14(5)2024 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-38472949

RESUMEN

The basic principles of ultrafast plasmonic PCR have been promulgated in the scientific and technological literature for over a decade. Yet, its everyday diagnostic utility remains unvalidated in pre-clinical and clinical settings. Although the impressive speed of plasmonic PCR reaction is well-documented, implementing this process into a device form compatible with routine diagnostic tasks has been challenging. Here, we show that combining careful system engineering and process control with innovative and specific PCR biochemistry makes it possible to routinely achieve a sensitive and robust "10 min" PCR assay in a compact and lightweight system. The critical analytical parameters of PCR reactions are discussed in the current instrument setting.

6.
Opt Express ; 21(7): 8724-35, 2013 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-23571961

RESUMEN

Due to ultra high quality factor (10(6) - 10(9)), axisymmetric optical microcavities are popular platforms for biosensing applications. It has been recently demonstrated that a microcavity biosensor can track a biodetection event as a function of its quality factor by using phase shift cavity ring down spectroscopy (PS-CRDS). However, to achieve maximum sensitivity, it is necessary to optimize the microcavity parameters for a given sensing application. Here, we introduce an improved finite element model which allows us to determine the optimized geometry for the PS-CRDS sensor. The improved model not only provides fast and accurate determination of quality factors but also determines the tunneling distance of axisymmetric resonators. The improved model is validated numerically, analytically, and experimentally.


Asunto(s)
Técnicas Biosensibles/instrumentación , Diseño Asistido por Computadora , Análisis Espectral/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Análisis de Elementos Finitos , Miniaturización , Sensibilidad y Especificidad
7.
Opt Express ; 21(19): 22817-28, 2013 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-24104168

RESUMEN

Optical microcavities are widely used for biological and chemical sensing applications. In these devices, a sensing event is estimated by measuring the shift in the resonant wavelength, or in the quality factor of the microcavity. However, all published works to date only use one of these measures to estimate the sensing event. Here, we show that the estimation accuracy of a sensing event can be improved by employing a combination of both the quality factor and the resonant wavelength measurements in a microcavity sensor. We further demonstrate an experimental application of this model by introducing a refractive index change for a microtoroidal cavity sensor immersed in a liquid. By further using the finite element method simulations in conjunction with the estimator model, we show the existence of three distinct measurement regimes as a function of the quality factor of the microcavity. Finally, the estimator model is extended to develop a sensing metric to compare performance of optical or non-optical sensors.


Asunto(s)
Algoritmos , Técnicas Biosensibles , Diseño Asistido por Computadora , Sistemas Microelectromecánicos/instrumentación , Dispositivos Ópticos , Interpretación Estadística de Datos , Funciones de Verosimilitud , Miniaturización
8.
Biomed Opt Express ; 14(12): 6629-6643, 2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-38420328

RESUMEN

Photothermal therapy (PTT) is a promising approach for cancer treatment that selectively heats malignant cells while sparing healthy cells. Here, the light-to-heat conversion efficiency of multiwalled carbon nanotubes (MWCNTs) within the near-infrared biological transmission window is enhanced by decorating them with plasmonic gold nanorods (GNRs). The results reveal a significant photothermal enhancement of hybrid MWCNTs-GNRs compared to bare MWCNTs, displaying a 4.9 enhancement factor per unit mass. The enhanced plasmonic PTT properties of MWCNTs-GNRs are also investigated in vitro using PC3 prostate cancer cell lines, demonstrating a potent ablation efficiency. These findings advance innovative hybrid plasmonic nanostructures for clinical applications.

9.
Opt Express ; 20(14): 15983-90, 2012 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-22772286

RESUMEN

We report on the design, fabrication, and demonstration of waveguide coupled channel drop filters at 1550 nm, on a silicon-on-insulator (SOI) substrate. These devices rely on resonant power transfer from a bus waveguide to side-walled Bragg resonators with quarter-wave shifts in the middle. By employing a second mirror resonator, and a tap-off waveguide, reflections along the bus waveguide can be reduced, leading to realization of circulator-free resonance filters. These devices were fabricated on SOI using e-beam lithography and inductively coupled plasma (ICP) etching. Fabricated devices with two coupled cavities are demonstrated to have rejection ratios greater than 20 dB and 3-dB bandwidths of 110 GHz, close to the values predicted by numerical modeling. We also demonstrate power tap-off at resonance of around 16 dB.

10.
Opt Express ; 20(8): 9090-8, 2012 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-22513620

RESUMEN

Optical resonant microcavities with ultra high quality factors are widely used for biosensing. Until now, the primary method of detection has been based upon tracking the resonant wavelength shift as a function of biodetection events. One of the sources of noise in all resonant-wavelength shift measurements is the noise due to intensity fluctuations of the laser source. An alternative approach is to track the change in the quality factor of the optical cavity by using phase shift cavity ring down spectroscopy, a technique which is insensitive to the intensity fluctuations of the laser source. Here, using biotinylated microtoroid resonant cavities, we show simultaneous measurement of the quality factor and the wavelength shift by using phase shift cavity ring down spectroscopy. These measurements were performed for disassociation phase of biotin-streptavidin reaction. We found that the disassociation curves are in good agreement with the previously published results. Hence, we demonstrate not only the application of phase shift cavity ring down spectroscopy to microcavities in the liquid phase but also simultaneous measurement of the quality factor and the wavelength shift for the microcavity biosensors in the application of kinetics measurements.


Asunto(s)
Técnicas Biosensibles/métodos , Análisis Espectral/métodos , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/estadística & datos numéricos , Biotina/química , Diseño de Equipo , Rayos Láser , Fenómenos Ópticos , Transición de Fase , Análisis Espectral/instrumentación , Análisis Espectral/estadística & datos numéricos , Estreptavidina/química
11.
Opt Lett ; 37(13): 2712-4, 2012 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-22743504

RESUMEN

We report on the observation of a dynamical thermal effect in InGaAsP microtubes at telecom wavelengths. The microtubes are fabricated by releasing a strained semiconductor bilayer and are picked up by abruptly tapered optical fibers for subsequent coupling with adiabatically tapered optical fibers. As a result of absorption by InAs quantum dots embedded in the tube structure, these microtubes show dynamical thermal effects at wavelengths around 1525 nm and 1578 nm, while they are passive at longer wavelengths near 1634 nm. The photon absorption induced thermal effect is visualized by generating a pair of microbottles. The dynamical thermal effect can be avoided or exploited for passive or active applications by utilizing appropriate resonance wavelengths.

12.
Analyst ; 137(19): 4475-81, 2012 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-22871797

RESUMEN

A plasmonic heating method for the polymerase chain reaction is demonstrated by the amplification of a section of the human androgen receptor gene. The thermocycler has a simple low-cost design, demonstrates excellent temperature stability and represents the first practical demonstration of plasmonic thermocycling.


Asunto(s)
ADN/análisis , Reacción en Cadena de la Polimerasa , Receptores Androgénicos/genética , Oro/química , Humanos , Nanopartículas del Metal/química , Temperatura
13.
Opt Express ; 19(13): 12164-71, 2011 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-21716453

RESUMEN

We report on single rolled-up microtubes integrated with silicon-on-insulator waveguides. Microtubes with diameters of ~7 µm, wall thicknesses of ~250 nm, and lengths greater than 100 µm are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from the handling GaAs substrate. The microtubes are then transferred from their host substrate to silicon-on-insulator waveguides by an optical fiber abrupt taper. The Q-factor of the waveguide coupled microtube is measured to be 1.5×10(5), the highest recorded for a semiconductor microtube cavity to date. The insertion loss and extinction ratio of the microtube are 1 dB and 34 dB respectively. By pumping the microtube with a 635 nm laser, the resonance wavelength is shifted by 0.7 nm. The integration of InGaAs/GaAs microtubes with silicon-on-insulator waveguides provides a simple, low loss, high extinction passive filter solution in the C+L band communication regime.


Asunto(s)
Arsenicales/química , Tecnología de Fibra Óptica/métodos , Galio/química , Indio/química , Rayos Láser , Puntos Cuánticos , Silicio/química , Tecnología de Fibra Óptica/instrumentación , Semiconductores , Telecomunicaciones/instrumentación
14.
Opt Lett ; 36(17): 3506-8, 2011 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-21886259

RESUMEN

We report on selective polarization mode excitation in InGaAs/GaAs rolled-up microtubes. The microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the microtube. We also show that the microtube can be used as a red (0.6 µm) to infrared light (1.5 µm) optical-optical modulator taking advantage of the thermal-optical effect.

15.
Opt Lett ; 36(1): 46-8, 2011 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-21209682

RESUMEN

A surface plasmon biosensing technique based on real-time measurement of the spectro-angular reflectance spectrum of a gold surface is presented. A significant improvement in refractive index resolution and drift compensation has been achieved for the spectro-angular technique to demonstrate a biosensing platform that is, in addition, applicable to plasmonic bandgap measurements. Instrumental improvements are detailed and constants for the model bovine serum albumin (BSA):oxacillin bioassay are presented.


Asunto(s)
Análisis Espectral/métodos , Resonancia por Plasmón de Superficie/métodos , Animales , Bovinos , Oxacilina/metabolismo , Albúmina Sérica Bovina/metabolismo , Análisis Espectral/instrumentación , Resonancia por Plasmón de Superficie/instrumentación , Factores de Tiempo
16.
Opt Express ; 18(8): 7732-42, 2010 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-20588614

RESUMEN

A dynamically reconfigurable nested photonic crystal cavity suitable for frequency conversion applications is proposed. Dynamic switching between two distinct cavities allows intermodal transition via spatially-uniform tuning of the refractive index. Exclusion of the initial resonant mode from the Eigen modes of the tuned cavity precludes the adiabatic wavelength conversion process. Multiple intermodal transitions are suppressed by the symmetry of the mode profiles of the two cavities. Over 90nm wavelength shift (from L-band to the S-band) is shown numerically.

17.
Opt Express ; 18(19): 20518-28, 2010 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-20940945

RESUMEN

We present the analysis and design of a superprism-based demultiplexer that employs both group and phase velocity dispersion of the photonic crystal (PhC). Simultaneous diffraction compensation and spatio-angular wavelength channel separation is realized in a slab region that divides the PhC. This avoids the excessive broadening of the beams inside the PhC and enhances the achievable angular dispersion of the conventional superprism topology. As a result, a compact demultiplexer with a relaxed requirement for low divergence input beams is attained. The dynamics of the beams envelops are considered based on the curvature of the band structure. Analysis shows at least 36-fold reduction of the PhC area and much smaller propagation length in slab compared to the preconditioned superprism, based on the same design model. PhC area scales as Δω(-2.5) with Δω being the channel spacing.


Asunto(s)
Refractometría/instrumentación , Procesamiento de Señales Asistido por Computador/instrumentación , Telecomunicaciones/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo , Fotones
18.
Opt Express ; 17(20): 17614-29, 2009 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-19907546

RESUMEN

Scalable optical space switches compatible with high bit rates which can be reconfigured on-the-fly are needed to increase the flexibility of optical networks. We present the design of integrated Fabry-Perot filters working at oblique incidence, which can be used to build optical space switches. A comprehensive planar waveguide optimization was conducted to minimize radiation losses in the deep-etch features forming the filter mirrors. Four high order cavities were coupled to create a 200 GHz comb wavelength response with passbands larger than 50 GHz and extinction ratio greater than 20 dB over the entire C-band. Gaussian beam propagation analysis showed that the minimum beam waist required to avoid distortion increases rapidly with incident angle.


Asunto(s)
Filtración/instrumentación , Interferometría/instrumentación , Dispositivos Ópticos , Procesamiento de Señales Asistido por Computador/instrumentación , Transductores , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
19.
Opt Lett ; 34(19): 3035-7, 2009 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-19794807

RESUMEN

Optical wavelength conversion over an ultrawide spectral range based on an intermodal transition induced by dynamic tuning of a double heterostructure photonic crystal cavity is numerically demonstrated. Exploiting the inherently large spectral separation between the eigenmodes and the field symmetries to suppress multiple mode couplings, a normalized wavelength shift of about 25% with feasible index tuning is achievable by coupling only two resonances.

20.
Opt Express ; 16(6): 4330-6, 2008 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-18542530

RESUMEN

We consider the conditions for negative refraction in the partial bandgap of photonic crystals and show that, in contrast to previously published studies, anisotropy is not a necessary condition for negative refraction, and that unrestricted imaging is possible. This analysis is made possible by the introduction of a negative local wavevector. In addition, we analyze the origins of the previously reported restricted and adjacent imaging properties and extend negative refraction to higher bands.


Asunto(s)
Modelos Teóricos , Refractometría/métodos , Cristalización , Luz , Fotones , Dispersión de Radiación
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