RESUMEN
Este trabalho objetivou desenvolver, caracterizar e avaliar a atividade osteogênica de formulações de CP com diferentes proporções de óxido de Nióbio (Nb2O5), substituindo o Bi2O3. Foram utilizados três grupos, um controle e dois experimentais: GC (MTA Angelus®), F6 (75% CP, 20% Nb2O5 e 5% CaSO4) e F7 (75% CP, 10% Bi2O3, 10% Nb2O5e 5% CaSO4). As formulações foram submetidas às análises de Difração de RaioX (DRX), Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), Espectrometria de Fluorescência de Raios-X (FRX), pH, tempo de presa, radiopacidade, resistência a compressão, citotoxicidade e bioatividade. Os dados obtidos foram avaliados estatisticamente pelo teste de variância (ANOVA) com correção de Bonferroni (p<0,05%). O resultado do teste de pH: Nióbio 10% Imediato (12,205 ±0,304); 24h; (12,770 ± 0,226) 48h: (12,910 ± 0,169). Nióbio 20%: imediato (12,080 ± 0,282); 24 h: (12,350 ± 0,593); 48 h: (12,580 ± 0,73). Para o tempo de presa inicial em segundos: MTA (397,500 ±10,606); Nióbio 10% (294,333 + 90,897) e Nióbio 20% (279,000 + 15,874). O tempo de presa final para os grupos foram: MTA (15,000 + 49,497), Nióbio 10% (560 ±38,587), sendo menor quando comparado ao MTA (p<0,001) e Nióbio 20% (715,666 ± 30,664) (p<0,01). Os valores da radiopacidade em mm Al do Nióbio 10% (3,888 ±0,340); Nióbio 20% (3,713 ± 0,712). A resistência a compressão em MPa foi: Nióbio 10% (694,150 + 78,951) Nióbio 20% (699,295 + 47,672). A viabilidade celular não apresentou diferença entre o MTA e grupos experimentais (p<0,05). Os resultados da capacidade osteogênese das formulações a partir do ensaio da fosfatase alcalina (FAL) em UI/L por grama de proteína para cada grupo foi: MTA (1,9 + 1,227) e Nióbio 20% (1,784 + 1,342) (p>0,05). Nossos achados apontam propriedades relevantes para as formulações com Nb2O5 como, pH alcalino, radiopacidade, resistência a compressão e atividade da fosfatase alcalina (AU).
Work aimed to develop, characterize and evaluate the osteogenic activity of PC formulations with different proportions of Niobium oxide (Nb2O5), replacing Bi2O3. Three groups were used, one control and two experimental: GC (MTA Angelus®), F6 (75% CP, 20% Nb2O5 and 5% CaSO4) and F7 (75% CP, 10% Bi2O3, 10% Nb2O5e 5% CaSO4) . The formulations were submitted to X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Fluorescence Spectrometry (FRX), pH, setting, radiopacity, compressive strength, cytotoxicity and bioactivity. The data obtained were statistically evaluated by the test of variance (ANOVA) with Bonferroni correction (p<0.05%). The pH test result: Niobium 10% Immediate (12.205 ±0.304); 24h; (12.770 ± 0.226) 48h: (12.910 ± 0.169). Niobium 20%: immediate (12.080 ± 0.282); 24h: (12.350 ± 0.593); 48 h: (12.580 ± 0.73). For initial setting time in seconds: MTA (397,500 ±10,606); Niobium 10% (294,333 + 90,897) and Niobium 20% (279,000 + 15,874). The final setting time for the groups were: MTA (15,000 + 49,497), Niobium 10% (560 ± 38,587), being smaller when compared to MTA (p<0,001) and Niobium 20% (715,666 ± 30,664) (p<0 .01). Radiopacity values in mm Al of 10% Niobium (3.888 ±0.340); Niobium 20% (3.713 ± 0.712). The compressive strength in MPa was: Niobium 10% (694.150 + 78.951) Niobium 20% (699.295 + 47.672). Cell viability showed no difference between MTA and experimental groups (p<0.05). The results of the osteogenesis capacity of the formulations from the alkaline phosphatase assay (ALF) in IU/L per gram of protein for each group were: MTA (1.9 + 1.227) and Niobium 20% (1.784 + 1.342) (p> 0.05). Our findings point to relevant properties for Nb2O5 formulations such as alkaline pH, radiopacity, compressive strength and alkaline phosphatase activity (AU).
Asunto(s)
Materiales Biocompatibles , Cementos Dentales , Endodoncia , Niobio , Espectrometría de Fluorescencia/instrumentación , Microscopía Electrónica de Rastreo , Análisis de Varianza , Espectroscopía Infrarroja por Transformada de Fourier , Materiales Dentales , Análisis de FourierRESUMEN
Given their photoluminescent character, portable quantum dot readers are often sophisticated and relatively expensive. In response, we engineered a "do it yourself" fluorescence reader employing paper materials and a mid-range smartphone camera. Black paperboard facilitated a versatile, lightweight and foldable case; whereas cellophane paper was observed to behave as a simple, yet effective, optical bandpass filter leading to an advantageous device for the quantitative interrogation of quantum dot nanocrystals concentrations (from 2.5 to 20 nM), which are suitable for optical point-of-care biosensing. The streptavidin-coated nanocrystals employed are commercially available and the developed reader was benchmarked with a standard portable quantum dot reader, thereby demonstrating advantages in terms of cost and linear analytical range.
Asunto(s)
Técnicas Biosensibles , Papel , Sistemas de Atención de Punto , Teléfono Inteligente , Técnicas Biosensibles/instrumentación , Humanos , Teléfono Inteligente/instrumentación , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
In recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description of recent advances in the development of methods for the quantification of pesticides used in agricultural activities. Current advances focus on improving sensitivity and selectivity through the use of nanomaterials in both sensor assemblies and new biosensors. In this study, we summarize the electrochemical, optical, nano-colorimetric, piezoelectric, chemo-luminescent and fluorescent techniques related to the determination of agricultural pesticides. A brief description of each method and its applications, detection limit, purpose-which is to efficiently determine pesticides-cost and precision are considered. The main crops that are assessed in this study are bananas, although other fruits and vegetables contaminated with pesticides are also mentioned. While many studies have assessed biosensors for the determination of pesticides, the research in this area needs to be expanded to allow for a balance between agricultural activities and environmental protection.
Asunto(s)
Técnicas Biosensibles/métodos , Colorimetría/métodos , Técnicas Electroquímicas/métodos , Mediciones Luminiscentes/métodos , Plaguicidas/aislamiento & purificación , Espectrometría de Fluorescencia/métodos , Agricultura , Técnicas Biosensibles/economía , Técnicas Biosensibles/instrumentación , Colorimetría/economía , Colorimetría/instrumentación , Conservación de los Recursos Naturales/métodos , Productos Agrícolas/efectos de los fármacos , Productos Agrícolas/microbiología , Productos Agrícolas/parasitología , Productos Agrícolas/virología , Técnicas Electroquímicas/economía , Técnicas Electroquímicas/instrumentación , Monitoreo del Ambiente/instrumentación , Monitoreo del Ambiente/métodos , Humanos , Límite de Detección , Mediciones Luminiscentes/economía , Mediciones Luminiscentes/instrumentación , Musa/efectos de los fármacos , Musa/microbiología , Musa/parasitología , Musa/virología , Espectrometría de Fluorescencia/economía , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
A rapid and multiplexed immunosensor was developed based on a quantum dot (QD)-reverse assaying strategy (RAS) and immuno-magnetic beads (IMBs) for one-step and simultaneous detection of Escherichia coli O157: H7 and Salmonella. In a conventional QD-based immunosensor, the fluorescence signal of the "IMBs-target-QD" immunoconjugate is directly used as the assaying readout. However, the fluorescence signal is affected by IMBs due to light scattering and the "IMBs-target-QD" immunoconjugate needs multiple washing and re-suspension steps. To address these problems, we use the surplus QD-antibody conjugate as signal readout in the RAS, which prevents interference from the IMBs, increases the fluorescence signal, and avoids complex operations. Compared with conventional QD-based immunosensor, the sensitivity of QD-RSA immunosensor for detection of Escherichia coli O157: H7 has been improved fifty-fold, and whole analysis procedure can be finished within 1h. Therefore, this RSA strategy is promising for improving the performance of QD-based immunosensors and could greatly broaden their applications.
Asunto(s)
Análisis de los Alimentos/instrumentación , Contaminación de Alimentos/análisis , Separación Inmunomagnética/instrumentación , Listeria/aislamiento & purificación , Puntos Cuánticos , Técnicas de Tipificación Bacteriana/instrumentación , Mezclas Complejas/análisis , Diseño de Equipo , Análisis de Falla de Equipo , Microbiología de Alimentos/instrumentación , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
A new method for zinc pre-concentration/separation and determination by molecular fluorescence is proposed. The metal was complexed with o-phenanthroline and eosin at pH 7.5 in Tris; a piece of filter paper was used as a solid support and solid fluorescent emission measured using a conventional quartz cuvette. Under optimal conditions, the limits of detection and quantification were 0.36 × 10(-3) and 1.29 × 10(-3) µg L(-1), respectively, and the linear range from 1.29 × 10(-3) to 4.50 µg L(-1). This method showed good sensitivity and selectivity, and it was applied to the determination of zinc in foods and tap water. The absence of filtration reduced the consumption of water and electricity. Additionally, the use of common filter papers makes it a simpler and more rapid alternative to conventional methods, with sensitivity and accuracy similar to atomic spectroscopies using a typical laboratory instrument.
Asunto(s)
Bebidas/análisis , Cuarzo , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Agua/química , Zinc/análisis , Filtración/instrumentación , Papel , Sensibilidad y EspecificidadRESUMEN
This work presents a green and very simple approach which enables the accurate and simultaneous determination of benzo[a]pyrene, dibenz[a,h]anthracene, benz[a]anthracene, and chrysene, concerned and potentially carcinogenic heavy-polycyclic aromatic hydrocarbons (PAHs) in interfering samples. The compounds are extracted from water samples onto a device composed of a small rotating Teflon disk, with a nylon membrane attached to one of its surfaces. After extraction, the nylon membrane containing the concentrated analytes is separated from the Teflon disk, and fluorescence excitation-emission matrices are directly measured on the nylon surface, and processed by applying parallel factor analysis (PARAFAC), without the necessity of a desorption step. Under optimum conditions and for a sample volume of 25 mL, the PAHs extraction was carried out in 20 min. Detection limits based on the IUPAC recommended criterion and relative errors of prediction were in the ranges 20-100 ng L(-1) and 5-7%, respectively. Thanks to the combination of the ability of nylon to strongly retain PAHs, the easy rotating disk extraction approach, and the selectivity of second-order calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles.
Asunto(s)
Membranas Artificiales , Nylons/química , Hidrocarburos Policíclicos Aromáticos/análisis , Extracción en Fase Sólida/métodos , Espectrometría de Fluorescencia/métodos , Contaminantes Químicos del Agua/análisis , Diseño de Equipo , Límite de Detección , Hidrocarburos Policíclicos Aromáticos/aislamiento & purificación , Extracción en Fase Sólida/instrumentación , Espectrometría de Fluorescencia/instrumentación , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
A modified spatial filtering method that improves the sensitivity of single-beam and mode-mismatched thermal lens spectroscopy (TLS) for fluorescence quantum yield measurement is presented. The method is based on the detection of the external part of a laser beam transmitted by the fluorescent sample (eclipsing detection mode). The experimental results show that the signal/noise (S/N) ratio of the absolute quantum yield of Rh6G can be enhanced up to ~1400% using the eclipsing detection mode on the TLS experimental setup. The method was evaluated by measuring the fluorescence quantum yield of varying concentration of ethanolic solutions of Rhodamine 6G.
Asunto(s)
Etanol/análisis , Lentes , Microquímica/instrumentación , Nanotecnología/instrumentación , Espectrometría de Fluorescencia/instrumentación , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Teoría Cuántica , TemperaturaRESUMEN
A significant increase in the use of the herbicide glyphosate has generated many questions about its residual accumulation in the environment and possible damage to crops. In this study, changes in chlorophyll a (chl-a) fluorescence induced by glyphosate in three varieties of glyphosate-resistant soybean plants were determined with an in vivo analysis based on a portable laser-induced fluorescence system. Strong suppression of chl-a fluorescence was observed for all plants treated with the herbicide. Moreover, the ratio of the emission bands in the red and far-red regions (685 nm/735 nm) indicates that the application of glyphosate led to chlorophyll degradation. The results also indicated that the use of glyphosate, even at concentrations recommended by the manufacturer, suppressed chl-a fluorescence. In summary, this study shows that fluorescence spectroscopy can detect, in vivo, very early changes in the photosynthetic status of transgenic soybeans treated with this herbicide.
Asunto(s)
Clorofila/análisis , Análisis de los Alimentos/métodos , Glycine max/efectos de los fármacos , Glycine max/metabolismo , Glicina/análogos & derivados , Rayos Láser , Espectrometría de Fluorescencia/instrumentación , Clorofila A , Tolerancia a Medicamentos , Glicina/farmacología , Herbicidas/farmacología , Herbicidas/provisión & distribución , Espectrometría de Fluorescencia/métodos , GlifosatoRESUMEN
A methodology based on second-order data (excitation emission matrices) modeling with one of most popular algorithms presenting the second-order advantage, parallel factor analysis (PARAFAC), combined with transference of calibration is proposed to predict the analyte concentration when significant inner filter effects occur, even in the presence of unexpected sample components. The quantitation of phenylephrine hydrochloride (PHE) in water samples (concentrations ranged between 250 and 750 ng mL(-1)) in the presence of ibuprofen, acetyl salicylic acid and paracetamol (which produce inner filter effect across the useful wavelength range) was achieved. The strategy allows reducing the experimental work and increasing the analytical sensitivity in the determination of the analyte of interest in the presence of unexpected compounds and matrix effect caused by inner filter, avoiding the preparation of a large number of solutions and maintaining acceptable figures of merit. Recoveries between 97 and 102% for validation and real spiked water samples, respectively, and a relative prediction error of 5% were achieved. Results were compared with those obtained after the application of the classical standard addition method combined with PARAFAC, carrying out five additions to each sample, in triplicate. The presented methodology constitutes a simple and low-cost method for the determination of PHE in water samples with a considerable reduction in standard handling and time. This methodology can be extended to other systems presenting matrix effect and, consequently, can become in a useful tool to know the amount of pharmaceuticals in the aquatic environment and to evaluate the effect of conventional wastewater treatment plants in the elimination of pharmaceutical compounds.
Asunto(s)
Modelos Químicos , Preparaciones Farmacéuticas/análisis , Fenilefrina/análisis , Espectrometría de Fluorescencia , Contaminantes Químicos del Agua/análisis , Acetaminofén/análisis , Algoritmos , Aspirina/análisis , Calibración , Ibuprofeno/análisis , Límite de Detección , Estándares de Referencia , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Espectrometría de Fluorescencia/normas , Aguas Residuales/químicaRESUMEN
An automatic method, based on flow-batch (FB), for determining glycerol in biodiesel was developed. The FB systems draw upon the useful features of flow, batch and multi-commutation approaches. The standards and samples preparation, as well as, derivatization and analysis were fully automated. For that purpose, a homemade chamber was built. The proposed method is based on liquid-liquid extraction of glycerol and simultaneous oxidation with periodate, generating formaldehyde that reacts with acetylacetone. A fluorescent product of 3,5-diacetyl-1,4-dihydrolutidine was obtained. The fluorescence signal was recorded at λ(ex) =417 nm and λ(em) = 514 nm. A linear response was observed from 0.10 to 5.00 mg L(-1) glycerol, variation coefficient 1.5%, sampling rate 14 h(-1) and detection limit 0.036 mg L(-1) glycerol. The procedure was successfully applied to the analysis of biodiesel samples, and the results agreed with the reference method (ASTM D6584-07) at 95% confidence level.
Asunto(s)
Biocombustibles/análisis , Dihidropiridinas/análisis , Glicerol/análisis , Espectrometría de Fluorescencia/métodos , Automatización de Laboratorios , Fluorescencia , Formaldehído/química , Límite de Detección , Extracción Líquido-Líquido/métodos , Oxidación-Reducción , Pentanonas/química , Ácido Peryódico/química , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
A rapid and sensitive spectrofluorimetric method was developed for the determination of amlodipine (AD), a calcium channel blocker, in the plasma. The type of solvent, the wavelength range, and the range of AD concentration were selected to optimize the experimental conditions. The calibration curves were linear (r² >0.997) in the concentration range of 0.1-12.5 ppm of AD. The limit of quantitation and limit of detection values for the method for plasma samples were 0.1 ppm and 0.07 ppm, respectively. The precision calculated as the relative standard deviation was less than 3.5%, and the accuracy (relative error) was better than 5.5% (n=6). The method developed in this study can be directly and easily applied for the determination of AD in the plasma without derivatization in plasma.
Método espectrofluorometrico rápido e sensível é descrito para a determinação de anlodipina (AD), um bloqueador de canais de cálcio, em amostras de plasma. O tipo de solvente, a faixa de comprimento de onda e a faixa de concentração foram escolhidas a fim de otimizar as condições experimentais. As curvas de calibração foram lineares (r > 0,997) na faixa de concentração de 0,1-12,5 ppm de AD. Os valores LoQ e LoD do método para amostras de plasma foram 0,1 ppm e 0,07 ppm, respectivamente. A precisão calculada como desvio padrão relativo (RSD) foi menor do que 3,5% e a precisão (erro relativo) foi melhor do que 5,5% (n=6). O método desenvolvido neste estudo pode ser fácil e diretamente aplicado para a determinação de AD sem derivatização no plasma.
Asunto(s)
Plasma , Espectrometría de Fluorescencia/instrumentación , Amlodipino/análisis , Espectrometría de Fluorescencia/clasificación , Estudio de ValidaciónRESUMEN
A new procedure for spectrofluorimetric determination of free and total glycerol in biodiesel samples is presented. It is based on the oxidation of glycerol by periodate, forming formaldehyde, which reacts with acetylacetone, producing the luminescent 3,5-diacetyl-1,4-dihydrolutidine. A flow system with solenoid micro-pumps is proposed for solution handling. Free glycerol was extracted off-line from biodiesel samples with water, and total glycerol was converted to free glycerol by saponification with sodium ethylate under sonication. For free glycerol, a linear response was observed from 5 to 70 mg L(-1) with a detection limit of 0.5 mg L(-1), which corresponds to 2 mg kg(-1) in biodiesel. The coefficient of variation was 0.9% (20 mg L(-1), n = 10). For total glycerol, samples were diluted on-line, and the linear response range was 25 to 300 mg L(-1). The detection limit was 1.4 mg L(-1) (2.8 mg kg(-1) in biodiesel) with a coefficient of variation of 1.4% (200 mg L(-1), n = 10). The sampling rate was ca. 35 samples h(-1) and the procedure was applied to determination of free and total glycerol in biodiesel samples from soybean, cottonseed, and castor beans.
Asunto(s)
Biocombustibles/análisis , Glicerol/análisis , Diseño de Equipo , Análisis de Inyección de Flujo/instrumentación , Análisis de Inyección de Flujo/métodos , Límite de Detección , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodosRESUMEN
An in vivo study was conducted to verify the ability of laser fluorescence (LF) to assess the activity status of occlusal caries in primary teeth, using different air-drying times. Occlusal sites (707) were examined using LF (DIAGNOdent) after air-drying for 3 s and 15 s, and the difference between readings (DIF15 s-3 s) was calculated. For concurrent validation of LF, visual criteria-Nyvad (NY) and Lesion Activity Assessment associated with the International Caries Detection and Assessment System (LAA-ICDAS)-were the reference standards for lesion activity. Histological exam using a pH-indicator dye (0.1% methyl red) was performed in 46 exfoliated/extracted teeth for criterion validation. LF readings and DIF15 s-3 s were compared using Kruskall-Wallis and Mann-Whitney tests. Receiver operating characteristic analyses were performed and validity parameters calculated, considering the caries activity assessment. Using NY, active lesions (3 s: 30.0+/-29.3; 15 s: 34.2+/-30.6) presented higher LF readings than inactive lesions (3 s: 17.0+/-16.3; 15 s: 19.2+/-17.3; p<0.05), different from LAA-ICDAS. Active cavitated caries resulted in higher LF readings (3 s: 50.3+/-3.5; 15 s: 54.7+/-30.2) than inactive cavitated caries (3 s: 19.9+/-16.3; 15 s: 22.8+/-16.8). Therefore, LF can distinguish cavitated active and inactive lesions classified by NY, but not by LAA-ICDAS; however, this difference might be related to the visual system rather than to LF. The air-drying time could be an alternative to improve the caries activity assessment; however, longer air-drying time is suggested to be tested subsequently.
Asunto(s)
Pruebas de Actividad de Caries Dental/métodos , Caries Dental/clasificación , Caries Dental/patología , Rayos Láser , Iluminación/instrumentación , Espectrometría de Fluorescencia/instrumentación , Diente Primario , Diseño de Equipo , Análisis de Falla de Equipo , HumanosRESUMEN
This paper presents a novel approach for the simultaneous determination of two widely used fungicides in a very interfering environment, combining the advantage of a spectrofluorimetric optosensor coupled to a flow-injection system and the selectivity of second-order chemometric algorithms. The sensor is based on the simultaneous retention of thiabendazole and fuberidazole on C18-bonded phase placed inside a flow-cell. After the arrival of the analytes to the sensing zone, the flow is stopped and the excitation-emission fluorescence matrix is read in a fast-scanning spectrofluorimeter. Parallel factor analysis (PARAFAC) and unfolded and multidimensional partial least-squares coupled to residual bilinearization (U- and N-PLS/RBL) were selected for data processing. These algorithms achieve the second-order advantage, and are in principle able to overcome the problem of the presence of unexpected interferences. The power of U-PLS/RBL to quantify both fungicides at parts-per-billion levels, even in the presence of high concentrations of spectral interferences such as carbaryl, carbendazim and 1-naphthylacetic acid, is demonstrated. Indeed, U-PLS/RBL allowed us to reach selectivity using a commercial but non-selective sensing support. To the best of our knowledge, this is the first time the potentiality of the 'second-order advantage' is evaluated on a flow-injection system, using an unspecific supporting material and in the presence of three real interferences. Using a sample volume of 2 mL, detection limits of 4 ng mL(-1) and 0.3 ng mL(-1) for thiabendazole and fuberidazol were respectively obtained in samples without interferences. In samples containing interferences, the limits of detection were 17 and 1 ng mL(-1) for thiabendazole and fuberidazol, respectively. The sample frequency, including excitation/emission fluorescence matrix measurements, was 12 samples h(-1). The sensor was satisfactorily applied to the determination of both analytes in real water samples.
Asunto(s)
Antifúngicos/análisis , Bencimidazoles/análisis , Espectrometría de Fluorescencia/métodos , Tiabendazol/análisis , Algoritmos , Análisis de Inyección de Flujo , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
The objective is to differentiate noncavitated caries enamel through time-resolved fluorescence and to find excitation and emission parameters that can be applied in future clinical practice for detection of caries lesions that are not clearly visible to the professional. Sixteen human teeth with noncavitiated white-spot caries were selected for this work. Fluorescence intensity decay was measured by using an apparatus based on the time-correlated single-photon counting method. An optical fiber bundle was employed for sample excitation (440 nm), and the fluorescence collected by the same bundle (500 nm) was registered. The average lifetime for sound enamel was 7.93+/-0.09, 2.46+/-0.04, and 0.51+/-0.02 ns, whereas for the carious enamel the lifetimes were 4.84+/-0.06, 1.35+/-0.02, and 0.16+/-0.01 ns. It was concluded that it is possible to differentiate between carious and sound regions by time-resolved fluorescence and that, although the origin of enamel fluorescence is still uncertain, the lifetime values seem to be typical of fluorophores like collagen I.
Asunto(s)
Biomarcadores/análisis , Caries Dental/diagnóstico , Caries Dental/metabolismo , Esmalte Dental/química , Diagnóstico por Computador/métodos , Tecnología de Fibra Óptica/instrumentación , Espectrometría de Fluorescencia/instrumentación , Algoritmos , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Técnicas In Vitro , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Espectrometría de Fluorescencia/métodosRESUMEN
O uso de interação da luz com a matéria não é um conceito novo em biologia para a detecção de processos físico-químicos, embora ainda seja utilizado de uma forma rudimentar. Já é sabido que imagens de refletância e fluorescência podem revelar informações importantes sobre tais processos em amostras biológicas. Apesar deste potencial, os sistemas experimentais disponíveis para a obtenção de tais imagens costumam serem complexos e de difícil implementação. Neste trabalho é descrita a construção e a caracterização de uma montagem experimental para produção de imagens hiperespectrais entre 400 e 1.000 nm. O sistema é composto de um espectrômetro, um conjunto de lentes para formação da imagem e uma câmera CCD para capturá-la. São descritos em detalhes o procedimento de calibração do sistema, o qual envolve os parâmetros largura da imagem, campo de visão, resolução espectral e espacial. O sistema de iluminação utiliza diodos emissores de luz de alta potência, tanto de luz branca quanto em 470 e 405 nm. Demonstramos que o sistema construído é capaz de obter imagens de fluorescência e/ou refletância de amostras biológicas. Como exemplos de aplicações, o instrumento aqui desenvolvido foi utilizado em dois campos distintos, a agricultura e a odontologia. Foram obtidas imagens de fluorescência de folhas de citros contaminadas com cancro cítrico, e de processos de desmineralização em dentes. Os resultados demonstram que o sistema construído está operando como projetado.
The use of light-mater interaction for the detection of chemicalphysical processes is not a new concept in biology, though it is still used in a rudimentary form. It is already known that reflectance as well as fluorescence images can reveal important information on such processes in biological samples. In spite of this potential, the experimental available image systems usually are complexes and of difficult implementation. In this work, we describe the construction and characterization of an experimental device to produce hyperspectral images between 400 and 1,000 nm. The system is composed of a spectrometer, a set of lenses for image formation and a CCD camera to capture it. We describe in details also the calibration procedure of the system, which involves parameters as image width, field of view, spectral and space resolution. The illumination system uses high power light emitting diodes, either at white light or at 470 and 405 nm. We demonstrate that our system is able to obtain reflectance as well as fluorescence images of biological samples. As examples of applications, we use it into two different fields, agriculture and dentistry. We obtained fluorescence images of citrus leaves contaminated with citrus canker and demineralization processes in teeth. Our results demonstrate that our system isoperating as designed.
Asunto(s)
Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Espectrometría de Fluorescencia , Análisis Espectral/instrumentación , Análisis Espectral/métodos , Diagnóstico por Imagen/instrumentación , Imagen Molecular/instrumentación , Interpretación de Imagen Asistida por Computador/instrumentación , Equipos de Medición de RiesgosRESUMEN
This review is focused on the advancements in biomedical engineering regarding the elaboration of new prototypes of optical fiber catheters to be applied in spectroscopic analysis, such as Raman and fluorescence spectroscopy. Our group has contributed to the development of new prototypes with interesting properties, such as side-viewing signal excitation and collection, distal tip with bending control, and Raman scattering minimization from the optical fiber. In addition, several groups have contributed to other new catheter-improving properties of this spectroscopic device. However, a relatively small number of studies has been published in the literature, due to industrial interest in this interdisciplinary and multidisciplinary area. To our knowledge, no review that has focused on the applications of catheters to several modes of spectroscopy has been published. In this work we revised this topic, analyzing the advancements and limitations of the recent biomedical catheters.
Asunto(s)
Cateterismo/instrumentación , Fibras Ópticas , Ingeniería Biomédica , Diseño de Equipo , Humanos , Espectrometría de Fluorescencia/instrumentación , Espectrometría Raman/instrumentaciónRESUMEN
We present an experimental and theoretical study of a new scheme for Near-Field Fluorescence Correlation Spectroscopy that, using the field enhancement by optical nanoantennas, allows the reduction of the observation volume 4 orders of magnitude below the diffraction limit. This reduction can be used in two different ways: to increase the sample concentration and to improve the spatial resolution of the dynamics under study. Our experimental results using individual gold nanoparticles and a 150 microM Rose Bengal solution in glycerol confirm the volume reduction.
Asunto(s)
Diseño Asistido por Computadora , Modelos Teóricos , Nanoestructuras/química , Nanoestructuras/ultraestructura , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Simulación por Computador , Diseño de Equipo , Análisis de Falla de Equipo , Luz , Reproducibilidad de los Resultados , Dispersión de Radiación , Sensibilidad y EspecificidadRESUMEN
Limit of accuracy for the fluorescence lifetime (FL) temperature-sensing method performed and marked that at lower temperature (< 400 K) it works well but for higher temperatures FL method does not found suitable. The non-radiative relaxation rate is noted to vary with increase in the temperature.
Asunto(s)
Espectrometría de Fluorescencia/métodos , Fluorescencia , Colorantes Fluorescentes/farmacología , Rayos Láser , Modelos Químicos , Teoría Cuántica , Reproducibilidad de los Resultados , Espectrometría de Fluorescencia/instrumentación , Temperatura , Termodinámica , Factores de TiempoRESUMEN
The growing incidence of microbial infections and the increasing ability of such organisms to acquire resistance to antimicrobial treatment lead the requirement of fast bacteria and fungi identification methods. In this work we explored optical spectroscopic techniques on fungal identification. We show that some fungal infections can be identified by ultraviolet optical excitation of fungi fluorescence followed by the spectral analysis of the emitted light. Moreover, we demonstrate that ultraviolet LED and LASER could be applied in fungal identification and a new device for fungal diagnosis is proposed.