共查询到20条相似文献,搜索用时 31 毫秒
1.
Broder J Majumder A Porter E Srinivasamoorthy G Keith C Lauderdale J Sornborger A 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(9):2921-2931
Ratiometric fluorescent indicators are becoming increasingly prevalent in many areas of biology. They are used for making quantitative measurements of intracellular free calcium both in vitro and in vivo, as well as measuring membrane potentials, pH, and other important physiological variables of interest to researchers in many subfields. Often, functional changes in the fluorescent yield of ratiometric indicators are small, and the signal-to-noise ratio (SNR) is of order unity or less. In particular, variability in the denominator of the ratio can lead to very poor ratio estimates. We present a statistical optimization method for objectively detecting and estimating ratiometric signals in dual-wavelength measurements of fluorescent, ratiometric indicators that improves on standard methods. With the use of an appropriate statistical model for ratiometric signals and by taking the pixel-pixel covariance of an imaging dataset into account, we are able to extract user-independent spatiotemporal information that retains high resolution in both space and time. 相似文献
2.
Activatable Semiconducting Theranostics: Simultaneous Generation and Ratiometric Photoacoustic Imaging of Reactive Oxygen Species In Vivo 下载免费PDF全文
Zhen Yang Yunlu Dai Chao Yin Quli Fan Wansu Zhang Justin Song Guocan Yu Wei Tang Wenpei Fan Bryant C. Yung Jie Li Xiang Li Xiangchun Li Yufu Tang Wei Huang Jibin Song Xiaoyuan Chen 《Advanced materials (Deerfield Beach, Fla.)》2018,30(23)
Enhancing the generation of reactive oxygen species (ROS) is an effective anticancer strategy. However, it is a great challenge to control the production and to image ROS in vivo, both of which are vital for improving the efficacy and accuracy of cancer therapy. Herein, an activatable semiconducting theranostic nanoparticle (NP) platform is developed that can simultaneously enhance ROS generation while self‐monitoring its levels through ratiometric photoacoustic (PA) imaging. The NP platform can further guide in vivo therapeutic effect in tumors. The theranostic NP platform is composed of: (i) cisplatin prodrug and ferric ion catalyst for ROS generation, a part of combination cancer therapy; and (ii) a ratiometric PA imaging nanoprobe consisting of inert semiconducting perylene‐diimide (PDI) and ROS activatable near‐infrared dye (IR790s), used in ratiometric PA imaging of ROS during cancer treatment. Ratiometric PA signals are measured at two near‐infrared excitation wavelengths: 680 and 790 nm for PDI and IR790s, respectively. The measurements show highly accurate visualization of ?OH generation in vivo. This novel ROS responsive organic theranostic NP allows not only synergistic cancer chemotherapy but also real‐time monitoring of the therapeutic effect through ratiometric PA imaging. 相似文献
3.
Tichauer KM Migueis M Leblond F Elliott JT Diop M St Lawrence K Lee TY 《Applied optics》2011,50(21):3962-3972
Time-domain fluorescence imaging is a powerful new technique that adds a rich amount of information to conventional fluorescence imaging. Specifically, time-domain fluorescence can be used to remove autofluorescence from signals, resolve multiple fluorophore concentrations, provide information about tissue microenvironments, and, for reflectance-based imaging systems, resolve inclusion depth. The present study provides the theory behind an improved method of analyzing reflectance-based time-domain data that is capable of accurately recovering mixed concentration ratios of multiple fluorescent agents while also recovering the depth of the inclusion. The utility of the approach was demonstrated in a number of simulations and in tissuelike phantom experiments using a short source-detector separation system. The major findings of this study were (1) both depth of an inclusion and accurate ratios of two-fluorophore concentrations can be recovered accurately up to depths of approximately 1 cm with only the optical properties of the medium as prior knowledge, (2) resolving the depth and accounting for the dispersion effects on fluorescent lifetimes is crucial to the accuracy of recovered ratios, and (3) ratios of three-fluorophore concentrations can be resolved at depth but only if the lifetimes of the three fluorophores are used as prior knowledge. By accurately resolving the concentration ratios of two to three fluorophores, it may be possible to remove autofluorescence or carry out quantitative techniques, such as reference tracer kinetic modeling or ratiometric approaches, to determine receptor binding or microenvironment parameters in point-based time-domain fluorescence applications. 相似文献
4.
Multiplexing and time averaging of signal are effective noise reduction protocols applied in many analytical measurement systems. The efficacy of these protocols may be reduced by random occurrences of high-magnitude noise that do not conform to the statistical distribution of noise for all other measurements in the data set. This high-magnitude noise, which may have an insignificant probability of occurrence for a single measurement, almost certainly affects data collected in a multichannel, multiplexed modality, such as Fourier transform infrared (FT-IR) spectroscopic imaging employing focal plane array detectors. To recover time-averaging advantages in these cases, we present a general coaddition method that uses two statistical measures, the mean and median of the ensemble of measurements of a signal, to obtain a better estimate of the true signal than that estimated by time averaging alone. This method, termed median filtered time averaging, is shown to be an effective noise removal procedure for FT-IR imaging data. The effects of noise removal on time averaging and multiplexing are examined theoretically and are demonstrated for hyperspectral infrared microspectroscopic imaging data obtained from human skin biopsies by using a rapid data acquisition procedure. 相似文献
5.
Noncontact optical imaging in mice with full angular coverage and automatic surface extraction 总被引:1,自引:0,他引:1
Meyer H Garofalakis A Zacharakis G Psycharakis S Mamalaki C Kioussis D Economou EN Ntziachristos V Ripoll J 《Applied optics》2007,46(17):3617-3627
During the past decade, optical imaging combined with tomographic approaches has proved its potential in offering quantitative three-dimensional spatial maps of chromophore or fluorophore concentration in vivo. Due to its direct application in biology and biomedicine, diffuse optical tomography (DOT) and its fluorescence counterpart, fluorescence molecular tomography (FMT), have benefited from an increase in devoted research and new experimental and theoretical developments, giving rise to a new imaging modality. The most recent advances in FMT and DOT are based on the capability of collecting large data sets by using CCDs as detectors, and on the ability to include multiple projections through recently developed noncontact approaches. For these to be implemented, we have developed an imaging setup that enables three-dimensional imaging of arbitrary shapes in fluorescence or absorption mode that is appropriate for small animal imaging. This is achieved by implementing a noncontact approach both for sources and detectors and coregistering surface geometry measurements using the same CCD camera. A thresholded shadowgrammetry approach is applied to the geometry measurements to retrieve the surface mesh. We present the evaluation of the system and method in recovering three-dimensional surfaces from phantom data and live mice. The approach is used to map the measured in vivo fluorescence data onto the tissue surface by making use of the free-space propagation equations, as well as to reconstruct fluorescence concentrations inside highly scattering tissuelike phantom samples. Finally, the potential use of this setup for in vivo small animal imaging and its impact on biomedical research is discussed. 相似文献
6.
A hierarchical method for evaluating products with quantitative and sensory characteristics 总被引:1,自引:0,他引:1
In some industries, such as food processing, product performance is assessed with multiple criteria including both quantitative measurements and subjective characteristics evaluated by a sensory panel. A sensory panel consists of trained individuals who compare products yielding data often in the form of matrices of paired comparisons. This paper presents a hierarchical method, based on the Analytic Hierarchy Process, for computing weights, or composite performance measures, for products of this type. The paper also presents a new method for collecting and analyzing sensory panel data. The proposed method enables comparison of alternative products taking into account multiple quantitative and sensory responses, their relative importance, and the experience and reliability of panel members. 相似文献
7.
Semiconducting polymer-based nanoparticles (Pdots) have recently emerged as a new class of ultrabright probes for biological detection and imaging. This paper describes the development of poly(2,5-di(3',7'-dimethyloctyl)phenylene-1,4-ethynylene) (PPE) Pdots as a platform for designing Fo?rster resonance energy transfer (FRET)-based ratiometric pH nanoprobes. We describe and compare three routes for coupling the pH-sensitive dye, fluorescein, to PPE Pdots, which is a pH-insensitive semiconducting polymer. This approach offers a rapid and robust sensor for pH determination using the ratiometric methodology where excitation at a single wavelength results in two emission peaks, one that is pH sensitive and the other one that is pH insensitive for use as an internal reference. The linear range for pH sensing of the fluorescein-coupled Pdots is between pH 5.0 and 8.0, which is suitable for most cellular studies. The pH-sensitive Pdots show excellent reversibility and stability in pH measurements. In this paper, we use them to measure the intracellular pH in HeLa cells following their uptake by endocytosis, thus demonstrating their utility for use in cellular and imaging experiments. 相似文献
8.
Wright P Garcia-Stewart CA Carey SJ Hindle FP Pegrum SH Colbourne SM Turner PJ Hurr WJ Litt TJ Murray SC Crossley SD Ozanyan KB McCann H 《Applied optics》2005,44(31):6578-6592
Design requirements for an 8000 frame/s dual-wavelength ratiometric chemical species tomography system, intended for hydrocarbon vapor imaging in one cylinder of a standard automobile engine, are examined. The design process is guided by spectroscopic measurements on iso-octane and by comprehensive results from laboratory phantoms and research engines, including results on temporal resolution performance. Novel image reconstruction techniques, necessary for this application, are presented. Recent progress toward implementation, including details of the optical access arrangement employed and signal-to-noise issues, is described. We present first cross-cylinder IR absorption measurements from a reduced channel-count (nontomographic) system and discuss the prospects for imaging. 相似文献
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富G序列AGRO100核酸探针与荧光染料硫磺素T(ThT)和N-甲基卟啉二丙酸IX(NMM)结合后,随着铅离子的加入ThT和NMM的荧光强度会发生相对变化,从而建立了用于铅离子定量分析的、免标记的广义比率型荧光传感方法。将该方法与新型荧光定量模型(QFM)相结合,分析4个不同地段湘江水中铅离子的浓度。研究结果表明:广义比率型荧光探针结合QFM,能够准确定量分析4个不同地段湘江水中铅离子的浓度,该分析结果与电感耦合等离子体质谱仪(ICP-MS)得到的结果基本一致,加标回收率均在91%~108%的范围内。 相似文献
10.
Statistical estimates from simulation involve uncertainty caused by the variability in the input random variables due to limited data. Allocating resources to obtain more experimental data of the input variables to better characterize their probability distributions can reduce the variance of statistical estimates. The methodology proposed determines the optimal number of additional experiments required to minimize the variance of the output moments given single or multiple constraints. The method uses multivariate t-distribution and Wishart distribution to generate realizations of the population mean and covariance of the input variables, respectively, given an amount of available data. This method handles independent and correlated random variables. A particle swarm method is used for the optimization. The optimal number of additional experiments per variable depends on the number and variance of the initial data, the influence of the variable in the output function and the cost of each additional experiment. The methodology is demonstrated using a fretting fatigue example. 相似文献
11.
Meng Yuan Xiao Fang Jianyong Liu Kaiqiong Yang Shenggan Xiao Sheng Yang Wei Du Jibin Song 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(11):2206666
Optical imaging in the second near-infrared (NIR-II, 900–1700 nm) window has been extensively investigated for bioimaging. However, a strong autofluorescence background from real-time excitation light significantly reduces the images’ quality of NIR-II fluorescence (FL) imaging. To resolve this issue, a NIR-II self-luminous small molecule (CLPD) based on bioluminescence (BL) resonance energy transfer (BRET) mechanism is first developed. The reactive oxygen species (ROS) can trigger NIR-II BL and reduce the NIR-II FL signals of the CLPD simultaneously, enabling ROS-correlated ratiometric BL/FL imaging. CLPD is used for high-contrast NIR-II BL imaging of osteoarthritis as well as guiding the treatment process by ratiometric BL/FL imaging. Moreover, CLPD is applied for NIR-II BL imaging of tumor triggered by the generated ROS during PDT. A correlation between the ratiometric NIR-II BL/FL signal and tumor size is constructed, providing a trustworthy tool for early assessment of PDT effect. Overall, this study presents a novel NIR-II self-luminous small molecular probe for in vivo imaging and provides a strategy for design a self-evaluation system of therapeutic effect. 相似文献
12.
Theranostic Upconversion Nanobeacons for Tumor mRNA Ratiometric Fluorescence Detection and Imaging‐Monitored Drug Delivery 下载免费PDF全文
Qianwen Ding Qiuqiang Zhan Xiaoming Zhou Tao Zhang Da Xing 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(43):5944-5953
Remote optical detection and imaging of specific tumor‐related biomarkers and simultaneous activation of therapy according to the expression level of the biomarkers in tumor site with theranostic probes should be an effective modality for treatment of cancers. Herein, an upconversion nanobeacon (UCNPs‐MB/Dox) is proposed as a new theranostic nanoprobe to ratiometrically detect and visualize the thymidine kinase 1 (TK1) mRNA that can simultaneously trigger the Dox release to activate the chemotherapy accordingly. UCNPs‐MB/Dox is constructed with the conjugation of a TK1 mRNA‐specific molecular beacon (MB) bearing a quencher (BHQ‐1) and an alkene handle modified upconversion nanoparticle (UCNP) through click reaction and subsequently loading with a chemotherapy drug (Dox). With this nanobeacon, quantitative ratiometric upconversion detection of the target with high sensitivity and selectivity as well as the target triggered Dox release in vitro is demonstrated. The sensitive and selective ratiometric detection and imaging of TK1 mRNA under the irradiation of near infrared light (980 nm) and the mRNA‐dependent release of Dox for chemotherapy in the tumor MCF‐7 cells and A549 cells are also shown. This work provides a smart and robust platform for gene‐related tumor theranostics. 相似文献
13.
Monitoring gene expression is at the center of research for a wide variety of medical, biological, and biotechnological applications. Currently no method exists for true multiple gene expression monitoring inside of a single living cell that allows for the gene expression profile of the cell to be directly compared with another single living cell. By microinjecting multiple molecular beacons with different fluorophores inside of single breast carcinoma cells and monitoring with advanced fluorescent microscopy, the expression of multiple genes can be simultaneously monitored inside single living cells. Using ratiometric analysis as a basis for the measurements allows the different gene expression levels to be compared from cell to cell. Not only does this allow differentiation of individual mRNA expression levels between multiple single cells but it also allows for mRNA expression trend analysis at the single cell level. 相似文献
14.
A new general approach for rapid assessment of polymerization catalysts is introduced. Native fluorescence emission of solid polymers is measured directly in combinatorial 96-microreactor arrays and polymers produced in a laboratory-scale validation reactor. Fluorescence features collected with a CCD-based spectrofluorometer are correlated with chemical properties of interest such as polymer molecular weight, amount of branching, and catalyst selectivity. The approach is illustrated by screening of selectivity of melt polymerization catalysts used in synthesis of an aromatic bisphenol A polycarbonate. Selectivity of catalysts correlated with the ratio of fluorescence intensities at 400 and 500 nm at 340-nm excitation. The relative standard deviation (RSD) in spectroscopic serial measurements was 1-12.5%. This spread included instrument variability (< or = 1% RSD) and sample inhomogeneity. Parallel quantitative screening of catalyst selectivity in combinatorial 96-microreactor arrays was performed as a two-wavelength ratiometric fluorescence imaging through 400- and 500-nm interference filters and showed a good correlation (R2 = 0.994) with serial screening. Our approach is an attractive alternative to traditional separation-based techniques if speed and nondestructive nature of analysis are critical and when the high cross-linking or solvent resistance of polymers complicates traditional analysis. 相似文献
15.
Walker WF 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2001,48(2):452-461
Conventional ultrasonic imaging systems depict tissue backscatter, that is, the ultrasonic energy reflected directly back toward the transmitter. Although diagnostically useful, these systems fail to exploit the information available in components of the sound field scattered in other directions. This paper describes a new method of imaging this angular scatter. First, the translating apertures algorithm (TAA) is used to acquire data at two scattering angles. Then, these data are processed to yield an image of the common scattering with angle and the differential scattering with angle. This paper explores the potential of these common-weighted (c-weighted) and difference-weighted (d-weighted) images using theory and simulations. In addition, it describes and analyzes the performance of the TAA when it is applied using multiple receive elements. Analysis is presented that shows that, in Rayleigh scattering environments, c- and d-weighted images depict compressibility and density variations, respectively. A simulated image and accompanying analysis are presented that show the potential of these techniques to improve soft tissue contrast and to increase the detectability of microcalcifications. A comparison with previous angular scatter measurement techniques shows that use of the TAA significantly reduces statistical variability in measured angular scatter profiles. Spatially localized, statistically reliable angular scatter measurements will enable a broad range of angular scatter imaging techniques. C- and d-weighted imaging may ultimately he applied clinically to identify calcification in atherosclerotic plaques and breast tumors 相似文献
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Electrokinetic transport in nanochannels. 2. Experiments 总被引:1,自引:0,他引:1
We present an experimental study of nanoscale electrokinetic transport in custom-fabricated quartz nanochannels using quantitative epifluorescence imaging and current monitoring techniques. One aim is to yield insight into electrical double layer physics and study the applicability of continuum theory to nanoscale electrokinetic systems. A second aim is to explore a new separation modality offered by nanoscale electrophoretic separations. We perform parametric variations of applied electric field, channel depth, background buffer concentration, and species valence to impose variations on zeta potential, effective mobility, and Debye length among other parameters. These measurements were used to validate a continuum theory-based analytical model presented in the first of this two-paper series. Our results confirm the usefulness of continuum theory in predicting electrokinetic transport and electrophoretic separations in nanochannels. Our model leverages independent measurements of zeta potential performed in a microchannel system at electrolyte concentrations of interest. These data yield a zeta potential versus concentration relation that is used as a boundary condition for the nanochannel electrokinetic transport model. The data and model comparisons together show that the effective mobility governing electrophoretic transport of charged species in nanochannels depends not only on ion mobility values but also on the shape of the electric double layer and analyte ion valence. We demonstrate a method we term electrokinetic separation by ion valence, whereby both ion valence and mobility may be determined independently from a comparison of micro- and nanoscale transport measurements. 相似文献
19.
Eunwoo Kim Yeji Han Hyunwook Park 《International journal of imaging systems and technology》2011,21(4):315-322
The stimulation paradigms of a functional MRI (fMRI) usually consist of one or more stimulations and a resting state in the block‐based and event‐related designs. To localize the activation areas in the human brain, each voxel is statistically analyzed using the fMRI data measured with the stimulation. The conventional method can be inefficient for experiments with multiple stimuli because of measuring the resting‐state signals repeatedly, causing redundancy in the scanning process. Although the phase mapping method can be applied to reduce the redundant resting‐state measurements, there are still limitations in the detection of regions activated by multiple stimuli and the periodic sequence of the multiple stimuli. In this article, a new fMRI data analysis method is presented that enables the detection of functional activations without the resting‐state images. This method estimates the reference signal from the signals acquired during multiple stimuli, and a random sequence and various durations of the multiple stimuli can be applied. Therefore, it can be used in the event‐related design as well as the block‐based design. The results of simulation and fMRI experiments show that the proposed method can correctly detect the activation regions of multiple stimuli, even for overlap regions, and can reduce the imaging time by skipping the resting‐state imaging. © 2011 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 21, 315–322, 2011 相似文献
20.
Near-field microwave nondestructive evaluation (NDE) techniques have shown great potential for disbond detection in multilayer dielectric composite structures. The high detection capability associated with these techniques stems from the fact that near-field microwave signals are sensitive to minute variations in the dielectric properties and geometry of the medium in which they propagate. In the past, the sensitivity of the near-field microwave NDE techniques to the presence and properties of disbonds in multilayer dielectric composites has been investigated extensively. However, a quantitative disbond thickness estimation method has yet to be introduced. In this paper, we propose a maximum-likelihood (ML) disbond thickness evaluation method utilizing multiple independent measurements obtained at different frequencies. We also introduce a statistical lower limit on the thickness resolution based on the mean-squared error in thickness estimation and a given confidence interval. The effectiveness of the proposed ML method is also verified by comparing simulation results with actual measurements. 相似文献