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Microfluidic Sensors with Impregnated Fluorophores for Simultaneous Imaging of Spatial Structure and Chemical Oxygen Gradients
摘要： Interior surfaces of polystyrene microfluidic structures were impregnated with the oxygen sensing dye Pt(II) tetra(pentafluorophenyl)porphyrin (PtTFPP) using a solvent-induced fluorophore impregnation (SIFI) method. Using this technique, microfluidic oxygen sensors are obtained that enable simultaneous imaging of both chemical oxygen gradients and the physical structure of the microfluidic interior. A gentle method of fluorophore impregnation using acetonitrile solutions of PtTFPP at 50oC was developed leading to a 10-μm-deep region containing fluorophore. This region is localized at the surface to sense oxygen in the interior fluid during use. Regions of the device that do not contact the interior fluid pathways lack fluorophores and are dark in fluorescent imaging. The technique was demonstrated on straight microchannel and pore network devices, the latter having pillars of 300 μm diameter spaced center to center at 340 μm providing pore throats of 40 μm. Sensing within channels or pores, and imaging across the pore network devices were performed using a Lambert LIFA-P frequency domain fluorescence lifetime imaging system on a Leica microscope platform. Calibrations of different devices prepared by the SIFI method were indistinguishable. Gradient imaging showed fluorescent regions corresponding to the fluid pore network, dark pillars, and fluorescent lifetime varying across the gradient, thus providing both physical and chemical imaging. More generally, the SIFI technique can impregnate the interior surfaces of other polystyrene containers, such as cuvettes or cell and tissue culture containers, to enable sensing of interior conditions.
关键词： Oxygen,sensor,impregnation,fluorophore,chemical imaging,pore network,polystyrene,microfluidic
更新于2025-09-23 15:22:29
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Recent Trends in Compressive Raman Spectroscopy Using DMD-Based Binary Detection
摘要： The collection of high-dimensional hyperspectral data is often the slowest step in the process of hyperspectral Raman imaging. With the conventional array-based Raman spectroscopy acquiring of chemical images could take hours to even days. To increase the Raman collection speeds, a number of compressive detection (CD) strategies, which simultaneously sense and compress the spectral signal, have recently been demonstrated. As opposed to conventional hyperspectral imaging, where full spectra are measured prior to post-processing and imaging CD increases the speed of data collection by making measurements in a low-dimensional space containing only the information of interest, thus enabling real-time imaging. The use of single channel detectors gives the key advantage to CD strategy using optical filter functions to obtain component intensities. In other words, the filter functions are simply the optimized patterns of wavelength combinations characteristic of component in the sample, and the intensity transmitted through each filter represents a direct measure of the associated score values. Essentially, compressive hyperspectral images consist of 'score' pixels (instead of 'spectral' pixels). This paper presents an overview of recent advances in compressive Raman detection designs and performance validations using a DMD based binary detection strategy.
关键词： Chemometrics,multivariate data analysis,digital light processor (DLP),digital micromirror device (DMD),optimal binary filters,spatial light modulators (SLM),Raman spectroscopy,chemical imaging,compressive detection
更新于2025-09-23 15:22:29
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An approach for broad molecular imaging of the root-soil interface via indirect matrix-assisted laser desorption/ionization mass spectrometry
摘要： Understanding rhizospheric processes is limited by the need for imaging complex molecular transformations at relevant spatial scales within the root soil continuum. Here, we demonstrate a method to enable this analysis by first extracting organic compounds from the rhizosphere onto a PVDF membrane while maintaining their 2D distribution and then imaging the distribution of chemical compounds using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This approach permitted us to visualize and identify compounds on the root surface and presumed root exudates in the rhizosphere. Within a 1.8 cm x 0.6 cm sampling area of a switchgrass rhizosphere, we could observe at least four chemically distinct zones. Using high performance Fourier transform ion cyclotron MS, we were able to accurately annotate numerous molecules co-localized to each of these zones.
关键词： chemical imaging,PVDF membrane,spatial metabolomics,MALDI,rhizosphere,liquid chromatography
更新于2025-09-23 15:21:01
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Investigation of minor elemental species within tablets using in situ depth profiling via laser-induced breakdown spectroscopy hyperspectral imaging
摘要： Laser-induced breakdown spectroscopy (LIBS) hyperspectral imaging allows for the determination of two-dimensional and three-dimensional spatial distributions of elemental species throughout complex samples. In this work, LIBS hyperspectral imaging was utilized to investigate minor elemental species within tablets. Representative LIBS spectra were initially collected on four complex, heterogeneous tablets, showing high concentrations of Ti in the tablet coating, with low and variable abundance of Na, Mg, and K. Principal component analysis revealed distinct resolution of the four tablets due to differences in Na, Mg, and K. Using two-dimensional LIBS hyperspectral imaging, spatial distributions of Na, Mg, and K within defined x and y regions of the tablet coating were generated. Subsequent three-dimensional LIBS hyperspectral imaging further elucidated the full x, y, and z spatial distributions of these minor elemental species within the tablet surface, tablet coating, and tablet core. As such, in situ depth profiling of the minor elemental species within each tablet was accomplished. Quantification of the homogeneity and uniformity of each tablet was determined. To our knowledge, this is the first report of multivariate analysis, LIBS, and LIBS hyperspectral imaging being utilized for the determination of both 2D and 3D spatial distributions of minor elemental species, along with quantification of tablet homogeneity, within tablets.
关键词： Chemical imaging,Laser-induced breakdown spectroscopy,Chemometrics,Pharmaceutical analysis,Atomic spectroscopy
更新于2025-09-23 15:19:57
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Smart Nanocontainers || Advanced spectroscopic technique for the study of nanocontainers: atomic force microscopy-infrared spectroscopy (AFM-IR)
摘要： Over the years, advances in the synthesis of nanostructures have enabled the appearance of a large number of nanocontainers. The materials constructing nanocontainers cover a wide range of compounds including small molecules, polymers, micelles, dendrimers, mesoporous silica nanoparticles, layered double hydroxides, halloysite nanotubes, and metal-organic frameworks (MOFs). The structure of nanocontainers based on them has an inner compartment that can be used for storage or encapsulation of guests including anticancer drugs, corrosion inhibitors, and water-treating absorbents. Because of this special structure, nanocontainers are of great interests in applications such as drug delivery system, corrosion prevention, and environment protection. For example, when nanocontainers are used as drug delivery devices, they are of great advantages to characterize the drug/device properties using spectroscopic techniques including Fourier transform infrared spectroscopy and Raman spectroscopy.
关键词： AFM-IR,nanoscale,spectroscopy,chemical imaging,nanocontainers
更新于2025-09-23 15:19:57
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An Expandable Mechanopharmaceutical Device (3): a Versatile Raman Spectral Cytometry Approach to Study the Drug Cargo Capacity of Individual Macrophages
摘要： Purpose To improve cytometric phenotyping abilities and better understand cell populations with high interindividual variability, a novel Raman-based microanalysis was developed to characterize macrophages on the basis of chemical composition, specifically to measure and characterize intracellular drug distribution and phase separation in relation to endogenous cellular biomolecules. Methods The microanalysis was developed for the commercially-available WiTec alpha300R confocal Raman microscope. Alveolar macrophages were isolated and incubated in the presence of pharmaceutical compounds nilotinib, chloroquine, or etravirine. A Raman data processing algorithm was specifically developed to acquire the Raman signals emitted from single-cells and calculate the signal contributions from each of the major molecular components present in cell samples. Results Our methodology enabled analysis of the most abundant biochemicals present in typical eukaryotic cells and clearly identified Bfoamy^ lipid-laden macrophages throughout cell populations, indicating feasibility for cellular lipid content analysis in the context of different diseases. Single-cell imaging revealed differences in intracellular distribution behavior for each drug; nilotinib underwent phase separation and self-aggregation while chloroquine and etravirine accumulated primarily via lipid partitioning. Conclusions This methodology establishes a versatile cytometric analysis of drug cargo loading in macrophages requiring small numbers of cells with foreseeable applications in toxicology, disease pathology, and drug discovery.
关键词： lipid-laden foamy macrophages,intracellular drug bioaccumulation,single-cell chemical imaging,confocal Raman microscopy,pulmonary alveolar macrophages
更新于2025-09-23 15:19:57
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Two-stage optimal scheduling of air conditioning resources with high photovoltaic penetrations
摘要： Infrared chemical microscopy through mechanical probing of light?matter interactions by atomic force microscopy (AFM) bypasses the diffraction limit. One increasingly popular technique is photoinduced force microscopy (PiFM), which utilizes the mechanical heterodyne signal detection between cantilever mechanical resonant oscillations and the photoinduced force from the light?matter interaction. So far, PiFM has been operated in only one heterodyne configuration. In this Article, we generalize heterodyne configurations of PiFM by introducing two new schemes: harmonic heterodyne detection and sequential heterodyne detection. In harmonic heterodyne detection, the laser repetition rate matches integer fractions of the difference between the two mechanical resonant modes of the AFM cantilever. The high harmonic of the beating from the photothermal expansion mixes with the AFM cantilever oscillation to provide the PiFM signal. In sequential heterodyne detection, the combination of the repetition rate of laser pulses and the polarization modulation frequency matches the difference between two AFM mechanical modes, leading to detectable PiFM signals. These two generalized heterodyne configurations for PiFM deliver new avenues for chemical imaging and broadband spectroscopy at ～10 nm spatial resolution. They are suitable for a wide range of heterogeneous materials across various disciplines: from structured polymer film, to polaritonic boron nitride materials, to isolated bacterial peptidoglycan cell walls. The generalized heterodyne configurations introduce flexibility for the implementation of PiFM and the related tapping-mode AFM-IR and provide possibilities for an additional modulation channel in PiFM for targeted signal extraction with nanoscale spatial resolution.
关键词： photoinduced force microscopy,nanoscale spatial resolution,chemical imaging,Infrared chemical microscopy,heterodyne configurations,broadband spectroscopy
更新于2025-09-19 17:13:59
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A Nondestructive Detection Method for Mixed Veterinary Drugs in Pork Using Line-Scan Raman Chemical Imaging Technology
摘要： This study reports a nondestructive detection method using Raman chemical imaging (RCI) technology for the simultaneous determination of multiple veterinary drugs, such as ofloxacin, chloramphenicol, and sulfadimidine, in pork. A line-scan Raman imaging system was employed to acquire images of pure veterinary drugs and pork samples containing single and mixed drugs. Raman characteristic peaks at 1623, 1353, and 1147 cm?1 were identified for ofloxacin, chloramphenicol, and sulfadimidine, respectively. An image processing method was proposed to calculate the Bpixel-ratio^ values in each feature image, and linear regression models for a single veterinary drug were then established between the Bpixel-ratio^ values and the actual concentrations. By applying the models to samples with mixed veterinary drugs, the concentrations of the three drugs were predicted with correlation coefficients of 0.978, 0.986, and 0.984. The satisfactory results indicated that along with the proposed Bpixel-ratio^ method, RCI technology enables the nondestructive quantitation and spatial distribution visualization of multiple veterinary drug residues.
关键词： Raman chemical imaging,Spatial distribution,Pork,Veterinary drugs,Pixel-ratio,Quantitative analysis
更新于2025-09-10 09:29:36
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Correlated Materials Characterization via Multimodal Chemical and Functional Imaging
摘要： Multimodal chemical imaging simultaneously offers high resolution chemical and physical information with nanoscale, and in select cases atomic resolution. By coupling modalities that collect physical and chemical information, we can address scientific problems in biological systems, battery and fuel cell research, catalysis, pharmaceuticals, photovoltaics, medicine and many others. The combined systems enable local correlation of material properties with chemical makeup, making fundamental questions in how chemistry and structure drive functionality approachable. In this review we present recent progress and offer a perspective for chemical imaging used to characterize a variety of samples by a number of platforms. Specifically, we present cases in infrared and Raman spectroscopies combined with scanning probe microscopy; optical microscopy and mass spectrometry; nonlinear optical microscopy; and finally, ion, electron and probe microscopies with mass spectrometry. We also discuss the challenges associated with the use of data originated by the combinatorial hardware, analysis, and machine learning as well as processing tools necessary for interpretation of multidimensional data acquired from multimodal studies.
关键词： raman spectroscopy,ion microscopy,nonlinear optical microscopy,mass spectrometry,electron microscopy,infrared spectroscopy,chemical imaging,scanning probe microscopy,data analytics,optical microscopy
更新于2025-09-10 09:29:36
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Advances in Raman spectroscopy and imaging techniques for quality and safety inspection of horticultural products
摘要： This paper gives an overview of Raman technology for inspecting quality and safety of horticultural products. Emphasis is put on introduction and demonstration of Raman spectroscopy and imaging techniques for practical uses to assess the horticultural products. Raman scattering principles are presented first, followed by introduction and comparison to Raman measurement techniques, such as backscattering Raman spectroscopy, transmission Raman spectroscopy, spatially offset Raman spectroscopy, Raman chemical imaging, surface-enhanced Raman spectroscopy, etc. Raman measurement instruments, including excitation sources, wavelength separation devices, detectors, commercial integrated and custom-developed systems, and system calibration methods, are discussed and compared. Raman data analysis methods, such as data preprocessing, spectral mixture analysis, and quantitative analysis, are presented with examples for analyzing Raman spectral and image data of selected horticultural products including tomato and carrot. Raman spectroscopy and imaging applications for quality and safety evaluation of the horticultural products are also reviewed.
关键词： Horticultural products,Raman spectroscopy,Quality,Lasers,Safety,Chemical imaging
更新于2025-09-09 09:28:46