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Label-free Evaluation of Myocardial Infarct in Surgically Excised Ventricular Myocardium by Raman Spectroscopy
摘要： Understanding the viability of the ischemic myocardial tissue is a critical issue in determining the appropriate surgical procedure for patients with chronic heart failure after myocardial infarction (MI). Conventional MI evaluation methods are; however, preoperatively performed and/or give an indirect information of myocardial viability such as shape, color, and blood flow. In this study, we realize the evaluation of MI in patients undergoing cardiac surgery by Raman spectroscopy under label-free conditions, which is based on intrinsic molecular constituents related to myocardial viability. We identify key signatures of Raman spectra for the evaluation of myocardial viability by evaluating the infarct border zone myocardium that were excised from five patients under surgical ventricular restoration. We also obtain a prediction model to differentiate the infarcted myocardium from the non-infarcted myocardium by applying partial least squares regression-discriminant analysis (PLS-DA) to the Raman spectra. Our prediction model enables identification of the infarcted tissues and the non-infarcted tissues with sensitivities of 99.98% and 99.92%, respectively. Furthermore, the prediction model of the Raman images of the infarct border zone enabled us to visualize boundaries between these distinct regions. Our novel application of Raman spectroscopy to the human heart would be a useful means for the detection of myocardial viability during surgery.
关键词： label-free evaluation,myocardial viability,Raman spectroscopy,partial least squares regression-discriminant analysis,myocardial infarction
更新于2025-09-11 14:15:04
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A New Device Based on Interferometric Optical Detection Method for Label-Free Screening of C-Reactive Protein
摘要： In previous work, the performance of a compact and cost-effective point-of-care (PoC) device based on the increase relative optical power (IROP) methodology is reported and it is determined the enhancement in comparison with standard high-resolution spectrometry in terms of limit of detection. This paper describes a new label-free IROP-based biomedical device capable of working with low concentration of reagents and low sample volume per measurement in order to be used for screening different steps necessary in immunoassay optimization. This new approach significantly improves the sensing performance in terms of read-out signal (ΔIROP) per nanometer of biofilm in comparison with our previous work. This improvement is achieved due to the implementation of a laser as light source of the optical read-out system and the redesign of Fabry–Perot transducers by optimizing their reflectivity response and reducing their sensing area. For demonstrating the screening capability of this new PoC device in several immunoassays steps and methodologies, a C-reactive protein detection assay was carried out as a potential application and assay model. It is remarkable that only 10 μL of sample was used per measurement. This label-free IROP-based device complies an easy-to-use and cost-effective tool for immunoassays optimization in terms of performance, reagents cost, and measuring time.
关键词： C-reactive protein (CRP),label-free optical screening,immunoassays,point-of-care (PoC) devices,biosensors
更新于2025-09-10 09:29:36
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Automatic classification of label-free cells from small cell lung cancer and poorly differentiated lung adenocarcinoma with 2D light scattering static cytometry and machine learning
摘要： Small cell lung cancer (SCLC) needs to be classified from poorly differentiated lung adenocarcinoma (PDLAC) for appropriate treatment of lung cancer patients. Currently, the classification is achieved by experienced clinicians, radiologists and pathologists based on subjective and qualitative analysis of imaging, cytological and immunohistochemical (IHC) features. Label-free classification of lung cancer cell lines is developed here by using two-dimensional (2D) light scattering static cytometric technique. Measurements of scattered light at forward scattering (FSC) and side scattering (SSC) by using conventional cytometry show that SCLC cells are overlapped with PDLAC cells. However, our 2D light scattering static cytometer reveals remarkable differences between the 2D light scattering patterns of SCLC cell lines (H209 and H69) and PDLAC cell line (SK-LU-1). By adopting support vector machine (SVM) classifier with leave-one-out cross-validation (LOO-CV), SCLC and PDLAC cells are automatically classified with an accuracy of 99.87%. Our label-free 2D light scattering static cytometer may serve as a new, accurate, and easy-to-use method for the automatic classification of SCLC and PDLAC cells.
关键词： static cytometry,2D light scattering,label-free,lung cancer,machine learning
更新于2025-09-10 09:29:36
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Determination of the activity of T4 polynucleotide kinase phosphatase by exploiting the sequence-dependent fluorescence of DNA-templated copper nanoclusters
摘要： A fluorometric method is described for the determination of the activity of the enzyme T4 polynucleotide kinase phosphatase (T4 PNKP). A short 3′-terminus phosphorylated DNA strand is hybridized with a long DNA strand to produce a partially double-stranded DNA (dsDNA) substrate. On addition of T4 PNKP, the substrate is dephosphorylated to generate the long dsDNA, and then the long dsDNA acted as a template for synthesizing copper nanoclusters (CuNCs). The dsDNA-templated CuNCs display fluorescence with excitation/emission peak wavelengths of 340/570 nm. The fluorescence is DNA sequence-dependent. A DNA substrate was designed to enhance fluorescence and to reduce the background in order to improve the sensitivity of the assay. The assay has an analytical range that extends from 0.07 U mL?1 to 15 U mL?1 and a detection limit of 0.06 U mL?1.
关键词： Near-zero background,Label-free,Copper nanoclusters,T4 polynucleotide kinase phosphatase activity,Fluorescent biosensing
更新于2025-09-10 09:29:36
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Label-free imaging of amyloid plaques in Alzheimer’s disease with stimulated Raman scattering microscopy
摘要： One of the key pathological features of Alzheimer’s disease (AD) is the existence of extracellular deposition of amyloid plaques formed with misfolded amyloid-β (Aβ). The conformational change of proteins leads to enriched contents of β sheets, resulting in remarkable changes of vibrational spectra, especially the spectral shifts of the amide I mode. Here, we applied stimulated Raman scattering (SRS) microscopy to image amyloid plaques in the brain tissue of an AD mouse model. We have demonstrated the capability of SRS microscopy as a rapid, label-free imaging modality to differentiate misfolded from normal proteins based on the blue shift (~10 cm?1) of amide I SRS spectra. Furthermore, SRS imaging of Aβ plaques was verified by antibody staining of frozen thin sections and fluorescence imaging of fresh tissues. Our method may provide a new approach for studies of AD pathology, as well as other neurodegenerative diseases associated with protein misfolding.
关键词： amyloid plaques,protein misfolding,Alzheimer’s disease,stimulated Raman scattering microscopy,label-free imaging
更新于2025-09-09 09:28:46
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Label-free detection of folic acid using a sensitive fluorescent probe based on ovalbumin stabilized copper nanoclusters
摘要： In this work, ovalbumin (OVA) stabilized copper nanoclusters (OVA-Cu NCs) were prepared through a simple protein-stabilized synthetic method and applied for the sensitive determination of FA. Cu2+ ions were directly reduced to Cu (0) by a mild reducing agent, N2H4·H2O, at room temperature without any other complicated procedure such as adjusting pH and controlling the temperature of the reaction mixture. The as-prepared OVA-Cu NCs showed good chemical stability, wonderful water solubility and excellent biocompatibility. The OVA-Cu NCs were obtained with an average particle size of 2.0 nm and good dispersibility in aqueous solution. They also showed strong red emitting at 625 nm with a quantum yield of 3.95%. The OVA-Cu NCs were then applied for label-free detection of FA based on a static quenching mechanism. The linear calibration curve of detecting FA served from 0.5 μM -200 μM with the detection limit of 0.18 μM. In addition, the developed method was also successfully applied to determine the content of FA in tablet, spinach, orange juice and biological samples with quantitative spike recoveries from 96.9% to 100.9%. For these reasons, the developed OVA-Cu NCs-based fluorescent strategy can thus offer a convenient label-free biosensor platform for the detection of FA in biomedical applications.
关键词： label-free detection,folic acid,red emitting,copper nanoclusters
更新于2025-09-09 09:28:46
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Label-Free Bioanalysis Based on Low-Q Whispering Gallery Modes: Rapid Preparation of Microsensors by Means of Layer-by-Layer Technology
摘要： Low-Q-whispering gallery modes (low-Q-WGM) can be used for label-free detection of interactions between biomolecules, measuring their binding and release kinetics or for analysis of changes in the medium in real-time. The main advantage of the low-Q-WGM approach over other label-free methods is the possibility of measurements in small cavities as the method uses microparticles down to 6 μm as sensors. Commercially available dye-doped microparticles that are used as low-Q-WGM sensors exhibit several drawbacks. Therefore, alternative particle types are developed and optimized as low-Q-WGM sensors. First, dye-doped particles made of different materials are screened. The most critical parameter for WGM performance is the refractive index (RI) of sensor particles. Furthermore, surface roughness of particles, determined by scanning electron microscopy and atomic force microscopy, affects their performance as WGM microsensors. In the second test, fluorescent dyes immobilized on nonfluorescent particles by means of nanometer thick layer-by-layer (LbL) films are shown to generate a strong WGM signal. The LbL-coated particles show remarkably less background fluorescence than dye-doped particles and are easier to prepare. Finally, this article proposes rapid preparation methods for WGM microparticle sensors based on various parameters such as material type, RI, surface roughness, and number of coated polymer layers.
关键词： fluorescent microparticles,whispering gallery mode,layer-by-layer coating,label-free bioanalytics
更新于2025-09-09 09:28:46
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Express and portable label-free DNA detection and recognition with SERS platform based on functional Au grating
摘要： Label-free SERS-based detection of DNA is considered as one of the most prospective analytical methods for portable and express bioanalysis. In this work, the SERS platform based on the functional surface plasmon polariton supported ordered structure is proposed as an extremely convenient and effective tool for the detection of specific DNA sequences. The designed SERS structure makes possible DNA analyses in near-real time using the portable Raman spectrometer, with high reproducibility and accuracy of the results and the detection limits of the order of 10-14 M. In order to overcome challenges, connected to meticulous affiliation and evaluation of Raman signals, principal component analysis (PCA) of raw SERS data was used for data evaluation. SERS results reproducibility was achieved through the creation of a periodical structure with homogenous distribution of plasmon energy, when the analysis functionality was implemented through the grafting of the oligonucleotide to gold surface and its further interaction with complementary, mispaired and noncomplementary oligonucleotides. It was demonstrated experimentally that with the SERS platform it is possible not only to detect and recognize pure DNA but also the simultaneous presence of complementary and mispaired DNA with estimation of their relative concentrations. Moreover, the developed SERS sensor demonstrated the perfect stability over 3 months storage period without loss of functionality.
关键词： surface functionalization,DNA recognition,label-free,plasmonic substrate,SERS
更新于2025-09-09 09:28:46
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Surface regeneration and reusability of label-free DNA biosensors based on weak polyelectrolyte-modified capacitive field-effect structures
摘要： The reusability of capacitive field-effect electrolyte-insulator-semiconductor (EIS) sensors modified with a cationic weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) for the label-free electrical detection of single-stranded DNA (ssDNA), in-solution- and on-chip-hybridized double-stranded DNA (dsDNA) has been studied. It has been demonstrated that via simply regeneration of the gate surface of the EIS sensor by means of an electrostatic adsorption of a new PAH layer, the same biosensor can be reused for at least five DNA-detection measurements. Because of the reversal of the charge sign of the outermost layer after each surface modification with the cationic PAH or negatively charged DNA molecules, the EIS-biosensor signal exhibits a zigzag-like behavior. The amplitude of the signal changes has a tendency to decrease with increasing number of macromolecular layers. The direction of the EIS-signal shifts can serve as an indicator for a successful DNA-immobilization or -hybridization process. In addition, we observed that the EIS-signal changes induced by each surface-modification step (PAH adsorption, immobilization of ssDNA or dsDNA molecules and on-chip hybridization of complementary target cDNA) is decreased with increasing the ionic strength of the measurement solution, due to the more efficient macromolecular charge-screening by counter ions. The results of field-effect experiments were supported by fluorescence-intensity measurements of the PAH- or DNA-modified EIS surface using various fluorescence dyes.
关键词： charge screening,label-free,field-effect sensor,DNA biosensor,reusability,weak polyelectrolyte
更新于2025-09-09 09:28:46
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DNA-Stabilized Silver Nanoclusters for Label-Free Fluorescence Imaging of Cell Surface Glycans and Fluorescence Guided Photothermal Therapy
摘要： A multifunctional nanoplatform that enables the integration of biological detection, imaging diagnosis, and synergistic therapy into a single nanostructure holds great promise for nanoscience and nanomedicine. Herein, a novel theranostic platform was presented for label-free imaging of cell surface glycans based on DNA/silver nanoclusters (AgNCs) via hybridization chain reaction (HCR) and fluorescence guided photothermal therapy (PTT). In this strategy, a dibenzocyclooctyne (DBCO)-functionalized DNA and two hairpin structures of DNA/AgNCs probes were involved. Following metabolic glycan labeling, the binding of DBCO-functionalized DNA to cell surface initiated HCR, and then cell surface glycans were specifically labeled by DNA/AgNCs fluorescent probes. Furthermore, this signal amplification strategy was adopted in quantitative analysis, and the detection limit could be achieved as low as 20 cells in 200 μL binding buffer. Moreover, the remarkable photothermal properties of DNA/AgNCs via HCR, led to efficient killing of cancer cell and inhibited the tumor growth under imaging guide. In this strategy, DNA/AgNCs were utilized to detect the cellular glycans, which aided in overcoming the high cost and instability of fluorescent dyes. Simultaneously, the HCR process avoided the introduction of excessive azido-sugars under the precondition of ensuring apparent fluorescence. These results indicated that the developed nanoplatform has great potential for specific cell surface glycans imaging and fluorescence guided PTT.
关键词： DNA-stabilized silver nanoclusters,fluorescence guided photothermal therapy,hybridization chain reaction,cell surface glycans,label-free fluorescence imaging
更新于2025-09-09 09:28:46