- 标题
- 摘要
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- 实验方案
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One-step hydrothermal synthesis of down/up-conversion luminescence F-doped carbon quantum dots for label-free detection of Fe3+
摘要： In this work, a kind of down/up-conversion luminescent F-doped carbon dots (F-CDs) with high fluorescence quantum yield was prepared by one-step hydrothermal treatment of perfluorooctanoic sulfonate (PFOS) and was used for the label-free detection of Fe3+. The obtained F-CDs have a uniform and monodispersed size at 4 nm, and show good properties such as down/up-conversion luminescence, good water-solubility, anti-photo-bleaching, salt tolerance, and high fluorescence quantum yield of about 35.2%. The down/up-conversion photoluminescence emissions both are independent on the excitation and both the emission peaks are at 447 nm, which indicates it is promising to be used as fluorescent whitening agent. Based on the quenching effect of iron ions, a simple, sensitive, low-cost and label-free fluorescent assay for iron ions has been developed with a liner range of 1–100 μM and a limit of detection (LOD) of 10 nM. Furthermore, the label-free nanoprobe has been successfully applied for the detection of Fe3+ in real samples.
关键词： Fe3+,Down/up-conversion,Carbon dots,F-doped,Label-free detection
更新于2025-09-12 10:27:22
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A label-free fluorescent sensor based on silicon quantum dots–MnO <sub/>2</sub> nanosheets for the detection of α-glucosidase and its inhibitor
摘要： A label-free fluorescent sensor based on silicon quantum dots–MnO2 nanosheets for the detection of α-glucosidase and its inhibitor?. α-Glucosidase and its inhibitors play a key role in diagnosis and treatment of diabetes. In the present work, we established a facile, sensitive and selective fluorescence method based on silicon quantum dots (SiQDs) and MnO2 nanosheets for the determination of α-glucosidase and one of its inhibitors acarbose. The fluorescence of SiQDs was greatly quenched by MnO2 nanosheets due to the inner filter effect. α-Glucosidase could easily catalyze the hydrolysis of L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) to produce ascorbic acid (AA), which could reduce MnO2 nanosheets to Mn2+, resulting in dramatic recovery of the fluorescence of SiQDs. The proposed sensing platform could provide a good linear relationship between the fluorescence intensity of SiQDs and the concentration of α-glucosidase in the range of 0.02–2.5 U mL?1 with a detection limit of 0.007 U mL?1. In addition, the sensing platform could be used for α-glucosidase inhibition. Acarbose was one of the most common and typical inhibitors, and this sensing platform can be utilized to detect acarbose in the range of 1–1000 μM. The developed fluorescence method was successfully validated for the determination of α-glucosidase in human serum samples.
关键词： silicon quantum dots,acarbose,label-free fluorescent sensor,MnO2 nanosheets,α-glucosidase
更新于2025-09-12 10:27:22
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Non-Invasive Plasmonic Based Real Time Characterization of Cardiac Drugs on Cardiomyocytes Functional Behavior
摘要： In fabrication of cardiac tissue, an important factor is continuous measurement of its contraction features. A module that allows for a dynamic system capable of non-invasive and label-free monitoring of contraction profile under administering chemicals and drugs, is highly valuable for understanding accurate tissue mechanobiology. In this research, we have successfully demonstrated the use of Surface Plasmon Resonance (SPR) technology for the first time to characterize the contractility of cardiac cells in response to Blebbistatin and ATP as drug exposure in real-time. An optimal flow rate of 10 μlit/min was selected for continuous flow of warm media and 10 μM drug administration effect was detected with high spatiotemporal sensitivity on contracting cardiomyocytes. Our drug screening has identified the source of SPR periodic signal to be directly cell contraction rather than action potentials or calcium signaling. Per our results, SPR has high potential in applications in least interference real-time and label-free tissue characterizations and cellular properties analysis from a functional and structural point of view.
关键词： drug development,cardiomyocyte contraction,surface plasmon resonance,in-vitro,label-free,biosensor,imaging
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Quantitative Phase Microscopy with Molecular Vibrational Sensitivity
摘要： Quantitative phase imaging (QPI) has become a valuable tool for studying optically transparent samples such as biological cells and tissues. It yields the sample-specific optical path-length delay at each spatial point of the field of view with a nanometer resolution, enabling high-contrast and objective analysis. The major advantage of QPI is its wide-field, label-free measurement capability of the transparent morphology. This allows for high-speed imaging limited by the image sensor’s frame rate while reducing optical and/or chemical damages to the sample which are troublesome in other imaging techniques such as fluorescence and Raman imaging. To date, QPI has been used for pathology diagnosis, phenotyping of live cancer cells, non-destructive measurement of cellular volume and dry-mass, study of cellular membrane dynamics, to just name a few. However, QPI lacks chemical sensitivity which limits its application to morphology-based diagnosis. Here, we report on our wide-field label-free molecular-vibrational (MV) microscopy method realized in the framework of QPI utilizing mid-infrared (MIR) photothermal effect. We measure local changes in the optical phase delay occurring upon absorption of the MIR light in the vicinity of the MV-resonant molecules, which is called photothermal effect, by means of QPI. This imaging scheme yields high-molecular-detection sensitivity based on MV-resonant MIR absorption having ~8 orders of magnitude larger cross-section compared to Raman scattering. Meanwhile, it also maintains the visible-light spatial resolution, high temporal resolution limited by the image sensor’s frame rate, and low photodamage to the sample with the wide-field, low-fluence optical illumination. Notably, our wide-field, parallelized detection scheme could even surpass the imaging speed of conventional label-free imaging methods such as coherent Raman imaging by an order of magnitude, as they typically employ a point-scanning mechanism for image synthesis. Our MV-sensitive QPI (MV-QPI) could offer new insights for optically-transparent complex dynamics by enabling high-speed, label-free cross-correlative analysis based on the quantitative morphology and the MV-spectroscopic chemical contrasts.
关键词： molecular-vibrational microscopy,Quantitative phase imaging,chemical sensitivity,label-free imaging,mid-infrared photothermal effect
更新于2025-09-12 10:27:22
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Attomolar Detection of Low-Molecular Weight Antibiotics Using Midinfrared-Resonant Toroidal Plasmonic Metachip Technology
摘要： Plasmonic metamaterials can be used to enhance midinfrared sensors and detectors for immunosensing applications. The major challenge with them is to integrate these technologies in low-cost, compact, and promising platforms. As an emerging technique, we utilize toroidal resonant plasmonic metamaterials to develop an ultrasensitive label-free analytical platform for the detection of specific antibiotics in the midinfrared spectra. Taking advantage of the unique sensitivity of robustly squeezed electromagnetic fields in the toroidal plasmonic meta-atoms, we demonstrate that our proposed approach based on toroidal metastructures provides recognition of extremely-low-weight (approximately 0.6 KDa) biological targets at attomolar densities. We envisage that this understanding extends the capabilities of plasmonic metamaterials to analyze the presence of specific biological molecules and organisms with ultrahigh precision.
关键词： midinfrared sensors,Plasmonic metamaterials,ultrasensitive label-free analytical platform,antibiotics detection,toroidal resonant plasmonic metamaterials
更新于2025-09-11 14:15:04
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Determination of Dopamine by a Label-Free Fluorescent Aptasensor Based on AuNPs and Carbon Quantum Dots
摘要： In order to reduce the complex modification process and obtain a fast and label-free aptasensor, a label-free fluorescent aptasensor based on gold nanoparticles (AuNPs) and carbon quantum dots (CQDs) was constructed for rapid determination of dopamine (DA). In the absence of DA, CQDs were adsorbed on the surface of AuNPs through the electrostatic force between CQDs and aptamer, which led to the fluorescence quenching of CQDs. When DA were added, they combined with the corresponding aptamers with higher affinity and selectivity, resulting in CQDs far from the surface of AuNPs and thus the fluorescence intensity of CQDs was recovered. Under the optimal condition, the fluorescence intensity of the released CQDs was linearly proportional to the concentration of DA in a range of 5×10-8~2.5×10-4mol/L with a detection limit of 1×10-8mol/L. Moreover, the aptasensor exhibited a satisfactory detection result of DA in human serum samples. This study provided a more effective method to detect a broad range of targets by using appropriate aptamers, holding great potential in the field of food safety and biomedical diagnostics.
关键词： Label-free,Gold nanoparticles,Fluorescent aptasensor,Carbon quantum dots
更新于2025-09-11 14:15:04
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Graphene-Based Biosensors for Detection of Composite Vibrational Fingerprints in the Mid-Infrared Region
摘要： In this study, a label-free multi-resonant graphene-based biosensor with periodic graphene nanoribbons is proposed for detection of composite vibrational ?ngerprints in the mid-infrared range. The multiple vibrational signals of biomolecules are simultaneously enhanced and detected by di?erent resonances in the transmission spectrum. Each of the transmission dips can be independently tuned by altering the gating voltage applied on the corresponding graphene nanoribbon. Geometric parameters are investigated and optimized to obtain excellent sensing performance. Limit of detection is also evaluated in an approximation way. Besides, the biosensor can operate in a wide range of incident angles. Electric ?eld intensity distributions are depicted to reveal the physical insight. Moreover, another biosensor based on periodic graphene nanodisks is further proposed, whose performance is insensitive to the polarization of incidence. Our research may have a potential for designing graphene-based biosensor used in many promising bioanalytical and pharmaceutical applications.
关键词： nanophotonics,label-free biosensors,surface plasmons,graphene,metasurface
更新于2025-09-11 14:15:04
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Spatiotemporal Dynamics of Laser-Induced Molecular Crystal Precursors Visualized by Particle Image Diffusometry
摘要： We have succeeded in label-free visualization of spatiotemporal dynamics of laser-induced crystal precursors in aqueous solutions. The tracking-free evaluation of the diffusion-coefficient field for the observation domain with tens of micrometers on a side from microscopy movie data is realized by particle image diffusometry (PID). PID revealed the time fluctuation of coverage composition with the nonuniform space distribution of diffusion coefficients by the prenucleation clusters. Furthermore, the results indicate the existence of a loose aggregation domain of prenucleation clusters where the order of viscosity corresponds to that of honey.
关键词： viscosity,spatiotemporal dynamics,particle image diffusometry,prenucleation clusters,laser-induced crystal precursors,label-free visualization
更新于2025-09-11 14:15:04
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Direct Detection of Bacteria Using Positively-charged Ag/Au Bimetallic Nanoparticles: A Label-Free SERS Study Coupled with Multivariate Analysis
摘要： Rapid detection and discrimination of pathogenic bacteria for food safety, environmental pollution, medical diagnoses, and chemical and biological threats remains a considerable challenge. In the present work, we demonstrate positively charged Ag/Au bimetallic nanoparticles (Ag/Au bmNPs) as a potential surface-enhanced Raman scattering (SERS) substrate for label-free detection and discrimination of three bacteria, viz., Escherichia coli, Salmonella typhimurium and Bacillus subtilis with excellent reproducibility. The approach relies on a priori synthesis of Ag/Au bmNPs and subsequent SERS studies on bacteria. The positive surface charge on Ag/Au bmNPs offers significant advantages of short acquisition time at very low power, high sensitivity, and simple operating procedure without the need of very specific procedures/protocols used to capture the bacteria. The reproducible and specific intrinsic fingerprint of the cell wall and intracellular components of three bacteria obtained by label-free SERS enables precise discrimination and classification of three bacteria using multivariate analysis such as principal component analysis and canonical discriminant analysis.
关键词： SERS,multivariate analysis,Optical,Magnetic,label-free study,and Hybrid Materials,bacteria detection,Ag/Au bimetallic nanoparticles,Plasmonics
更新于2025-09-11 14:15:04
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Immune cell type, cell activation, and single cell heterogeneity revealed by label-free optical methods
摘要： Measurement techniques that allow the global analysis of cellular responses while retaining single-cell sensitivity are increasingly needed in order to understand complex and dynamic biological processes. in this context, compromises between sensitivity, degree of multiplexing, throughput, and invasiveness are often unavoidable. We present here a noninvasive optical approach that can retrieve quantitative biomarkers of both morphological and molecular phenotypes of individual cells, based on a combination of quantitative phase imaging and Raman spectroscopy measurements. We then develop generalized statistical tools to assess the influence of both controlled (cell sub-populations, immune stimulation) and uncontrolled (culturing conditions, animal variations, etc.) experimental parameters on the label-free biomarkers. These indicators can detect different macrophage cell sub-populations originating from different progenitors as well as their activation state, and how these changes are related to specific differences in morphology and molecular content. The molecular indicators also display further sensitivity that allow identification of other experimental conditions, such as differences between cells originating from different animals, allowing the detection of outlier behaviour from given cell sub-populations.
关键词： single cell heterogeneity,label-free optical methods,cell activation,immune cell type
更新于2025-09-11 14:15:04