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Effect of Cr3+ doping on structural and optical property of ZnGa2O4 synthesized by sol gel method
摘要： Zinc gallate host and chromium ions doped ZnGa2O4 nano-powders was synthesized by citric acid assisted sol-gel method. The dopant molar percentage were varied between (0–2.5 mol. %). The x-ray di?raction (XRD) patterns shown that all synthesized nano powders are cubic structured and doping of Cr3+ ions did not a?ect the structure at all. The scanning electron microscope micrographs show small particles in nano range that are uniformly distributed, but became ag-glomerated with high doping of chromium concentrations. The high-resolution transmission electron microscope (HR-TEM) image shows the formation of several agglomerated particles with clear grain boundary and di?erent sizes. Energy dispersive x-ray spectroscopy measurements con?rm the presence of the expected elements. Ultraviolet–visible spectrophotometer measurement shows the % re?ectance in the UV–vis region to be dependents on Cr3+ ions and the estimated band gap was found to vary between 4.46 and 4.80 eV. Un-doped ZnGa2O4 nano powder displays a broad blue emission but doping with Cr3+ ions caused the emission to occur in the near infrared region. An increase in Cr3+ ions up to 2.0 mol% lead to signi?cantly en-hancement in the near infra-red (NIR) emission but decrease thereafter. The CIE color co-ordinates values located in blue and NIR of the spectrum for undoped and Cr3+ doped samples, respectively. The photoluminescence emission intensity was also observed to be dependent on the excitation wavelength and the emission PL spectrum perfectly match the transparency window of living tissues and can e?ectively be used for bio imaging application.
关键词： Zinc gallate,Cr3+ doping,Photoluminescence,Bio imaging
更新于2025-09-23 15:23:52
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Thermodynamics and structural stability of tissues for bio-imaging analysis – The case of intracranial aneurysm rupture risk assessment
摘要： Based on thermodynamic principles, structure stability analysis like stress response and fracture formation is well established for inorganic but not for organic bio-materials. In this study, three equations were established to assess intracranial aneurysm (IA) rupture risk based on patient's IA and internal carotid artery (ICA) angiography images, by incorporating tissue thermodynamics. Our objectives are: (1) establish foundations to help understand the physics behind the observed morphological changes prior to IA rupture, and (2) provide first-principles equations to aide in rupture risk assessment. Subsequently, we validated the new equations using available experimental and numerical simulation results, and revealed new IA rupture physics. In particular, our models correlated well with most of the available experiment and computer fluid dynamics simulation data. Among the three common structure failure modes, the axial stress and the bending moment loading are the control mechanism. The rupture risk reaches its peak when (1) the aneurysm inclination angle (ω) is close to 63.4°, (2) IA diameter / ICA diameter ?1, and (3) IA length / IA diameter ≈1.6. This study provides strong physical foundations and sound understanding to aid in rupture risk assessment. It presents insights on detailed thermodynamics that govern the previously observed IA rupture behaviors, reported from both experiments and numerical simulations. By integrating angiography images with first-principles tissue thermodynamics, we (1) advance the IA research, which is currently dominated by experimental and imaging-data-statistic approaches, and (2) introduce Calphad research into a new exciting research field - bio-imaging analysis.
关键词： Young's Modulus,Entropy,Thin-walled cylinders,Bio-imaging,Intracranial aneurysm
更新于2025-09-23 15:22:29
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Preparation of graphene quantum dots with high quantum yield by a facile one-step method and applications for cell imaging
摘要： The preparation and biological applications of graphene quantum dots (GQDs) have attracted much attention. Here, a one-step hydrothermal method for synthesizing nitrogen-doped GQDs (N-GQDs) using graphene oxide (GO), ethylenediamine and hydrogen peroxide, simultaneously achieved oxidative cleavage and chemical reduction of GO. The average size of the synthesized N-GQDs was about 1.84±0.28 nm and their quantum yield of the N-GQDs reached about 0.46, which was higher than that of other GQDs synthesized by top-down methods. The cytotoxicity of these N-GQDs on Hela cells was evaluated using a cell counting Kit-8 assay. The effects of N-GQDs on different cell lines and fluorescence imaging were also observed by confocal laser scanning microscopy. The results suggested that these N-GQDs penetrated into cells by endocytosis and were promising fluorescent probes for biological imaging.
关键词： Carbon materials,Hydrothermal reaction,Luminescence,Graphene quantum dots,Bio-imaging
更新于2025-09-23 15:21:01
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Composition and size controlled I-V-VI semiconductor nanocrystals
摘要： Non-isovalent ternary and quaternary semiconductors (i.e., having two or more cations with different valence) have unique structural and electronic properties that are leveraged in photovoltaic, thermoelectric, and phase-change memory devices. Making these complex semiconductors in the form of colloidal nanocrystals imparts size-dependent properties and solution processability. Here, we present results on I‐V‐VI group colloidal nanocrystals. We focus on achieving sub-10 nm sizes for a wide range of I-V-VI selenide nanocrystals, including AgSbSe2, AgSb2Se3, CuSbSe2, Cu3SbSe4, AgBiSe2, and CuBiSe2. To highlight one possible application for these I-V-VI colloidal nanomaterials, we analyze the optical absorption and show that through composition and size control, this class of materials offers bandgaps in the mid- to near-IR. Absorption coefficients of AgSbSe2, CuSbSe2, and Cu3SbSe4 nanocrystals are on par with or higher than the well-studied PbS nanocrystals highlighting their potential for devices such as solar cells, (mid-)infrared photodetectors, and near-infrared bio-imaging systems.
关键词： solar cells,optical absorption,bio-imaging systems,colloidal nanocrystals,infrared photodetectors,mid- to near-IR,I-V-VI semiconductor nanocrystals,bandgaps
更新于2025-09-23 15:19:57
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Orthogonal Shortwave Infrared Emission Based on Rare Earth Nanoparticles for Interference-free Logical Code and Bio-imaging
摘要： Shortwave infrared (SWIR) photoluminescence has received intense interest in many fields in the recent years thanks to the advantages of its wide wavelength, high tissue imaging ability and it is invisible to the naked eye. However, achieving orthogonal SWIR emission still remains challenge. In the present study, synthesized NaErF4@NaLuF4 (Er@Lu) and NaYF4:Nd@NaLuF4 (Y:Nd@Lu) nanoparticles emitted atom-liked SWIR emission, respectively, and the separated distance between the SWIR emission was beyond 50 nm, which permitted orthogonal SWIR signal acquirement with optical filters. Furthermore, we designed an invisible logical code by manipulating the orthogonal SWIR emission of the lanthanide fluoride nanoparticles, which was further operated by basic logical operations and applied in information encryption and anti-counterfeit. In addition, the emission between these two hydrophilic nanoparticles could be also separated in vivo without signals interference and the orthogonal SWIR imaging mode was achieved, which was demonstrated in bio-imaging experiment in vivo. This demonstration extended the orthogonal SWIR emission capacity by controlling the orthogonal emission, opening new opportunities in the data security, diseases diagnosis and non-interference label in vivo.
关键词： bio-imaging,anti-counterfeit,Orthogonal shortwave infrared,SWIR logical codes,lanthanide fluoride nanoparticles
更新于2025-09-19 17:15:36
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Biocompatible quantum dot-antibody conjugate for cell imaging, targeting and fluorometric immunoassay: crosslinking, characterization and applications
摘要： Quantum dots (QDs) are important fluorescent probes that offer great promise for bio-imaging research due to their superior optical properties. However, QDs for live cell imaging and the tracking of cells need improving labeling efficiency, and reducing more investigation to simplify processing procedures, chronic toxicity. In this study, QDs were functionalized with bovine serum albumin (BSA) via a chemical linker. Anti-human immunoglobulin antibodies were oxidized by sodium periodate to create reactive aldehyde groups for a spontaneous reaction with the amine groups of BSA-modified QDs. An antibody-labeled QD bioconjugate was characterized using agarose gel electrophoresis, dynamic light scattering, and zeta potential. Using fluorescence spectroscopy, we found that the fluorescence of QDs was retained after multiple conjugation steps. The cell-labeling function of the QD bioconjugate was confirmed using an image analyzer and confocal microscopy. The QD bioconjugate specifically targeted the human immunoglobulin on the membrane surface of recombinant cells. The QD bioconjugate applied in fluorometric immunoassay was effective for the quantitative analysis of human immunoglobulin in an enzyme-linked immunosorbent assay. The developed QD bioconjugate may offer a promising platform to develop biocompatible tools to label cells and quantify antibodies in the immunoassay.
关键词： Quantum dots,Bio-imaging,Fluorescent probes,Cell labeling,Fluorometric immunoassay
更新于2025-09-16 10:30:52
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Metallic Nanomaterials (Part B) || 5. Size-controlled atomically precise copper nanoclusters: Synthetic protocols, spectroscopic properties and applications
摘要： Noble metal nanoclusters (NCs) are a new class of nanomaterials which are considered being a missing link between isolated metal atoms and metal nanoparticles (NPs). The sizes of the NCs are comparable to the Fermi wavelength of the conduction electrons, and this renders them to be luminescent in nature. They exhibit size-dependent fluorescence properties spanning almost the entire breath of the visible spectrum. Among all the noble metal NCs being explored, copper NCs (CuNCs) are the most rarely investigated primarily because of their propensity of getting oxidised. In this chapter, we have given a comprehensive understanding as to why these NCs are luminescent in nature. We have also given a detailed overview regarding the various templates used for the synthesis of these CuNCs along with the respective protocols being followed. The various instrumental techniques used to characterize these CuNCs are discussed which provides an in-depth understanding as to how these CuNCs can be properly examined. Finally, we have highlighted some of the most recent applications of these CuNCs which make them unique to serve as the next-generation fluorophores.
关键词： nano-thermometry,bio-imaging,sensing,synthetic protocols,instrumentations,spectroscopic properties,templates,luminescent nanoclusters
更新于2025-09-16 10:30:52
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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) - Label-Free Multiphoton Microscopy in Human Tissue Enabled by an Er:Fiber-Laser Based Tunable Source
摘要： Multiphoton microscopy (MPM) is an important bio-imaging tool. Different modalities can serve as a contrast agent, such as second-/third-harmonic generation (SHG/THG) and two-/three-photon excitation fluorescence (2PEF/3PEF). Ultrafast lasers with flexible wavelength tunability are crucial for driving MPM bio-imaging, and the conventional solution relies on ultrafast Ti:sapphire lasers plus an optical parametric oscillator/amplifier. Recently, we have demonstrated that ultrafast fiber lasers are a potential solution to implementing compact, robust, and wavelength tunable femtosecond sources for driving MPM. To realize wavelength tunability we employ self-phase modulation (SPM) in optical fibers to broaden a narrowband input spectrum of Yb-/Er-doped fiber lasers (YDFLs/EDFLs) up to >400-nm wide with well-isolated spectral lobes; filtering the leftmost/rightmost lobes leads to nearly transform-limited pulses [1–6]. Such a SPM-enabled spectral selection (SESS) allows us to obtain wavelength widely tunable femtosecond pulses for MPM [2,5,6]. In this submission, we representatively demonstrate label-free harmonic generation microscopy (HGM) in human skin and brain tissues. Figure 1(a) depicts a scanning microscope driven by an EDFL-based SESS source. The EDFL operates at 31-MHz repetition rate and generates 290-fs pulses centered at 1550 nm. The narrowband EDFL [blue curve in Fig. 1(a)] is coupled into 9-cm optical fiber (10-μm mode-field diameter and -10 fs2/mm group-velocity dispersion at 1550 nm). The output spectrum is shown as the red curve in Fig. 1(b) under 85-nJ coupled pulse energy. We use optical filters to select the leftmost spectral lobe peaking at 1250 nm, which leads to 11.7-nJ, 47-fs pulses. Then we employ these pulses to drive a scanning microscope and conduct HGM in human skin and brain tissues. Figure 1(c) shows the dermal papilla at the junction of epidermis and upper dermis in human skin. Basal cells are visualized by THG (cyan hot) due to optical inhomogeneity at the interface (e.g., cell membrane); SHG (red hot) originates from the non-centrosymmetric structure of collagen fibers. In Fig. 1(d), neural network and brain vasculature in human brain tissue can be visualized by THG and SHG, respectively [Fig. 1(d)]. THG contrast inside the vasculature shows also red blood cells. In conclusion, we report on MPM deep-tissue imaging enabled by an EDFL-based SESS source. It is noteworthy that besides HGM excited by 1250-nm femtosecond pulses demonstrated here, the SESS source also supports 1300-/1700-nm illumination for 3PEF of green/red fluorescent protein (GFP/RFP) [7,8]. Such a fiber-based solution can be applied to many important applications, such as histopathology, morphology, and neuroscience.
关键词： ultrafast fiber lasers,Multiphoton microscopy,self-phase modulation,bio-imaging,harmonic generation microscopy
更新于2025-09-12 10:27:22
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Magnetic Field Imaging of Superparamagnetic Particles Using High-Density, Perfectly Oriented NV Centers in Diamond CVD Film
摘要： The spatial and temporal resolutions of bio-imaging with magnetic nanoparticles (MNP) as a label and a diamond substrate as a magnetic field imager are investigated. To realize fast and accurate magnetic field imaging even for a substrate with unresolved hyperfine peaks, relative fluorescence is measured at four operation points corresponding to the steepest slopes of two dips in the ODMR spectrum. The (111) diamond substrate with a 3.5-μm thick chemical vapor deposition film with an NV density of 1.6 (cid:3) 1016 cm(cid:1)3 allows us to detect 1-μm MNPs scattered on its surface with an accumulated exposure time of 19 s under external DC magnetic field of 1.3 mT. Theoretical limit of temporal sensitivity is estimated to be more than four orders of magnitude smaller than measured. Although for measurement in culture medium, an objective lens with longer working distance is required and the condition will become somewhat worse, a spatiotemporal resolution of <1 s and <1 μm for the density and quality of the NV centers used in this study is expected if the already reported sensitivity enhancement technologies are further incorporated.
关键词： diamond,CVD,NV center,bio-imaging
更新于2025-09-10 09:29:36
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Recent advances in the synthesis of [ <i>a</i> ]-benzo-fused BODIPY fluorophores
摘要： This feature article summarizes the di?erent strategies for the synthesis of [a]-benzo-fused BODIPYs that have been reported in the literature until 2018. These p-extended BODIPYs are promising fluorophores for bio-imaging and organic photovoltaic applications due to both their attractive photophysical properties in the near-infrared area and their higher (photo)chemical stability compared to conventional bis-styryl derivatives. The four main strategies described in this review can be used to access either directly the expected [a]-benzo-fused BODIPYs or through the di-/tetra-hydroisoindole.
关键词： organic photovoltaic,fluorophores,near-infrared,BODIPY,bio-imaging
更新于2025-09-04 15:30:14