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Cell Imaging Using Two-Photon Excited CdS Fluorescent Quantum Dots Working within the Biological Window
摘要： In recent years, two-photon excited semiconductor quantum dots (QDs) have been the subject of intense investigation due to their long excitation wavelength which helps to achieve deeper penetration and higher image resolution in optical bioimaging. In this paper, water-soluble CdS QDs were synthesized using a hydrothermal method and applied to human liver hepatocellular carcinoma (HepG2) cells. The first-principles calculation suggested that the S-rich defected structure contributes to a narrower band gap compared to the pristine structure. The resulting fluorescence wavelength was significantly red shifted, which was attributed to the deep defect states emission. The large Stokes shifts (> 200 nm) of the QDs can eliminate the possible cross-talk between the excitation light and the emission light. Two-photon induced red fluorescence emission can avoid overlapping with the autofluorescence emission of biological samples. The uptake and cell viability measurements of the HepG2 cells showed a good biocompatibility and a low toxicity of CdS QDs. Two-photon excited scanning microscopy images revealed that the HepG2 cells incubated with CdS QDs emitted bright red upconversion fluorescence and the fluorescence brightness was 38.2 times of that of the control group. These results support CdS QDs as a good candidate for application in cellular imaging.
关键词： two-photon absorption,CdS quantum dots,deep defect states,HePG2 cells,biological imaging
更新于2025-11-21 11:24:58
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Investigation of Keratinizing Squamous Cell Carcinoma of the Tongue Using Terahertz Reflection Imaging
摘要： We investigated the feasibility of using terahertz (THz) reflection imaging to detect keratinizing squamous cell carcinoma (SCC) of the tongue. Four fresh keratinizing SCC tissues were studied, which had been surgically resected. All of the keratinizing SCCs were well distinguished from normal healthy tissues. We showed that the tumor regions exhibited low THz reflection despite having higher water content than normal regions. The refractive indices and absorption coefficients were low in the tumor tissues despite the relatively high water content. Our results showed that there were dominant factors such as keratin pearls, other than the water content affecting the THz reflection signal.
关键词： Optical diagnostics for medicine,Tissue diagnostics,Terahertz imaging,Medical and biological imaging,Terahertz spectroscopy
更新于2025-09-23 15:23:52
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Exploring phase contrast imaging with a laser-based K?± x-ray source up to relativistic laser intensity
摘要： this study explores the ability of a hard Kα x-ray source (17.48 keV) produced by a 10 TW class laser system operated at high temporal contrast ratio and high repetition rate for phase contrast imaging. For demonstration, a parametric study based on a known object (PET films) shows clear evidence of feasibility of phase contrast imaging over a large range of laser intensity on target (from ~1017 W/cm2 to 7.0 × 1018 W/cm2). To highlight this result, a comparison of raw phase contrast and retrieved phase images of a biological object (a wasp) is done at different laser intensities below the relativistic intensity regime and up to 1.3 × 1019 W/cm2. this brings out attractive imaging strategies by selecting suitable laser intensity for optimizing either high spatial resolution and high quality of image or short acquisition time.
关键词： biological imaging,laser intensity,phase contrast imaging,high repetition rate,Kα x-ray source
更新于2025-09-23 15:19:57
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Ultrafast fabrication of fluorescent organic nanoparticles with aggregation-induced emission feature through the microwave-assisted Biginelli reaction
摘要： Because of its unique optical properties, the aggregation-induced emission (AIE) dye has attracted extensive attention for various applications. Especially, the utilization of AIE-active dyes for fabrication of fluorescent organic nanoparticles (FONs) has attracted the most research interest for biomedical applications. Therefore, the development of novel and effective strategies to design and prepare AIE-active FONs should be of great importance for the biomedical applications of AIE-active FONs. In this report, we reported an ultrafast strategy that based on the one-pot microwave-assisted Biginelli reaction for fabrication of AIE-active poly(AA-AEMA-TPE) copolymers, which use the 2-(methacryloyoxy) ethylacet, acrylic acid (AA) and 4',4'''-(1,2-diphenylethene-1,2-diyl) bis([1,1'-biphenyl]-4-carbaldehyde) (TPE-CHO) as the substrates. The microwave-assisted Biginelli reaction is simple, efficient and atom-economical and can be accomplished within 3 min. Owing to their amphiphilicity, poly(AA-AEMA-TPE) copolymers will self-assemble into FONs with small size and high water dispersibility. The proton nuclear magnetic resonance (1H NMR) spectroscopy, UV-Vis spectrum and fluorescence spectrometer were used to characterize the resultant copolymers. We demonstrated that poly(AA-AEMA-TPE) FONs possess many excellent properties, such as high water dispersibility, intense fluorescence, obvious AIE feature and favorable biocompatibility. The above results suggest that poly(AA-AEMA-TPE) FONs are of great potential for fluorescent imaging. Moreover, the microwave-assisted Biginelli reaction can occur under a rather benign environment with high efficiency and good substrate adaptability. Therefore, we believe that the method developed in this work could greatly advance the applications of AIE-active functional materials.
关键词： microwave-assisted Biginelli reaction,biological imaging,fluorescent polymer nanoparticles,Aggregation-induced emission,living controlled polymerization
更新于2025-09-19 17:15:36
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Tailored Photoluminescence Properties of Ag(In,Ga)Se <sub/>2</sub> Quantum Dots for Near-Infrared in vivo Imaging
摘要： Multinary semiconductor quantum dots (QDs) that have less toxicity and show near-infrared light responsivity have attracted much attention for in vivo bioimaging. In this study, we controlled the optical properties of Ag-In-Se QDs by modulating the non-stoichiometry and the degree of Ga3+ doping. Precise tuning of the Ag/In ratio of Ag-In-Se QDs enabled a sharp band-edge emission to emerge without broad defect-site emission. Ga3+ doping into Ag-In-Se (AIGSe) QDs enlarged their energy gap, resulting in a blue shift of band-edge PL peak from from 890 to 630 nm. The band-edge PL intensity was remarkably enlarged by surface coating with a thin GaSx shell followed by treatment with trioctylphosphine, the highest PL yield being 38% for the PL peak at 800 nm. Thus-obtained QDs were successfully used as near-IR PL probes for three-dimensional in vivo bio-imaging in which the wavelengths of excitation and detection lights could be selected in the first biological window and then the signals were clearly detected from AIGSe@GaSx core-shell QDs injected into biological tissues by ca. 5 mm in depth.
关键词： I-III-VI2 semiconductor,Quantum dots,Semiconductor nanocrystals,Band-edge emission,Biological imaging,Near-IR photoluminescence
更新于2025-09-19 17:13:59
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Highly Luminescent Ternary Nanocomposite of Polyaniline, Silver Nanoparticles and Graphene Oxide Quantum Dots
摘要： Quantum dots (QDs) with photostability show a potential application in optical sensing and biological imaging. In this work, ternary nanocomposite (NC) of high fluorescent polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped silver nanoparticles (NPs)/graphene oxide quantum dots (PANI/Ag (AMPSA)/GO QDs) have been synthesized by in situ chemical oxidative polymerization of aniline in the presence of Ag (AMpSA) nps and Go QDs. Ag (AMpSA) nps and Go QDs were prepared by AgNO3 chemical reduction and glucose carbonization methods, respectively. The prepared materials were characterized using UV-visible, Fourier transform infrared (FTIR), photoluminescence and Raman spectroscopies, X-Ray diffractometer (XRD) and high- resolution transmission electron microscopy (HRTEM). HRTEM micrographs confirmed the preparation of GO QDs with an average size of 15 nm and Ag (AMPSA) NPs with an average size of 20 nm. PANI/Ag (AMPSA)/GO QDs NC showed high and stable emission peak at 348 nm. This PANI/Ag (AMPSA)/GO QDs NC can emerge as a new class of fluorescence materials that could be suitable for practical sensing applications.
关键词： Fluorescent materials,Biological imaging,Quantum dots,Graphene oxide quantum dots,Polyaniline,Optical sensing,Polymeric nanocomposites,Silver nanoparticles
更新于2025-09-11 14:15:04
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Faster, sharper, and deeper: structured illumination microscopy for biological imaging
摘要： Structured illumination microscopy (SIM) allows rapid, super-resolution (SR) imaging in live specimens. We review recent technical advances in SR-SIM, with emphasis on imaging speed, resolution, and depth. Since its introduction decades ago, the technique has grown to offer myriad implementations, each with its own strengths and weaknesses. We discuss these, aiming to provide a practical guide for biologists and to highlight which approach is best suited to a given application.
关键词： Structured illumination microscopy,resolution,biological imaging,super-resolution imaging,imaging speed,depth
更新于2025-09-09 09:28:46
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Chemometric Approaches for Developing Infrared Nanosensors to Image Anthracyclines
摘要： Generation, identification, and validation of optical probes to image molecular targets in a biological milieu remains a challenge. Synthetic molecular recognition approaches leveraging the intrinsic near-infrared fluorescence of single-walled carbon nanotubes is a promising approach for long-term biochemical imaging in tissues. However, generation of nanosensors for selective imaging of molecular targets requires a heuristic approach. Here, we present a chemometric platform for rapidly screening libraries of candidate single-walled carbon nanotube nanosensors against biochemical analytes to quantify fluorescence response to small molecules including vitamins, neurotransmitters, and chemotherapeutics. We further show this approach can be leveraged to identify biochemical analytes that selectively modulate the intrinsic near-infrared fluorescence of candidate nanosensors. Chemometric analysis thus enables identification of nanosensor-analyte ‘hits’ and also nanosensor fluorescence signaling modalities such as wavelength-shifts that are optimal for translation to biological imaging. Through this approach, we identify and characterize a nanosensor for the chemotherapeutic anthracycline doxorubicin, which provides an up to 17 nm fluorescence red-shift and exhibits an 8 μM limit of detection, compatible with peak circulatory concentrations of doxorubicin common in therapeutic administration. We demonstrate selectivity of this nanosensor over dacarbazine, a chemotherapeutic commonly co-injected with DOX. Lastly, we demonstrate nanosensor tissue compatibility for imaging of doxorubicin in muscle tissue by incorporating nanosensors into the mouse hindlimb and measuring nanosensor response to exogenous DOX administration. Our results motivate chemometric approaches to nanosensor discovery for chronic imaging of drug partitioning into tissues and towards real-time monitoring of drug accumulation.
关键词： fluorescence response,single-walled carbon nanotubes,infrared nanosensors,biological imaging,doxorubicin,chemometric approaches,anthracyclines
更新于2025-09-09 09:28:46
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Cell-Penetrating Peptides Transport Noncovalently Linked Thermally Activated Delayed Fluorescence Nanoparticles for Time-Resolved Luminescence Imaging
摘要： Luminescent probes and nanoparticles (NPs) with long excited state lifetimes are essential for time-resolved biological imaging. Generally, cell membranes are physiological barriers that could prevent the uptake of many unnatural compounds. It is still a big challenge to prepare biocompatible imaging agents with high cytomembrane permeability, especially for nonmetallic NPs with long-lived luminescence. Herein, an amphiphilic cell-penetrating peptide, F6G6(rR)3R2, was designed to transport hydrophobic fluorophores across cellular barriers. Three classical thermally activated delayed fluorescence (TADF) molecules, 4CzIPN, NAI-DPAC, and BTZ-DMAC, could self-assemble into well-dispersed NPs with F6G6(rR)3R2 in aqueous solution. These NPs showed low cytotoxicity and could penetrate membranes easily. Moreover, long-lived TADF enabled them to be used in time-resolved luminescence imaging in oxygenic environments. These findings greatly expanded the applications of cell-penetrating peptides for delivery of molecules and NPs by only noncovalent interactions, which were more flexible and easier than covalent modifications.
关键词： cell-penetrating peptide,Luminescent probes,time-resolved biological imaging,nanoparticles,noncovalent interactions,thermally activated delayed fluorescence
更新于2025-09-04 15:30:14