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Probing Polarity and Heterogeneity of Lipid Droplets in Live Cells Using a Push–Pull Fluorophore
摘要： Lipid droplets (LDs) are organelles composed of a lipid core surrounded by a phospholipid monolayer. Lately, LDs attracted a considerable attention due to recent studies demonstrating their role in a variety of physiological processes as well as diseases. Herein we synthesized a push-pull molecule named DAF (Dimethyl Aniline Furaldehyde) that possesses a strong positive solvatochromism in emission of 119 nm from toluene to methanol. Its impressive fluorogenic properties from water to oil (2000-fold) as well as its high quantum yields (up to 0.97) led us to investigate its ability to sense the distribution of polarity in live cells by fluorescence ratiometric imaging. When added to live cells and excited at 405 nm, DAF immediately and brightly stain lipid droplets using a blue channel (410-500 nm) and cytoplasm in a red channel (500-600 nm). DAF also proved to be compatible with fixation thus allowing 3D imaging of LDs in their cytoplasm environment. Taking advantage of DAF emission in two distinct channels, ratiometric imaging was successfully performed and led to the polarity mapping of the cell unraveling some heterogeneity in polarity within LDs of the same cell.
关键词： Environment Sensitive Fluorescent Probe,Lipid Droplets,Ratiometric Imaging,Multicolor Fluorescent imaging
更新于2025-09-23 15:23:52
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Stimuli-Responsive Nanotheranostics for Real-Time Monitoring Drug Release by Photoacoustic Imaging
摘要： Molecular photoacoustic imaging (PA) is a promising technology to understand tumor pathology and guide precision therapeutics. Despite the capability of activatable PA probes to image tumor-specific biomarkers, limitations in their molecular structure hamper them from effective drug delivery and the drug release monitoring. Herein, we developed a perylene diimide (PDI) based theranostic platform that provides noninvasive PA imaging signals to monitor tumor-specific pH-responsive drug release. Methods: we first designed and synthesized an acid-responsive amine-substituted PDI derivative. The pH sensitive properties of the PDI was demonstrated by density functional theory (DFT) calculations, UV-vis experiments and PA studies. The theranostic platform (THPDINs) was fabricated by self-assembly of the acid-responsive PDI, a pH irrelevant IR825 dye, and anti-cancer drug doxorubicin (DOX). The PA properties in various pH environment, drug delivery, cytotoxicity, cell uptake, ratiometric PA imaging and anti-tumor efficacy of the THPDINs were investigated in vitro and in vivo by using U87MG glioma cell line and U87MG tumor model. Results: We found that our designed PDI was sensitive to the tumor specific pH environment, reflected by absorbance shift, PA intensity and aggregation morphology changes in aqueous solution. The as-synthesized pH sensitive PDI acted as a molecular switch in the THPDINs, in which the switch can be triggered in the mild acidic tumor microenvironment to accelerate DOX release. Meanwhile, the DOX release could be monitored by ratiometric PA imaging. Conclusions: We developed a multifunctional PDI based theranostic platform for noninvasive real-time ratiometric PA imaging of tumor acidic pH and monitoring of drug release in living mice simultaneously. This strategy will shed light on the development of smart activatable theranostic nanoplatforms and will significantly advance the application of PA theranostics in biology and medicine.
关键词： photoacoustic imaging,drug delivery,pH-responsive,ratiometric imaging,theranostics
更新于2025-09-23 15:22:29
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L-cystine-linked BODIPY-adsorbed monolayer MoS2 quantum dots for ratiometric fluorescent sensing of biothiols based on the inner filter effect
摘要： This study fabricated a dual-emission probe consisting of monolayer MoS2 quantum dots (M-MoS2 QDs) and L-cystine-linked boron-dipyrromethene (L-Cys-BODIPY) molecules for ratiometric sensing of biothiols, thiol product-related enzyme reactions, and ratiometric imaging of glutathione (GSH)-related reactions in HeLa cells. The formation of L-Cys-BODIPY-adsorbed M-MoS2 QDs (named as BODIPY-M-MoS2 QDs) was demonstrated by comparing them with M-MoS2 QDs using transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The BODIPY-M-MoS2 QDs exhibited dual-emission bands, excellent biocompatibility, and good resistance to photobleaching. It was found that the adsorbed L-Cys-BODIPY molecules rarely quenched the fluorescence of M-MoS2 QDs, and meanwhile, they were self-quenched by π-π stacking between each BODIPY backbones. The presence of biothiols induced the reduction of weakly fluorescent L-Cys-BODIPY to strongly fluorescent of L-cysteine-conjugated BODIPY. Since having a much higher molar absorption coefficient than L-Cys-BODIPY, the liberated L-cysteine-conjugated BODIPY behaved as an effective inner filter to absorb the excitation light and subsequently quenched the fluorescence of M-MoS2 QDs. The appearance of L-cysteine-conjugated BODIPY could barely affected to the fluorescence lifetime of M-MoS2 QDs, confirming the inner filter effect of L-cysteine-conjugated BODIPY onto the fluorescence of M-MoS2 QDs. The present probe not only provided a linear ratiometric response to 1–10 mM GSH, 1-10 μM cysteine, and 1-10 μM of homocysteine but also remarkably showed the ratiometric detection of thiol products from the reactions of 1–900 units L-1 S-adenosylhomocysteine (SAH) hydrolase and SAH as well as 1-850 units L-1 GSH reductase and disulfide GSH. Additionally, the present probe was well-suited for ratiometric imaging of intracellular GSH levels in non-treated and drug-treated HeLa cells
关键词： ratiometric imaging,BODIPY,biothiols,ratiometric sensor,MoS2 quantum dots,enzymatic reaction
更新于2025-09-23 15:21:01
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Noninvasive In Situ Ratiometric Imaging of Biometals Based on Self-Assembled Peptide Nanoribbon
摘要： Development of probes for accurate sensing and imaging of biometals in situ is still a growing interest owing to their crucial roles in cellular metabolism, neurotransmission, and apoptosis. Among them, Zn2+ and Cu2+ are two important cooperative biometals closely related to Alzheimer’s disease (AD). Herein, we developed a multifunctional probe based on self-assembling peptide nanoribbon for ratiometric sensing of Zn2+, Cu2+, or Zn2+ and Cu2+ simultaneously. Uniform peptide nanoribbon (AQZ@NR) was rationally designed by coassembling a Zn2+-specific ligand AQZ-modified peptide (AQZKL-7) with peptide KL-7. The nanoribbon further combined with Cu2+-sensitive near-infrared quantum dots (NIR QDs) and Alexa Fluor 633 as an inner reference molecule, which was endowed with the capability for ratiometric Zn2+ and Cu2+ imaging at the same time. The peptide-based probe exhibited good specificity to Zn2+ and Cu2+ without interference from other ions. Importantly, the nanoprobe was successfully applied for noninvasive Zn2+ and Cu2+ monitoring in both living cells and zebrafish via multicolor fluorescence imaging. This gives insights into the dynamic Zn2+ and Cu2+ distribution in an intracellular and in vivo mode, as well as understanding the neurotoxicity of high concentration of Zn2+ and Cu2+. Therefore, the self-assembled nanoprobe shows great promise in multiplexed detection of many other biometals and biomolecules, which will benefit the diagnosis and treatment of AD in clinical applications.
关键词： fluorescence imaging,biometals,ratiometric imaging,peptide nanoribbon,Cu2+,Zn2+,self-assembly,Alzheimer’s disease
更新于2025-09-23 15:21:01
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Visualizing Endogenous Sulfur Dioxide Derivatives in Febrile Seizure-Induced Hippocampal Damage by a Two-Photon Energy Transfer Cassette
摘要： Febrile seizure (FS), a frequently encountered seizure disorder in pediatric populations, can cause hippocampus damage. It has been elucidated that sulfur dioxide (SO2) content is overproduced during the development of FS and related brain injury. Thus, in situ monitoring the level of endogenous SO2 in FS-related models is helpful to estimate the pathogenesis of FS-induced brain injury, but effect detection method remains to be explored. Herein, we developed a two-photon energy transfer cassette based on acedan-anthocyanidin scaffold, TP-Ratio-SO2, enabling to achieve this purpose. TP-Ratio-SO2 specifically responds to SO2 derivatives (HSO3-/SO32-) in ultrafast fashion (less than 3s), and HSO3-/SO32- can be sensitively determined with a detection limit of 26 nM. Moreover, it exhibits significant changes in two well-resolved ?uorescence emission (?λ = 140 nm) by reacting with HSO3-/SO32-, behaving as a ratiometric fluorescent sensor. Importantly, ratiometric imaging of endogenous SO2 derivatives generation in hyperpyretic U251 cells and as well as in rat model of FS-treated hippocampus damage were successfully carried out by TP-Ratio-SO2, demonstrating that it may be a promising tool for studying the role of SO2 in FS-associated neurological diseases.
关键词： Two-photon fluorescence probe,Febrile seizure,Sulfur dioxide,Ratiometric imaging,Hippocampus damage
更新于2025-09-09 09:28:46