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Intriguing “chameleon” fluorescent bioprobes for the visualization of lipid droplet-lysosome interplay
摘要： The interplay of lipid droplets (LDs) and lysosome plays an important role in cell metabolism, and the visualization of this process can provide useful information of organelle communication and function. However, fluorescent bioprobes based on organic fluorophores that can respond to LD-lysosome interplay are much rare. Herein, fluorescent bioprobes with high photostability, excellent biocompatibility and intracellular polarity sensitivity are achieved by encapsulating a new red fluorogenic molecule TPA-BTTDO within polymeric matrix (DSPE-PEG2000). They can sequentially localize in lysosome and LDs with red and cyan emissions, respectively. By monitoring the emission color change, the interesting dynamic processes of the probes escaping from lysosome and then enriching in LDs, and finally returning to lysosome after LDs consumption are visualized. In addition, the tracing of dynamic movement and consumption of LDs is realized by the probes with a high signal-to-noise ratio. The unique labeling behaviors and distinguished dual emissions of the probes in LDs and lysosome make them promising agents for fluorescence visualization studies of LD-lysosome related bioprocess and metabolism diseases.
关键词： lipid droplet,aggregation-induced emission,nanomaterials,lysosome,fluorescent bioprobe
更新于2025-11-21 11:08:12
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Translating chemometric analysis into physiological insights from in vivo confocal Raman spectroscopy of the human stratum corneum
摘要： The superficial layer of the skin, the stratum corneum (SC), consists of corneocytes surrounded by lipid regions and acts as a protective barrier for the body against water loss, toxic agents and microorganisms. As most substances permeate the stratum corneum through the lipid regions, lipid organization is considered crucial for the skin barrier function. Here, we investigate the potential of in vivo confocal Raman spectroscopy to describe the composition and organization of the SC. Confocal Raman spectroscopy is finding increasing use in the characterization of skin in biomedical, pharmaceutical and cosmetic applications. In this work, we analyze the spectra using chemometric methods and obtain principal components that correspond to the primary skin constituents: protein (keratin), natural moisturizing factor (NMF), water and lipid contributions in both ordered (orthorhombic) and disordered structural organization. By identifying these important components of the SC, these results highlight the utility of this in vivo, non-invasive, and depth resolved tool at the forefront of skin research.
关键词： Skin barrier,Natural moisturizing factor,Multivariate curve resolution,Keratin,Lipid organization
更新于2025-11-14 15:16:37
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Non-invasive method to monitor molecular changes in human stratum corneum during acute barrier disruption using reflectance NIR spectroscopy
摘要： Stratum corneum is the outer most part of skin for barrier function. Disorder in stratum corneum is related with many skin diseases including acne, atopic dermatitis and psoriasis. In developed countries, about 20% of the population has disorder in the barrier function of stratum corneum. Adhesive tape stripping is a method to disrupt skin barrier function in studying disorder in stratum corneum. In this study, we obtained NIR (Near-Infrared) spectrum of human skin after tape stripping. Changes in skin spectra after barrier disruption were investigated through principal component analysis (PCA) of spectrum. PCA analysis revealed that peaks for –NH stretching and –CH vibration mainly contributed to the spectral variation caused by barrier disruption. Furthermore, second derivative of spectrum revealed that acute barrier disruption contributes to spectral changes in the region related with secondary structure of protein, lipid and water associated with lipid in stratum corneum. We demonstrated that acute barrier disruption affected features in NIR spectrum. These spectral changes revealed that acute barrier disruption affected keratin protein and ceramide in human stratum corneum. These results suggest that NIR spectroscopy can be used to monitor changes in filamentous network and lamellar structure in stratum corneum. NIR spectroscopy can provide non-invasive method to investigate skin disease related with barrier disruption by monitoring disturbance in protein and lipid structure in stratum corneum.
关键词： protein,barrier disruption,Stratum corneum,tape stripping,water,NIR spectroscopy,lipid
更新于2025-11-14 15:14:40
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Spectroscopic Ellipsometry of fluid and gel phase Lipid Bilayers in hydrated conditions
摘要： The biological membranes play a crucial role in the various biological processes due to their characteristic physical properties. The parameters such as membrane composition, thickness undulations, and the influence of external stimuli play a crucial role in the phase state behavior of biological membranes. The supported lipid bilayer (SLBs) systems closely represent cell membranes and are often studied to understand their behavior. In the current study, we have implemented spectroscopic Ellipsometry (SE) technique to explore the optical properties of various single component lipid bilayers having different phase state (fluid and gel) under hydrated or native conditions. The measurement of ellipsometric angles ψ and Δ were obtained from SE and were utilized to realize an explicit phase state dependence. Further, we obtained the thickness (t) and refractive index (n) by modeling of these SE results. These results were found to be inter-related to the phase state and lateral organization. The bilayer thickness is further verified against values obtained from coarse-grained molecular dynamics simulations. The proposed method was tested on various lipid bilayers under their native phase state at room temperature and was found to have a correlation with AFM measurements.
关键词： fluid phase,Optical properties,gel phase,Spectroscopic Ellipsometry,Lipid membranes,Phase state
更新于2025-09-23 15:23:52
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Double-exponential kinetics of binding and redistribution of the fluorescent dyes in cell membranes witness for the existence of lipid microdomains
摘要： New technique of detecting lateral heterogeneity of the plasma membrane of living cells by means of membrane-binding fluorescent dyes is proposed. The kinetics of dye incorporation into the membrane or its lateral diffusion inside the membrane is measured and decomposed into exponential components by means of the Maximum Entropy Method. Two distinct exponential components are obtained consistently in all cases for several fluorescent dyes, two different cell lines and in different types of experiments including spectroscopy, flow cytometry and fluorescence recovery after photobleaching. These components are attributed to the liquid-ordered and disordered phases in the plasma membrane of studied cells in their dynamic equilibrium.
关键词： Kinetics,Maximum Entropy Method,Decomposition,Lipid phases,Plasma membrane heterogeneity
更新于2025-09-23 15:23:52
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Antimicrobial photodynamic inactivation of fungal biofilm using amino functionalized mesoporus silica-rose bengal nanoconjugate against Candida albicans
摘要： Candida albicans is an opportunistic fungal pathogen that causes both superficial and systemic infection and an important candidate that contribute to high morbidity and mortality rates in immunocompromised patients. The ability of C. albicans to switch from yeast to filamentous form and thereby forming biofilms make them resistant to most of the antifungal drugs available today. Thus the development of more effective antifungal drugs are essential and crucial at this point of time. Antimicrobial photodynamic therapy is an alternative modality to treat such biofilm forming resistant strains. This study aims to investigate the enhanced efficiency of newly synthesized MSN-RB conjugate as an antimicrobial photosensitizer for antimicrobial photodynamic therapy against C. albicans. Functionalization of MSN with amino groups was performed to increase the dye loading capacity. Conjugation process of MSN-RB was confirmed using different techniques including UV–Vis spectroscopy, Fluorescent spectroscopy and FTIR analysis. A low power green laser 50 mW irradiation was applied (5 min) for activation of MSN-RB conjugate and RB against C. albicans biofilm and planktonic cell. The comparative study of MSN-RB conjugate and free RB on aPDT was evaluated using standard experimental procedures. Antibiofilm efficacy was determined using biofilm inhibition assay, cell viability, EPS quantification and CLSM studies. The results revealed that MSN-RB conjugate has a significant antimicrobial activity (88.62 ± 3.4%) and antibiofilm effect on C. albicans when compared to free dye after light irradiation. The MSN-RB conjugate based aPDT can be employed effectively in treatment of C. albicans infections.
关键词： Antimicrobial photodynamic therapy,Conjugation,Amino functionalization,Mesoporus silica nanoparticles,Lipid peroxidation,Anti-biofilm activity
更新于2025-09-23 15:23:52
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An AIEgen-based fluorescent probe for highly selective and specific imaging of lipid droplets in L02 and HepG2 cells
摘要： Lipid droplets (LDs), as dynamic organelles, are associated with physiologically and pathologically metabolic processes. Especially, in human liver cancer cells (HepG2 cells) the lipid metabolism shows significant difference by comparing with the human normal liver cell (L02 cells). In this work, a new highly selective and specific fluorescent probe TPA-SD for the detection of LDs has been rationally designed and easily prepared from triphenylamine and salicylaldehyde, which possesses aggregation-induced emission (AIE) and excited state intramolecular proton transfer characteristics (ESIPT). Ideal probes for LDs imaging require high concentration accumulation of fluorophores in LDs and lack of self-quenching in the aggregated state, so the AIE property is necessary. TPA-SD can successfully and specifically accumulate in LDs, thus facilitating clearly distinguishing L02 cells from HepG2 cells according to obvious difference in the number of dot-shaped LDs marked by TPA-SD. The dot-shaped LDs in the HepG2 cells is found to be obviously more than that in the L02 cells. Moreover, the spatial distribution of LDs could be identified by TPA-SD. The results indicate TPA-SD possesses great potential in imaging and diagnosis of LDs-related diseases.
关键词： fluorescent probe,aggregation-induced emission,dot-shaped LDs number,lipid droplets (LDs) imaging
更新于2025-09-23 15:23:52
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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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Single Particle Tracking and Super-Resolution Imaging of Membrane-Assisted Stop-and-Go Diffusion and Lattice Assembly of DNA Origami
摘要： DNA nanostructures offer the possibility to mimic functional biological membrane components due to their nanometer-precise shape configurability and versatile biochemical functionality. Here we show that the diffusional behavior of DNA nanostructures and their assembly into higher order membrane-bound lattices can be controlled in a stop-and-go manner and that the process can be monitored with super-resolution imaging. The DNA structures are transiently immobilized on glass-supported lipid bilayers by changing the mono- and divalent cation concentrations of the surrounding buffer. Using DNA-PAINT super-resolution microscopy, we confirm the fixation of DNA origami structures with different shapes. On mica-supported lipid bilayers, in contrast, we observe residual movement. By increasing the concentration of NaCl and depleting MgCl2, a large fraction of DNA structures restarts to diffuse freely on both substrates. After addition of a set of oligonucleotides that enables three Y-shaped monomers to assemble into a three-legged shape (triskelion), the triskelia can be stopped and super-resolved. Exchanging buffer and adding another set of oligonucleotides triggers the triskelia to diffuse and assemble into hexagonal 2D lattices. This stop-and-go imaging technique provides a way to control and observe the diffusional behavior of DNA nanostructures on lipid membranes that could also lead to control of membrane-associated cargos.
关键词： single-particle tracking,DNA origami,diffusion,super-resolution microscopy,lipid membrane,DNA nanotechnology
更新于2025-09-23 15:23:52
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Different effects of alpha-Synuclein mutants on lipid binding and aggregation detected by single molecule fluorescence spectroscopy and ThT fluorescence-based measurements
摘要： Six alpha-Synuclein point mutations are currently known to be associated with familial parkinsonism: A30P, E46K, H50Q, G51D, A53E and A53T. We performed a comprehensive in vitro analysis to study the impact of all aSyn mutations on lipid binding and aggregation behavior. Markedly reduced lipid binding of A30P, moderately attenuated binding of G51D and only very slightly reduced binding for the other mutants were observed. A30P was particularly prone to form metal ion induced oligomers, whereas A53T exhibited only weak tendencies to form oligomers. In turn, fibril formation occurred rapidly in H50Q, G51D and A53T, but only slowly in A30P, suggesting mutants prone to form oligomers tend to form fibrils to a lesser extent. This was supported by the observation that fibril formation of wild type aSyn, A30P and A53T was impaired in the presence of ferric iron. Additionally, we found the aggregation kinetics of mixtures of A30P or A53T and wt aSyn to be determined by the faster aggregating aSyn variant. Our results implicate differential mechanisms playing a role in aSyn pathology on the molecular level. This might contribute to a better understanding of Parkinson′s disease pathogenesis and provide potential links to develop prevention strategies and disease-modifying therapy.
关键词： synucleinopathy,Alpha-synuclein (α‐Synuclein),Parkinson′s disease,protein‐lipid interaction,protein aggregation,mutant
更新于2025-09-23 15:23:52