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Scanning Surface Plasmon Microscope for Sensing Lipid Array and Au Film Defect
摘要： We demonstrated a scanning radially-polarized surface plasmon microscopy (SSPM) with submicron lateral resolution and high refractive index sensitivity. According to the captured images, SSPM could be used to verify the quality of deposited Au film and Au structure on surface plasmon sensing chip. The defect on the SPR chip, which disturbed the plasmonic wave around the focal point, could be easily detected by our system. Moreover, the application of SSPM in imaging lipid array was showed in this article. The 1, 2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) array was made by dip-pen nanolithography. The results indicated that SSPM system could be used in comparing the thickness of DOPC array. Because of the high sensitivity and high spatial resolution of the system, we expected the SSPM to be used in measuring the properties of nanogold array structures and apply to digital-array biosensors in nanoscale.
关键词： 1,2-Dioleoyl-sn-glycero-3-phosphocholine,Scanning surface plasmon microscope,lipid array,nanostructure
更新于2025-09-23 15:22:29
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Pulsed light treatment for the reduction of Salmonella Typhimurium and Yersinia enterocolitica on pork skin and pork loin
摘要： The aim of the presented study was to investigate the impact of pulsed light on the reduction of Salmonella Typhimurium and Yersinia enterocolitica on pork skin and loin. Fluences of 0.52 to 19.11 J/cm2 were applied to the pathogen-inoculated products to perform microbiological studies, as well as analyses of color, temperature, lipid peroxidation and odor. Reductions on pork skin ranged from 1.73 to 3.16 log for Salmonella and from 1.48 to 4.37 log for Yersinia. Microbial reduction was significantly lower on pork loin, varying between a minimum of 0.4 and a maximum of 1.7 log for both pathogens. Treatments ≥7.36 J/cm2 modified the color parameters of pork skin and fluences ≥9.66 J/cm2 rendered pork loin samples less red. All studies with pulsed light resulted in odor changes, except for the experiment on pork skin at 0.52 J/cm2. Despite significant microbiological reduction on pork skin, further studies should be carried out to optimize this promising technology.
关键词： Pulsed broad spectrum light,Lipid peroxidation,Microbial reduction,Pork,Sensory analysis
更新于2025-09-23 15:22:29
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Quantitative imaging of membrane micropolarity in living cells and tissues by spectral phasors analysis
摘要： Intracellular micropolarity is essential in several metabolic processes, as it controls membrane permeability, fluxes of molecules and energy. Here we describe a method for the determination of the micropolarity in living cells using spectral confocal microscopy. The method is based on a phasor analysis of spectrally resolved images of live cells, labelled with the solvatochromic probe Nile Red. An application is provided to extract a polarity profile from the acquired Spectral datasets, which represent the contribution of hyperpolar, polar and non-polar lipids, and to generate a micropolarity map at submicrometric spatial resolution. A metabolic parameter, representing a quantitative index of the fatty acid-triacylglycerol turnover, is also furnished. This method allows a functional profiling of cells and tissues and the detection of metabolic imbalances between lipid storage and usage.
关键词： Membranes micropolarity,Nile Red,Fatty acids,Triglycerides,Lipid droplets,Confocal microscopy,Metabolic imaging,Spectral phasors,Lipids
更新于2025-09-23 15:22:29
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Gramicidin Lateral Distribution in Phospholipid Membranes: Fluorescence Phasor Plots and Statistical Mechanical Model
摘要： When using small mole fraction increments to study gramicidins in phospholipid membranes, we found that the phasor dots of intrinsic ?uorescence of gramicidin D and gramicidin A in dimyristoyl-sn-glycero-3-phosphocholine (DMPC) unilamellar and multilamellar vesicles exhibit a biphasic change with peptide content at 0.143 gramicidin mole fraction. To understand this phenomenon, we developed a statistical mechanical model of gramicidin/DMPC mixtures. Our model assumes a sludge-like mixture of ?uid phase and aggregates of rigid clusters. In the ?uid phase, gramicidin monomers are randomly distributed. A rigid cluster is formed by a gramicidin dimer and DMPC molecules that are condensed to the dimer, following particular stoichiometries (critical gramicidin mole fractions, Xcr including 0.143). Rigid clusters form aggregates in which gramicidin dimers are regularly distributed, in some cases, even to superlattices. At Xcr, the size of cluster aggregates and regular distributions reach a local maximum. Before a similar model was developed for cholesterol/DMPC mixtures (Sugar and Chong (2012) J. Am. Chem. Soc. 134, 1164–1171) and here the similarities and differences are discussed between these two models.
关键词： lipid bilayers,membrane organization,gramicidins,statistical mechanics,?uorescence spectroscopy,peptide-lipid interactions
更新于2025-09-23 15:21:21
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Photooxidation of unilamellar vesicles by a lipophilic pterin: Deciphering biomembrane photodamage
摘要： Pterins are natural products that can photosensitize the oxidation of DNA, proteins and phospholipids. Recently, a new series of decyl-chain (i.e., lipophilic) pterins were synthesized and their photophysical properties investigated. These decyl-pterins led to efficient intercalation in large unilamellar vesicles and produce, under UVA irradiation, singlet molecular oxygen, a highly oxidative species that react with polyunsaturated fatty acids (PUFAs) to form hydroperoxides. Here, we demonstrate that the association of 4-(decyloxy)pteridin-2-amine (O-decyl-Ptr) to lipid membranes is key to its ability to trigger phospholipid oxidation in unilamellar vesicles of phosphatidylcholine rich in PUFAs used as model biomembranes. Our results show that O-decyl-Ptr is at least one order of magnitude more efficient photosensitizer of lipids than pterin (Ptr), the unsubstituted derivative of the pterin family, which is more hydrophilic and freely passes across lipid membranes. Lipid peroxidation photosensitized by O-decyl-Ptr was detected by the formation of conjugated dienes and oxidized lipids, such as hydroxy and hydroperoxides derivatives. These primary products undergo a rapid conversion into short-chain secondary products by cleavage of the fatty acid chains some of which are due to subsequent photosensitized reactions. As a consequence, a fast increase in membrane permeability is observed. Therefore, lipid oxidation induced by O-decyl-Ptr could promote cell photodamage due to the biomembrane integrity loss which, in turn, may trigger cell death.
关键词： alkyl-pterins,membrane permeability,lipid peroxidation,photosensitization
更新于2025-09-23 15:21:21
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Further Development of Near-Infrared Mediated Quantum Dots and Paclitaxel Co-loaded Nanostructured Lipid Carrier System for Cancer Theragnostic
摘要： Of colloidal systems, ceteris paribus, nanostructured lipid carriers are second to none in offering a single-unit platform for multifunctional benefits. Quantum dots are known to possess unique properties that make them ideal for imaging purpose and that they may be used for cancer detection. For several decades, paclitaxel has been the most effective drug against a wide range of solid tumours. Theragnostic nanomedicine provides a platform to monitor, evaluate, and individualize treatment in real time. Evaluation of cancer treatment outcome at an early stage therapy is key to increase survival prospects of a patient. Previously, a novel co-loaded nanostructured lipid carriers’ theragnostic system for parenteral administration was developed. The aim of this study was to further investigate the co-loaded nanostructured lipid carriers in order to provide interpretation necessary for preclinical elucidation of the formulation, in part. The co-loaded nanostructured lipid carriers were prepared by oil/water emulsification-solvent evaporation technique. In this study, stability and co-loaded nanostructured lipid carriers’ internalization by MCF 7 and HepG2 cells were investigated. The co-loaded nanostructured lipid carriers was stable at 4(cid:2)C for 1 month. The formulation was successfully internalized by MCF-7 and HepG2 cells. Nevertheless, the co-loaded nanostructured lipid carrier was more apt for MCF-7 cells. This finding affirms the formulation to be the most appropriate for breast cancer treatment. In addition, if taken correctly by a patient for a month, the formulation would give true reflection of the contents’ amounts, the factor paramount to appropriate changes in treatment protocol. It can therefore safely be concluded that the co-loaded nanostructured lipid carrier formulation may be potentially an effective theragnostic translational system.
关键词： translational system,cellular uptake,theragnostic,stability study,co-loaded nanostructured lipid carrier
更新于2025-09-23 15:21:01
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Pulsed interleaved excitation-based line-scanning spatial correlation spectroscopy (PIE-lsSCS)
摘要： We report pulsed interleaved excitation (PIE) based line-scanning spatial correlation spectroscopy (PIE-lsSCS), a quantitative fluorescence microscopy method for the study of dynamics in free-standing lipid bilayer membranes. Using a confocal microscope, we scan multiple lines perpendicularly through the membrane, each one laterally displaced from the previous one by several ten nanometers. Scanning through the membrane enables us to eliminate intensity fluctuations due to membrane displacements with respect to the observation volume. The diffusion of fluorescent molecules within the membrane is quantified by spatial correlation analysis, based on the fixed lag times between successive line scans. PIE affords dual-color excitation within a single line scan and avoids channel crosstalk. PIE-lsSCS data are acquired from a larger membrane region so that sampling is more efficient. Moreover, the local photon flux is reduced compared with single-point experiments, resulting in a smaller fraction of photobleached molecules for identical exposure times. This is helpful for precise measurements on live cells and tissues. We have evaluated the method with experiments on fluorescently labeled giant unilamellar vesicles (GUVs) and membrane-stained live cells.
关键词： lipid bilayer membranes,dual-color excitation,live cells,line-scanning spatial correlation spectroscopy,fluorescence microscopy,tissues,GUVs,confocal microscope,photobleaching,Pulsed interleaved excitation
更新于2025-09-23 15:21:01
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Intravascular Photothermal Strain Imaging for Lipid Detection
摘要： Cardiovascular disease (CVD) is one of the major threats to humanity, accounting for one-third of the world’s deaths. For patients with high-risk CVD, plaque rupture can lead to critical condition. It is therefore important to determine the stability of the plaque and classify the patient’s risk level. Lipid content is an important determinant of plaque stability. However, conventional intravascular imaging methods have limitations in ?nding lipids. Therefore, new intravascular imaging techniques for plaque risk assessment are urgently needed. In this study, a novel photothermal strain imaging (pTSI) was applied to an intravascular imaging system for detecting lipids in plaques. As a combination of thermal strain imaging and laser-induced heating, pTSI differentiates lipids from other tissues based on changes in ultrasound (US) velocity with temperature change. We designed an optical pathway to an intravascular ultrasound catheter to deliver 1210-nm laser and US simultaneously. To establish the feasibility of the intravascular pTSI system, we experimented with a tissue-mimicking phantom made of fat and gelatin. Due to the difference in the strain during laser heating, we can clearly distinguish fat and gelatin in the phantom. The result demonstrates that pTSI could be used with conventional intravascular imaging methods to detect the plaque lipid.
关键词： photothermal strain imaging,intravascular ultrasound (IVUS),thermal strain imaging,lipid detection,unstable plaque,intravascular imaging,cardiovascular disease
更新于2025-09-23 15:21:01
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Effect of Infrared Low-Intensity Laser Irradiation on Lipid Peroxidation under Conditions of Experimental Circulatory Hypoxia of Visual Analyzer
摘要： The physiological stress modeled by circulatory hypoxia activates LPO processes in various tissues. In posthypoxic period, the infrared low-intensity laser irradiation significantly decreased the chemiluminescence parameters in blood plasma, normalized the retinal levels of diene and triene conjugates, and decreased MDA in the rat brain attesting to the correcting effect of this irradiation during various types of physiological stresses.
关键词： infrared low-intensity laser irradiation,lipid peroxidation,rats,visual analyzer
更新于2025-09-23 15:19:57
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Out-of-Plane Nanoscale Reorganization of Lipid Molecules and Nanoparticles Revealed by Plasmonic Spectroscopy
摘要： Lipid bilayers assembled on solid substrates have been extensively studied with single-molecule resolution as the molecules diffuse in 2D, however the out-of-plane motion is typically ignored. Here we present sub-nanometer out-of-plane diffusion of nanoparticles attached to hybrid lipid bilayers (HBLs) assembled on metal surfaces. The nanoscale cavity formed between Au nanoparticle and Au film provides strongly-enhanced optical fields capable of locally probing HBLs assembled in the gaps. This allows us to spectroscopically resolve the nanoparticles assembled on bilayers, near edges, and in membrane defects, showing the strong influence of charged lipid rafts. Nanoparticles sitting on the edges of the HBL are observed to flip onto and off the bilayer, with flip energies of 10 meV showing how thermal energies dynamically modify lipid arrangements around a nanoparticle. We further resolve the movement of individual lipid molecules by doping the HBL with low concentrations of Texas-red (TxR) dye-labeled lipids.
关键词： Purcell factor,Plasmonics,Single-molecule,Nano-assembly,Nanocavities,Lipid bilayers
更新于2025-09-23 15:19:57