Fluorogenic Biosensing with Tunable Polydiacetylene Vesicles.

Polydiacetylenes (PDAs) are conjugated polymers that are well known for their colorimetric transition from blue to red with the application of energetic stimulus. Sensing platforms based on polymerized diacetylene surfactant vesicles and other structures have been widely demonstrated for various colorimetric biosensing applications. Although less studied and utilized, the transition also results in a change from a non-fluorescent to a highly fluorescent state, making polydiacetylenes useful for both colorimetric and fluorogenic sensing applications.

Quantitative Characterization of Localized Hydrophobicity Surrounding Polymer Particle Surfaces for Aqueous Antibacterial Colloids.

Aqueous antibacterial colloids are potential agents that kill bacteria via physical contact. Conventionally, antibacterial agents are designed to be small, cationic, or hydrophobic. However, hydrophobic materials easily aggregate in aqueous media, drastically inhibiting their activity.

Amyloid beta (Aβ) fibrillation kinetics and its impact on membrane polarity.

Fibrillation of the amyloid beta (Aβ) peptide has often been associated with neurodegenerative pathologies such as Alzheimer's disease. In this study we examined the influence of several potential compositions of the lipid membrane on Aβ fibrillation by using liposomes as a basic model membrane. Firstly, it was revealed that Aβ fibrillation kinetics were enhanced and had the potential to occur at a faster rate on more fluid membranes compared to solid membranes.

A Quantitative Approach to Characterize the Surface Modification on Nanoparticles Based on Localized Dielectric Environments.

Nanoparticles (NPs) are utilized for the functionalization of composite materials and nanofluids. Although oxide NPs (e.g.

Surface lattice resonance in three-dimensional plasmonic arrays fabricated via self-assembly of silica-coated gold nanoparticles.

Hypothesis: Three-dimensional plasmonic nanoparticle arrays in which the nanoparticles are assembled with a certain distance apart are expected to exhibit unique optical properties attributed to surface lattice resonances because of the interactions between the nanoparticle layers.

Experiments: Multi-layered gold nanoparticle arrays were created to experimentally prove surface lattice resonances from three-dimensional arrays. Silica-coated gold nanoparticles were employed as building blocks for the array because the distance between the nanoparticles can be tuned by adjusting the thickness of the silica coating.

Fluorescence Spectroscopic Analysis of Lateral and Transbilayer Fluidity of Exosome Membranes.

Exosomes are small extracellular vesicles (sEVs) involved in distal cell-cell communication and cancer migration by transferring functional cargo molecules. Membrane domains similar to lipid rafts are assumed to occur in exosome membranes and are involved in interactions with target cells. However, the bilayer membrane properties of these small vesicles have not been fully investigated.

Preferential adsorption of L-tryptophan by L-phospholipid coated porous polymer particles.

Chiral selective adsorption of L-amino acid, tryptophan (Trp) was achieved using phospholipid membrane-coated porous polymer particles (PPPs). PPPs with numerous pores were prepared by in situ polymerization of divinylbenzene, and then coated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, L-phospholipid) via the impregnation method. Elemental mapping of energy dispersive X-ray (EDX) analysis revealed that DPPC molecules were distributed to the surface and the inner part of PPPs, where almost all the DPPC molecules applied for impregnation were deposited on PPPs.

Surface Characteristics of Antibacterial Polystyrene Nanoparticles Synthesized Using Cationic Initiator and Comonomers.

Polymer nanoparticles have attracted attention as antibacterial materials, but the function of the polymer itself has not yet been clarified sufficiently. To estimate the essential surface properties of antibacterial polymer nanoparticles, herein, we synthesized cationic polystyrene (PSt) nanoparticles via soap-free emulsion polymerization using 2,2'-azobis-[2-(1,3-dimethyl-4,5-dihydro-1-imidazol-3-ium-2-yl)]propane triflate (ADIP) as initiator. The conversion of total monomers was drastically increased through the addition of the commoner (vinylbenzyl)trimethylammonium chloride (VBTMAC), where unimodal size distributions ( ≤ 10%) were obtained at comonomer molar ratios between 0.

Insight into the Exosomal Membrane: From Viewpoints of Membrane Fluidity and Polarity.

Numerous research studies have been done for exosomes, particularly focusing on membrane proteins and included nucleic acids, and the volume of the knowledge about the lipids in the exosomal membrane has been increasing. However, the dynamic property of the exosomal membrane is hardly studied. By employing milk exosome as an example, herein the exosomal membrane was characterized focusing on the membrane fluidity and polarity.

Correlation of Secondary Particle Number with the Debye-Hückel Parameter for Thickening Mesoporous Silica Shells Formed on Spherical Cores.

Mesoporous silica shells were formed on nonporous spherical silica cores during the sol-gel reaction to elucidate the mechanism for the generation of secondary particles that disturb the efficient growth of mesoporous shells on the cores. Sodium bromide (NaBr) was used as a typical electrolyte for the sol-gel reaction to increase the ionic strength of the reactant solution, which effectively suppressed the generation of secondary particles during the reaction wherein a uniform mesoporous shell was formed on the spherical core. The number of secondary particles ( ) generated at an ethanol/water weight ratio of 0.

Modulation of the Belousov-Zhabotinsky Reaction with Lipid Bilayers: Effects of Lipid Head Groups and Membrane Properties.

The Belousov-Zhabotinsky (BZ) reaction is an oscillating reaction due to periodic oscillations that happen in the concentration of some intermediates. Such systems can be applied together with hydrophobic membranes to create an autonomous behavior in artificial systems. However, because of a complex set of reactions happening in such systems, the interferences caused by hydrophobic membranes are not easily understood.

Investigation of Quercetin interaction behaviors with lipid bilayers: Toward understanding its antioxidative effect within biomembrane.

Quercetin (QCT), existing in common dietary sources, is an abundant bioflavonoid with planar structure and exerts multiple pharmacological effects. Herein, four kinds of liposomes were prepared as model biomembranes, and then the partition coefficient, distribution in lipid membrane and influence of the QCT on the membrane properties were evaluated. The partition of QCT to lipid membranes was affected by both membrane phase state and the interference of QCT on membrane properties.

Systematic Characterization of Nanostructured Lipid Carriers from Cetyl Palmitate/Caprylic Triglyceride/Tween 80 Mixtures in an Aqueous Environment.

Nanostructured lipid carriers (NLCs) are gaining attention as the new generation of lipid vehicles. These carriers consist of saturated lipids with small drops of liquid oil dispersed into the inner lipid matrix and are stabilized by a surfactant. Conventionally, NLC-based drug delivery systems have been widely studied, and many researchers are looking into the composition of NLC properties to improve the performance of NLCs.

Double-Inverse-Opal-Structured Particle Assembly as a Novel Immobilized Photocatalytic Material.

Immobilization of photocatalysts on supports is an important method of adding highly active photocatalysts to a continuous flowing system without the need for photocatalyst recovery. However, direct immobilization prevents exposure to all photocatalytically active surfaces. Therefore, to immobilize particulate photocatalysts, while exposing the photocatalytic surface to organic pollutant water in a continuous flowing system, in this study, we employed double-inverse-opal (DIO) with periodically arranged, interconnected macropores, each containing a single photocatalytic particle.

Changes Caused by Liposomes to the Belousov-Zhabotinsky Reaction.

The Belousov-Zhabotinsky (BZ) reaction has been applied to give autonomous dynamic behaviors to artificial systems. This reaction is conducted in an aqueous system, but it produces some hydrophobic intermediates, such as bromine. On the basis of previous works about reactions in the lipid bilayer, we investigated how liposome membranes (water-oil interface) affect the BZ reaction.

Evaluation of Molecular Ordering in Bicelle Bilayer Membranes Based on Induced Circular Dichroism Spectra.

Bicelles are submicrometer-sized disc-shaped molecular self-assemblies that can be obtained in aqueous solution by dispersing mixtures of certain amphiphiles. Although phospholipid bicelle and phospholipid vesicle assemblies adopt similar lipid bilayer structures, the differences in bilayer characteristics, especially physicochemical properties such as bilayer fluidity, are not clearly understood. Herein, we report the lipid ordering properties of bicelle bilayer membranes based on induced circular dichroism (ICD) and fluorescence polarization analyses using 1,6-diphenyl-1,3,5-hexatriene (DPH) as a probe.

Enzymatic hydrolysis of cellulose recovered from ionic liquid-salt aqueous two-phase system.

Regenerated cellulose can be prepared by treatment with an ionic liquid (IL) and an anti-solvent such as water, which significantly enhances the enzymatic hydrolysis in comparison to crystalline cellulose. The IL-aqueous two-phase system (IL-ATPS) is consisted of IL-condensed top phase and salt-condensed bottom phase, which could be suitable to produce regenerated cellulose with smaller amount of IL. Using IL-ATPS with different pH, the enzymatic saccharification efficiency of crystalline cellulose was determined.

Membrane Surface-Enhanced Raman Spectroscopy for Cholesterol-Modified Lipid Systems: Effect of Gold Nanoparticle Size.

A gold nanoparticle (AuNP) has a localized surface plasmon resonance peak depending on its size, which is often utilized for surface-enhanced Raman scattering (SERS). To obtain information on the cholesterol (Chol)-incorporated lipid membranes by SERS, AuNPs (5, 100 nm) were first functionalized by 1-octanethiol and then modified by lipids (AuNP@lipid). In membrane surface-enhanced Raman spectroscopy (MSERS), both signals from 1,2-dioleoyl--glycero-3-phosphocholine (DOPC) and Chol molecules were enhanced, depending on preparation conditions (size of AuNPs and lipid/AuNP ratio).

Melting-Temperature-Dependent Interactions of Ergosterol with Unsaturated and Saturated Lipids in Model Membranes.

Sterols such as cholesterol (Chol) and ergosterol (Erg) are known to regulate membrane properties in higher eukaryotes and in lower eukaryotes, respectively. To better understand the modulation of membrane properties by Erg, binary lipid membranes composed of Erg and diacylglycerophosphocholine (PC) were studied in Langmuir monolayer and bilayer vesicle systems. From the excess area measured by pressure-area isotherms, attractive interactions between Erg and saturated PC were significant above the melting temperature () of PC.

Ergosterol-Induced Ordered Phase in Ternary Lipid Mixture Systems of Unsaturated and Saturated Phospholipid Membranes.

The sterol ergosterol (Erg) is ubiquitous in the membranes of lower eukaryotes such as fungi. To investigate the interactions between Erg and phosphocholine (PC) molecules, we studied ternary lipid mixture systems composed of unsaturated 1,2-dioleoyl--glycero-3-phosphocholine (DOPC), saturated 1,2-dipalmitoyl--glycero-3-phophocholine (DPPC), and Erg. Bilayer membrane fluidity and polarity were systematically analyzed using fluorescent probes.

Characterization of Ionic Liquid Aqueous Two-Phase Systems: Phase Separation Behaviors and the Hydrophobicity Index between the Two Phases.

1-Allyl-3-methylimidazolium chloride [Amim][Cl] and 1-butyl-3-methylimidazolium chloride [Bmim][Cl] are water-soluble ionic liquids (ILs) that can from an aqueous two-phase system (ATPS) when mixed with specific salts. Herein, we prepared [Amim][Cl]- and [Bmim][Cl]-ATPSs by adding the salts (KCO, KHPO). To investigate the phase separation behavior of the IL-ATPSs, binodal curves were drawn at different temperatures and the length and slope of the tie lines were analyzed.

Lipid-Surrounding Water Molecules Probed by Time-Resolved Emission Spectra of Laurdan.

The hydration states of the interfacial region of lipid bilayers were investigated on the basis of the time-resolved emission spectra (TRES) analysis of 6-lauroyl-2-dimethylamino naphthalene (Laurdan), a common fluorescence probe used to analyze membrane hydration. TRES derived from long and short lifetime components were extracted from samples of different lipid species: 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl- sn-glycero-3-phosphocholine (DOPC), d- erythro- N-palmitoyl-sphingosylphosphorylcholine (PSM), and a DOPC/PSM binary bilayer system. Neither lifetime component (short or long) corresponded with the hydration properties; the short lifetime component of DOPC (1.

Solvatochromic Modeling of Laurdan for Multiple Polarity Analysis of Dihydrosphingomyelin Bilayer.

The hydration properties of the interface between lipid bilayers and bulk water are important for determining membrane characteristics. Here, the emission properties of a solvent-sensitive fluorescence probe, 6-lauroyl-2-dimethylamino naphthalene (Laurdan), were evaluated in lipid bilayer systems composed of the sphingolipids D-erythro-N-palmitoyl-sphingosylphosphorylcholine (PSM) and D-erythro-N-palmitoyl-dihydrosphingomyelin (DHPSM). The glycerophospholipids 1-palmitoyl-2-palmitoyl-sn-glycero-3-phosphocholine and 1-oleoyl-2-oleoyl-sn-glycero-3-phosphocholine were used as controls.

Direct Observation of Amyloid Behavior at Phospholipid Membrane Constructed on Gold Nanoparticles.

Amyloid (A) is a potential biomarker of Alzheimer's disease (AD), and its fibrillation behavior is of interest and value. In this study, the A behaviors on phospholipid membranes were observed by Membrane Surface-Enhanced Raman Spectroscopy (MSERS) method. Phospholipid (PL) membranes, consisting of DMPC and DMPS with a molar ratio of 9:1, were fabricated on gold nanoparticles with diameter of 100 nm (Au@PL).

Aggregation of chlorophyll a induced in self-assembled membranes composed of DMPC and DHPC.

The J-aggregate of chlorophyll a (Chla) functions as a light-harvesting antenna in natural systems. In this study, we employed the phospholipid membranes composed of longer-chain 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and shorter-chain 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), as a platform to induce Chla aggregates. The DMPC/DHPC assembly at the mixing ratio (q) = 1.