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1.
Understanding the interactions of gold nanoparticles (AuNPs) with cellular compartments, especially cell membranes, is of fundamental importance in obtaining their control in biomedical applications. An effort is made in this paper to investigate the interactions of 2.2 nm core AuNPs with negative model bilayer membranes by coarse-grained (CG) molecular dynamics (MD) simulation. The CG model of lipid bilayer was taken from Marrink et al. ( J. Phys. Chem. B 2004, 108, 750-760 ), whereas the CG AuNPs model was developed on the basis of both atomistic MD simulations and experimental data. It was found that AuNPs functionalized with cationic ligands penetrated into the negative bilayer membranes and generated significant disruptions on bilayers. The lipids surrounding the nanoparticle were highly disordered and the bulk surface of the bilayer exhibits some defective areas. Most importantly, it is observed that a nanoscale hole can be formed and expanded spontaneously on the peripheral regions of the 20 × 20 nm bilayer. The expansion of the hole is on the time scale of hundreds of nanosceonds. The fully expanded hole had a radius of ~5.5 nm and could transport water molecules at a rate of up to ~1100 molecule/ns. However holes could not be formed on a larger bilayer (28 × 28 nm). The factors that can eliminate hole formation on the bilayer also include the decrease of cationic lignads on the AuNP, the reduction of negative lipids in the bilayer, the release of bilayer surface tension, the lowering of temperature, and the addition of a high concentration of salt. The results suggest that a hole can only be formed on living cell membranes under extreme conditions.  相似文献   

2.
Cubosomes are highly stable nanoparticles formed from the lipid cubic phase and stabilized by a polymer based outer corona. Bicontinuous lipid cubic phases consist of a single lipid bilayer that forms a continuous periodic membrane lattice structure with pores formed by two interwoven water channels. Cubosome composition can be tuned to engineer pore sizes or include bioactive lipids, the polymer outer corona can be used for targeting and they are highly stable under physiological conditions. Compared to liposomes, the structure provides a significantly higher membrane surface area for loading of membrane proteins and small drug molecules. Owing to recent advances, they can be engineered in vitro in both bulk and nanoparticle formats with applications including drug delivery, membrane bioreactors, artificial cells, and biosensors. This review outlines recent advances in cubosome technology enabling their application and provides guidelines for the rational design of new systems for biomedical applications.  相似文献   

3.
Stimuli-responsive nanocarriers offer favorable properties for the target-specific delivery of drugs. Herein, we employed photoirradiation as an external stimulus for the construction of a molecular system that encapsulated small molecules, which were released upon photoirradiation. These nanocarriers consisted of DNA amphiphiles (ODAz 1), in which an oligodeoxynucleotide and an alkyl chain were employed as the hydrophilic and hydrophobic parts, respectively, and these two parts were linked by a photochromic azobenzene unit. In aqueous solutions, ODAz 1 formed nanosized aggregates that encapsulated hydrophobic molecules in their hydrophobic core. Photoirradiation induced isomerization of the azobenzene unit led to changes in aggregate size and the immediate release of the molecules. The aggregate smoothly penetrated the cell membrane, and the photochemical release and delivery of small molecules into living cells were achieved. Thus, ODAz 1 aggregates represent promising photosensitive nanocarriers that may be applicable to drug delivery and targeting.  相似文献   

4.
The fabrication of core-shell structural nanosilica@liposome nanocapsules as a drug delivery vehicle is reported. SiO(2) nanoparticles are encapsulated within liposomes by a W/O/W emulsion approach to form supramolecular assemblies with a core of colloidal particles enveloped by a lipid bilayer shell. A nanosilica core provides charge compensation and architectural support for the lipid bilayer, which significantly improves their physical stability. A preliminary application of these core-shell nanocapsules for hemoglobin (Hb) delivery is described. Through the H-bonding interaction between the hydroxyl groups on nanosilicas and the amino nitrogens of Hb, Hb-SiO(2) nanocomplexes in which the saturated adsorption amount of Hb on SiO(2) is 0.47 g g(-1) are coated with lipids to generate core-shell Hb-SiO(2)@liposome nanocapsules with mean diameters of 60-500 nm and Hb encapsulation efficiency of 48.4-87.9%. Hb-SiO(2)@liposome supramolecular nanovehicles create a mode of delivery that stabilizes the encapsulated Hb and achieves long-lasting release, thereby improving the efficacy of the drug. Compared with liposome-encapsulated Hb and Hb-loaded SiO(2) particles, such core-shell nanovehicles show substantially enhanced release performance of Hb in vitro. This finding opens up a new window of liposome-based formulations as drug delivery nanovehicles for widespread pharmaceutical applications.  相似文献   

5.
The fluorescence spectra of 6-propionyl-2-(dimethylamino)naphthalene (Prodan) were observed as a function of pressure for the bilayer membrane systems of dilauroylphosphatidylcholine (DLPC), dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), and distearoylphosphatidylcholine (DSPC). The wavelength of the emission maximum, lambdamax, was found to be 480, 430, and 500 nm for the liquid crystalline (Lalpha), ripple gel (P'beta), and pressure-induced interdigitated gel (LbetaI) phase, respectively. Since the lambdamax reflects the solvent property around the probe molecules, we could speculate on the location of the Prodan molecules in the bilayer membranes; in the Lalpha phase of the lipid bilayer, the Prodan molecules distribute around the phosphate of the lipids (i.e. the polar region). The Lalpha/P'beta phase transition caused the Prodan molecules to move into the less polar region near the glycerol backbone. The fluorescence intensity of the Prodan in the P'beta phase was dependent on the chain length of the lipids and on pressure; the shorter the chain length of the lipid, the stronger the fluorescence intensity of the Prodan. Moreover, for the DLPC bilayer membrane system, the fluorescence intensity at 430 nm increased with increasing pressure, indicating that the partition of Prodan into the DLPC bilayer membrane is promoted by applying pressure. In the case of the DPPC and DSPC bilayers, as the pressure increased further, the pressure-induced interdigitation caused the Prodan molecules to squeeze out of the glycerol backbone region and to move the hydrophilic region near the bilayer surface. The ratio of fluorescence intensity at 480 nm to that at 430 nm, F480/F430, showed a sharp change at the phase-transition pressure. In the case of the DPPC and DSPC bilayers, the values of F480/F430 showed an abrupt increase above a certain pressure higher than the Lalpha/P'beta transition pressure, which corresponds to the interdigitation from the P'beta to the LbetaI phase. The plot of F480/F430 versus pressure is available for recognition of the bilayer phase transitions, especially the bilayer interdigitation.  相似文献   

6.
Kim P  Lee SE  Jung HS  Lee HY  Kawai T  Suh KY 《Lab on a chip》2006,6(1):54-59
We present simple soft lithographic methods for patterning supported lipid bilayer (SLB) membranes onto a surface and inside microfluidic channels. Micropatterns of polyethylene glycol (PEG)-based polymers were fabricated on glass substrates by microcontact printing or capillary moulding. The patterned PEG surfaces have shown 97 +/- 0.5% reduction in lipid adsorption onto two dimensional surfaces and 95 +/- 1.2% reduction inside microfluidic channels in comparison to glass control. Atomic force microscopy measurements indicated that the deposition of lipid vesicles led to the formation of SLB membranes by vesicle fusion due to hydrophilic interactions with the exposed substrate. Furthermore, the functionality of the patterned SLBs was tested by measuring the binding interactions between biotin (ligand)-labeled lipid bilayer and streptavidin (receptor). SLB arrays were fabricated with spatial resolution down to approximately 500 nm on flat substrate and approximately 1 microm inside microfluidic channels, respectively.  相似文献   

7.
Three types of water-soluble polymeric drug carrier systems facilitating targeted drug delivery and controlled drug release were synthesized. All systems consist of an inert soluble synthetic polymer, drug and homing device (targeting moiety). In the first “classical” system, both drug and targeting moiety are bound to a nondegradable polymer by means of biodegradable oligopeptide side chains statistically distributed along the polymer chain. The second, “star-like” system contains a targeting moiety (antibody) in the centre and a hydrophilic polymer, bearing drug molecules, in the shell of the system. The third, “biodegradable” carrier system is based on block copolymers of poly(ethylene glycol) containing biodegradable oligopeptide sequences both in the main polymer chain and in the spacers between main chain and drug molecules. Strategy and details of the synthesis of all three systems are given.  相似文献   

8.
As the pharmaceutical industry continues the daunting search for novel drug candidates, there remains a need for rapid screening methods not only for biological activity, but for physiochemical properties as well. It is invaluable that adequate model systems for absorption and/or bioavailability be developed early in the drug evaluation process to avoid the loss of promising compounds late in development. The focus of this paper is the use of vesicle EKC (VEKC) as a high-throughput, easy, cost-effective, and predictive model for the passive transcellular diffusion of drug candidates in the intestinal epithelium. Vesicles are large aggregates of molecules containing a spherical bilayer structure encapsulating an internal cavity of solvent. It is this bilayer structure that makes vesicles attractive as model membranes. In this study, vesicles were synthesized from both phospholipids and surfactant aggregates, and then employed as pseudostationary phases in EKC (VEKC). The interaction of drug molecules with vesicles in EKC was then used as the basis for an in vitro assay to evaluate passive diffusion. The VEKC technique showed a statistical correlation between the retention of drug candidates using surfactant and phospholipid vesicles and passive diffusion data (log Pow and colon adenocarcinoma). VEKC analysis offers high-throughput capabilities due to the short run times, low sample, and solvent volumes necessary, as well as instrument automation. However, due to the complexity of drug absorption in the intestine, difficulty arises when a single in vitro model is used to predict in vivo absorption characteristics. Therefore, the retention of drug candidates using VEKC in conjunction with other permeability prediction methods can provide a primary screen for a large number of drug candidates early in the drug discovery process with minimal resources.  相似文献   

9.
The cytochrome P450 (P450) enzymes are mainly localized to the endoplasmic reticulum (ER), where they function within catalytic complexes metabolizing xenobiotics and some endogenous substrates. However, certain members of families 1–3 were also found in other subcellular compartments, such as mitochondria, plasma membrane, and lysosomes. The physiological function of these enzymes in non-ER locations is not known, although plasma-membrane-associated P450s have been described to be catalytically active and to participate in immune-mediated reactions with autoantibody formation that can trigger drug-induced hepatitis. Several retention/retrieval mechanisms are active in the ER retention of the P450s and inverse integration of the translated P450 into the ER membrane appears to be responsible for transport to the plasma membrane. Furthermore, hydrophilic motifs in the NH2-terminal part have been suggested to be important for mitochondrial import. Phosphorylation of P450s has been described to be important for increased rate of degradation as well as for targeting into mitochondria. It was also suggested that the mitochondria-targeted P450s from families 1–3 could be active in drug metabolism using an alternative electron transport chain. In this review we present an update of the field emphasizing studies concerning localization, posttranslational modification, such as phosphorylation, and intracellular transport of microsomal P450s.  相似文献   

10.
本文用~(31)P.NMR和~1HNMR谱分析了卵磷脂的组分和结构,并以小角X射线散射法(SAXS)研究了所合成的六种四乙酰氧基卟啉金属配合物与卵磷脂的相互作用,发现卟啉分子镶嵌于磷脂双层的疏水链之间,使双分子层间距变大,而金属卟啉分子因其与磷脂的极性头基的静电相互作用,所形成的磷脂双分子层的间距介于纯卵磷脂和含有卟啉分子的卵磷脂所构成的双分子层之间.  相似文献   

11.
The molecular interaction between cardiolipin vesicles and two representative anthracyclines, daunomycin and 5-iminodaunomycin, has been studied at pH 7.1 by laser time-resolved fluorescence, for a cardiolipin-to-anthracycline ratio r ranging from 0.02 to 5. The fluorescence lifetime of daunomycin is 1.03 ns. For r = 0.3 - 5 a longer-lived transient (1.91 - 1.49 ns) is present and originates from the excitation of daunomycin bound on a single phosphate group of cardiolipin. At r = 0.3 two lifetimes are observed, the second one being due, partially, to free daunomycin and bound drug molecules embedded in the lipid bilayer. The fastest-decaying species is present for r = 0.5 - 2.0 and identified as two adjacent, stacked-up daunomycin molecules bound onto the two phosphate groups of the cardiolipin. In the case of 5-iminodaunomycin, a less cardiotoxic analogue, three-exponential decay is never observed and a fast-decaying component, pi approximately 0.2 ns, is already present at low r and vanishes for r greater than 0.5. The constancy of the lifetimes of the longer-lived species may originate from the reorientation of the bound drug from the hydrophilic to the lipid domain.  相似文献   

12.
Self-assembled lipid tubules with crystalline bilayer walls are promising candidates for controlled drug delivery vehicles on the basis of their ability to release preloaded biological molecules in a sustained manner. While a previous study has shown that the release rate of protein molecules from lipid tubules depends on the associated molecular mass, suggesting that the pertinent diffusion follows the well-known Stokes-Einstein relationship, only a few attempts have been made toward investigating the details of molecular diffusion in the tubule interior. Herein, we have characterized the diffusion rates of several molecules encapsulated in lipid tubules formed by 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) using the techniques of fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS). Our results show that the mobility of these molecules depends not only on their positions in the DC8,9PC tubules but also on their respective concentrations. While the former indicates that the interior of the DC8,9PC tubules is heterogeneous in terms of diffusion, the latter further highlights the possibility of engineering specific conditions for achieving sustained release of a "drug molecule" over a targeted period of time. In addition, our FCS results indicate that the molecular diffusions inside the crystalline bilayer walls of the DC8,9PC tubules strongly deviate from the normal, stochastic processes, with features characterizing not only anomalous subdiffusions but also motions that are superdiffusive in nature.  相似文献   

13.
We show that a two-step process, involving spontaneous self-assembly of lipids and apolipoproteins and surface patterning, produces single, supported lipid bilayers over two discrete and independently adjustable length scales. Specifically, an aqueous phase incubation of DMPC vesicles with purified apolipoprotein A-I results in the reconstitution of high density lipoprotein (rHDL), wherein nanoscale clusters of single lipid bilayers are corralled by the protein. Adsorption of these discoidal particles to clean hydrophilic glass (or silicon) followed by direct exposure to a spatial pattern of short-wavelength UV radiation directly produces microscopic patterns of nanostructured bilayers. Alternatively, simple incubation of aqueous phase rHDL with a chemically patterned hydrophilic/hydrophobic surface produces a novel compositional pattern, caused by an increased affinity for adsorption onto hydrophilic regions relative to the surrounding hydrophobic regions. Further, by simple chemical denaturation of the boundary protein, nanoscale compartmentalization can be selectively erased, thus producing patterns of laterally fluid, lipid bilayers structured solely at the mesoscopic length scale. Since these aqueous phase microarrays of nanostructured lipid bilayers allow for membrane proteins to be embedded within single nanoscale bilayer compartments, they present a viable means of generating high-density membrane protein arrays. Such a system would permit in-depth elucidation of membrane protein structure-function relationships and the consequences of membrane compartmentalization on lipid dynamics.  相似文献   

14.
This work demonstrates the use of photocleavable cholesterol derivatives to create supported bilayer lipid membrane arrays on silica. The photocleavable cholesteryl tether is attached to the surface by using the reaction of an amine-functionalized self-assembled monolayer (SAM) and the N-hydroxysuccinimide-based reagent 9. The resultant SAM contains an ortho-nitrobenzyl residue that can be cleaved by photolysis by using soft (365 nm) UV light regenerating the original amine surface, and which can be patterned using a mask. The photoreaction yield was approximately 75 % which was significantly higher than previously found for related ortho-nitrobenzyl photochemistry on gold substrates. The SAMs were characterized by means of contact angle measurements, ellipsometry and X-ray photoelectron spectroscopy. Patterned surfaces were characterized with SEM and AFM. After immersing the patterned surface into a solution containing small unilamellar vesicles of egg phosphatidylcholine (PC), supported lipid membranes were formed comprised of lipid bilayer over the amine functionalized "hydrophilic" regions and lipid monolayer over the cholesteryl "hydrophobic" regions. This was confirmed by fluorescence microscopy and AFM. FRAP studies yielded a lateral diffusion coefficient for the probe molecule of 0.14+/-0.05 microm(2) s(-1) in the bilayer regions and approximately 0.01 microm(2) s(-1) in the monolayer regions. This order of magnitude difference in diffusion coefficients effectively serves to isolate the bilayer regions from one another, thus creating a bilayer array.  相似文献   

15.
Aspirin and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) are deposited from their alcoholic mixed solution onto highly oriented pyrolytic graphite (HOPG) by spin coating. The film structure and morphology are characterized by atomic force microscopy (AFM). The barely soluble DMPE forms a highly oriented stripe phase as a result of its one-dimensional epitaxy with the HOPG lattice. The bilayer stripe pattern exposes the cross section of the lipid bilayer lamellae and enables the direct visualization of the molecular interactions of drug or biological molecules with either the hydrophobic or the hydrophilic part of the phospholipid bilayer. The bilayer pattern affects the aspirin molecular deposition and aggregation. AFM shows that the aspirin molecules prefer to deposit and aggregate along the aliphatic interior part of the bilayer pattern, giving rise to parallel dimer rods in registry with the underlying pattern. The nonpolar interactions between aspirin and the phospholipid bilayer are consistent with the lipophilic nature of aspirin. The bilayer pattern not only stabilizes the rodlike aggregate structure of aspirin at low aspirin concentration but also inhibits crystallization of aspirin at high aspirin concentration. Molecular models show that the width of the DMPE aliphatic chain interior can accommodate no more than two aspirin dimers. The bilayer confinement may prevent aspirin from reaching its critical nucleus size. This study illustrates a general method to induce a metastable or amorphous form of an active pharmaceutical ingredient (API) by chemical confinement under high undercooling conditions. Metastable and amorphous solids often display better solubility and bioavailability than the stable crystalline form of the API.  相似文献   

16.
两亲嵌段共聚物可以在水溶液中自组装形成亲水性链段为外壳、疏水性链段为内核的胶束,这种胶束能够用作药物载体而引起人们极大的关注。本文综述了两亲嵌段共聚物胶束用作医用材料的研究进展,主要内容包括医用两亲嵌段共聚物的种类,胶束化,以及用作诊断试剂载体、药物缓释载体、靶向载体等。两亲嵌段共聚物胶束用作磁共振造影剂载体有利于肿瘤的诊断,用作药物缓释载体可以有效增溶难溶性抗肿瘤药物,延长药物在体内的血液循环时间。此外,通过对胶束表面进行修饰或者施加外场,还可以实现靶向功能。因此,两亲嵌段共聚物胶束在医用材料领域有着广阔的发展前景。  相似文献   

17.
The present paper investigates the selective incorporation of preformed nanoparticles (hydrophobic Au-NP (2 nm); hydrophilic Au-NP (12 nm); hydrophobic CdSe-NP (1.9 nm); retrovirus-particles (approximately 30 nm)) into the interface of lipid vesicles and polymersomes via TEM and DLS investigations. Lipid membranes were made from N,N-dimethyl-N,N-dioctadecylammonium bromide (DODAB), di-oleoyl-phosphatidylcholine (DOPC), whereas polymersome-membranes were fabricated from the diblock copolymer poly-(butadiene-block-ethylenoxide). Stabilization of the final structures was achieved via sol/gel processes at the outside of the membranes, thus stabilizing the structure by a silicate shell. Whereas hydrophobic Au-NPs can be successfully embedded into the polymersome- and lipid-vesicle membranes, hydrophilic nanoparticles were found evenly distributed in the inner- and outer compartments of the vesicles and polymersomes. Significant effects such as size reduction, selective enrichment of all nanoparticles within only few polymersomes as well as budding effects of larger entities (i.e., viral particles) are described.  相似文献   

18.
Multifunctional envelope-type gene delivery nanodevices (MENDs) are promising non-viral vectors for gene therapy. Though MENDs remain strong in prolonged exposure to blood circulation, have low immunogenic response, and are suitable for gene targeting, their fabrication requires labor-intensive processes. In this work, a novel approach has been developed for rapid fabrication of MENDs by a touch-and-go lipid wrapping technique in a polydimethylsiloxane (PDMS)/glass microfluidic device. The MEND was fabricated on a glass substrate by introduction of a condensed plasmid DNA core into microfluidic channels that have multiple lipid bilayer films. The principle of the MEND fabrication in the microfluidic channels is based on electrostatic interaction between the condensed plasmid DNA cores and the coated lipid bilayer films. The constructed MEND was collected off-chip and characterized by dynamic light scattering. The MEND was constructed within 5 min with a narrow size distribution centered around 200 nm diameter particles. The size of the MEND showed strong dependence on flow velocity of the condensed plasmid DNA core in the microfluidic channels, and thus, could be controlled to provide the optimal size for medical applications. This approach was also proved possible for fabrication of a MEND in multiple channels at the same time. This on-chip fabrication of the MEND was very simple, rapid, convenient, and cost-effective compared with conventional methods. Our results strongly indicated that MENDs fabricated with our microfluidic device have a good potential for medical use. Moreover, MENDs fabricated by this microfluidic device have a great potential for clinical use because the devices are autoclavable and all the fabrication steps can be completed inside closed microfluidic channels without any external contamination.  相似文献   

19.
Transport of surface active anesthetic drugs through silicone hydrogel contact lenses containing nanosized vitamin E aggregates is explored for achieving extended anesthetics delivery. Commercial silicone hydrogel contact lenses release most ophthalmic drugs including local anesthetics for only a few hours, which is not adequate. Here we focus on creating dispersion of highly hydrophobic vitamin E aggregates in the lenses as barriers for drug diffusion for increasing the release durations. This approach has been shown previously to be successful in extending the release durations for some common hydrophilic ophthalmic drugs. The topical anesthetic drugs considered here (lidocaine, bupivacaine, and tetracaine) are hydrophilic at physiologic pH due to the charge, and so these cannot partition into the vitamin E barriers. However, these surface active drug molecules adsorb on the surface of the vitamin E barriers and diffuse along the surface, leading to only a small decrease in the effective diffusivity compared to non-surface-active hydrophilic drugs. The drug adsorption can be described by the Langmuir isotherm, and measurements of surface coverage of the drugs on the vitamin E provide an estimate of the available surface area of vitamin E, which can then be utilized to estimate the size of the aggregates. A diffusion controlled transport model that includes surface diffusion along the vitamin E aggregates and diffusion in the gel fit the transport data well. In conclusion, the vitamin E loaded silicone contact lens can provide continuous anesthetics release for about 1-7 days, depending on the method of drug loading in the lenses, and thus could be very useful for postoperative pain control after corneal surgery such as the photorefractive keratectomy (PRK) procedure for vision correction.  相似文献   

20.
Nanovesicles based on tripodal amphiphilic pseudopeptides are prepared as carriers for p-coumaric acid (p-CA) delivery. Loaded nanovesicles are obtained by both thin film hydration and ethanol injection methods with positive Z-potential values. The last technique renders lower particle sizes and excellent polydispersity index, with average values of 130 nm and 0.123, respectively, although the drug loading obtained after ultracentrifugation is lower. In vitro release experiments, including the use of different external stimuli such as pH and proteolytic enzymes, provide interesting results. The prepared nanovesicles are tested on normal cells (VERO), displaying a high safety profile scoring with a 50% inhibitory concentration (IC50) of 1,822 μg/mL. A 40-times increase in the in vitro cytotoxic effect of p-CA on Glioma GL261 brain cancer cells, from IC50 1,082 μg/mL to 29 μg/mL, is observed using the loaded pseudopeptide nanovesicles. 1H NMR studies reveal that the drug is mainly located inside the nanoparticle bilayer. Transmembrane carboxyfluorescein studies reveal that the amphiphilic compound does not provide a significant membrane fluidification. Experimental data suggest that the observed biological activity can be associated to an enhanced permeability and retention effect. The present results highlight the potential of such nanovesicles as potent p-CA carriers for brain cancer therapy.  相似文献   

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