Pyrene In Micellar Solutions Research Articles

Smart drug carrier based on polyurethane material for enhanced and controlled DOX release triggered by redox stimulus

A series of amphiphilic polymer mPEG-PUSS-mPEG were developed by a combination of ring opening polymerization (ROP) and polyaddition reaction and its self-assembled micelles were developed for hydrophobic anticancer drugs delivery. Polymeric critical micellar concentration (CMC) values in aqueous solution were about 2.8–5.5 mg/L. And the partition equilibrium constant (Kv) of pyrene in micellar solutions ranged from 1.52 × 105 to 2.20 × 105. The average sizes of the self-assembled blank and DOX-loaded micelles were 160–180 nm determined by dynamic light scattering (DLS). The morphology of the DOX-loaded micelles was spherical by transmission electron microscopy (TEM) and scanning electron microscopy (SEM).The in vitro drug release behaviors of DOX and PTX from mPEG-PUSS-mPEG micelles were investigated at different simulated conditions. We found that the PTX release was significantly accelerated by redox stimuli compared with DOX-loaded reduction-sensitive PU micelles. The change of the size of this system under different conditions was further evaluated by DLS. DOX-loaded mPEG-PUSS-mPEG micelles in 50% fetal bovine serum (FBS) were evaluated the hemocompatibility. In addition, the self-assembly process of polymers mPEG-PUSS-mPEG in aqueous solution for micellar formation was also investigated by means of dissipative particle dynamics (DPD) simulations.AndCCK-8 assays revealed that the mPEG-PUSS-mPEG materials had low toxicity, but the DOX-loaded micelles showed a high cytotoxicity against HepG2 tumor cells. All results demonstrate that mPEG-PUSS-mPEG self-assembled micelles are a very promising for hydrophobic anticancer drugs delivery.

Synthesis and Physicochemical Characterization of Amphiphilic Triblock Copolymer Brush Containing pH-Sensitive Linkage for Oral Drug Delivery

A novel and well-defined pH-sensitive amphiphilic triblock copolymer brush poly(lactide)-b-poly(methacrylic acid)-b-poly(poly(ethylene glycol) methyl ether monomethacrylate) (PLA-b-PMAA-b-PPEGMA) and its self-assembled micelles were developed for oral administration of hydrophobic drugs. The copolymer and its precursors were synthesized by the combination of activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and ring-opening polymerization (ROP) techniques. The molecular structures and characteristics were confirmed by GPC, (1)H NMR, and FT-IR. The critical micelle concentration (CMC) values of PLA-b-PMAA-b-PPEGMA in aqueous medium varied from 1.4 to 2.6 mg/L, and the partition equilibrium constant (K(v)) of pyrene in micellar solutions ranged from 2.873 × 10(5) to 3.312 × 10(5). The average sizes of the self-assembled blank and drug-loaded micelles were 140-250 nm determined by DLS in aqueous solution. The morphology of the micelles was found to be spherical by SEM. Nifedipine (NFD), a poorly water-soluble drug, was selected as the model drug and wrapped into the core of micelles via dialysis method. The in vitro release behavior of NFD from the micelles was pH-dependent. In simulated gastric fluid (SGF, pH 1.2), the cumulative release percent of NFD was relative low, while in simulated intestinal fluid (SIF, pH 7.4), more than 96% was released within 24 h. All the results showed that the pH-sensitive PLA-b-PMAA-b-PPEGMA micelle may be a prospective candidate as oral drug delivery carrier for hydrophobic drugs with controlled release behavior.

Synthesis and self‐assembly behavior of pH‐responsive amphiphilic copolymers containing ketal functional groups

AbstractPolymeric micelles that are responsive to pH are particularly attractive for application in drug delivery systems. In this study, one type of amphiphilic block copolymers with hydrophobic building blocks bearing pH‐sensitive ketal groups was designed. In an acidic environment, the polarity transfer from amphiphile to double hydrophile for this copolymer destroyed the driving force of micelle formation, which triggered the release of encapsulated hydrophobic molecules. The amphiphilic block copolymers monomethoxy‐poly(ethylene glycol)‐block‐poly(2,2‐dimethyl‐1,3‐dioxolane‐4‐yl)methyl acrylate (MPEG‐block‐PDMDMA) was fabricated by atom transfer radical polymerization using MPEG‐Br as macroinitiator. The critical micelle concentration of various compositions of this copolymer in aqueous solution ranged from 4.0 to 10.0 mg L−1, and the partition equilibrium constant (Kv) of pyrene in micellar solutions of the copolymers varied from 1.61 × 105 to 4.86 × 105. Their overall effective hydrodynamic diameters from dynamic light scattering measurements were between 80 and 400 nm, and the micellar morphology showed spherical geometry as investigated using transmission electron microscopy. At pH = 1.0, all of these polymeric micelles presented 100% payload release in 24 h of incubation, while at pH = 3.0, nearly 70 and 25% of pyrene was released for MPEG‐block‐PDMDMA (44/18) and MPEG‐block‐PDMDMA (44/25) in 260 h, respectively. The pH‐responsive MPEG‐block‐PDMDMA polymeric micelles having good encapsulation efficiency for hydrophobic drugs are potential candidates for biomedical and drug delivery applications. Copyright © 2010 Society of Chemical Industry

Two-dimensional fluorescence correlation spectroscopy II: spectral analysis of derivatives of anthracene and pyrene in micellar solutions

Generalized two-dimensional (2D) correlation spectroscopy has been applied to the analysis of fluorescence spectra in two micellar systems: (1) a mixture of pyrene and 1,3,6,8-pyrenetetrasulfonic acid in the cationic micellar solutions of cetyltrimethylammonium chloride (CTAC) and (2) a mixture of pyrene and 9-anthracencepropionic acid in anionic micellar solutions of sodium dodecyl sulfate (SDS). Fluorescence quenching is employed as a perturbation mode for causing intensity changes in fluorescence bands ( quenching perturbation). Iodide ion (I −) is used as a quencher in the former system, and cetyl pridinium chloride (CPC) is used in the latter. Vibronic bands in the complicated fluorescence spectra of the mixture of the analytes were successfully resolved. It is shown that asynchronous maps are especially useful for spectral resolution enhancement when the quenching perturbation is employed in 2D fluorescence correlation spectroscopy. Furthermore, the information about the order of response of the bands to quenching is obtained by comparing the signs of synchronous and asynchronous cross-peaks.

Sensitized room temperature phosphorescence of pyrene in sodium dodecylsulfate micelles with triphaflavine as energy donor

The sensitized room temperature phosphorescence (SRTP) of pyrene in micellar solutions of sodium dodecylsulfate (SDS) based on triplet–triplet (T–T) energy transfer has been investigated. Triphaflavine as a triplet energy donor, thallium(I) nitrate as a heavy atom, and sodium sulfite as a scavenger of oxygen were used. The effects of triphaflavine, SDS, and thallium nitrate concentrations on pyrene-SRTP intensity, lifetime, and decay rate constants were studied. A comparative study of selectivity factors for pyrene determination by room temperature phosphorescence (RTP) and SRTP has also been made. The analytical figures of merit for SRTP determination of pyrene are given.

Solubilization of PAH Mixtures by a Nonionic Surfactant

Enhanced solubilization of naphthalene, phenanthrene, and pyrene in micellar solutions of Triton X-100 was studied for single compounds and their binary and ternary mixtures. Experimental results were obtained for the following conditions: (i) naphthalene, phenanthrene, and pyrene as single compounds at saturation; (ii) naphthalene, phenanthrene, and pyrene as binary and ternary mixtures at satura tion; (iii) phenanthrene at saturation in a range of naphthalene concentrations; (iv) pyrene at saturation in a range of naphthalene concentrations. The solubility enhancement of naphthalene was slightly reduced in the presence of phenanthrene and/or pyrene. A synergistic effect on the solubilization of phenanthrene was observed in the presence of different amounts of naphthalene. The solubility of phenanthrene was greatly enhanced in both binary mixtures and in the ternary mixture. The solubility of pyrene was slightly reduced in the presence of naphthalene, remained unaffected in the presence of phenanthrene, and increased significantly in the ternary mixture. The increase in the partition coefficient values is explained by the partitioning of the solubilzate at the micellar core−water interface, which changes the interfacial free energy and effectively increases the volume of the core leading to a higher solubilization potential.

ChemInform Abstract: Pressure Effects on the Fluorescence Decay of Pyrene in Micellar Solutions

The monomer fluorescence decay of pyrene was measured in sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium chloride (HDTCl) micellar solutions as a function of pressure from 0.1 to 203 MPa at 25 /sup 0/C by a single-photon-counting technique. The decay curves were analyzed successfully by a conventional fluorescence decay analysis for micellar solution over the pressure ranges examined. From the analysis, it was found that the rate constant (k/sub E/) for intramicellar excimer formation decreased significantly with increasing pressure in both micellar solutions, while the cmc and the aggregation number (N) for SDS and HDTCl micelles were found to be almost independent of pressure. The activation volumes for excimer formation were 19 and 16 cm/sup 3//mol for SDS and HDTCl micellar solutions, respectively. An attempt to obtain an activation volume for a nonionic detergent was unsuccessful because of the failure of the decay profile to fit the theoretical model. However, activation volumes for microviscosity were obtained by studying the pressure dependence of intramolecular excimer formation of a dinaphthylpropane probe. The diffusion process in micelles and microviscosities are discussed by comparing the activation volume for excimer formation with those for microviscosities determined by the pressure effect on intrmolecular excimer formation, and bymore » comparing the results with those reported in the literature for a dipyrenylpropane probe.« less

Pressure effects on the fluorescence decay of pyrene in micellar solutions

The monomer fluorescence decay of pyrene was measured in sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium chloride (HDTCl) micellar solutions as a function of pressure from 0.1 to 203 MPa at 25 /sup 0/C by a single-photon-counting technique. The decay curves were analyzed successfully by a conventional fluorescence decay analysis for micellar solution over the pressure ranges examined. From the analysis, it was found that the rate constant (k/sub E/) for intramicellar excimer formation decreased significantly with increasing pressure in both micellar solutions, while the cmc and the aggregation number (N) for SDS and HDTCl micelles were found to be almost independent of pressure. The activation volumes for excimer formation were 19 and 16 cm/sup 3//mol for SDS and HDTCl micellar solutions, respectively. An attempt to obtain an activation volume for a nonionic detergent was unsuccessful because of the failure of the decay profile to fit the theoretical model. However, activation volumes for microviscosity were obtained by studying the pressure dependence of intramolecular excimer formation of a dinaphthylpropane probe. The diffusion process in micelles and microviscosities are discussed by comparing the activation volume for excimer formation with those for microviscosities determined by the pressure effect on intrmolecular excimer formation, and bymore » comparing the results with those reported in the literature for a dipyrenylpropane probe.« less

A Study on the Permeability of the Triton X-100 Micelles by Fluorescence Decay Kinetics of Probe Molecules

Abstract The third armonic (355 nm) of a pulsed Nd-YAG laser has been used to excite pyrene in micellar solutions of Triton X-100. Fluorescence quenching by nitromethane and triethylamine of the excited state of pyrene in Triton X-100 has been studied. Quenching rate constant values of 4.94 ± 0.13 × 108M−1s−1 and 1.50 ± 0.04 × 108M−1s−1 for deactivation by nitromethane and triethylamine, respectively, have been measured. The values obtained are discussed in terms of the interface permeability.

Quenching of fluorescence from pyrene in micellar solutions by cationic quenchers

The fluorescence from the S 1 state of pyrene solubilized within the hydrophobic region of sodium dodecyl sulfate micelles has been studied as a function of concentration of some cationic additives to the aqueous phase. At concentrations of added quencher below ca. 10 −3 mol dm −3 the fluorescence decay follows a complex rate law; at long time, the decay is exponential with the same time constant as that of pyrene (S 1) without added quencher. The initial slope of the decay curve depends linearly on the concentration of added cation. These results are discussed in terms of the recently proposed model which requires the water-hydrocarbon interface to penetrate the micelle in the region of the probe. An analytical treatment is presented which, on the premises stated, serves to explain the observed kinetic features.