“…The benzamide emission band experiences a shift to 485 nm at pH 7 and to 496 nm at pH 9, respectively, which demonstrates its sensitivity towards the solvent environment. [9] The plots of I BA / I BA,max as a function of the concentration of 4 ( Figure 4) follow qualitatively the same trends as those determined for 4 treated with 12 equivalents of NaOH.…”
supporting
confidence: 51%
“…The light emission is caused by twisted intramolecular charge transfer (TICT). [9] This TICT arises either from electron transfer between twisted donor-acceptor groups or from a change in the configuration of the amino nitrogen from pyramidal to planar in the ICT. Fluorescence spectra of 4 12À are shown for a concentration range between 4.5 10 À8 and 2.7 10 À4 mol L À1 in Figure 1.…”
The synthesis and precise supramolecular organization of new amphicalixarene 4 bearing four rodlike aligned fluorescent terephthalic benzamide moieties in the upper rim is reported. The aggregation of 4 was monitored by a combination of fluorescence, conductometry, and cryo-TEM measurements at different pH values and revealed significant structural differences. Most interestingly, we found that exactly 12 molecules of 4 assemble to form a spherical and structurally persistent micelle at pH 7, which coexists with rodlike micelles. In contrast to other examples of structurally defined micelles reported previously, this new type of self-labeled amphiphile serves as a fluorescence reporter with the terephthalic units additionally providing an extended cavity structure in the hydrophilic part, which facilitates the inclusion of guest molecules. In addition to the observed formation of well-defined micelles, the other highly important finding from this study is the fact that guest molecules directly influence the micellar organization because they can interact with both the free amphiphiles below the critical micelle concentration (cmc) or the micellar aggregate itself. These two types of interactions are especially pronounced in the case of the cationic pyrene derivative 10, which binds electrostatically with the amphiphile 4. In addition, a very unique membrane structure exhibiting a regular hexagonal pattern of 5 nm pores is formed by 4 at pH 4.
“…The benzamide emission band experiences a shift to 485 nm at pH 7 and to 496 nm at pH 9, respectively, which demonstrates its sensitivity towards the solvent environment. [9] The plots of I BA / I BA,max as a function of the concentration of 4 ( Figure 4) follow qualitatively the same trends as those determined for 4 treated with 12 equivalents of NaOH.…”
supporting
confidence: 51%
“…The light emission is caused by twisted intramolecular charge transfer (TICT). [9] This TICT arises either from electron transfer between twisted donor-acceptor groups or from a change in the configuration of the amino nitrogen from pyramidal to planar in the ICT. Fluorescence spectra of 4 12À are shown for a concentration range between 4.5 10 À8 and 2.7 10 À4 mol L À1 in Figure 1.…”
The synthesis and precise supramolecular organization of new amphicalixarene 4 bearing four rodlike aligned fluorescent terephthalic benzamide moieties in the upper rim is reported. The aggregation of 4 was monitored by a combination of fluorescence, conductometry, and cryo-TEM measurements at different pH values and revealed significant structural differences. Most interestingly, we found that exactly 12 molecules of 4 assemble to form a spherical and structurally persistent micelle at pH 7, which coexists with rodlike micelles. In contrast to other examples of structurally defined micelles reported previously, this new type of self-labeled amphiphile serves as a fluorescence reporter with the terephthalic units additionally providing an extended cavity structure in the hydrophilic part, which facilitates the inclusion of guest molecules. In addition to the observed formation of well-defined micelles, the other highly important finding from this study is the fact that guest molecules directly influence the micellar organization because they can interact with both the free amphiphiles below the critical micelle concentration (cmc) or the micellar aggregate itself. These two types of interactions are especially pronounced in the case of the cationic pyrene derivative 10, which binds electrostatically with the amphiphile 4. In addition, a very unique membrane structure exhibiting a regular hexagonal pattern of 5 nm pores is formed by 4 at pH 4.
“…Thus, the intensity ratio ( I 1 / I 3 ) of peak 1 to peak 3 serves as a measure of the micropolarity. A larger I 1 / I 3 ratio means greater polarity. − Figure demonstrates the I 1 / I 3 ratio of pyrene monomer fluorescence vs the mole fraction of PEG−lipid. 7 Effect of PEG−lipid on the micropolarity of liposomal bilayer membranes: plots of I 1 / I 3 ratio of pyrene monomer fluorescence vs mole fraction of PEG−lipid.…”
The effect of lipid with covalently attached poly(ethylene glycol) (PEG−lipid) on the surface properties
of liposomal bilayer membranes was examined from standpoints of particle size, surface potential,
microviscosity, micropolarity, and permeability. The particle size and the absolute value of the ζ potential
of liposomes decreased with increasing mole fraction of PEG−lipid. The permeability of PEG−liposomes
was decreased as compared with regular liposomes. The microviscosity and the micropolarity of liposomal
bilayer membranes showed a maximum and a minimum value, respectively, at 6 mol % of PEG−lipid. The
packing state of liposomal bilayer membranes became rigid and the lipid bilayers were microscopically
stabilized by the addition of PEG−lipid, and the optimum amount of PEG−lipid in liposomes was 6 mol
%.
“…This ratio equals 1.96 in polar solvents such as water and decreases with increasing solvent apolarity. [15][16][17] The ratios of I 1 /I 3 for pyrene in liposome and the EYK-pyrene solution mixed with the liposome were 1.03 and 1.05, respectively. It indicated that the pyrene has transferred from the peptide encapsulation into the hydrophobic lipid bilayer.…”
In recent years, the study of self-assembly peptide used in drug delivery system has been attracted great interest from scientists. In the category are self-assembly peptides in the structure either with one hydrophobic surface and another hydrophilic or a hydrophobic head and a hydrophilic tail. Here, we focus on a novel designed peptide EYK with double amphiphilic surfaces, investigating on the capability of peptide as a carrier for hydrophobic compound model pyrene. The fluorescence data presented the dynamic process of the transfer, showing that the pyrene was in the crystalline form in peptide solution, and molecularly migrated from its peptide encapsulations into the membrane bilayers when the peptide-pyrene suspension was mixed with liposome vesicles. The results indicated that the peptide EYK could stabilize hydrophobic pyrene in aqueous solution and delivered it into EPC liposome as a potential carrier.
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