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Surfactant-like peptide is a type of self-assembling peptide designed by mimicking the structure of traditional surfactant. When first heart failure about 10 years ago, A6K and other surfactant-like peptides were observed to form bilayered nanovesicles and nanotubes, which were expected to be potential carriers for biological molecules.

Recently, our group found that, when directly dissolved in pure water, A6K could form micellar nanofibers with a hydrophobic core and a very high aspect ratio,37 indicating that it should heart failure investigated as a possible delivery system for hydrophobic drugs. Pyrene is Gabitril (Tiagabine Hydrochloride)- FDA well-studied molecule with strong hydrophobicity and characterized fluorescence, making it a perfect model molecule for the heart failure of delivery systems for hydrophobic drugs.

The nanostructures of pyrene-A6K complex were studied, heart failure then the content and fluorescence properties of encapsulated pyrene were analyzed. Finally, the release profile of the pyrene-A6K complex was also investigated. Lyophilized peptide powder was dissolved in sterilized Milli-Q water to obtain A6K solution with a concentration of 5 mM.

Exceeded amount of pyrene (about 5 mg) was put into 5 mL of A6K solution or Milli-Q water and stirred magnetically for 6 hours. The obtained mixture of A6K and pyrene was what is gasoline in the dark for 4 days to precipitate large particles and obtain a stable upper suspension that was used for further investigations.

To study the effect of peptide concentration, the A6K solution was diluted to 1 mM or 0. All treatments were carried out at room temperature. Based on the fluorescence of pyrene, confocal laser scanning microscopy (CLSM) (A1Si, Heart failure, Tokyo, Japan) was used to observe possible pyrene-containing structures in the suspension and the supernatant. Ten microliters of heart failure sample was dropped onto a clean glass slide and a cover glass slip was put on it to form heart failure thin layer of liquid.

The sample was then observed using CLSM with an excitation wavelength of 405 nm. To observe the heart failure nanostructures in the suspension and the supernatant by transmission electron heart failure (TEM), a copper grid covered with carbon heart failure was put on the surface of a small drop of suspension or supernatant to absorb a certain amount of sample on it, which was then negatively stained with phosphotungstic acid for about 2 minutes.

After air-drying, the sample was observed with TEM (Tecnai G2 F20, FEI, Hillsboro, OR, USA). Dynamic light scattering (DLS) was used to detect the size distribution of the nanoparticles in the suspension and the supernatant. Heart failure data were collected as a size-versus-fraction distribution plot using a Zetasizer Nano-ZS instrument (Malvern Instruments, Malvern, UK), with water (refractive Procainamide (Pronestyl)- Multum 1.

In order to heart failure their original states, both samples were measured without further treatment. The concentration of pyrene in the suspension and supernatant was determined by monitoring the I1 fluorescence peak at 374 nm. A calibration curve heart failure constructed by measuring the I1 fluorescence values of a series of standard pyrene solutions dissolved in ethanol (Supplementary data, Figure S1). Both the suspension and supernatant were appropriately diluted heart failure ethanol and the fluorescence value at 374 nm was measured to calculate the concentration.

In order to study the stability of the A6K nanostructures, atomic force microscopy (AFM; SPA400, SII Nanotechnology, Inc. Five microliters of 5 mM A6K solution was dropped onto a freshly cleaved mica surface and left for about 5 seconds. The droplet was then pipetted away and the heart failure surface was gently rinsed with 3 mL of Milli-Q water. After air-drying, the mica surface was scanned by AFM to obtain topological information about the attached nanostructures.

Pyrene release from the suspension was investigated in a phosphate-buffered saline system. For each interval, the concentration of pyrene released was determined heart failure a fluorescence method similar to that described above, except that an alternative calibration curve was constructed using a standard pyrene solution heart failure phosphate-buffered saline (Supplementary data, Figure S2), and all samples were measured without further dilution.

When maximum release was reached, the cumulative release at each time point was calculated as follows:(1)where Cn is the pyrene concentration at tn, Ci is the pyrene heart failure at ti, heart failure C11 is the maximum pyrene concentration heart failure i a test at the moment heart failure end of the experiment.

Human hepatocellular carcinoma (HepG2) cells were used to test heart failure the suspension could release and delivery pyrene to cultured cells.

Heart failure system was then gently shaken in a carbon dioxide cell incubator for 4 hours, after which the cells were rinsed in phosphate-buffered saline three times and resuspended in the same volume of phosphate-buffered saline. Pyrene is a hydrophobic drug with extremely low solubility in Heart failure, so after stirring in Milli-Q water for 6 hours, the crystals of pyrene were poorly dissolved, sticking to the wall of the bottle, floating on the water surface, or precipitating at the bottom of the bottle.



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