8 ± 4.3nm, 25.6 ± 3.2nm, and 4.6 ± 0.7nm, respectively. As a comparison, Figure1(b) is a 300 × 300nm2 AFM topography image of original micelles on ultraflat Au. The measured height of the unloaded micelle is 1.9nm, as shown in cursor 4. Figure 1(d) is the phase image of unloaded micelle, from which the lateral boundaries are clearly visible. The short and long axis of the unloaded micelle is 17.3nm and 25.2nm, respectively, as shown in cursors 5 and 6. Among the 50 unloaded micelles measured, the a, b, and h measure 23.7 ± 2.4nm, 17.2 ± 2.3nm, and 1.8 ± 0.2nm, respectively. Figure 1 AFM characterization

of paclitaxel- (PTX-) loaded HS-PEG5k-CA8 micelles Inhibitors,research,lifescience,medical and Inhibitors,research,lifescience,medical unloaded HS-PEG5k-CA8 micelle on gold substrate in aqueous solution. The first

column is AFM topography (a), phase image (b) and corresponding cursors of PTX-loaded micelle. AFM … The volume, V, of each micelle can be calculated using the simple geometric formula: V = (1/6πh)(3/4ab + h2)[28]. From Figures1(a) and 1(c), the height of PTX-loaded micelle is 4.0nm, the lateral dimensions are a = 33.0nm, b = 28.1nm, thus V = 1490.1nm3. From Figures1(b) and 1(d), the unloaded micelle, measures a = Inhibitors,research,lifescience,medical 25.2nm, b = 17.3nm, and h = 1.9nm, which corresponds to V = 328.9nm3. The average volume of PTX-loaded micelle and unloaded micelle is 1475.8 ± 396.2nm3 and 295.1 ± 62.6nm3, respectively. PTX-loaded micelle exhibits a larger volume than unloaded micelle. Our Investigations also reveal that the amounts of PTX uptake affect

the volume of micelles. By assuming that the micelle has a spherical shape in water solution, we can estimate the diameter of micelles in solution based on V = 4/3π(D/2)3. Here, Inhibitors,research,lifescience,medical V is volume and D is the diameter. The volume of a typical PTX-loaded micelle in Figure1(a) is 1490.1 nm3, the corresponding diameter is 14.2nm. Inhibitors,research,lifescience,medical Among the 49 PTX-loaded micelles measured, the average diameter is 14.2 ± 1.2nm. The volume of a typical unloaded micelle in Figure1(b) is 328.9nm3, the corresponding diameter is 8.6nm. Among the 50 unloaded micelles measured, the average diameter is 8.2 ± 0.6nm. The diameter of PTX-loaded and unloaded micelle obtained from the dynamic light scatting (DLS) Oxymatrine measurement is 23 ± 8 and 16 ± 4nm, respectively [16]. One notes that the size of adsorbed micelles as determined from AFM experiments is smaller than the corresponding diameter measured from the DLS in solution. While DLS gives the averaged hydrodynamic radius of the scattering particles, AFM provides true 3D Selleckchem ZD1839 measurements of individual micelle. The dimensions extracted from AFM measurements more truly reflect the true geometry of the micelles, In addition, it is difficult to reach high accuracy if the particle is very small and nonspherical, for example, <10nm [41], while AFM does not have such a limitation.