It can

be seen that the GPC curves presented in Additional file 1: Figure S2 appeared monomodal symmetric distribution and the values of M w /M n were below 1.50, which are acceptable for further application of delivering drugs. It was also found that GPC analysis for (PCL)2(PDEA-b-PPEGMA)2 tended to underestimate the molecular weight (which was typically smaller) as compared to their linear counterpart due to the reduced hydrodynamic volumes. The characterization of the molar masses of star polymers by GPC is not straightforward. Since standard samples with exactly the same topology and with known molar masses do not exist, the calibration with narrow standards cannot be applied [38, 39]. Characterization of the empty and DOX-loaded

micelles The formation of micelles self-assembled from (PCL)2(PDEA-b-PPEGMA)2 in aqueous phase was verified Vadimezan supplier using a fluorescence technique with pyrene as a fluorescence probe [40–42]. When the (PCL)2(PDEA-b-PPEGMA)2 micelles were formed, pyrene molecules preferably located www.selleckchem.com/products/azd5582.html inside or closed to the hydrophobic core of micelles, and consequently, Nutlin-3a cost the photophysical characteristics were changed. In the excitation spectra of polymer/pyrene solutions (see Additional file 1: Figure S3), with increasing the concentrations of (PCL)2(PDEA-b-PPEGMA)2, the fluorescence intensity increased and the (0, 0) band shifted from 336 to 339 nm in the excitation spectra of pyrene. The ratios of I 339 to I 336 were plotted against (PCL)2(PDEA-b-PPEGMA)2 concentrations, which can be seen in Figure 4. The CMC values of (PCL)2(PDEA-b-PPEGMA)2 were determined

from the crossover points which were in the range of 0.0024 to 0.0043 mg/mL, increasing as the weight fraction of PCL decreased [43]. For example, the CMC values 0.0043, 0.0040, and 0.0024 mg/mL of (PCL24)2(PDEA16-b-PPEGMA19)2, (PCL32)2(PDEA20-b-PPEGMA19)2, and (PCL38)2(PDEA17-b-PPEGMA9)2, respectively, were Thiamet G decreased in order. Moreover, as the samples were prepared with deionized water (pH 7.4), most tertiary amine residues of PDEA were still deprotonated and exhibited as hydrophobic. Hence, taken the hydrophobicity of PDEA block into the consideration, the CMC of (PCL24)2(PDEA37-b-PPEGMA15)2 (0.0030 mg/mL) was much lower than the CMC of (PCL24)2(PDEA16-b-PPEGMA19)2 (0.0043 mg/mL). Figure 4 Graphs of intensity ratios ( I 339 / I 336 ) as function of logarithm of (PCL) 2 (PDEA- b -PPEGMA) 2 concentrations in aqueous solution. The (PCL24)2(PDEA16-b-PPEGMA19)2 was used as an example to encapsulate hydrophobic drug DOX. The D h of the empty micelles self-assembled from the polymer (PCL24)2(PDEA16-b-PPEGMA19)2 at pH 7.4 was 63 nm observed by DLS measurement. After drug loading, the DOX-loaded micelles showed a larger size than the empty micelles with D hs around 110 nm, which were shown in Figure 5A,B.