the line width of 1 H signal at 3.71 ppm, which statistical difference between these two treatments. As a control, originates from oxyethylene (O–CH 2 –CH 2 ) protons of PEG, was empty PEG-DSPE/TPGS mixed micelles at concentrations equiva- approximately as narrow as that in DMSO-d 6 ( 1/2 = 2.81 Hz in lent to those present in the drug-loaded Risperidone micelles caused less than D 2 O versus 1.83 Hz in DMSO-d 6 ), indicating that the PEG moiety is 5% inhibition on the proliferation of SKOV-3 cells. The cytotoxicity located at the corona region of the micelles, where the motion of the protons is not affected significantly by the micelle formation. In contrast, DSPE had much more broadened 1 H peaks at 0.87 ppm, 1.28 ppm and ∼ 5–8 ppm in the aqueous micelle sample than the Fig. 3. The size distribution of empty PEG-DSPE micelles, empty PEG-DSPE/TPGS Fig. 4. Cytotoxicity of 17-AAG-loaded PEG-DSPE/TPGS mixed micelles against mixed micelles, and 17-AAG-loaded PEG-DSPE/TPGS mixed micelles.
Each profile human ovarian cancer SKOV-3 cells. Results show representative data obtained from shows representative data obtained from three independent experiments. three independent experiments and are reported as the means ± SD ( n = 3). 5 T. Chandran et al. / International Journal of Pharmaceutics 392 (2010) 170–177 175 ing the enhanced hydrophobic interactions within the core of the mixed micelles. Furthermore, compared to the narrow line width in the DMSO control sample, although FWHH of 1 H Risperidone 106266-06-2 signal of the PEG moiety at 3.71 ppm was slightly increased (from 1/2 = 2.85 Hz in Fig. 5 C to 3.41 Hz in Fig. 5 D), the base of the peak was increased drastically (from 29.15 Hz in Fig. 5 C to 95.57 Hz in Fig. 5 D). In con- trast, the base of the PEG peak in PEG-DSPE micelles was 34.20 Hz ( Fig. 5 B).
As a result of broader line width of the PEG peak in the PEG-DSPE/TPGS mixed micelles, the relative spectral intensity of oxyethylene protons of PEG at 3.71 ppm to methyl (CH 3 ) protons of DSPE at 0.87 ppm was markedly decreased from 455 in PEG- DSPE micelles ( Fig. 5 B) to 35 in PEG-DSPE/TPGS mixed micelles ( Fig. 5 D). These data strongly indicate that the presence of TPGS in the mixed micelles partially limits the buy Risperidone mobility of the PEG moi- ety, resulting in two partitions of PEG protons: one experiencing fast motion and the other with restricted mobility. Taken together, these results provide convincing evidence that the incorporation of TPGS into PEG-DSPE micelles substantially reduces internal molec- ular motions in both the corona and core regions of the mixed micelles. 4. Discussion There have been several recent reports on the devise of 17-AAG- loaded polymeric micelles, with the specific intention to eliminate the use of organic solvents and to improve tumor-targeted delivery of the drug. For instance, 17-AAG was incorporated into PEG- poly( d,l -lactide) (PEG-PLA) micelles with a maximum loading of about 2.6–6.6 mM ( Shin et al., 2009; Xiong et al., 2009 ). The release kinetics of 17-AAG-loaded PEG-PLA micelles from the dialysis cas- sette closely resembled that of free 17-AAG, indicating a very rapid release of 17-AAG molecules from PEG-PLA micelles under the sink condition.
Consequently, the drug-loaded PEG-PLA micelles Fig. 5. 1 H NMR spectra of (A) the mixture of PEG-DSPE and 17-AAG in DMSO-d 6 ; (B) 17-AAG-incorporating PEG-DSPE micelles prepared in HBS/D 2 O buffer; (C) the mixture of PEG-DSPE, TPGS and 17-AAG in DMSO-d 6 ; and (D) 17-AAG-incorporating PEG-DSPE/TPGS mixed micelles prepared in HBS/D 2 O buffer. The concentrations of PEG-DSPE, TPGS and 17-AAG were 5.3 mM, 10.6 mM and 0.6 mM, respectively. The inserts in the region of 0.0–2.9 ppm and 5.0–10.0 ppm are the intensity-scale expansions. The insert spectra are plotted with different y fat -scales to display the weak peaks. The 1 H signals of 17-AAG were not present in the insert of B and D even though the intensity scale was expanded more times than those of A and C. The expanded spectrum at l