pH-Sensitive Mixed Micelles Assembled from PDEAEMA-PPEGMA and PCL-PPEGMA for Doxorubicin Delivery: Experimental and DPD Simulations Study

Abstract

To decrease critical micelle concentration (CMC), improve stability, and keep high drug-loading capacity, three pH-sensitive mixed micelles applied for anticancer drug controlled delivery were prepared by the mixture of polymers poly (N,N-diethylaminoethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PDEAEMA-PPEGMA) and polycaprolactone-b-poly (poly(ethylene glycol) methyl ether methacrylate) (PCL-PPEGMA), which were synthesized and confirmed by ¹H NMR and gel permeation chromatographic (GPC). The critical micelle concentration (CMC) values of the prepared mixed micelles were low, and the micellar sizes and zeta potentials of the blank mixed micelles demonstrated good pH-responsive behavior. Combined experimental techniques with dissipative particle dynamics (DPD) simulation, the particle sizes, zeta potentials, drug loading content (LC), encapsulation efficiency (EE), aggregation morphologies, and doxorubicin (DOX) distribution of the mixed micelles were investigated, and the high DOX-loading capacity of the mixed micelles was found. Both in vitro DOX release profiles and DPD simulations of the DOX dynamics release process exhibited less leakage and good stability in neutral conditions and accelerated drug release behavior with a little initial burst in slightly acidic conditions. Cytotoxicity tests showed that the polymer PDEAEMA-PPEGMA and the blank mixed micelles had good biocompatibility, and DOX-loaded mixed micelles revealed certain cytotoxicity. These results suggest that the drug-loaded mixed micelles that consisted of the two polymers PDEAEMA-PPEGMA and PCL-PPEGMA can be new types of pH-responsive well-controlled release anticancer drug delivery mixed micelles.

Keywords: dissipative particle dynamics simulation; drug delivery system; mixed micelles; pH-responsive; well-controlled release.

Scheme 1

Scheme of DOX-loaded mixed micelles formation and pH-sensitive release of DOX.

Scheme 2

Synthetic routes for poly (N,N-diethylaminoethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PDEAEMA-PPEGMA) (A) and polycaprolactone-b-poly (poly(ethylene glycol) methyl ether methacrylate) (PCL-PPEGMA) (B).

Figure 1

¹H NMR spectra of PDEAEMA-PPEGMA (A) and PCL-PPEGMA (B) in CDCl₃; gel permeation chromatographic (GPC) traces (C) of PDEAEMA-PPEGMA, PCL-PPEGMA, and PCL-OH.

Figure 2

Different ratios of pyrene in neutral aqueous solution for PCL-PPEGMA (A), PDEAEMA-PPEGMA (B), and mixed polymers (C) at various concentrations.

Figure 3

(A) Particle sizes and (B) zeta potentials of the polymeric mixed micelles dependence on pH values in aqueous solution.

Figure 4

Equilibrium states (A) and cross-setion views (B) of the DOX-loaded mixed micelles at different DOX concentrations.

Figure 5

Morphologies of MIX1, MIX2, and MIX3 at 120,000 steps with 3% volume fraction of PDEAEMA-PPEGMA, 3% volume fraction of PCL-PPEGMA, and 3% volume fraction of DOX.

Figure 6

TEM images of blank MIX1 micelles (A) and DOX-loaded MIX1 micelles (B).

Figure 7

In vitro drug release profiles (A) at pH 7.4 and pH 5.0; (B) DOX release process of MIX1 (LC, 31.23%) in acidic aqueous solution; (C) radial distribution functions (RDF) curves between DOX and the micellar center; (D) mean square displacements (MSD) curves of the DOX-loaded mixed micelles MIX1 (LC, 31.23%), MIX2 (LC, 26.53%), and MIX3 (LC, 23.36%).

Figure 8

In vitro cytotoxicity of blank MIX1 and polymer PDEAEMA_28.8-PPEGMA_12.4 (A), free DOX and DOX-loaded mixed micelles (B) and in HepG2 cells. *p < 0.05.