DPD simulations on morphologies and structures of blank PLGA-b-PEG-b-PLGA polymeric micelles and docetaxel-loaded PLGA-b-PEG-b-PLGA polymeric micelles

Dissipative particle dynamics (DPD) simulation was used to study the morphologies and structures of blank (no drug) poly(lactic-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) (PLGA-b-PEG-b-PLGA) polymeric micelles and the docetaxel (Dtx)-loaded PLGA-b-PEG-b-PLGA polymeric micelles. We focused on the influences of PLGA-b-PEG-b-PLGA copolymer concentration, composition, Dtx drug content and the shear rate on morphologies and structures of the micelles. Our simulations show that the PLGA-b-PEG-b-PLGA copolymers in the aqueous solutions could aggregate and form blank micelles while Dtx drug and PLGA-b-PEG-b-PLGA could aggregate and form drug-loaded micelles. Under different PLGA-b-PEG-b-PLGA concentrations and drug content, the blank and drug-loaded micelles are observed as spherical, onionlike, columnar, and lamellar structures. The onionlike structures are comprised of the PEG hydrophilic core, the PLGA hydrophobic middle layer, and the PEG hydrophilic shell. As the structure of micelles varies from a spherical core-shell structure to a core-middle layer-shell onionlike structure, the distribution of the Dtx drugs diffuses from the core to the PLGA middle layer of the aggregate. In addition, the drug release process of the Dtx-loaded micelles under shear flow is also simulated. And the results show that the spherical micelles turn into a columnar structure under a shear rate from 0.2 to 3.4. When the shear rate increases to 3.5, the Dtx drugs released gradually increase until all are released with time evolution. These findings illustrate the dependence of the structural morphologies on the detailed molecular parameters of PLGA-b-PEG-b-PLGA and Dtx.

Morphological transitions of micelles induced by the block arrangements of copolymer blocks: Dissipative particle dynamics simulation

Polymer micelles with distinct morphologies and unique microphase separation microstructures can exhibit different properties and functions, holding the great promises for a range of biomedical applications. In current work, the...

Temperature-responsive morphology formation of a PS-b-PI copolymer: a dissipative particle dynamics simulation study

Self-assembly responsiveness to stimuli of polystyrene-block-polyisoprene (PS-b-PI) diblock copolymer materials is explored by means of classical molecular dynamics (MD) and dissipative particle dynamics (DPD) simulations. A concerted relationship between the parameters achieved from atomistic and DPD simulations is obtained for this molecular recognition as clearly pronounced in a phase transition. Effects of temperature, model size and composition on the morphological formation were systematically investigated for the diblock copolymeric system. Structural changes resulting in the evolution of rheology as well as an equilibrium ordered structure were analyzed in terms of order parameters and radial distribution functions. From our models, various morphologies were observed including discrete clusters (sphere-liked morphology), connected clusters (gyroid-liked morphology), hexagonally packed cylinders (HEX), connected cylinders, irregular cylinders, perfect lamellae, perforated lamellae and defected lamellae. Based on this finding, a bottom-up multi-scale simulation of the PS-b-PI diblock copolymer provides a link between equilibrium copolymeric morphologies and the crucial parameters.