Pluronic F68 Micelles as Carriers for an Anti-Inflammatory Drug: A Rheological and Scattering Investigation

Abstract

Age-long ambition of medical scientists has always been advancement in healthcare and therapeutic medicine. Biomedical research indeed claims paramount importance in nanomedicine and drug delivery, and the development of biocompatible storage structures for delivering drugs stands at the heart of emerging scientific works. The delivery of drugs into the human body is nevertheless a nontrivial and challenging task, and it is often addressed by using amphiphilic compounds as nanosized delivery vehicles. Pluronics belong to a peculiar class of biocompatible and thermosensitive nonionic amphiphilic copolymers, and their self-assemblies are employed as drug delivery excipients because of their unique properties. We herein report on the encapsulation of diclofenac sodium within Pluronic F68 self-assemblies in water, underpinning the impact of the drug on the rheological and microstructural evolution of pluronic-based systems. The selfassembly and thermoresponsive micellization were studied through isothermal steady rheological experiments at different temperatures on samples containing 45 wt % Pluronic F68 and different amounts of diclofenac sodium. The adoption of scattering techniques, small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS), allowed for the description of the system features at the nanometer length scale, providing information about the characteristic size of each part of the micellar structures as a function of temperature and drug concentration. Diclofenac sodium is not a good fellow for Pluronic F68. The triblock copolymer aids the encapsulation of the drug, highly improving its water solubility, whereas diclofenac sodium somehow hinders Pluronic self-assembly. By using a simple empirical model and no fitting parameters, the steady viscosity can be predicted, although qualitatively, through the volume fraction of the micelles extracted through scattering techniques and compared to the rheological one. A tunable control of the viscous behavior of such biomedical systems may be achieved through the suitable choice of their composition.

Poloxamer-Based Mixed Micelles Loaded with Thymol or Eugenol for Topical Applications

“…These aggregates can be easily fabricated from different types of polymer surfactants, including Poloxamers. These biocompatible polymers belong among the poly­(ethylene oxide)-poly­(propylene oxide)-poly­(ethylene oxide) (PEO–PPO-PEO) triblock copolymer surface active agents (Figure ) that can be used for the preparation of suitable carriers with an outer hydrophilic chain and inner hydrophobic core in an aqueous medium. , Compared to traditional low molecular weight surface active agents, Poloxamer molecules contain long chains with an M w of thousands g/mol. Poloxamer aggregates can form micelles, reversed micelles, and lyotropic liquid crystals, including lamellar, hexagonal, and cubic aggregates.…”