Electrochemical probing of encapsulation process for polymeric micelles

Many of the drugs used in pharmaceutical formulations are not photoactive. Cyclic voltammetry and differential pulse voltammetry can unveil hidden information about the binding mechanism between the host and guest. This work aims to demonstrate that electrochemical techniques can be used to monitor the binding mechanism. The electrochemical reversibility, stability, and the effect of time were investigated. Also, the kinetics parameter, binding constant, and apparent diffusion coefficient were estimated. The reversibility and stability increased when toluidine blue was in the surfactant medium. The effect of time showed that the toluidine blue did not permeate the copolymeric micelles. Although F-127 copolymer is more hydrophilic, the toluidine blue, bonded more effectively in P-123 (K_b = 3,846 L/mol) than in F-127 (K_b = 184 L/mol). The kinetics parameter corroborated with the K_b. The D_app found in P-123 and F-127 micelles followed an unexpected trend, 3.7 and 4.8 μcm² s⁻¹, respectively.