A GO@PLA@HA Composite Microcapsule: Its Preparation and Multistage and Controlled Drug Release

Abstract

In this work, a new kind of multiple drug‐release system, graphene oxide (GO)@polylactic acid (PLA)@hydroxyapatite (HA) composite microcapsule, was constructed through the double Pickering emulsion method. In the preparation of the microcapsules, GO and HA were used as stabilizers for the water‐in‐oil (W1/O) and oil‐in‐water (O/W2) systems, respectively. Furthermore, GO, as the internal water phase (W1), could carry a hydrophilic drug (5‐FU), while PLA, as the oil phase (O), was employed to effectively embed a hydrophobic drug (coumarin). Additionally, the pH‐sensitive HA in an external water phase (W2) could also act as a vector to carry hydrophilic rose bengal, due to its excellent adsorption ability. Dynamic optical experiment results show that the uniform size and complete structure of the GO@PLA@HA composite microcapsules can be obtained at a volume ratio of W1/O/W2 = 3:20:100. The prepared GO@PLA@HA composite microcapsules present good biocompatible, biodegradable, and pH‐sensitive features. The respective drug encapsulation efficiencies of 5‐FU, coumarin, and rose bengal are estimated to be 13.38 %, 48.58 %, and 53.24 %, and their loading efficiencies are 0.15 %, 4.49 %, and 5.3 %, respectively. The controlled release of drugs can be realized by the degradation of HA in the simulated acidic tumoral environment, which illustrates the pH‐triggered drug‐release behavior of HA. More importantly, the above three different drugs, with their hydrophilic or hydrophobic natures, could be loaded into the single W1@O@W2 microcapsule, and they exhibited multistage sustained release in PBS solution at pH 5.0. Thus, the as‐synthesized composite microcapsules, with their multistage drug‐delivery function, may act as a new and promising drug‐delivery system in the medical field.