pH-controllable stability of iron oxide@chitosan nanocomposite-stabilized magnetic Pickering emulsions

• Published in: European polymer journal Vol. 186; p. 111870
• Main Authors: Sia, Chin Siew, Lim, Hui Peng, Lin, Yi Ning, Beh, Lee Chey, Tey, Beng Ti, Goh, Bey-Hing, Low, Liang Ee
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.03.2023
• Subjects: Iron oxide-chitosan nanocomposite; pH-responsive; Pickering emulsion; pH-responsive; Pickering emulsion; Iron oxide-chitosan nanocomposite
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2023.111870

This research paper discusses the stability of pH-controllable iron oxide@chitosan nanocomposite-stabilized magnetic Pickering emulsions. [Display omitted] •Palm-based Pickering emulsion were prepared using iron oxide@chitosan nanocomposite (IOCS).•The IOCS-PE showed obvious responses when subjected to pH changes.•The IOCS-PE was more stable at pH 4.0 than at alkaline pH (pH > 6.3) due to particle-droplet interactions.•The magnetic property of IOCS-PE remain unaffected by pH variations. The pH-responsiveness of iron oxide@chitosan nanocomposite (IOCS)-stabilized Pickering emulsion (PE) (denoted as IOCS-PE) was investigated. Preparation of the IOCS-PE at pH 4.0 has resulted in PE with the smallest size (1.4 ± 0.2 μm) and highest stability against deformation as compared to those prepared at alkaline conditions (pH ≥ 6.3), due to the change in IOCS surface wettability at increasing pH. To further verify the pH-dependent stability, the IOCS-PE at pH 4.0 was subjected to a simple pH variation to pH 1.5 and pH 7.4, respectively. Superior stability was observed for IOCS-PE tuned to pH 1.5 as compared to pH 7.4 over 120 min with or without magnetic field. This difference in stability could be attributed to the reduction in interparticle electrostatic repulsion stemming from the deprotonation of chitosan’s amino group and IONP’s hydroxyl group at pH 7.4. The magnetic responsiveness of the IOCS-PE was also evaluated by subjecting it to an external magnetic field, demonstrating the feasibility of retaining the IOCS-PE in a specific location of interest via magnetic attraction. In conclusion, the stability of IOCS-PE was found to be pH-dependent, and its retention time could be increased by applying an external magnetic field. The outcomes displayed the potential of the IOCS-PE as stimuli-responsive emulsions for food or pharmaceutical applications.