Palm olein-in-water Pickering emulsion stabilized by Fe3O4-cellulose nanocrystal nanocomposites and their responses to pH

• Preparation of palm olein-in-water Pickering emulsion using MCNC.
• The zeta potential of MCNC is greatly influenced by Fe3O4 nanoparticles.
• MCNC-stabilized Pickering emulsions possessed both pH and magnetic responsiveness.
• The resultant emulsions showed excellent colloidal stability upon storage.

We studied the formation of palm olein-in-water (O/W) Pickering emulsion stabilized by Fe3O4-cellulose nanocrystals (MCNC) nanocomposites obtained by ultrasound assisted in-situ co-precipitation method. The synthesized MCNC nanocomposites successfully stabilized Pickering emulsion with dual responses. The magnetic tests revealed a direct-relation between attractability of MCNC-stabilized Pickering emulsions and the emulsion droplet diameter. The Pickering emulsions were stable under pH ranging from 3 to 6. The stability substantially reduced around pH 8–10, and regained slowly when approaching pH 13. From microscopic and mastersizer analysis, monodisperse emulsion droplets were noticed at pH 3–6, and 13, while polydisperse emulsion were obtained at pH 8–12. The Pickering emulsions prepared at pH 6 are stable up to 14 days, while Pickering emulsions at pH 8 experienced coalescence. In this study, the dual stimuli-responsive Pickering emulsion stabilized by MCNC may hold potentials for biomedical and drug delivery as new generation of smart nanotherapeutic carrier.

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