pH and temperature dual-responsive Pickering emulsion stabilized by alginate-based microgel particles for encapsulation of curcumin

Natural polysaccharides are widely used in biomedical and pharmaceutical applications due to their biocompatibility and biodegradability. In this study, alginate-based Poly( N -vinylcaprolactam)- co -sodium alginate (P(VCL- co -SA)) microgel particles with different mass ratios of VCL/SA were synthesized and employed as stabilizers for curcumin-loaded Pickering emulsions. The obtained P(VCL- co -SA) microgels display a uniform, spherical morphology with low polydispersity. Moreover, the microgels demonstrated high interfacial activity at the dodecane/water interface, enabling the stabilization of dodecane-in-water emulsions across a broad pH range (3–9) at 25°C. At an elevated temperature (55°C), the emulsions remained stable at pH 6 and 9 (above the p K a of alginate, ∼3.5), while phase separation was observed at pH 3 below the p K a . The emulsion stability was further enhanced by optimizing Ca 2+ ion concentration. Furthermore, high internal phase soybean oil-in-water emulsions stabilized by P(VCL 83 - co -SA 17 ) microgels were successfully developed for curcumin encapsulation. The emulsions provided excellent protection for curcumin at room temperature. When incubated at 37°C, curcumin retention was significantly enhanced after the addition of Ca 2+ ions. Compared to previously reported systems that encapsulate curcumin in emulsions, the present approach exhibits superior performance, such as, encapsulation efficiency and retention rate. These findings provide insights into the development of high-performance Pickering emulsions that are stabilized by natural products and highlight their potential applications in food technology and the pharmaceutical industry.