The pH-responsive characteristic of Fe₃O₄@CNC (MCNC)-stabilized Pickering emulsions (MCNC-PEs) under the influence of an external magnetic field were investigated. The Pickering emulsions were prepared using MCNC nanocomposites as the emulsifier. The results demonstrated that the MCNC-PEs exhibited reversible pH-dependent stability that was affected by the presence of magnetic fields. The MCNC-PE droplets prepared with 0.3 wt% MCNC was observed to be stable in acidic solution (pH 1.5–5.0) but broken down in alkaline medium (pH ≥ 7.5). This phenomenon could be owing to an abrupt change of MCNC wetting properties as resulted by the combined effects of superparamagnetic hysteresis and high solubility of MCNCs in alkaline environment. The formulated emulsion can be cycled between stable and unstable 3 times upon a simple pH variation. The unique pH-dependent stability was, however, not observed in the emulsion systems prepared using 0.5 wt% MCNCs, suggesting that MCNC-PE with higher degree of surface coverage by MCNC particles were highly stable against both pH changes and magnetic field. This study revealed the reversible inter-droplet stability of MCNC-PEs upon changes in pH with the presence of magnetic field, therefore these engineered emulsions could find potential applications in encapsulation and controlled release of pharmaceutically active compounds.

Fe ₃ O ₄的pH响应特性研究了在外部磁场影响下@CNC（MCNC）稳定的Pickering乳液（MCNC-PEs）。使用MCNC纳米复合材料作为乳化剂制备Pickering乳液。结果表明，MCNC-PEs表现出可逆的pH依赖性稳定性，受到磁场的影响。观察到用0.3 wt％MCNC制备的MCNC-PE液滴在酸性溶液（pH 1.5-5.0）中是稳定的，但在碱性介质（pH≥7.5）中会分解。这种现象可能是由于超顺磁性磁滞现象和MCNC在碱性环境中的高溶解度的综合作用所导致的MCNC润湿性能的突然变化所致。在简单的pH值变化下，配制的乳液可以在稳定和不稳定之间循环3次。但是，独特的pH依赖性稳定性是 在使用0.5重量％MCNC制备的乳液体系中未观察到，这表明MCNC-PE具有较高的MCNC颗粒表面覆盖度，对pH值变化和磁场都高度稳定。这项研究揭示了在磁场作用下pH值变化时MCNC-PEs的可逆液滴间稳定性，因此这些工程乳化液可在药物活性化合物的包封和控释中找到潜在的应用。