A thermosensitive Pickering gel emulsion with a high oil–water ratio for long-term X-ray imaging and permanent embolization of arteries

Iodized oil has an excellent X-ray imaging effect, but it shows poor embolization performance. When used as an embolic agent, it is easily washed off by the blood flow and eliminated from the body. Therefore, it is essential to use iodized oil in combination with solid embolic agents such as gelatin sponge or to perform multiple embolization procedures to achieve the therapeutic effect. In the present study, a poly(N-isopropyl acrylamide)-co-acrylic acid (PNCAA) temperature-sensitive nanogel was synthesized by emulsion polymerization; the nanogel was then emulsified with iodized oil to prepare a thermosensitive iodized oil Pickering gel emulsion (TIPE). The oil-water (O/W) ratio of an O/W emulsion system can reach 4 : 6. When injected into the body, TIPE transforms into a nonflowing coagulated state at physiological temperature; the iodized oil is locked in the emulsion structure, thereby achieving local embolization and continuous imaging effects, which not only retain the X-ray imaging effect of the iodized oil but also improve its embolization effect. Subsequently, we further evaluated renal artery embolization in a normal rabbit renal artery model, and the results showed that TIPE shows a long-term conformal embolization performance and excellent long-term X-ray imaging ability.