Permanent and peripheral embolization is a requirement of embolic materials in the transcatheter arterial embolization of liver tumors. So far, it has been difficult to find materials that have both good flowability and high mechanical strength. In the present work, a temperature‐sensitive p(N ‐isopropylacrylamide‐co‐butyl methylacrylate) (PIB) nanogel is explored as a novel blood‐vessel‐embolic material in the interventional therapy of liver tumors. With increasing temperature, the PIB nanogel dispersion sequentially exhibits three phase states; swollen gel, flowable sol, and finally shrunken gel. Iohexol, a nonionic X‐ray contrast agent, increases the volume‐phase transition temperature of the PIB nanogel and decreases the critical gelation concentration. Angiographical and histological studies on the embolization in the liver arteries of VX2 tumor‐bearing rabbits indicate that the PIB nanogel dispersion mixed with iohexol (designated as PIB‐I‐6150) completely occludes all levels of blood vessels, including peripheral vessels. In addition, data on tumor volume, necrosis level, and the number of metastatic foci indicate that PIB‐I‐6150 has better peripheral embolization than Lipiodol. Experiments concerning cytotoxicity, hemolysis, histology, and liver function indicate that PIB‐I‐6150 has good biocompability.

Silver nanoparticles (SNPs) translocate to the brain through the blood stream after they are implanted in vivo. The aim of this study was to investigate the distribution of SNPs that crossed through the blood-brain barrier (BBB). An in vitro BBB model established by co-cultures of rat brain microvessel vascular endothelial cells (BMVECs) with astrocytes (ACs) was cultured with cell culture medium containing 100 microg/mL of either SNPs or silver microparticles (SMPs). After 4 hours of culture, the ultrastructure and its silver content of BBB was evaluated with transmission electronic microscopy (TEM) and inductively-coupled plasma mass spectrometry (ICP-MS) respectively. Results demonstrated that SNPs crossed the BBB and accumulated inside BMVECs, while the SMPs did not. The data indicated a special distribution of SNPs in the BBB and suggested that SNPs pass the BBB mainly by transcytosis of capillary endothelial cells. Further study would be necessary to evaluate the actual biological effects of SNPs on the brain.

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