A PTX/nitinol stent combination with temperature-responsive phase-change 1-hexadecanol for magnetocaloric drug delivery: Magnetocaloric drug release and esophagus tissue penetration

An antitumor drug/esophagus stent combination can palliatively relieve malignant esophageal stricture and exert local chemotherapy to cancer. It is vital for effective treatment of cancer to control drug release and facilitate drug penetration into deep tissue after the combination is placed in the malignant strictured esophagus part. In this study, we firstly designed and prepared a novel antitumor drug/esophagus stent combination: a magnetocaloric nitinol stent coated with a bilayered film that consisted of one ethylene-vinyl acetate copolymer (EVA) layer as drug blocking layer and one EVA layer containing 10% paclitaxel (PTX) and 30% temperature sensitive phase-change fatty alcohol (1-tetradecanol, 1-hexadecanol or 1-octadecanol). The drug release and penetration into rabbit esophagus wall from the combination were investigated. It was found that, under an alternating electromagnetic field at a power of 0.1 kW, the combination was heated to 43 °C, the PTX was faster and more released from the combination, as well as the amount of PTX in esophagus tissue or its deep muscle tissue penetrated from the combination was much higher than that without alternating electromagnetic field. The pathological data showed that the combination was biocompatible and safe after placement in rabbit esophagus even under an alternating electromagnetic field. Overall, the PTX could be magnetocalorically released and effectively penetrated into esophagus wall from the PTX/nitinol stent combination.