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Urine-powered nanobots shrink bladder cancer tumors in mice by 90%
Researchers have developed a novel way to treat bladder cancer. Powered by urea, a waste substance found in urine, nanobots propel themselves to and penetrate the tumor to deliver their onboard radioactive treatment. After one dose, tumors in mouse models shrank by almost 90%, opening the door to a promising alternative treatment for this cancer, which tends to recur.
Current treatments for non-muscle-invasive bladder cancer, which represents approximately 75% of cases, include the administration of immunotherapeutic and/or chemotherapy drugs into the bladder following tumor resection. While these treatments show good survival rates, they have limited effectiveness, as evidenced by five-year recurrence rates of 30% to 70%, requiring the patient to undergo regular and costly bladder surveillance procedures (cystoscopy) and, potentially, further treatment.
In an effort to improve the effectiveness of bladder cancer treatment, researchers from the Institute for Research in Biomedicine (IRB) Barcelona, in collaboration with the Institute for Bioengineering of Catalonia (IBEC), CIC biomaGUNE, and the Autonomous University of Barcelona (UAB), developed self-propelled nanobots that accumulate at the tumor site to deliver cancer-fighting treatment directly.
Taking advantage of the bladder’s internal environment, the researchers’ tiny robots are powered by urine, specifically the urea in urine. The surface of a nanosized porous silica sphere is modified to carry components with specific functions. One is urease, an enzyme that catalyzes the hydrolysis of the urea present in urine to ammonia and carbon dioxide, causing the nanobot to propel itself. Another key surface component is radioactive iodine, iodine-131, a radioisotope commonly used for the localized treatment of tumors.
After injecting their urease-powered nanobots into the bladders of mouse models of bladder cancer, the researchers used positron emission tomography (PET) scans to show that the bots accumulated at the tumor site. Examination under microscopy, which researchers from IRB Barcelona had developed specially, showed that the bots penetrated the tumor. The nanobots’ administration of iodine-131 at the tumor site resulted in a reduction in tumor volume of nearly 90%.
“With a single dose, we observed a 90% decrease in tumor volume,” said Samuel Sánchez, one of the study’s corresponding authors. “This is significantly more efficient than current treatments, given that patients with this type of tumor typically have between six and 14 hospital appointments. This therapeutic approach would increase efficiency by reducing the length of hospitalizations and the cost of treatment.”
The novel treatment paves the way for more effective treatments for bladder cancer. The next step for the researchers, which they’re already working on, is determining whether the tumors recur after treatment.
注释：
cystoscopy: n
表示" [医]膀胱镜检查"，如：The patient mentioned that he was scheduled to go in for cystoscopy in a couple weeks because there had been blood in his urine. 病人提到，他将在未来的几周内安排个膀胱镜检查，因为在他尿中带血。
urea: n
表示" 尿素"，如：A kidney also takes urea and mineral salts out of the blood. 肾还排出血液中的尿素和无机盐。
hydrolysis: n
表示" 水解"，如：On hydrolysis carbon dioxide is evolved. 水解时，放出二氧化碳。
positron: n
表示" 正电子"，如：The result is that the electron shadow and the positron shadow are separated. 结果将使得电子的阴影和正电子的阴影被分开。
中文简要说明：
在科幻电影「星际迷航」(STAR TREK：The Next Generation)当中，有一种高科技种族「博格人」(Borg)，他们身上的细胞大多都被纳米机器人取代，使他们的自我修复能力超强。现在医学界正在研发类似技术，利用纳米机器人来清除癌肿瘤。研究人员开发出一种由尿素驱动的纳米机器人，可以破坏膀胱癌肿瘤，在小鼠实验中，肿瘤缩小了近 90%。
新阿特拉斯(New Altas)报导，巴塞罗那生物医学研究所 (IRB) 、加泰隆尼亚生物工程研究所 (IBEC)、巴塞罗那自治大学 (UAB) 的合作团队，发了可一种自行推进的纳米机器人，前往肿瘤部位，逐步的破坏肿瘤。
研究人员还利用膀胱的内部环境，设计出直接以尿液中的尿素作为动力的机制。机器人安装一种催化尿素的酵素-脲酶，它具有水解为氨和二氧化碳的功能，这些就可成为纳米机器人的推力。而机器人的「武器」则是放射性碘，即碘 131，它是放射治疗法中的常用同位素。
纳米机器人注射到膀胱癌小鼠的膀胱后，研究人员使用正电子断层扫描（PET），追查机器人的工作状态，发现它们自动在肿瘤部位聚集。穿透肿瘤表面，并注射碘 131，使得肿瘤体积缩小了近 90%。
这些纳米机器人存在时间不长，不久就会随尿液排出，这算是完成了一次治疗。
研究作者之一的山谬‧沙奇斯(Samuel Sánchez)说：「这效果超群，单次剂量，肿瘤体积就减少了 90%。在以往，患者通常需要 6 到 14 次疗程，可见纳米机器人要有效得多。」
这是纳米机器人治疗癌症的里程碑表现，研究人员的下一步，是确定肿瘤在治疗后是否会复发。
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