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[资源] zz美研究人员设计出杀灭癌细胞的“纳米机器”

http://news.xinhuanet.com/newsce ... content_7928826.htm
新华网洛杉矶４月５日电（记者高原）美国研究人员新设计出一种“纳米机器”，它可以储藏、输送抗癌药物并在光的作用下释放药物攻击癌细胞。研究人员说，这是利用“纳米机器”治疗癌症迈出的第一步。

美国加利福尼亚大学洛杉矶分校的研究人员在新一期纳米技术期刊《Ｓｍａｌｌ》网络版上发表报告说，这种被称为“纳米推进器”的装置是第一种由光驱动的“纳米机器”，可在活细胞内发挥作用。该装置由中孔硅纳米粒子制成，其内部细孔涂覆了化学物质偶氮苯，抗癌药物可以装载在这种细孔中。偶氮苯具有光致变色特性，在光的作用下具有两种振动形态。

研究人员用结肠癌和胰腺癌等多种人类癌细胞进行了实验。他们首先使上述“纳米机器”在黑暗中进入置于玻璃器皿中的人类癌细胞内，然后用光照射使“纳米机器”振动，“纳米机器”细孔中的抗癌药物随之被释放出来攻击癌细胞。显微镜图像显示，抗癌药物释放量等可以通过光的强度、波长和照射时间来进行精确调控。

杰弗里·津克教授等研究人员说，开发出能在光的作用下对付癌细胞的“纳米机器”非常令人兴奋。他们认为，这种“纳米机器”在精确输送药物等方面具有潜在用途，或许会成为治疗结肠癌和胃癌等癌症的“下一代平台”。

UCLA researchers design nanomachine that kills cancer cells
'Nanoimpeller' releases anticancer drugs inside of cancer cells
Researchers from the Nano Machine Center at the California NanoSystems Institute at UCLA have developed a novel type of nanomachine that can capture and store anticancer drugs inside tiny pores and release them into cancer cells in response to light.

Known as a "nanoimpeller," the device is the first light-powered nanomachine that operates inside a living cell, a development that has strong implications for cancer treatment.

UCLA researchers reported the synthesis and operation of nanoparticles containing nanoimpellers that can deliver anticancer drugs March 31 in the online edition of the nanoscience journal Small.

The study was conducted jointly by Jeffrey Zink, UCLA professor of chemistry and biochemistry, and Fuyu Tamanoi, UCLA professor of microbiology, immunology and molecular genetics and director of the signal transduction and therapeutics program at UCLA's Jonsson Comprehensive Cancer Center. Tamanoi and Zink are two of the co-directors for the Nano Machine Center for Targeted Delivery and On-Demand Release at the California NanoSystems Institute.

Nanomechanical systems designed to trap and release molecules from pores in response to a stimulus have been the subject of intensive investigation, in large part for their potential applications in precise drug delivery. Nanomaterials suitable for this type of operation must consist of both an appropriate container and a photo-activated moving component.

To achieve this, the UCLA researchers used mesoporous silica nanoparticles and coated the interiors of the pores with azobenzene, a chemical that can oscillate between two different conformations upon light exposure. Operation of the nanoimpeller was demonstrated using a variety of human cancer cells, including colon and pancreatic cancer cells. The nanoparticles were given to human cancer cells in vitro and taken up in the dark. When light was directed at the particles, the nanoimpeller mechanism took effect and released the contents.

The pores of the particles can be loaded with cargo molecules, such as dyes or anticancer drugs. In response to light exposure, a wagging motion occurs, causing the cargo molecules to escape from the pores and attack the cell. Confocal microscopic images showed that the impeller operation can be regulated precisely by the intensity of the light, the excitation time and the specific wavelength.

"We developed a mechanism that releases small molecules in aqueous and biological environments during exposure to light," Zink said. "The nanomachines are positioned in molecular-sized pores inside of spherical particles and function in aqueous and biological environments."

"The achievement here is gaining precise control of the amount of drugs that are released by controlling the light exposure," Tamanoi said. "Controlled release to a specific location is the key issue. And the release is only activated by where the light is shining."

"We were extremely excited to discover that the machines were taken up by the cancer cells and that they responded to the light. We observed cell killing as a result of programmed cell death," Tamanoi and Zink said.

This nanoimpeller system may open a new avenue for drug delivery under external control at specific times and locations for phototherapy. Remote-control manipulation of the machine is achieved by varying both the light intensity and the time that the particles are irradiated at the specific wavelengths at which the azobenzene impellers absorb.

"This system has potential applications for precise drug delivery and might be the next generation for novel platform for the treatment of cancers such as colon and stomach cancer," Zink and Tamanoi said. "The fact that one can operate the mechanism by remote control means that one can administer repeated small-dosage releases to achieve greater control of the drug's effect."

Tamanoi and Zink say the research represents an exciting first step in developing nanomachines for cancer therapy and that further steps are required to demonstrate actual inhibition of tumor growth.

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http://cegroup.blog.sohu.com/
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