Tattoo made of gold nanoparticles for diagnostics

Professor Carsten Sönnichsen's research group at JGU has been using gold nanoparticles as传感器to detect tiny amounts of proteins in microscopic flow cells for many years. Gold nanoparticles act as small antennas for light: They strongly absorb and scatter it and, therefore, appear colorful. They react to alterations in their surrounding by changing color. Sönnichsen's team has exploited this concept for implanted medical sensing.

The sensor is based on color-stable goldnanoparticlesthat are modified with receptors for specific molecules. Embedded into an artificial polymeric tissue, the nanogold is implanted under the skin where it reports changes in drug concentrations by changing its color.

To prevent the tiny particles from swimming away or being degraded by immune cells, they are embedded in a porous hydrogel with a tissue-like consistency. Once implanted under the skin, smallblood vessels细胞生长到孔中。传感器集成在组织中，并且不会被拒绝为异物。“我们的传感器就像一个看不见的纹身，而不是比一分钱更瘦，而不是一毫米，”JGU的纳米医生学群体负责人CarstenSönnichsen教授说。由于金纳米颗粒是红外线，因此眼睛不可见。然而，一种特殊的测量装置可以通过皮肤非侵略地检测它们的颜色。

在他们的研究发表在纳米字母, the JGU researchers implanted their gold nanoparticle sensors under the skin of hairless rats. Color changes in these sensors were monitored following the administration of various doses of an antibiotic. The drug molecules are transported to the sensor via the bloodstream. By binding to specific receptors on the surface of the gold nanoparticles, they induce color change that is dependent on drug concentration. Thanks to the color-stable gold nanoparticles and the tissue-integratinghydrogel, the sensor was found to remain mechanically and optically stable over several months.

Huge potential

"We are used to colored objects bleaching over time. Gold nanoparticles, however, do not bleach but keep their color permanently. As they can be easily coated with various different receptors, they are an ideal platform for implantable sensors," explained Dr. Katharina Kaefer, first author of the study.

新颖的概念是推广的，并且具有延长可植入传感器的寿命。将来，基于金纳米粒子的可植入传感器可用于观察同时体内不同生物标志物或药物的浓度。这种传感器可以在药物开发，医学研究或者中找到应用个性化的药物，如管理层chronic diseases.

Sönnichsen在2004年开始使用黄金纳米颗粒作为植入的传感器，当时他开始研究生物物理化学作为Mainz的初级教授。然而，该项目直到十年后，与jgu的科学家斯施罗德博士和Katharina Kaefer博士合作。SCHROEDER在生物研究和实验室动物科学中经历过，已经在美国完成了几年的研究工作。

Kaefer was looking for an exciting topic for her doctorate and was particularly interested in the complex and interdisciplinary nature of the project. Initial results led to a stipend awarded to Kaefer by the Max Planck Graduate Center (MPGC) as well as financial support from Stiftung Rheinland-Pfalz für Innovation. "Such a project requires many people with different scientific backgrounds. Step by step we were able to convince more and more people of our idea," said Sönnichsen happily. Ultimately, it was interdisciplinary teamwork that resulted in the successful development of the first functional implanted sensor with gold nanoparticles.