“Our research shows…the potential for implanted sensors to revolutionize personalized medicine. We have demonstrated a strategy that incorporates nanotechnology and implants, which will probably lead to other nanotechnology applications in living organisms as well.”Carsten Sönnichsen
Interdisciplinary researchers at Johannes Gutenberg University Mainz (JGU) have developed a new implantable sensor that can operate in the body for up to several months to provide medical diagnostics. The sensor acts as an invisible tattoo revealing concentration changes of substances in the blood by color change, and is based on color-stable gold nanoparticles that are altered for specific molecules.
Using implantable sensors to transmit information on the values and concentrations of drugs in the body has long been an area of research, but have remained unsuitable as they need replacing after only a short period and the body can identify them as a foreign object. However, as described in Nano Letters [Kaefer et al. Nano Lett. (2021) DOI: 10.1021/acs.nanolett.1c00887], here the color changes of the gold nanoparticles embedded in a porous hydrogel show the concentration changes of substances in the body to allow constant monitoring of disease progression and therapeutic success, and with the potential to extend the lifetime of implantable sensors.
The research group of Carsten Sönnichsen has used gold nanoparticles as sensors to detect proteins in microscopic flow cells for many years. The nanoparticles react to alterations in their surrounding by changing color and act as small antennas for light, as they strongly absorb and scatter it and therefore appear colorful. In this study, to stop the particles moving away or being degraded by immune cells, they were embedded in an innovative porous hydrogel with a tissue-like consistency. After being implanted under the skin, tiny blood vessels and cells grow into the pores to allow the sensor to integrate in the tissue and not be rejected as a foreign body.
As the gold nanoparticles are infrared, they are not visible to the eye, but can be measured to detect their color non-invasively through the skin. The sensor was shown to remain mechanically and optically stable over several months. Gold nanoparticles also do not bleach but retain their color permanently, and can be easily coated with different receptors. As team leader Carsten Sönnichsen told Materials Today, “Our research shows…the potential for implanted sensors to revolutionize personalized medicine. We have demonstrated a strategy that incorporates nanotechnology and implants, which will probably lead to other nanotechnology applications in living organisms as well.”
These sensors could find uses in monitoring concentrations of different biomarkers or drugs in the body at the same time, and could be applied in drug development, medical research and personalized medicine. The team now hope to improve their approach by making the implants more reliable, and tailor them to specific areas of interest.
Implantable sensor acts as an invisible tattoo revealing concentration changes of substances in the blood by color change