Invisible biosensor
Scientists have demonstrated a blood composition sensor "growing" under the skin
Sergey Vasiliev, Naked Science
In recent years, scientists from different countries have been actively working on the creation of miniature sensors that would be able to track the content of various substances in the blood. It is important that the device functions imperceptibly and comfortably for the patient, does not cause rejection by the body and does not require regular intervention to replace batteries or reagents. A working prototype of such a device was recently demonstrated by developers from the Gutenberg University (JGU) in Mainz, Germany.
The sensor uses colored gold nanoparticles bound to specific receptors for target substances and immersed in an inert polymer. According to JGU professor Carsten Zonichsen, the finished device is "like an invisible tattoo no bigger than a coin and thinner than a millimeter" and has already been successfully tested when implanted under the skin of laboratory animals. Zonihsen and his colleagues write about this in an article published in the journal Nano Letters (Kaefer et al., Implantable Sensors Based on Gold Nanoparticles for Continuous Long-Term Concentration Monitoring in the Body).
Gold nanoparticles are capable of strongly absorbing and scattering infrared radiation. Scientists are actively trying to apply this ability to treatment, diagnostics and science. Professor Zonihsen's team supplemented such nanoparticles with molecules capable of binding one or another desired substance (in the experiments conducted, the antibiotic kanamycin). Its appearance changes the environment of nanoparticles, affecting the length of the scattered light, which can be detected using external sensors, through the skin.
The modified nanoparticles are placed in a biocompatible hydrogel, a porous, liquid—filled polymer that does not cause an immune response. After implantation, the thinnest capillaries grow into the hydrogel under the skin, which bring the target substance to the nanoparticles. In experiments with hairless laboratory rats, it was shown that the sensor allows you to register the presence of different doses of kanamycin in the blood and works stably for at least several months.
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