Tattoo biosensors
Scientists from Germany have developed the technology of biosensory "tattoos"
Maria Azarova, Naked Science
A team of scientists led by chemist Ali Yetisen from the Technical University of Munich (TUM) has developed a "subcutaneous" technology a tattoo that is able to react and change its color when glucose, albumin and pH levels change. The study is reported in Angewandte Chemie International Edition (Yetisen et al., Dermal Tattoo Biosensors for Colorimetric Metabolite Detection).
"Modification of the body by introducing pigments under the skin is a custom that is more than four thousand years old. <...> We have created a technology that combines the art of tattooing and colorimetric biosensors. The tattoo sensors functioned as diagnostic displays, displaying color changes in the visible spectrum in response to changes in pH, glucose and albumin concentrations," the scientists say.
Glucose, albumin and pH were chosen because they show most clearly that any negative processes are taking place in the body. Thus, albumin is a blood plasma protein, a low level of which may indicate kidney or liver problems, and a high level indicates heart problems. The level of glucose (sugar) in the blood, as you know, needs to be monitored for diabetes. A low pH level indicates acidosis (increased acidity), an elevated one indicates alkalosis (increased content of alkaline substances). Violation of the acid-base balance in any case should be monitored by doctors.
German experts have created a dye applied under the skin that changes color and thereby helps to track changes in each of these biomarkers in interstitial (tissue) fluid.
The albumin sensor is a yellow dye that can turn bluish-green when protein levels rise. The glucose sensor – from light green to dark green, respectively, changes with an increase in blood sugar levels. The pH sensor ranges from yellow (increased acidity) to blue (increased alkali content).
So far, the new technology has been tested only on pig skin, but the results are promising: the "tattoo" changed color when scientists changed the concentrations of key biomarkers. In the future, such an invention will help doctors and their patients track the course of chronic diseases.
In addition, the problem is that only the biomarker showing the pH level was reversible. Therefore, now the task of scientists is to find out how to make such subcutaneous tattoos reversible and, therefore, reusable. The next step will be animal testing, as a result of which it will be possible to understand whether the ink causes any adverse reactions.
At the beginning of the month, scientists from the Technical University of Munich announced the invention of a "smart" pill that is able to sequentially secrete up to three different drugs directly into the body.
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