Wearable Sensor Patch Continuously Monitors ‘Last Line of Defense’ Antibiotic with Less Pain than Blood Draw

Since the first use of penicillin in 1928, bacteria have continually evolved, finding ways to resist or entirely evade the effects of antibiotics. However, medical professionals still have a reserve of seldom-used antibiotics that work against these resistant bacteria strains. Now, a team of researchers has combined its earlier research on painless microneedles with nanoscale sensors to develop a wearable patch that can continuously monitor the levels of one such antibiotic.

Researchers at Sandia National Laboratories (Albuquerque, NM, USA) have focused on an antibiotic named vancomycin, which is considered a last-resort treatment for treating severe bacterial infections. Continuous monitoring is crucial for vancomycin, as it has a narrow range within which it can kill bacteria without harming the patient. The team used sensors known as aptamers, which are DNA strands featuring a surface linker on one end and an electrically sensitive chemical on the other. When these DNA strands attach to vancomycin, they change shape, pulling the electrically sensitive chemical closer to the gold surface, causing a detectable change in electrical current. When there is a reduction in the vancomycin concentration, some DNA regain its original shape, which is also detected electrically

After building these microneedle sensors, the researchers first tested their ability to detect vancomycin in a saline solution, simulating the conditions within the human body. Once confirmed, they then ran tests in a far more complex medium: pure cow's blood, where the system remained effective. Subsequently, they conducted experiments inserting the sensor patch into pig skin multiple times to examine both the electronic signal and its capability to detect vancomycin. Following the successful results, they now aim to fully test the sensor patch system in humans or other animals.

In the future, a similar setup using different DNA aptamers could be employed for monitoring cytokines—tiny proteins that transmit signals inside the body—and other molecules whose levels fluctuate during infections. This technology could enable quicker diagnoses and even aid in emergency triage. The team has also been investigating potential elements in blood and skin that could impede the sensor's precision. They discovered that fibrinogen, a protein vital to blood clotting, can interfere with the sensor's signals.

“This is a great application because it requires tight control,” said Philip Miller, a Sandia biomedical engineer who advised on the project. “In a clinical setting, how that would happen is a doctor would check on the patient on an hourly basis and request a single time-point blood measurement of vancomycin. Someone would come to draw blood, send it to the clinic and get an answer back at some later time. Our system is one way to address that delay.”

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Sandia National Laboratories