MEDIC implant measures drug levels in the bloodstream

Determining how effectively a drug is being absorbed by the human body is a tricky business.

While age and weight can give doctors a good indication, a patients’ metabolism, the foods they eat and other drugs they might be taking can all have an effect on efficacy.

Looking to solve this problem, engineers from the University of California, Santa Barbara have developed an implantable device that provides real time feedback on how much medication is currently in a person’s bloodstream.

While still in the early stages of development, the researchers say the prototype device, called MEDIC (Microfluidic Electrochemical Detector for In vivo Concentrations), could revolutionise the way treatment is given and measured in the future.

Kevin Plaxco, a professor of biomolecular science and engineering, believes it could even be used to deliver drugs automatically, with dosages based on the feedback generated by the device.

An artificial pancreas, which monitors glucose levels in diabetics and uses this information to inject a controlled amount of insulin, is an example of one such system.

The MEDIC device consists of a microfluidic chamber lined with gold electrodes from which drug-recognising biomolecules – in this case artificial DNA strands called aptamers – extend.

When the target molecule comes in contact with an aptamer, the strand recognises it and wraps around the molecule, delivering electrons from its tip to the electrode at the aptamer’s base. The tiny jolt of current signals the presence of the molecule.

Because previous iterations of the device failed within half an hour – due to the components in whole blood clinging to the sensors – the researchers decided to introduce a second flow into the chamber.

This acted like a filter, separating the large blood components from the small drug molecules.

In tests, the researchers found they could easily and accurately measure the effectiveness of a particular drug in the bloodstream, even when a cocktail of drugs was administered.

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