New molecule enables quicker drug monitoring

A new group of proteins have been found to enable the quick and simple detection of how much of a drug remains in a person's bloodstream.

The findings, published in the Nature Chemical Biology journal, saw a team of scientists from the Ecole Polytechnique Fédérale de Lausanne (EPFL), discovered that light-emitting sensor proteins can quickly and simply show how much drug is in a patient's bloodstream by changing the colour of their light. It is thought that this method is so simple that patients themselves could use it.

Monitoring the levels of drug concentration in blood is crucial for delivering effective treatment of patients, especially for those diagnosed with cancer, heart disease, epilepsy and immunosuppression after organ transplants. However, the current methods are expensive, time-consuming, and require specialists to carry out the procedure.

This is because effective drug treatment relies on balancing the efficiency and toxicity of the drug, which lies at the core of personalised medicine. However, as each patient is individual, this can vary from one to another and so requires constant monitoring to prevent prevent side-effects or poisoning. 

Current drug-monitoring methods have to be carried out in diagnostic labs away from the patient's point-of-care, but the study could see quick, low-cost methods developed, which would improve patient care and reduce costs.

Professor Kai Johnsson, from the Institute of Chemical Sciences and Engineering at EPFL, developed the novel biosensor molecule that accurately measures drug concentration without the need for expensive infrastructure as it uses a regular digital camera. 

The molecule is the result of innovative protein engineering and organic chemistry, and has been shown to work on a range of common drugs used in treatments for cancer, epilepsy and immunosuppression.

It works by binding the drug circulating in the patient's bloodstream and changing colour accordingly. The molecule itself constitutes four components, a receptor to bind the molecules of the target drug, a small molecule similar to the target drug, a light-producing enzyme called luciferase, and a fluorophore molecule that can change the colour of the luciferase's light.

If no drug is present, the receptor and the drug-like molecule bind together, which brings the fluorophore close to the luciferase enzyme, and the system produces a red light.