In developing nations, unscrupulous companies routinely produce counterfeit or diluted antibiotics. Unfortunately, those same countries often lack the expensive lab equipment needed to detect fakes. There could be hope, however, in the form of a simple new paper device.

Developed at Colorado State University, the paper used in the device incorporates a dried chemical known as nitrocefin in one area, along with an enzyme called beta-lactamase in another – that enzyme is naturally produced by bacteria, and it binds with portions of the antibiotic molecule. The enzyme also binds with nitrocefin, causing that chemical to change color as it does so.

In order to test an antibiotic, a user dissolves it in water, and then adds that solution to the paper. There, it rehydrates the nitrocefin, and carries it into a "target area" where the beta-lactamase enzyme is located. Both the antibiotic and the nitrocefin then proceed to compete with one another, trying to bind with the enzyme.

If the antibiotic is as strong as it's supposed to be, it will outcompete the nitrocefin, and no color-change will take place. Should the antibiotic be unusually weak, however, the nitrocefin will win out, and it (along with the paper) will turn red as it binds with the enzyme. The paper additionally has a pH-indicating section that lets users know if an antibiotic has been diluted with filler ingredients such as baking soda.

Each device costs only about a quarter of a US dollar to make, and the testing can be conducted by untrained personnel in approximately 15 minutes. The research, which was led by Prof. Chuck Henry, is described in a paper that was recently published in the journal ACS Sensors.