Prototypes of smart bandages include those that can change colour in response to heat, kill bacteria, monitor chronic wounds and deliver drugs on a schedule, but it still takes time to figure out if a particular infection is drug-resistant or not. Researchers from the Chinese Academy of Sciences (CAS) in Beijing have introduced a new concept bandage that changes colour to signal the presence of drug-resistant or drug-sensitive bacteria and releases the appropriate chemicals to kill them off.

Its colour-changing mechanism is made possible by a simple pH indicator loaded into the paper-based bandage, which responds to the acidic environments created by pathogenic bacteria. Beginning with olive green when it is first applied to the wound, detecting antibiotic-sensitive bacteria will turn the bandage yellow over about four hours and; if it detects drug-resistant bacteria, it will turn red.

As for its mode of attack, nanomaterials in the bandage containing the antibiotic ampicillin will dissolve under the acidic conditions of bacterial infection and subsequently kill the bacteria. However, for drug-resistant bacteria,the bandage also contains reactive oxygen species (ROS) that is released on bright light and are known to deal high damage to microbes.

This concept allows doctors and patients to respond as needed and saves antibiotics from being used unnecessarily, thus contributing to antibiotic resistance.It also cuts back on the time-consuming processes usually required to diagnose infections and determine if they’re drug-resistant, and slows the spread of that resistance.