Palm-T2: A Colorimetric Paper Sensor for Detecting Heterocyclic Amine/Carbonyl, Lactate, Moisture, Trimethylamine and Tryptophan Derivatives in Wound Infections

Abstract

Currently, assessment of bacteria from wound infections requires costly or time-consuming methods that require either trained personnel, multiple sample preparation steps or complex instrumentation procedures. Hence, it is crucial to develop simple and inexpensive methods that enable accurate, point-of-care assessment of bacteria in wound infections. Herein, we developed a Paper sensor to detect characteristic metabolites, i.e. heterocyclic Amine/Carbonyl, Lactate, Moisture, Trimethylamine and Tryptophan derivatives (termed PALM-T2) that are released from prevalent wound bacterial species. PALM-T2 consists of a paper strip with five sensing zones, branched out into a palm-like shape and connected via a sampling arm. Each sensing zone contains a colorimetric sensor that generates unique colour responses upon interaction with certain bacteria metabolites. Images of PALM-T2 were captured using a smartphone. An image processing software, ImageJ, was used to analyze colour changes in each sensing zone to reveal the type and concentration of bacterial species present in an infected wound. Experiments with simulated wound fluid and ex-vivo pig skin ‘wound’ models were used to demonstrate PALM-T2’s performance in simultaneous detection of multiple bacteria metabolites within 30 minutes.  Our PALM-T2 sensor displays a great potential for point-of-care detection of bacteria with a detection threshold of 105 CFU/mL, the lowest bacterial concentration, observed from an infected wound.

Keywords: Wound healing, Bacteria infection, Paper fluidic sensor, Bacteria metabolites, Colorimetric, Colour image analysis