Ligands for label-free detection of whole bacteria on biosensors: A review

• Bacterial detection by biosensor devices should reduce the time-to-result.
• Whole-cell assays reduce the sample processing steps.
• The ligand choice is crucial for the efficiency of the biosensor system.
• A wide range of natural or engineered ligands can be used in biosensor systems.
• Label-free detection eliminates the drawbacks of using secondary reagents.

With the aim of getting earlier, sensitive and specific information on the presence –or absence – of bacterial pathogens, biosensors are getting an increasing interest for more than two decades. This is partly due to their reduced format, to the possibility to address several questions with a single device and also to the increasing panel of physical approaches that can be exploited for signal transducing. When designing a biosensor, the choice of the ligand motif remains a key element as it drives the efficiency and sensitivity of the assay. In this review, we propose to gather and comment different ligands used for the detection of whole cell bacteria. Because time is a crucial issue when looking for a pathogen, our attention was focused on whole cell assays and label-free methods, which enable the user to skip sampling processing steps and decrease the overall test cost.