A chemosensor to recognize N-acyl homoserine lactone in bacterial biofilm

Abstract A simple, sensitive, and rapid assay has been developed for detection of N-acyl homoserine lactone (HSL) autoinducers involved in bacterial quorum sensing (QS) by a new coumarin appended rhodamine derivative (RNC) ensembled with Cu2+. RNC-Cu2+ conjugate shows “turn on” fluorescence while binding with HSLs. The interaction of ensemble with HSL is found to be 1:1 stoichiometry on the basis of absorption and fluorescence titrations with the detection limit of 2.4 μM at neutral pH. NMR, IR titrations and DFT calculations were performed in order to demonstrate the sensing mechanism and the electronic properties of the receptor-donor complex. The present chemosensor improves upon any previous biosensor-based approaches to selectively quantitate HSL, both in cell-free and in whole-cell assay system.