Fluorescent probes for microorganisms

Abstract

One of the main problems with infectious diseases is their late and unspecific diagnosis. To overcome this problem, optical molecular imaging can be applied using target selective fluorescent probes. The focus of this work has been the development of a series of fluorescent probes for microorganism detection that can be applied in a number of clinical scenarios allowing rapid diagnosis. In the first part of this work, a set of fluorogenic probes was synthesised based on an antimicrobial peptide. These probes show the labelling of bacteria and fungi and do not require any washing steps. The use of D-amino acids provides high proteolytic stability.

Another set of probes was developed based on the antifungal drug amphotericin B. They were assessed on the labelling of a range of fungal species, including clinically isolated strains and biofilms. Selective labelling of fungi in comparison with bacteria has allowed the application of red-emitting fungal probe together with reported bacteria-specific probes for multiplexed imaging of a fungi-bacteria mixture.

A library of probes for selective labelling of mycobacteria was synthesised using a range of fluorophores (covering the spectral window of 400 to 650 nm) and trehalose molecule. It has been shown that mycobacteria can uptake endogenous and exogenous trehalose and incorporate it into mycomembrane. Two probes with spectral overlap were utilised as FRET pair for imaging of mycobacteria. All of the developed probes showed efficient labelling of microorganisms and can be used as a foundation for the development of future rapid diagnostic techniques.