Proteus Smartprobes are custom molecules that allow the detection of key pathologies across a spectrum of wavelengths and fluorescence lifetimes.

The development and validation of novel fluorescent Smartprobes is a key area within Proteus. These probes provide a rapid way to determine the molecular basis of a range of physiological conditions deep within the patient lung (or indeed in other organs).

Many Smartprobe candidates, each with distinct chemical properties, have been designed and synthesised by the team with the aim of interacting with defined biological targets. This interaction activates the probe to induce changes in its emission properties, which can be detected and related with the presence of bacterial infection or overexpressed enzymes.

BAC ONE is based on a fragment of the antimicrobial peptide Ubiquicidin, arranged into a novel structure containing three peptide chains and three dyes per molecule. This compound inserts itself into the membrane of both Gram-positive and Gram-negative bacteria. When it binds, the Smartprobe is activated and fluoresces, making it a global identifier of all bacteria.

BAC TWO is based on the known antibiotic Polymyxin, and is labelled with a fluorescent compound (also known as a ‘fluorophore’), NBD. This compound inserts itself into the membrane of Gram-negative bacteria and the fluorophore is activated, enabling the detection and therefore a distinction between Gram-positive and Gram-negative bacteria to be made.

Both bacterial probes have been extensively screened in sheep lung ventilation models. Within this system, the efficiency and speed at which the bacteria are detected have been determined with real-time imaging using an optical fibre.

In order to be used in our clinical trials, BAC ONE and BAC TWO have been synthesised to Good Manufacturing Practice (GMP) levels in our own Active Pharmaceutical Ingredient (API) lab, and are now been tested in humans for the first time.

A brief video describing the difference between Gram-positive and Gram-negative bacteria.
Credit: BiologyExams4U

The Neutrophil Activation Probe (NAP) is a Smartprobe that becomes active (fluorescent) in the presence of an enzyme named Human Neutrophil Elastase, which exists within neutrophils – the hallmark of acute inflammation. This probe lights up upon contact with activated neutrophils, and is currently being used in clinical trials.

We are also developing a range of key enzymatic cleavage probes that fluoresce in the presence of its target enzyme.

Matrix Metalloproteinases (MMP) are key enzymes in extracellular matrix remodelling. Identifying the presence of high levels of MMPs in a lung will provide indications of aberrant biological events (e.g. fibrosis or nodules). FIB ONE is a probe designed to detect high MMP activity. It has been also prepared in our API lab and is being used in the first clinical trials together with Versicolour, our initial multi-colour fibre-based imaging device.