SmartProbes

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Our 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. They 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.

Read about each of our SmartProbes in detail using the slider below:
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Bacteria Probe

The Problem

Currently, clinicians rely on x-rays, airway samples and blood tests for the diagnosis of bacterial infections deep in the lung, but these can be slow, prone to contamination and therefore imprecise. Patients are often treated with many different antibiotics as a precaution, which exposes them to potential side effects and contributes to the emergence of antimicrobial resistance (AMR) in bacteria.

Since different antibiotics interact in different ways depending on what type of bacteria they are attacking, it is vital that clinicians are able to tell exactly which cells are causing the infection in order to be able to treat it correctly and efficiently.
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The Solution

Tiny amounts of chemical SmartProbeswill be sprayed into the deepest parts of the human lung, emitting light when they attach to specific types of bacteria in a physical process known as ‘fluorescence’. The fluorescence is detected using tiny fibre optic tubes that are inserted deep into the patient’s lung through a bronchoscope. The glowing bacteria are then shown on a screen at the patient’s bedside, thus allowing clinicians to see what is causing the infection within just 60 seconds.

This will potentially revolutionise how lung infections are assessed and treated. Most importantly, this technology will allow clinicians to decide which antibiotics should be continued and which can be safely stopped.

A cut-away diagram of a bacterium, showing where the capsule, cell wall and membrane are located.

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The Method

All bacteria can be categorised as one of two types, depending on their structure: ‘Gram-positive’, or ‘Gram-negative’. Traditionally, clinicians must take a sample from the patient to a laboratory in order to carry out tests and determine what the bacterial infection is.

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In the lab, a water-soluble dye called crystal violet is used to distinguish between Gram-positive and Gram-negative bacteria.  During the process, called ‘Gram staining’, Gram-positive bacteria turn violet due to their thick cell wall which retains the crystal violet. Gram-negative bacteria turn red due to it having a thinner cell wall, which does not retain the crystal violet.
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Gram-negative bacteria (L), Gram-positive bacteria (R)

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Proteus has developed two bacterial SmartProbes which couldremove the need to take a sample to a lab in order to determine whether it is Gram-positive or Gram-negative bacteria causing the infection.

The BAC ONE SmartProbe is used first, as it can identify allof the bacteria present in the patient. The SmartProbe inserts itself into the bacteria membranes, binds to them, and fluoresces. This fluorescence is then viewed on a screen at the bedside.

The BAC TWO Smartprobe is used next to distinguish between Gram-positive and Gram-negative bacteria. BAC TWO inserts itself into the membrane of Gram-negative bacteria and fluoresces, making it detectable.

By using the two SmartProbes in conjunction with each other, the clinician is able to tell whether both Gram-positive and Gram-negative bacteria are present, or just Gram-negative. The appropriate antibiotics can then be administered by the patient’s doctor.

Both bacterial probes have been extensively tested in the Proteus labs, and are now in the process of being tested in humans for the first time as part of on-going clinical trials. This is the first time that SmartProbes like these have been used in the clinic for bacterial detection.

Video Summary

Created by Ellie Cawthera, with contributions from Hannah Stewart and Caroline Lyth (MSc Science Communication and Public Engagement at the University of Edinburgh).

Scarring Probe

A cartoon depiction of our scarring probe, FIB ONE

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The Problem

Scarring, or ‘fibrosis’, is a natural part of the body’s healing process after illness or injury, designed to repair wounds if the normal process fails. Scar tissue results from an excess of a protein called collagen, which are connective fibres that provide structural support between skin, muscle and nerve cells.

Although the collagen itself remains unchanged after injury, what does change is how it lays itself out. Instead of a random formation akin to a basket-weave found in normal tissue, scarring sees the collagen align in a single direction. This singular alignment results in the area of tissue becoming thicker and stiffer, creating the the tell-tale raised bump of a scar.

A photo showing a scar on a hand

In the lungs, scarring can build up around the tiny air sacs known as alveoli, making it difficult for the patient to take in oxygen and therefore breathe. Fibrosis may occur across large parts of the lung as is the case with idiopathic pulmonary fibrosis (IPF; which means that the cause of scarring in the lungs is unknown), or it can occur in much smaller patches, such as around tumours

Currently, the diagnosis of conditions involving fibrosis relies on a number of different measures, including lung biopsy, and available treatments following diagnosis are often limited. As such, if clinicians can detect areas of scarring around suspected or confirmed lung cancer (for example), it can help provide an early and accurate diagnosis for the patient.

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The Solution

Tiny amounts of chemical Smartprobes will be sprayed into the deepest parts of the human lung, emitting light, also known as ‘fluorescence, in the presence of a particular enzyme called MMP – a protein that is released in excessive amounts when scar tissue is present, in an attempt to break it down.

The fluorescence is then detected using tiny fibre optic tubes that are inserted deep into the patient’s lung through a bronchoscope, and shown on a screen at the patient’s bedside within a couple of minutes.
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The Method

In case of fibrosis, three particular types of MMP protein are secreted: MMP-2, MMP-9 and MMP-13. The FIB ONE Smartprobe is designed to detect each of these.

Video Summary

Created by Ellie Cawthera, with contributions from Hannah Stewart and Caroline Lyth (MSc Science Communication and Public Engagement at the University of Edinburgh)

Inflammation Probe

.The Problem

Some lung diseases can cause ‘inflammation’, a protective response generated by the body in retaliation to damage to tissue caused by injury and illness. It clears away dead cells and starts the repairing process.

Two examples of where inflammation is related to lung disease are:

  1. Acute Respiratory Distress Syndrome (ARDS), where inflammation brought about by infection or injury causes fluid from nearby blood vessels to leak into the tiny air sacs of the lungs. This leads to potentially life-threatening low oxygen levels in the blood, and makes breathing difficult.
  2. Pneumonia, as a result of bacterial infection, can lead to inflammation of the tissue in one or both lungs, and may cause fluid to leak into the tiny air sacs.

It is therefore important that clinicians can quickly identify the sites of inflammation in order to treat them effectively.
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The Solution

Tiny amounts of chemical SmartProbes will be sprayed into the deepest parts of the human lung, emitting light (‘fluorescence’) in the presence of a particular ‘inflammation’ enzyme – a protein made by the body that brings about a specific chemical reaction. The fluorescence is then detected using tiny fibre optic tubes that are inserted deep into the patient’s lung through a bronchoscope, and shown on a screen at the patient’s bedside within a couple of minutes.
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The Method

The Neutrophil Activation Probe (NAP) is a Smartprobe that fluoresces when it comes into contact with elastase, an enzyme that exists inside a type of immune cell called a ‘neutrophil’, when the neutrophil is activated in inflammation.

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A diagram showing the internal structure of a neutrophil, highlighting granules and a segmented nucleus
3D rendered image credit: Bruce Blaus (2014) ‘Medical Gallery of Blausen Medical 2014’, WikiJournal of Medicine.

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Neutrophils are a type of white blood cell that are part of the body’s first line of defence against infection. Inside neutrophils are small granules that release enzymes when ‘activated’, designed to kill invading microorganisms. Elastase exists inside these granules. Neutrophils can also ingest microbes, other cells and foreign particles.

A unique feature of immune cells like neutrophils that have segmented nuclei is that they can eject their DNA to create a sticky net called a ‘Neutrophil Extracellular Trap’ (NET), which traps and kills foreign bodies in the blood. This process is called NETosis, during which the neutrophil is also destroyed.

The result of these attack mechanisms against intruders is inflammation in the affected area. Therefore, by using the NAP Smartprobe, clinicians will be able to directly see sites of inflammation in the body by highlighting where the neutrophils are.

Stained neutrophils showing NETosis, looking like a star gone supernova.

Neutrophils undergoing NETosis

Click to read more about this image: ‘Neutrophil Supernova’

Video Summary

Created by Ellie Cawthera, with contributions from Hannah Stewart and Caroline Lyth (MSc Science Communication and Public Engagement at the University of Edinburgh).
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