Interview with Daniel Roxbury

We believe this could be a game-changer for a number of reasons. A point-of-care and real-time method of monitoring wounds for infection, without the need to remove the bandage, reduces associated pain and chance of exacerbating the infection. This is especially true in the case of patients with large wounds in hospitals, which can be tedious for healthcare workers to remove, clean, and rebandage.

Our lab has been developing biosensors from carbon nanotubes for many years. In other projects, we have developed carbon nanotubes that detect lipids and other biomarkers inside of living cells and animals. This current project featuring the carbon nanotubes in a wearable technology is somewhat different and a new direction for our lab.

Certain formulations of carbon nanotubes give off near-infrared light (longer wavelength) when they are illuminated with visible light (shorter wavelength), most commonly known as fluorescence. The near-infrared light can be modulated by molecules in the vicinity of the nanotubes. One such formulation of nanotubes responds to hydrogen peroxide. We took this formulation and encapsulated the nanosensors within individual microfibres that stabilised them but allowed the hydrogen peroxide to reach the nanotubes, thus creating a wearable sensing platform. It should be noted that in parallel to the wearable sensor, we are developing a miniaturised, hand-held device that illuminates the platform and detects the near-infrared light.

Most cells in the body produce at least some hydrogen peroxide. In wounds, it is produced primarily by white blood cells (macrophages) and its role is two-fold. At low concentrations, it can signal other cells to migrate towards the wound and aid in tissue repair. At higher levels, it can indicate the presence of pathogenic infections that the body is attempting to deactivate and/or kill (in the case of bacteria).

They do, and they use the peroxide as a "signalling molecule" for normal cell functions.

There are many other biomarkers that can indicate infection in wounds. We had already been investigating the formulation of carbon nanotubes that specifically detect hydrogen peroxide and so we decided to use that as the sensor. In future iterations, developing sensors for other biomarkers is desired.

Microfibres are composed of two FDA-approved polymers in a core-shell fashion. The nanosensors are loaded into the core along with polyethylene glycol (PEG) and surrounded by a shell composed of polycaprolactone (PCL). Both polymers were carefully chosen to enhance the properties of the final product. The microfibres are smaller than the fibres in a gauze bandage.

We are developing a hand-held device to obtain the readout from the wearable sensors. As the technology progresses, we hope to translate the hand-held instrument into an even more compact, wearable device. The information is transmitted optically through near-infrared light to the device.

We imagine the data will be most helpful to healthcare workers in a hospital or nursing home setting caring for patients with chronic wounds (elderly or diabetic). The information can inform the nurses and doctors to change the bandage and/or administer antibiotics.

We are currently testing the bandages in in-vitro wound mimics. These are laboratory-grown cells undergoing infection. Preliminary results are promising. We will next move to animal models to test the bandages.

A provisional patent has been filed to protect the intellectual property.

Carbon nanotubes have commercial applications as additives in materials and electronics. My general research interest is in giving carbon nanotubes a "new job" in the biomedical field.