New biosensor could give gout patients real-time blood urate readings
I know a thing or two about gout. It's horrible. If you're susceptible to it, eating the wrong food can trigger deposits of uric acid salts to crystallize into spiky pain bombs in your joints. Often, this happens in the big toe, but in my case they seem to center around old injuries in my ankles and knees. The pain is excruciating; three times I've been to the doctor thinking I've somehow broken my ankle or knee, only to find out it was gout. Left untreated, it can cause permanent damage.
The key metric determining when you'll get an attack is your blood urate level, something that generally requires a fasting blood test to establish. But new work from researchers at Texas A&M University appears to point the way toward a sub-dermal implant that could give gout sufferers 24-hour access to an instant blood urate level reading, letting them see exactly which foods they're reacting to and help stave off painful attacks.
The technology relies on a new discovery: that urate levels in the blood could be effectively measured using LED light and benzoporphyrin sensors. Benzoporphyrin molecules are typically used to measure the oxygen content of blood, and the researchers found that this measurement could be reliably correlated to urate levels, as urate reacts with oxygen and an enzyme called uricase to form allantoin in the blood.
The researchers devised a system using a biocompatible hydrogel containing benzoporphyrins and uricase – which could eventually be embedded just under the skin – and an LED light sensor that could both shine light on the benzoporphyrins and measure how much comes back out. This would give an oxygen level reading, and the team hypothesized that the lower the oxygen dropped in the presence of uricase, the higher the urate levels would be.
They tested it by putting thin discs of the hydrogels in saline-filled chambers, each receiving a steady flow of oxygen and kept at body temperature. Then, they added different levels of urate to each chamber, and proceeded with the light measurements. The readings "failthfully followed urate levels," giving the team a solid research basis from which to work towards a human-implantable device.
If the hydrogel proves to have a good enough service life – and this is yet to be determined – the researchers believe they could be placed just under the skin in a minimally invasive procedure, and then patients could use a simple computer peripheral to do the light measurements and take a blood urate reading at any time. In this way, the effects of certain foods, drinks or medications could be measured in near-to real time, helping people to prevent gout flare-ups and saving themselves a ton of pain.
A neat discovery that will hopefully bear fruit as an effective device in the future.
The team's research appears in the journal Sensors.
Source: Texas A&M University