Professor Yoon Dae-sung’s Group Develops Nano-biosensor for Accurate and Early Detection of Gout
The sensor is based on the coating of an electrode with kidney cell membrane.
The results of the study were published in Biosensors & Bioelectronics, the most prominent journal in the field of analytical chemistry.

Professor Yoon Dae-sung’s group at the School of Biomedical Engineering, College of Health Science have coated conventional electrochemical sensors with kidney cell membrane to increase the selective permeability of the uric acid in the blood, thereby allowing for accurate and early detection of gout. The results of the study were published online in Biosensors & Bioelectronics (IF=10.257, top 0.581% in JCR), the most prominent journal in the field of analytical chemistry, on Thursday, June 10.

Gout is caused by the accumulation of uric acid, usually at the joints of fingers and toes. Uric acid is the final metabolite of purine, which is very abundant in meat and fish. Hence, gout used to be called ‘the disease of kings’, in that people of a high social class who enjoy oily food usually contracted the disease. However, it is now classified as a disease of ordinary people due to the rich Western diet which is so prevalent. An increase of the uric acid level in the blood can lead to its crystallization in the joints, resulting in inflammation. The uric acid crystals cause pain each time a joint is called into action, thus disrupting people's daily lives. The current methods of diagnosing gout rely on the optical microscope and on X-rays. When an optical microscope is used to check for the presence of uric acid crystals in synovial fluid that has been extracted from a patient’s joint, the extraction causes pain to the patient. Conversely, a diagnosis based on an X-ray does not cause such pain, but the low resolution makes it impossible to use this technique for the early detection of gout.

To overcome these problems, attempts have been made to measure the uric acid concentration in the blood to achieve early gout detection. However, because uric acid is an antioxidant that is found at a relatively low concentration in the body, it has been difficult to precisely measure its presence due to the presence of other antioxidants.

With a focus on the excretion of uric acid from the kidneys, Professor Yoon’s group found that a cell protein, which is referred to as a uric acid transporter, plays an important role in the uric acid excretion, and thus extracted and purified at a high concentration a kidney cell membrane containing the uric acid transporter. Subsequently, the group coated a conventional electrochemical sensor with the kidney cell membrane, and assessed its performance in identifying and measuring uric acid (Figure 1). This sensor displayed a sensitivity that was similar to that of a conventional uric acid electrochemical sensor, and provided stable signals without being affected by other antioxidants (ascorbic acid (vitamin C), barbituric acid, lipoic acid, glutathione, niacinamide, etc.) that hinder the detection of uric acid (Figure 2). Moreover, the newly-developed electrochemical sensor had a detection limit of 8.5 µM within the uric acid concentration range of 0 to 1000 µM, which is suitable for the early detection of uric acid, and its performance did not diminish after three weeks of storage.

Professor Yoon said, “The kidney cell membrane-coated uric acid electrochemical sensor that we developed in this study may help to overcome the weaknesses of the conventional gout diagnosis method, such as the pain suffered by patients and the difficulty of making early diagnoses.” He added, “We need to continue to refine our methods to accurately detect uric acid by isolating it from the antioxidants in the body as well as various other substances.”