Development, optimization and evaluation of a microfluidic, paper-based, analytical device for glucose and uric acid detection: a proof-of-concept

Glucose and uric acid are systemic metabolites of clinical interest in patients with obesity. Glucose plays a crucial role in multiple metabolic processes and is an indicator of pathological conditions in obesity-related diseases such as diabetes. Additionally, untreated hyperuricemia, defined as serum uric acid levels exceeding 400 µM, is associated with obesity and can lead to the development of conditions such as gout and kidney dysfunction. Therefore, regular testing of glucose and uric acid levels can be relevant as preventive measures for screening and monitoring purposes. Within the field of point-of-care testing, microfluidic, paper-based analytical devices offer several advantages, including compact size, portability, affordability, biocompatibility, and simplicity. Enzymatic colorimetry serves as an effective detection method due to its low cost, rapid response time, and high selectivity. Furthermore, no complex equipment is required, and a smartphone can be employed to capture the color response for analysis in ImageJ. As a microfluidic pattern generation method, selective wet etching stands out given its fast, simple, and inexpensive procedure. In this work, a microfluidic, paper-based, colorimetric device is developed to detect glucose and uric acid in solution. Trimethoxy(octyl)silane was used to turn the surface of the paper hydrophobic, and NaOH was used as the etching agent to generate the hydrophilic pattern. The detection limits for glucose and uric acid were 0.02 and 0.04 mM, respectively. Additionally, the glucose and uric acid assays exhibit linear responses encompassing the physiological range found in saliva and serum. In the future, this device could be further adapted and validated for the detection of glucose and uric acid in relevant biofluids.