2025 AIChE Annual Meeting

Development of a Point-of-Care Potassium Diagnostic for Early Detection of Chronic Kidney Disease

Chronic kidney disease (CKD), the twelfth leading cause of death in the world, is treatable if detected early, but is difficult to diagnose due to a lack of symptoms in the early stage. Therefore, concentrations of small molecules in the blood indicative of CKD must be frequently monitored to enable early diagnosis. For example, potassium levels above or below 3.5-5.0 mmol/L are correlated with CKD. However, current strategies to quantify potassium levels require expensive equipment and trained personnel, prohibiting use in low-resource nations where the burden of kidney disease is highest. To address this critical need, we are designing an inexpensive, user-friendly potassium assay by utilizing cell-free expression (CFE) systems, due to their affordability, ease-of-use, small volumes, and transportability. CFE systems allow for transcription and translation (key elements of protein synthesis) to easily be performed at the point-of-care by extracting the protein synthesis machinery from whole cells in the form of a lysate.

Our approach involves a series of three enzymatic reactions that produce an easily detectable reporter protein, super folder Green Fluorescent Protein (sfGFP), in the presence of potassium. Preliminary results from cell-free reactions incorporating our sensor show that sfGFP expression is significantly enhanced in the presence of potassium.

Next steps will focus on evaluating the specificity of the sensor to detect potassium. The sensor will then be further optimized to lower the limit of detection and increase sensitivity within clinically relevant levels. Once this is achieved, the sensor can be engineered to be field-deployable with a semi-quantitative colorimetric output. To the best of our knowledge, this work is the first demonstration of proof-of-concept for a mechanistic pathway where the target molecule of interest is a cofactor for an enzyme in a complex, multi-step enzymatic reaction. More importantly, our sensor aims to lay the foundation for the development of a robust, reliable tool for potassium detection.