2023 AIChE Annual Meeting

Development of a Point-of-Care Potassium Biosensor

Chronic kidney disease (CKD), the twelfth leading cause of death in the world, is difficult to diagnose due to a lack of symptoms in the early stage. CKD is treatable if detected early; 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 systems, which are affordable and transportable. Specifically, we are using a series of three enzymatic reactions to produce an easily detectable reporter protein, super folder Green Fluorescent Protein (sfGFP), in the presence of potassium. Here, we have shown that the latter ⅔ of the reaction pathway can be recapitulated by pre-expressing enzymes into cell-free lysates. Our findings show that we need higher levels of the enzymes than we could achieve with pre-expression. Thus, next steps will focus on combining the three enzymatic reactions in a cell-free lysate enriched with the three enzymes to create a reliable, robust sensor.