A fluorescent sensor array for rapid and facile point-of-care creatinine detection in saliva

In recent years, the prevalence of kidney disorders has been increasing. In this context, creatinine is a crucial biomarker for assessing kidney function. Impaired kidney functions can lead to various acute and chronic conditions, including diabetic nephropathy, kidney cancer, abnormal glomerular filtration rate, and preeclampsia. Consequently, monitoring creatinine levels is essential for the prevention of serious kidney-related diseases and holds significant medical importance. In this study, we present a point-of-care device designed to detect creatinine levels in human saliva without pretreatment of a sample. This device is based on a sensor array containing different fluorescent chemical receptors (BODIPY, rhodamine, and naphthylamides) that interact with creatinine by non-covalent interactions, providing measurable changes in fluorescence output. To validate the device, calibration, recovery, and selectivity tests were performed. Notably, the array demonstrated a linear response to creatinine in a concentration range from 10 mM to 10 nM, as confirmed through partial least squares (PLS) analysis. Additionally, high selectivity was demonstrated by the excellent recovery of creatinine in an artificial saliva sample containing common interferents present in human saliva. Furthermore, our device was tested with real saliva, supporting the possibility to use this device in real life. This prototype represents the first point-of-care device able to quantify creatinine in human saliva in a single analysis, without pretreatments of the sample, covering a broader concentration range and a lower limit of detection (10 nM) with respect to other reported methods.