The new sensor is used to measure the patient’s creatinine level quickly and easily in a laboratory. The amount of creatinine—a metabolite present in urine—indicates how the kidneys are functioning
To date, most laboratories have been using a technique that was designed in 1886 (by the German pathologist Max Jaffe) to detect this metabolite
Researchers from the University of Granada (UGR) have designed a new sensor that can measure the patient’s creatinine levels quickly and easily in the laboratory. The amount of creatinine—a metabolite present in urine—is used to diagnose kidney function.
These days, measuring creatinine levels in urine is a routine procedure in clinical analysis laboratories. The typical method of conducting this test is that developed by the German pathologist Max Jaffe in 1886. In fact, this is the only clinical analysis method from that period still in use in the modern-day laboratory. While the method is not without its drawbacks, such as its lack of specificity, it is nevertheless quick and cheap. However, the quest to develop new procedures for measuring creatinine is justifiably of interest.
The normal concentration of creatinine in urine is between 0.7 and 1.2 mg/dL. Any result higher or lower that this can indicate some type of kidney problem or the loss or destruction of muscle tissue.
A single-use sensor
The UGR’s ECsens Research Group at the Department of Analytical Chemistry has developed a single-use sensor that measures the concentration of creatinine in urine samples quickly and easily in the laboratory. Only small volumes of urine and reagents are required.
The sensor is a polyvinyl chloride (PVC) membrane containing the reagents necessary to perform the measurement. When the sensor is inserted into the urine, it changes colour from yellow to orange, depending on the concentration of creatinine in the sample. Unlike the Jaffe method, the reaction of the membrane is unaffected by other components of the urine, thanks to the use of a molecule called calix  pyrrole, which is able to detect creatinine specifically.
Once the sensor is prepared for use, the technician can calculate the concentration of creatinine in urine at typical levels to within an accuracy of 6%, simply by inserting the membrane and waiting 3 minutes before measuring the colour. This method is environmentally friendly as it requires only a very small amount of reagents and it generates little waste.
The study has been published by ACS Sensors, the research journal of the American Chemical Society.
Ionophore-based optical sensor for urine creatinine detection
Miguel M. Erenas, Inmaculada Ortiz-Gómez, Ignacio de Orbe-Payá, Daniel Hernández-Alonso, Pablo Ballester, Pascal Blondeau, Francisco J. Andrade, Alfonso Salinas-Castillo, Luis Fermín Capitán-Vallvey.
ACS Sensors 4(2), 421–426 (2019)
The UGR researchers who conducted the study
Illustration of the membrane
Miguel Erenas Rodríguez
Department of Analytical Chemistry, UGR
Tel: +34 958 240 796