Accurate and sensitive detection of bacteria is crucial in medicine for diagnosis and effective treatment of infectious diseases. Current state‐of‐the art methods consist of either traditional time consuming microbiological analysis or rapid, sensitive molecular techniques that require expensive readout equipment. In previous work, the authors of this paper combined synthetic bacteria receptors, so‐called surface imprinted polymers (SIPs), with a novel thermal biosensor readout methodology for the detection of bacteria in urine. In this follow‐up study, the potential of the method for application in urinary tract infection (UTI) diagnosis is further studied. The reproducibility of the method is assessed by expanding the study and analyzing the sensor's performance in urine samples obtained from four healthy adults. The samples are spiked with increasing concentrations of Escherichia coli to obtain different dose‐response curves. The results of this study show that the method is reproducible over the studied population and variables such as age, gender and osmolality do not seem to influence the test. All results fall within the previously established dynamic range of 104–105 bacteria mL−1 which fits well within the diagnostic window of classical microbiological UTI tests. Further tests conducted on a urine sample 24 h after spiking illustrate the problem with traditional microbiology tests as the sensor response has significantly decreased due to the presence of a significant amount of dead bacteria in the day‐old sample. These results confirm that fast, point‐of‐care analysis of fresh urine samples is advantageous over classic laborious techniques in terms of accurate diagnosis.

Chronic kidney disease (CKD) is represented by a diminished filtration capacity of the kidneys. End-stage renal disease patients need dialysis treatment to remove waste and toxins from the circulation. However, endogenously produced uremic toxins (UTs) cannot always be filtered during dialysis. UTs are among the CKD-related factors that have been linked to maladaptive and pathophysiological remodeling of the heart. Importantly, 50% of the deaths in dialysis patients are cardiovascular related, with sudden cardiac death predominating. However, the mechanisms responsible remain poorly understood. The current study aimed to assess the vulnerability of action potential repolarization caused by exposure to pre-identified UTs at clinically relevant concentrations. We exposed human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and HEK293 chronically (48 h) to the UTs indoxyl sulfate, kynurenine, or kynurenic acid. We used optical and manual electrophysiological techniques to assess action potential duration (APD) in the hiPSC-CMs and recorded IKr currents in stably transfected HEK293 cells (HEK-hERG). Molecular analysis of KV11.1, the ion channel responsible for IKr, was performed to further understand the potential mechanism underlying the effects of the UTs. Chronic exposure to the UTs resulted in significant APD prolongation. Subsequent assessment of the repolarization current IKr, often most sensitive and responsible for APD alterations, showed decreased current densities after chronic exposure to the UTs. This outcome was supported by lowered protein levels of KV11.1. Finally, treatment with an activator of the IKr current, LUF7244, could reverse the APD prolongation, indicating the potential modulation of electrophysiological effects caused by these UTs. This study highlights the pro-arrhythmogenic potential of UTs and reveals a mode of action by which they affect cardiac repolarization.

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