Unlocking diagnostic potential: Advances in biosensing platforms for detection of cystatin C, a kidney disease biomarker

The most significant challenge in kidney disease management is early diagnosis. In the initial stages of chronic kidney disease (CKD), symptoms are often minimal or absent, making it difficult to recognize the disease until it has inevitably progressed. The kidneys play crucial roles in maintaining body functions, such as regulating homeostasis, controlling blood pressure, balancing water and electrolytes, and removing metabolic waste. Detecting renal dysfunction early and selecting effective treatment methods can significantly reduce mortality in affected patients. Traditional indicators of kidney function, however, often lack the specificity and sensitivity needed for early detection. Recent studies suggest that cystatin C (CysC) could be an ideal biomarker for assessing glomerular filtration. CysC, a cysteine protease inhibitor, is synthesized by all nucleated cells and is readily filtered due to its positive charge and low molecular weight. Monitoring CysC levels in body fluids is therefore essential for the timely diagnosis and treatment of various kidney diseases, including CKD. In addition to conventional methods, different types of biosensors have been developed to detect CysC, offering a promising approach by combining the specificity of biomarkers with the high sensitivity of advanced technology. These biosensors, particularly electrochemical and optical types, have shown significant potential for precise and timely CysC detection. In this review, we provide a comprehensive insight into the current biosensors used in detecting CysC and explore their applications as a novel approach for identifying this crucial CKD biomarker.