Refreshable Biosensors for Continuous Renal Function Monitoring

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Project Summary The goal of the proposed exploratory research is to design and develop novel refreshable biosensors that overcome key fundamental challenges associated with existing biosensors to achieve real-time, quantitative, continuous monitoring of protein biomarkers in complex body fluids, including urine, blood, interstitial fluid, saliva and sweat. Conventional techniques such as enzyme-linked immunosorbent assay (ELISA), Western Blot, and mass spectrometry have enabled discovery and study of proteins in biological samples. These conventional bioassays are typically limited to one-time or short time use due to the poor stability of biological recognition elements. Furthermore, they rely on additional reagents or pH change to remove bound analytes for reusability. These traditional processes are not compatible with wearable and implantable devices for continuous molecular monitoring. Therefore, there is a critical need to develop refreshable biosensors that enable real-time, quantitative, continuous monitoring of protein biomarkers in complex body fluids. In this investigation, acute kidney injury (AKI) is employed as a disease model. Various protein biomarkers including tissue inhibitor of metalloproteinases-2, insulin-like growth factor-binding protein 7, and neutrophil gelatinase-associated lipocalin have been identified for early diagnosis/prognosis of AKI. Each biomarker has a specific time course in a specific setting of injury. Continuously monitoring a panel of AKI biomarkers relevant to physiologic and pathophysiologic processes in the injured tissue is very important, considering that AKI can evolve quickly. However, current protein quantification technologies cannot determine when an insult actually happens in the clinical setting, and fail to provide real-time evaluation of renal function for prompt clinical interventions. The long-term goal is to transform kidney disease treatment by developing a fully wireless, miniaturized, multifunctional biosensor that can be directly interfaced to a urinary catheter or the internal surface of patient bladder. The overall objective of this project is to design and develop a novel refreshable biosensor and to demonstrate continuous real-time monitoring of AKI protein biomarkers in patient urine. Specific aims include: 1. Design and realize biorecognition elements with high sensitivity, specificity and stability for refreshable biosensors. Based on feasibility studies, the biorecognition elements achieved by molecular imprinting of polymers exhibit high affinity to target protein biomarkers and are chemically, thermally, and mechanically stable under extreme conditions, which is critical for the proposed refreshable biosensor. 2. Design, develop and validate stimulators that locally and focally deliver surface acoustic energy to refresh biorecognition elements. The primary hypothesis is that locally and focally delivered high surface acoustic energy can desorb specifically bound target proteins and refresh the biorecognition sites of the biosensors. Such a new capability is highly valuable for monitoring the renal function of critically ill patients at risk of or with AKI, including patients with sepsis, shock, major surgery, and trauma.