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Background: Uric acid (UA) is an important metabolic intermediate of the human body. Abnormally high levels of UA will cause diseases. However, UA monitoring with commercial products relies on invasive blood collection, which not only causes pain in patients but also risks bacterial infections and skin irritation. In recent years, new models of noninvasive detection through body surface penetration have raised higher expectations for the sensitivity of uric acid detection, and rapid, accurate and highly sensitive UA sensors will become powerful tools for the diagnosis of UA-related diseases. Objective: This study aimed to identify the differences in catalytic efficiency between regular PB from spray crystallization (RPB) and irregular PB from electrodeposition (EDPB), which is used for fabricate a high sensitive uric acid sensor. Methods: Regular Prussian blue nanocrystals (RPB) were grown on graphene oxide flakes (GO), on the surface of a custom screen-printed carbon electrode (SPCE), using a spray method assisted by a constant magnetic field (CMF). After immobilizing uricase, the uric acid biosensor Uricase/RPB/CMF-GO/SPCE was obtained. Results: The detection range of the sensor response to UA was 0.005 2.525 mM, and the detection limit was as low as 3.6 μM. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that compared to amorphous electrodeposited Prussian blue (EDPB), RPB more favorably accelerated electron transport. Conclusion: This novel uric acid biosensor exhibits high sensitivity over a wide concentration range, strong anti-interference ability, and good stability and reproducibility. Thus, it has good application prospects for determining uric acid in physiological samples.

BackgroundIntracranial vertebral artery (V4 segment) stenosis quantification traditionally uses the narrowest stenosis diameter. However, the stenotic V4 lumen is commonly irregularly shaped. Optical coherence tomography (OCT) allows a more precise calculation of V4 geometry. We compared the narrowest diameter stenosis (DS), measured by digital subtraction angiography (DSA), with the area stenosis (AS), measured by OCT. We hypothesized that DS is the gold standard for measuring the degree of stenosis.MethodsFive neuroradiologists evaluated 49 stenosed V4 segments in a blinded protocol. V4 stenosis was measured in millimeters on DSA at its narrowest diameter. OCT was used to estimate the cross-sectional luminal area. We also used automated software to measure DS. Three different angles (anterior, lateral, and oblique views) were used for calculations, and the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and Warfarin–Aspirin Symptomatic Intracranial Disease (WASID) methods were used in all measurements. Spearman’s R values were calculated. Non-linear regression analysis was performed between the DS and AS, with statistically different correlations.ResultsA high correlation was observed between the WASID and NASCET methods to measure DS with observer measurement and automated software. A good correlation was found between DS measured by observers and AS measured by OCT. Non-linear regression analysis showed that only observer measurement using the oblique view and the WASID method could attain statistically significant differences, but it was weak (r=0.389).ConclusionMeasurement of the narrowest diameter was not a reliable predictor of the cross-sectional area of V4 stenosis. Larger studies are therefore needed to develop a new evaluation system based on V4 stenosis.