Abstract
In this study, we developed a low-cost, reusable, and highly sensitive analytical platform for the detection of the human metabolite uric acid (UA). This novel analysis platform combines the graphene chemoresistor detection technique with a magnetic bead (MB) system. The heterojunction (single-layer graphene and HfO2 thin-film material) of our graphene-based biosensor worked as a transducer to detect the pH change caused by the specific catalytic reaction between UA and uricase, and hence acquires a UA concentration. Immobilization of uricase on MBs can decouple the functionalization steps from the sensor surface, which allows the sensor to be reusable. Our microsensor platform exhibits a relatively lower detection limit (1 μM), high sensitivity (5.6 mV/decade), a linear range (from 1 μM to 1000 μM), and excellent linearity (R2 = 0.9945). In addition, interference assay and repeatability tests were conducted, and the result suggests that our method is highly stable and not affected by common interfering substances (glucose and urea). The integration of this high-performance and compact biosensor device can create a point-of-care diagnosis system with reduced cost, test time, and reagent volume.
Highlights
The detection and quantification of biomarkers are essential for medical diagnostics, environmental monitoring, and bioresearch
We evaluated the performance of our biosensor in acidic, neutral, and alkaline solutions
By atomic layer deposition, 20 nm of HfO2 was deposited on the surface of high-quality graphene to improve the pH response of the graphene sensor
Summary
The detection and quantification of biomarkers are essential for medical diagnostics, environmental monitoring, and bioresearch. Due to the aforementioned limitations of these conventional methods, there is an urgent need to develop low-cost, high-performance, and portable uric acid sensors for point-of-care detection [13]. Graphene-based nanomaterials are used as transducers of biosensors, which are involved in converting the interactions between the receptor and the target molecules into detectable measurements [14,15]. The surface of the graphene channel is functionalized by binding receptors for the specific target of interest. We first proposed combining MBs and graphene chemoresistors as a microsensor platform for uric acid detection. This method overcomes the aforementioned drawbacks of the traditional sensor method. The proposed uric acid sensor is portable, reusable, and simple and has a low-cost fabrication process. Miniaturization of the micro-biosensing platform endows itself with a promising prospect of application in a portable real-time instrument for point-of-care diagnostics
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