Paper-based colorimetric microfluidic device for visual detection of glucose coupling different-shaped gold nanostructures with cerium oxide nanozyme

Diabetes mellitus is a rapidly spreading chronic disease whose prevalence has increased by over 50 % in the past decade, owing to current trends in lifestyle, food choices, and increasing obesity rate. Therefore, there is a need to develop cheap and user-friendly glucose monitoring detection methods, especially in low-income countries. In this study, we explored different gold nanoparticles (AuNP) in combination with cerium oxide (CeO2) to assess the effects of nanoparticle morphological structure on their enzyme-mimicking properties. Our results showed that gold nanorods (AuNR) displayed the highest enzyme-mimicking properties compared to other AuNPs like gold nanowires, nanospheres, nanourchins, and microrods. Subsequently, we developed a nanozyme paper microchip using CeO2-AuNR bimetallic nanocomposite as peroxidase mimics that allow for visual identification towards glucose detection. The paper microchip was developed by simple thermal printing over filter paper that gave a visual response through a colourimetric signal. An intense blue-coloured response directly proportional to glucose concentration was observed on the paper sensor, displaying high sensitivity, sensitivity, and reproducibility even in clinical samples, including serum and urine. The sensor demonstrated a linear detection range of 0.5 to 500 mg/dL, with a limit of detection (LOD) of 0.65 mg/dL and showed excellent recovery rates (93 % -98.27 % in serum and 91.84 % - 109.5 % in urine), indicating its potential for real-world applications. Thus, the paper sensor developed in this work is a potential blueprint for developing next-generation simple, portable, and user-friendly nanozyme-based point-of-care (POC) biosensors for glucose monitoring.