A paper-based label-free plasmonic nanosensor for portable pre-diagnosis of multiple metabolic diseases

Early diagnosis is crucial for improving the prognosis of patients with metabolic diseases. In this study, we developed an innovative, multiplexed, and user-friendly paper-based plasmonic nanosensor by integrating previously established FeHOAuC (Fe 2+ -catalyzed H 2 O 2 prevents the aggregation of AuNPs by oxidizing cysteine) label-free plasmonic nanosensor. Initially, we prepared a paper art with designated sampling and colorimetric sections by applying polydimethylsiloxane onto cellulose and nitrocellulose papers. Subsequently, we fabricated and optimized the oxidase-coupled FeHOAuC system on the paper platform. The proposed nanosensor's sensitivity, specificity, and feasibility were evaluated using a quantitative color algorithm. In this sensor, pre-loaded oxidases convert target analytes into H 2 O 2 , which subsequently induces a color change in AuNPs by oxidizing cysteine under the catalytic action of Fe 2+ . This paper-based sensor can quantitatively measure glucose, cholesterol, uric acid, and lactate within 40 minutes. The limit of detection of 5–10 μM, combined with its demonstrated specificity, makes it highly suitable for the early diagnosis of related metabolic diseases. Importantly, through a straightforward dropping procedure and a smartphone camera, the plasmonic nanosensor can distinguish disease-related small molecules in real serum samples. In conclusion, the proposed paper-based plasmonic nanosensor device exhibited favorable performance with simple operation, presenting significant potential for domiciliary early diagnosis of multiple metabolic diseases.