▎ 摘　　要

Paper-based sensor technology represents a new class of point-of-care (POC) diagnostic devices that is affordable, portable, rapid and scalable for manufacturing. One of the goals of developing new paperbased POC diagnostics is the need to recognize targets with high specificity and sensitivity. Herein, a graphene oxide-circular aptamer based assay is described for highly specific and sensitive detection of a target protein on bioactive paper. The circular aptamer was self-assembled onto graphene oxide to generate the biorecognition moieties, followed by the desorption reaction induced by the specific binding of the target. The released circular aptamer then hybridizes to paper-bound DNA primers, thus initiating the rolling circle amplification reaction to produce a long DNA molecule containing multiple horseradish peroxidase-mimicking DNAzyme units, which further catalyze the oxidation of substrates by H2O2 in the presence of hemin to yield a distinct colorimetric signal on paper. Under the optimal conditions, this dual amplification method can achieve detection of platelet-derived growth factor (PDGF) at a concentration as low as 100 pM. Overall, this strategy of paper-based nanobiosensors may hold great potential for rapid, accurate and inexpensive biomarker detection in POC applications.