LAUSR

Abstract A new ternary plasmonic photocatalyst based on multilayered gold nanoparticles decorated graphene (GR)-TiO 2 heteronanostructure ((AuNPs) x /GR-TiO 2 ) was fabricated via a simple poly(diallyldimethylammonium chloride) (PDDA) assisted calcination process in combination with the layer-by-layer (LbL) assembly technique. A remarkably enhanced charge separation efficiency of TiO 2 was obtained due to the synergistic effect of electron-conducting GR sheets and plasmonic AuNPs. Compared with bare TiO 2 and GR-TiO 2 , the as-prepared (AuNPs) 2 /GR-TiO 2 showed significantly enhanced photocurrent intensity (6-fold of bare TiO 2 and 3-fold of GR-TiO 2 ). A sandwich thrombin photoelectrochemical aptasensor was fabricated by using (AuNPs) 2 /GR-TiO 2 immobilized aptamer 1 as the capture probe and graphene oxide, horseradish peroxidase (HRP), and AuNPs triple-labeled aptamer 2 (GO-HRP-AuNPs-apt 2) as the detection probe. On the basis of HRP catalyzed oxidation of 4-chloro-1-naphthol by H 2 O 2 to yield an insulating product on the transducer surface that obstructs the electron transfer of the electron donor (ascorbic acid) to the electrode surface, the detection of thrombin can be carried out by the decrement of photocurrent intensity. The covalent immobilization of HRP on GO can effectively improve the HRP enzyme loading and thus the sensitivity of the sensor. Under the optimum conditions, a linear response was obtained over the range of 0.05–110 pM, with a limit of detection (LOD) of 0.02 pM ( S / N  = 3). The sensor was successfully used for detection of thrombin in serum samples.