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Herein we designed a novel photoelectrochemical sensing platform based on Fe 3+ doped ZnO-Ag photocatalyst (Fe 3+ /ZnO-Ag) for ultrasensitive Hg 2+ detection by using exonuclease III-assisted target recycling and DNAzyme-catalyzed amplification. Firstly, Fe 3+ /ZnO-Ag was synthesized to provide photocurrent under visible light irradiation. Secondly, target Hg 2+ was determined by hairpin DNA probes on the Fe 3+ /ZnO-Ag modified ITO based on T-Hg 2+ -T, and then Hg 2+ was released by the digestion of exonuclease III to double-stranded DNA. Finally, the photocurrent markedly decreased due to catalysis of hemin/G-quadruplex toward 4-chloro-1-naphthol. Under optimal conditions, the photocurrents were linearly related to Hg 2+ concentrations form 0. 5 nM to 100 nM with a detection limit of 0. 1 nM at the 3 S blank criterion. More importantly, the developed biosensor exhibited good selectivity, repeatability, and stability, meanwhile, this analysis platform held great potential for testing real water samples in future. [ABSTRACT FROM AUTHOR]

Abstract: A simple sensor for simultaneous measurement of refractive index and temperature in solutions based on fiber Bragg grating (FBG) is proposed. The sensor contains only a normal FBG with a pigtail fiber. When the FBG is immersed in different liquids of refractive index, the side mode suppression ratio of the FBG varies due to the Fresnel reflection of the pigtail fiber. The sensor is also capable of simultaneous measurement refractive index and temperature combining the thermo-optic effect of the FBG. Its ease of fabrication and low-cost offer the attractive applications in chemical and biological sensing. [Copyright &y& Elsevier]