Optical and photoelectrochemical sensing of glucose based on Au nanohole arrays coupled with TiO2/Al films

Abstract

The mainstream technology used in commercial glucose sensors is enzymatic electrochemical sensing. Although the use of enzymatic electrodes can specifically detect glucose, this sensor has many deficiencies such as large environmental impacts, complex enzyme-modification processes and relatively high cost. Constructing well-designed metal nanostructures can excite environment-dependent surface plasmon resonance (SPR) and generate hot electrons. By monitoring the central wavelength shift of SPR and collecting the photocurrent generated from the hot electrons, labelfree, enzyme-free, optical and photoelectrochemical (PEC) dual-mode sensing of glucose can be realized. Here, we combine magnetron sputtering, thermal treatment, nanosphere lithography, electron beam evaporation and lift-off processes to fabricate hexagonally-arranged gold nanohole arrays (Au NHAs) with adjustable diameters on aluminum (Al)/titanium dioxide (TiO2) film substrates, and constructed an enzyme-free glucose sensor based on the Al/TiO2/Au NHAs structure. The sensor is demonstrated to work in both optical sensing and PEC sensing modes. For optical sensing mode, the shift of the SPR peak corresponding to the glucose concentration range of 0-10 mM is observed, with an optical sensing sensitivity of 857 nm/RIU. For PEC sensing mode, the sensor at zero bias shows a linear range of 1 M-10 mM for glucose detection under simulated one-sun illumination, along with the detection of limit down to 1 M and the photocurrent sensing sensitivity of 0.53×logC A μM -1 cm -2 (where C is the molar concentration of glucose). Furthermore, the as-prepared glucose sensor also shows good stability and specific selection for glucose detection.