New Titanium Dioxide-Based Heterojunction Nanohybrid for Highly Selective Photoelectrochemical Electrochemical Dual-Mode Sensors

A new titanium dioxide (TiO2)-based heterojunction nanohybrid (HJNH) composed of TiO2, graphene (G), poly[3-aminophenylboronic acid] (PAPBA), and gold nanoparticles (Au NPs) was synthesized and designated as TiO2(G) NW@PAPBA-Au HJNH. The TiO2(G) NW@ PAPBA-Au HJNH possesses dual-mode signal photoelectrochemical (PEC) and electrochemical transduction capabilities to sense glucose and glycated hemoglobin (HbAlc) independently. The synthesis of the HJNH material involved 1GAu 11) NIMP two sequential stages: (i) simple electrospinning synthesis of 1%-3111 APH 4. G-embedded TiO2 nanowires [TiO2(G) NWs] and (ii) onestep synthesis of Au NP-dispersed PAPBA nanocomposite (NC) in the presence of TiO2(G) NWs. The as-synthesized TiO2(G) NW@PAPBA-Au HJNH was characterized by field emission scanning electron microscopy, field emission transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, thermogravimetric analysis, and UV-visible diffuse reflectance spectroscopy. A PEC platform was developed with TiO2(G) NW@PAPBA-Au HJNH for the selective detection of glucose without any enzyme auxiliary. The PEC glucose sensor presents an acceptable linear range (from 0.5 to 28 mM), good sensitivity (549.58 mu A mM(-1) cm(-2)), and low detection limit (0.11 mM), which are suited for diabetes glucose monitoring. Besides, the boronic acid groups in PAPBA were utilized as a host to capture HbAlc. We fabricated the electrochemical HbAlc sensor based on monitoring the electrocatalytic reduction current of hydrogen peroxide produced by HbAlc tethered to the sensor probe. The amperometric electrochemical sensor for HbAlc exhibited linear responses to HbAlc levels from 2.0 to 10% (with a detection limit of 0.17%). Notably, the performances of the fabricated glucose and HbAlc sensors are superior in the dual-signal transduction modes as compared to the literature, suggesting the significance of the newly designed bifunctional TiO2(G) NW@PAPBA-Au HJNH.