Ultrasensitive photoelectrochemical aptasensor for diclofenac sodium based on surface-modified TiO 2 -FeVO 4 composite
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RESEARCH PAPER
Ultrasensitive photoelectrochemical aptasensor for diclofenac sodium based on surface-modified TiO2-FeVO4 composite Liwei Yang 1 & Lele Li 1 & Fen Li 1 & Hejie Zheng 1 & Tongtong Li 1 & Xiaoqiang Liu 1 & Jichun Zhu 2 & Yanmei Zhou 1 & Subbiah Alwarappan 3 Received: 24 August 2020 / Revised: 28 September 2020 / Accepted: 5 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Herein, a photoelectrochemical (PEC) aptasensing platform was designed by integrating surface oxygen vacancy (OV) defects, Ti3+ self-doping, the heterojunction, and resonance energy transfer (RET) effect into one platform for the detection of diclofenac sodium (DCF). Briefly, OV defects were introduced on TiO2 nanospheres with simultaneous Ti3+ self-doping, followed by a well-separated deposition of FeVO4 nanoparticles on TiO2 to obtain a Ti3+-O-TiO2/FeVO4 heterojunction. The surface modification of OVs, Ti3+ doping, and deposition of FeVO4 were confirmed by SEM, XPS, EPR, DRS, and PEC measurements. The surface OVs and doping of Ti3+ species created a new donor (defect) energy level under the conduction band of TiO2, which minimized the bandgap and thereby improved the visible light absorption of TiO2. Moreover, the capture of photo-excited electrons by surface OVs could hinder the electron-hole recombination. Due to the intimate surface contact and perfect energy matching between TiO2 and FeVO4, the formation of heterojunction decreased the bandgap and facilitated the electron-hole separation of TiO2. All these above events contributed to the enhancement of the PEC signals, which were then quenched by the RET effect between Ti3+-O-TiO2/FeVO4 and Au nanoparticle (AuNP)–labeled cDNA that had been attached to its complementary DCF aptamer on Ti3+-O-TiO2/FeVO4|ITO. The addition of target-DCF detached AuNP-labeled cDNA from the electrode to recover the photocurrent, resulting in a “signal-on” PEC aptasensor that exhibited a 0.1–500-nM linear range and a detection limit of 0.069 nM for DCF, attributed to the excellent amplification of the proposed aptasensing platform. Keywords Ti 3+ self-doping . Oxygen vacancy . Ti 3+ -O-TiO 2 /FeVO 4 heterojunction . Resonance energy transfer . Photoelectrochemical aptasensor
Introduction Liwei Yang and Lele Li contributed equally to this work. * Xiaoqiang Liu [email protected] * Jichun Zhu [email protected] * Subbiah Alwarappan [email protected] 1
Henan Joint International Research Laboratory of Environmental Pollution Control Materials, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, China
2
Miami College of Henan University, Kaifeng 475004, Henan, China
3
CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630003, India
With the rapid advancements in nanotechnology [1–3], several semiconductor nanostructures, especially TiO2-based heterojunctions were employed for the design of highly efficient PEC biosensors due to their strong photoelectric conversion capability, large surface area, superior bioco
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