Hollow TiO2 modified reduced graphene oxide microspheres encapsulating hemoglobin for a mediator-free biosensor

Abstract

Hollow TiO modified reduced graphene oxide microspheres (hollow TiO-rGO microspheres or H-TiO-rGO MS) have been synthesized and then be used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of hollow TiO-rGO microspheres were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Results of spectroscopy and electrochemistry tests revealed that hollow TiO-rGO microsphere is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. The hollow TiO-rGO microspheres with special structure and component enhance the immobilization efficiency of proteins and facilitate the direct electron transfer, which result in the better HO detection performance-the wide linear range of 0.1-360μM for HO (sensitivity of 417.6 μA mM cm) and the extremely low detection limit of 10nM for HO. Moreover, the hollow microsphere can provide a protective microenvironment for Hb to make the as-prepared biosensor improve long-term stability. The as-prepared biosensor retains 95.4% of the initial response to HO after 60-d storage. Hence, this work suggests that if can be fabricated a mediator-free biosensor, hollow TiO-rGO microspheres will find wide potential applications in environmental analysis and biomedical detection.

Carbon Nanomaterials as Versatile Platforms for Biosensing Applications

“…GR nanocomposites with inorganic nanostructures [ 76 , 77 , 78 , 79 ], conducting polymers [ 80 , 81 , 82 , 83 ] and organic materials [ 84 ] can enhance the analytical response of sensors and biosensors, mainly improving their sensitivity, limit of detection, and reproducibility of electrochemical biosensors for the detection of biomolecules. Functionalized GR/reduced GO (rGO) with a variety of materials, iridium oxide [ 85 ], Au nanostructures [ 86 , 87 , 88 , 89 ], AgNP [ 90 , 91 ], FeNP [ 92 ], PtNPs [ 93 , 94 , 95 , 96 ], Pd–Pt NPs [ 97 , 98 ], TiO 2 NPs [ 99 , 100 ], CuO 2 NPs [ 101 ], ZrO 2 NPs [ 102 ], or CNTs [ 103 ], have been used as electrochemical biosensors for enhancing the electron transfer property between electrode substrates and enzymes.…”

Graphene-based bioelectrochemistry and bioelectronics: A concept for the future?

“…The examples of graphene based electrochemical and electrical based biosensors are countless and vary not only in the way the graphene based interface is used, but also in the manner electrical or electrochemical read out is achieved ( Table 1). [31] CA: chronoamperometry; CEA: carcinoembryonic antigen; DPV: differential pulse voltammetry; ESI: Electrochemical impedance spectroscopy; EPD: electrophoretic deposition; FAB: folic acid protein; G: pristine graphene, PA: 1-pyrenebutyric acid, PASE: 1-pyrenebutanoic acid succinimidyl ester, prGO: porous reduced graphene oxide, PSA: prostate specific-antigen; rGO: reduced graphene oxide; SNP: single nucleotide polymorphism; SWP: single sweep potential.…”

Water on Graphene-Coated TiO2: Role of Atomic Vacancies

“… 8 − 10 On one hand, graphene can act as an electron acceptor to effectively hinder the electron–hole pair recombination upon UV irradiation of TiO 2 ; 8 , 9 , 11 , 15 − 18 on the other, if TiO 2 –graphene nanocomposites are exposed to visible light, graphene can act as sensitizer with electrons being photoexcited within the graphene states and then eventually trapped by Ti atoms, after direct transfer to the TiO 2 conduction band. 10 , 19 , 20 Moreover, graphene-coated TiO 2 nanoparticles exhibit great applications in lithium-ion batteries, 21 − 23 in biosensors, 24 and are also rather promising in the field of nanomedicine because graphene and TiO 2 have a good performance for carrying bioactive molecules 25 and for photodynamic therapy, 26 respectively.…”