title: Surface plasmon resonance enhanced real-time photoelectrochemical protein sensing by gold nanoparticle-decorated TiO₂ nanowires.
abstract: Recently developed photoelectrochemical (PEC) sensing systems represent a unique potential detection method for real-time analysis of chemical/biological molecules, while the low absorption of TiO2 nanomaterials in the visible wavelength region and the slow surface charge transfer efficiency limit the ultimate sensitivity. Here we develop a gold nanoparticle-decorated TiO2 nanowire sensor for PEC detection of protein binding. The direct attachment of Au nanoparticles to TiO2 nanowires offers strong surface plasmon resonance for electrochemical field effect amplification, yielding a ~100% increase of photocurrent density. In addition, the surface functionalization of gold nanoparticles allows for direct capturing of target proteins near the Au/TiO2 interface and thus substantially enhances the capability of attenuation of energy coupling between Au and TiO2, leading to much-improved sensor performance. As a proof of concept, cholera toxin subunit B has been robustly detected by the TiO2-Au nanowire sensor functionalized with ganglioside GM1, with a high sensitivity of 0.167 nM and excellent selectivity. Furthermore, the real-time feature of photoelectrochemical sensing enables direct measurement of binding kinetics between cholera toxin subunit B and GM1, yielding association and disassociation rate constants and an equilibrium constant K(d) of 4.17 nM. This surface plasmon resonance-enhanced real-time, photoelectrochemical sensing design may lead to exciting biodetection capabilities with high sensitivity and real-time kinetic studies.
authors.affiliation: Laboratory of Advanced Materials, Department of Chemistry, Fudan University , Shanghai 200433, People's Republic of China.
authors.forename: Peimei
authors.initials: P
authors.lastname: Da
authors.forename: Wenjie
authors.initials: W
authors.lastname: Li
authors.forename: Xuan
authors.initials: X
authors.lastname: Lin
authors.forename: Yongcheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Tang
authors.forename: Gengfeng
authors.initials: G
authors.lastname: Zheng
mesh_terms: D002772:Cholera Toxin / Q000032:analysis* / Q000378:metabolism; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005677:G(M1) Ganglioside / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry*; D053770:Nanowires / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods*; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D005677:G(M1) Ganglioside; D006046:Gold; D002772:Cholera Toxin; D014025:Titanium