title: A novel photoelectrochemical immunosensor by integration of nanobody and TiO₂ nanotubes for sensitive detection of serum cystatin C.
abstract: Cystatin C (CysC) is a sensitive marker for the estimation of the glomerular filtration rate and the clinical diagnosis of different diseases. In this paper, CysC-specific nanobodies (Nbs) were isolated from a phage display nanobody library. A simple and sensitive photoelectrochemical immunosensor based on TiO2 nanotube arrays (TNAs) was proposed for the sensitive detection of CysC. The TiO2 nanotube arrays deposited by electrochemical anodization displayed a high and stable photocurrent response under irradiation. After coupling CysC-specific nanobody to TNA (Nb/TNA), the proposed immunosensor for CysC can be utilized for tracking the photocurrent change of Nb/TNA caused by immunoreactions between CysC and the immobilized CysC-specific Nb. This allowed for the determination of CysC with a calibration range from 0.72 pM to 7.19 nM. The variation of the photocurrent was in a linear relationship with the logarithm of the CysC concentration in the range of 0.72 pM-3.6 nM. The immunosensor had a correlation coefficient of 0.97 and a detection limit of 0.14 pM at a signal-to-noise ratio of 3. The proposed immunosensor showed satisfactory intra- and inter-assay accuracy, high selectivity and good stability. As a result, this proposed strategy would offer a novel and simple approach for the detection of immunoreactions, provide new insights in popularizing the diagnosis of CysC, and extend the application of TiO2 nanotubes.
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Mi
authors.affiliation: Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China.
authors.forename: Pingyan
authors.initials: P
authors.lastname: Wang
authors.affiliation: Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China.
authors.forename: Junrong
authors.initials: J
authors.lastname: Yan
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Jusheng
authors.initials: J
authors.lastname: Lu
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Jiachao
authors.initials: J
authors.lastname: Yu
authors.affiliation: Plexera LLC, WA 98072, USA.
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Plexera LLC, WA 98072, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China; Jiangsu Nanobody Engineering and Research Center, Nantong 226010, People's Republic of China. Electronic address: ywansystemsbiology@gmail.com.
authors.forename: Yakun
authors.initials: Y
authors.lastname: Wan
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China. Electronic address: liusq@seu.edu.cn.
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D015374:Biosensing Techniques; D055316:Cystatin C / Q000097:blood*; D004563:Electrochemistry; D006801:Humans; D057230:Limit of Detection; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes; D010777:Photochemistry; D061905:Single-Domain Antibodies; D020349:Surface Plasmon Resonance; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D055316:Cystatin C; D061905:Single-Domain Antibodies; C009495:titanium dioxide; D014025:Titanium
keywords: Covalence; Cystatin C; Nanobody; Photoelectrochemical immunosensor; TiO(2) nanotube arrays