title: Label-free photoelectrochemical immunosensor for neutrophil gelatinase-associated lipocalin based on the use of nanobodies.
abstract: Acute renal failure (ARF) represents a very important and potentially devastating disorder in clinical nephrology. Neutrophil gelatinase-associated lipocalin (NGAL) is an early biomarker for ARF in a wide range of different disease processes, which is frequently detected in clinical diagnosis. Herein, we present a label-free and sensitive photoelectrochemical (PEC) immunosensor for NGAL by utilizing a biotinylated anti-NGAL Nanobody (Nb) orientedly immobilized to streptavidin-coated cobalt 2,9,16,23-tetraaminophthalocyanine (CoPc)-sensitized TiO2 electrode. The Nb was biotinylated at the C-terminus, which is situated at the opposite site of the antigen binding region. Using highly oriented Nb as receptor molecules, a label-free PEC immunosensor for NGAL was developed by monitoring the changes in the photocurrent signals of the electrode resulting from immunoreaction. Immobilization of Nb to streptavidin-coated CoPc-sensitized TiO2 electrode surface provides high binding capacity to NGAL; thus, it can lead to a high sensitivity. The limit of detection (LOD) of the proposed immunosensor has been significantly lowered to 0.6 pg mL(-1). This proposed immunosensor reveals high specificity to detect NGAL, with acceptable intra-assay precision and excellent stability. In addition, the present work provides a new approach to design Nb-based PEC immunosensor and increases versatility of Nbs.
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Henan
authors.initials: H
authors.lastname: Li
authors.forename: Yawen
authors.initials: Y
authors.lastname: Mu
authors.forename: Junrong
authors.initials: J
authors.lastname: Yan
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cui
authors.forename: Weijun
authors.initials: W
authors.lastname: Ou
authors.forename: Yakun
authors.initials: Y
authors.lastname: Wan
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000175:diagnosis*; D000209:Acute-Phase Proteins / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000097:blood; D002162:Camelus; D055664:Electrochemical Techniques / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D057230:Limit of Detection; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood* / Q000276:immunology; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000097:blood* / Q000276:immunology; D061905:Single-Domain Antibodies / Q000737:chemistry* / Q000276:immunology
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D061905:Single-Domain Antibodies