title: Electrochemical immunosensor for detection of epidermal growth factor reaching lower detection limit: toward oxidized glutathione as a more efficient blocking reagent for the antibody functionalized silver nanoparticles and antigen interaction.
abstract: Blocking reagent is of vital importance for an immunosensor because it ensures the antifouling of the sensing interface and thus selective determination of the target. This Letter investigates a small inactive peptide, oxidized glutathione (GSSG), to replace the commonly used bovine serum albumin (BSA) as blocking reagent for immunosensor fabrication to lower the detection limit of electrochemical immunosensors. The EGF (epidermal growth factor) detection as an example is used here to compare the blocking effects from GSSG and BSA, respectively. The relatively big size of BSA sterically hinders EGF and antibody functionalized silver nanoparticles (Ab-AgNPs) binding. By comparison, GSSG cannot hinder EGF and Ab-AgNPs binding since it is much smaller than EGF, verified by scanning electron microscopy (SEM) results. The established GSSG blocking-based immunosensor for EGF reaches a very low detection limit of 0.01 pM, exhibits wide linearity range between 0.1 pM and 0.1 μM and is more sensitive than the BSA blocking strategy. The proposed GSSG-blocking strategy in the immunoassay paves an attractive platform for other biomolecules to reach a lower detection limit.
authors.affiliation: †Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Lin
authors.affiliation: †Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Kangyu
authors.initials: K
authors.lastname: Liu
authors.affiliation: †Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: †Department of Chemistry, Capital Normal University, Beijing 100048, China.|‡College of Resources Environment and Tourism, Capital Normal University, Beijing 100048, China.
authors.forename: Linbo
authors.initials: L
authors.lastname: Li
authors.affiliation: †Department of Chemistry, Capital Normal University, Beijing 100048, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D000941:Antigens / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D055664:Electrochemical Techniques; D004815:Epidermal Growth Factor / Q000032:analysis*; D005978:Glutathione / Q000737:chemistry*; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012834:Silver / Q000737:chemistry*
chemical_list: D055910:Antibodies, Immobilized; D000941:Antigens; D012710:Serum Albumin, Bovine; D012834:Silver; D004815:Epidermal Growth Factor; D005978:Glutathione