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Abstract An electrochemical immunosensor for ultrasensitive detection of acrylamide (AA) in water and food samples was developed. SnO 2 -SiC hollow sphere nanochains with high surface area and gold nanoparticles with good electroconductivity were fabricated onto the surface of a glassy carbon electrode pre-coated with chitosan. The coating antigen (AA-4-mercaptophenylacetic acid-ovalbumin conjugate, AA-4-MPA-OVA) was immobilized on the electrode. Polyclonal antibody specific for AA-4-MPA was conjugated to gold nanorod (AuNR) as primary antibody (AuNR-Ab 1). Horseradish peroxidase labelled anti-rabbit antibody produced in goat was conjugated to AuNR as secondary antibody (HRP-AuNR-Ab 2). For detection, the analyte (AA-4-MPA) in sample competed with coating antigen for binding with AuNR-Ab 1. After washing, HRP-AuNR-Ab 2 was added to capture the AuNR-Ab 1 , and the electrical signal was obtained by addition of hydroquinone and H 2 O 2. After investigation of the binding ability on nanomaterials and optimization of competitive immunoassay conditions, the proposed immunosensor exhibited a sensitive response to AA with a detection limit of 45.9 ± 2.7 ng kg−1, and working range of 187 ± 12.3 ng kg−1 to 104 ± 8.2 μg kg−1 for drinking water samples. Recoveries of AA from spiked samples were ranged from 86.0% to 115.0%. The specificity, repeatability and stability of the immunosensor were also proved to be acceptable, indicating its potential application in AA monitoring. Graphical abstract Image 1 Highlights • An electrochemical immunosensor capable of detecting acrylamide sensitively and selectively was developed. • Signal amplification strategy based on chitosan/SnO2-SiC HSNC/gold nanomaterials was used. • The immunosensor was able to detect acrylamide with a LOD of 45.9 ± 2.7 ng kg−1 for drink water samples. [ABSTRACT FROM AUTHOR]

Progesterone (P4) is a kind of hormone that can cause neuropathic disturbances in humans when the concentration overpasses a certain degree. In this work, an electrochemical immunosensor capable of detecting P4 sensitively and selectively was developed. Thionine-graphene oxide (Thi-GO) composites with excellent biocompatibility were synthesized and coated to a clear glassy carbon electrode. P4 coating antigen (P4-OVA) was immobilized to the electrode, then sample as well as biotinylated antibody (biotin-P4 Ab) were added. The free P4 can compete with P4-OVA for binding to biotin-P4 Ab. After the further addition of streptavidin-HRP, H 2 O 2 was introduced to develop electrical signal for quantitative determination of P4. After careful optimization of assay conditions, the proposed immunosensor showed a linear range from 0.02 to 20ngmL −1 for P4 in milk samples. The averaged recoveries from spiked samples ranged from 84.0% to 102.0%, which correlated well with standard HPLC-MS/MS. The biosensor also showed good specificity, reproducibility and stability, indicating its potential application in monitoring of P4 in a simple and low cost manner. [ABSTRACT FROM AUTHOR]