High-sensitive photometric microplate assay for tumor necrosis factor-alpha based on Fe@BC nanozyme.

Abstract Optical immunoassay for the detection of protein biomarker tumor necrosis factor-α (TNF-α) is reported based on core–shell Fe@BC structure nanozyme as label. The nanozyme is composed of Fe nanoparticles as core and carbon layer as shell with element B doped into the carbon shell. The nanozyme displays good peroxidase-like activity that can oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to oxTMB in the presence of H2O2, generating blue colored compound. The detection of TNF-α was following the ELISA protocol by replacing traditional enzyme horseradish peroxidase (HRP) with nanozyme Fe@BC. The assay can be finished by about 2 h and has wide linear range for TNF-α from 5 pg/mL to 1 ng/mL with limit of detection of 2 pg/mL. The assay was applied for the detection of TNF-α in human serum samples with detection results comparable to commercial ELISA.