This work presents an effective strategy for the well-oriented immobilization of
antibodies in which
boronic acid is directly attached to the surface and with no need of the long and flexible spacer. A magnetic
graphene nanoribbon-
boronic-acid-based immunosensor was developed and tested for the impedimetric detection of
lymphoma cancer cells, a
blood cancer biomarker. Magnetic
graphene nanoribbons (MGNRs) were modified with
boronic acid (BA) to create a supporting matrix that is utilized by immobilizing anti-CD20
antibodies with good orientation. The prepared biosensing layer (MGNR/BA/Ab) with well-oriented
antibodies was premixed into whole blood samples to interact with
lymphoma cancer cell receptors. In the presence of target cell receptors, an immunocomplex was formed between anti-CD20
antibodies and
lymphoma cancer cell receptors. Then, the biosensing layer was magnetically collected on a screen-printed
carbon electrode (SPCE) and placed in a homemade electrochemical cell configuration to measure impedimetric signals. The fabrication steps of the immunosensor were characterized by various techniques, such as resonance light scattering, fluorescence, electrochemical impedance spectroscopy, and cyclic voltammetry. The assay is highly sensitive: the calculated limit of detection of
lymphoma cancer cells was as low as 38 cells/mL, and the detection was linear from 100 to 1 000 000 cells/mL. The specificity of the immunosensor is also very high, and there is no interference effect with several potential interferents, such as the
breast cancer (MCF-7), human embryonic kidney (HEK293), and
leukemia (HL-60 and KCL-22) cell lines. The performance of the immunosensor for
lymphoma cancer cells in clinical blood samples is consistent with that of commercial flow cytometric assays.