• Abstract The classical way to modify a gold electrode surface for immunosensor development is through self-assembly of functionalised thiols for subsequent attachment of antibodies. Here is described a new pathway for surface modification using a diazonium salt-based immunosensor for detection of methotrexate (MTX) with electrochemical immittance spectroscopy (EIS). The diazonium salt, 4-carboxybenzenediazonium tetrafluoroborate was synthesized using a diazotization reaction and characterized by IR and cyclic voltammetry (CV). The Au electrode was electrografted with diazonium and used for anti-MTX antibody immobilization. The EIS detection of MTX was studied with and without application of redox probe; Fe(CN)63−/4−. MTX could not be detected using Fe(CN)63−/4−as redox probe, whereas EIS measurements without redox probe and analysis of the data with singular decomposition (SVD) gave good results. A multivariate calibration model showed good linear behavior on a logarithmic scale with a detection limit for MTX of 7×10−12molL−1.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

Nyckelord

4-carboxybenzenediazonium tetrafluoroborate

Gold electrode

Antibody

Immunosensor

Singular value decomposition

Cyclic voltammetry

Chronoamperometry

Electrochemical impedance spectroscopy

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