Determination of p53 biomarker using an electrochemical immunoassay based on layer-by-layer films with NiFe2O4 nanoparticles.

A disposable electrochemical immunosensors is presented suitable to detect cancer biomarker p53 using screen-printed carbon electrodes modified with a layer-by-layer (LbL) matrix of carboxylated NiFe2O4 nanoparticles and polyethyleneimine, onto which anti-p53 antibodies were adsorbed. Under optimized conditions, the immunosensors exhibited high surface coverage and high concentration of immobilized antibodies, which allowed for detection of p53 in a wide dynamic range from 1.0 to 10 × 103 pg mL-1, with a limit of detection of 5.0 fg mL-1 at a working potential of 100 mV vs. Ag/AgCl. The immunosensors also exhibited good selectivity with negligible interference upon incubation in complex matrices containing high concentrations of proteins (i.e., fetal bovine serum and cell lysate). The immunosensor performance is among the best reported in the literature for determination of p53, with the additional advantage of being disposable and operating with low-volume solutions.Graphical abstract Schematic representation of immunosensor fabrication depicting the immobilization of specific antibodies against p53 protein onto the surfaces of disposable printed electrodes modified with films of polyethyleneimine and different concentrations of carboxylated magnetic nanoparticles.

Screen-printed electrodes modified with carbon black and polyelectrolyte films for determination of cancer marker carbohydrate antigen 19-9.

Electrochemical immunosensors have been developed to determine the carbohydrate antigen 19-9 (CA19-9). They are based on screen-printed carbon electrodes (SPCEs) coated with layer-by-layer (LbL) films of carbon black (CB) and polyelectrolytes. Owing to a suitable choice of LbL film architecture, the procedures for immobilization of anti-CA19-9 antibodies on the electrode surfaces were straightforward. Mechanically flexible immunosensors were capable of detecting CA19-9 within a dynamic range of 0.01 to 40 U mL-1 and a limit of detection of 0.07 U mL-1 using differential pulse voltammetry. In addition to detecting CA19-9 at clinically relevant concentrations for pancreatic cancer in standard solutions, the immunosensors provide the determination of CA19-9 on cell lysate and human serum samples. Using LbL films led to immunosensors with superior performance compared to similar systems obtained by drop casting. The fabrication of this relatively simple, inexpensive platform is a demonstration that SPCEs modified with cost-effective materials are able to detect cancer biomarkers and may be adapted to other disposable immunosensors. Graphical abstract Schematic representation of assembly and characterization of electrochemical immunosensors for the determination of carbohydrate antigen 19-9 based on printed electrodes modified with composites of carbon black and polyelectrolyte films.