Developing enhanced magnetoimmunosensors based on low-cost screen-printed electrode devices

Electrochemical magnetoimmunosensors combine a number of issues that guarantee extremely high performance and also compatibility with the study of complex sample matrices. First, analyte immunocapture exploits the high affinity and specificity of antibodies. Second, magnetic particles (MP) provide faster and more efficient immunocapture than binding on two-dimensional structures, separation from nontarget sample components, and concentration of the target analyte. Finally, electrochemical detection supplies sensitivity and fast signal generation using robust and potentially miniaturized measurement equipment and transducers. On the contrary, MP handling is slightly more complex for end-users and more difficult to integrate in point-of-care devices than the manipulation of a classical biosensor. Attempts have been made to automate immunomagnetic binding, and the first robotized systems and platforms for the fluorescent and spectrophotometric detection of magnetoimmunoassays have already reached the market. Among the different types of electrodes available, screen-printed electrodes (SPE) stand out because of their low production cost and yet acceptable performance and interdevice reproducibility, which make them an excellent choice for analytical applications. In addition, each SPE entails a whole electrochemical cell stamped on a planar physical substrate, which makes it possible detection in small volumes and is especially favorable for the magnetic confinement of MP and the integration of microfluidic structures. In this article, we discuss the advantages obtained by using SPE and MP for the production of electrochemical magnetoimmunosensors and the clues for the successful development of such devices. We then revise some of the most outstanding works published in the literature.