Readiness of Magnetic Nanobiosensors for Point-of-Care Commercialization

Nanobiosensors contribute to point-of-care (POC) efforts to make routine biodiagnostics more accessible to patients with respect to both expense and convenience. However, devices whose operation is based on magnetic phenomena appear delayed in their progress toward POC commercialization despite their promise of better sensitivity, as compared to devices based on optical, mechanical, or electrochemical phenomena. This review aims to elucidate the technical challenges preventing magnetic nanobiosensors from reaching market readiness. The following types of magnetic nanobiosensor operation are reviewed: giant magnetic impedance (GMI), superconducting quantum interference device (SQUID), anisotropic magnetoresistance, giant magnetoresistance (GMR), resonant coil, Hall effect, and microcantilever. In particular, a careful comparison of each type in terms of their advantages, disadvantages, recently overcome challenges, and sensitivities will be presented. For example, a disadvantage of GMI sensors, and certain others reviewed here, is the fact that ferromagnetic materials used in their construction directly impact the biosensing event since magnetic nanoparticle (MNP) labels are involved in the strategy. Other challenges associated with use of MNP labels will be addressed. Furthermore, some of the more interesting state-of-the-art magnetic nanobiosensor efforts will be discussed in order to provide an overview of target analytes and sample media under consideration. This review identifies GMR sensors as poised to dominate the market owing to their good sensitivity and ease of use. On the other hand, SQUID sensors, at their current stage of development, are revealed as unsuitable for POC applications due to their high operational cost and unwieldy instrumentation. Magnetics experts endeavoring to progress the field toward commercialization will find this review indispensable.