Review—Potential of Tunneling Magnetoresistance Coupled to Iron Oxide Nanoparticles as a Novel Transducer for Biosensors-on-Chip

Biosensors-on-chip (BoC), compact and affordable public diagnostic devices, are vital for preventing health crises caused by viral and bacterial mutations, climate change, and poor diets. Clinical, remote, and field use are possible with these devices. BoC is used in food safety, environmental monitoring, and medical diagnosis. The coupling of tunneling magnetoresistance (TMR) sensing elements in chip form with surface functionalized iron oxide nanoparticles (IONPs) as a biomarker, known as TMR/ IONPs, allows BoC devices to be made. The functional framework of BoC based on TMR/ IONPs, the instrument system, and biomolecule immobilization will be covered in this review. This review aims to overview the recent research on a biosensor using TMR technology with IONPs biomarkers and discuss its future advances in point-of-care diagnostics. TMR sensors have revolutionized low-magnetic field sensing technologies, yet biosensing faces challenges. However, it’s important to recognize that TMR sensors exclusively utilize out-of-plane connections. that creates a larger separation between biomolecules and the sensing layer, leading to a decrease in the sensitivity of biomolecules. Large magnetization of dispersed IONPs to generate sufficient stray-field, compact and inexpensive instrumentation to sense the low voltage yielded by the TMR/IONPs system, and high-selectivity bio-analyte immobilization to the surface of IONPs to increase sensor sensitivity are the notable issues to address this problem. The utilization of the green synthesized method in producing IONPs for magnetic labeling can enhance the sensitivity of a TMR-based biosensor. This is achieved through the formation of IONPs with a capping agent on its surface that inhibits the aggregation and facilitates the immobilization of the biomolecule target. Additionally, improving device performance requires creating high-TMR materials. Despite challenges, research and technological advances hold great promise for TMR/GS-IONP bio-applications.