Enhanced detection of bovine serum albumin using single- and double-chip configuration of tunneling magnetoresistance-based biosensor with green-synthesized magnetite/Ag nanotag.

A tunneling magnetoresistance (TMR)-based biosensor is introduced that coupled with green-synthesized magnetite/Ag nanoparticles nanotag for albumin assays, using bovine serum albumin (BSA) serving as a model for human serum albumin. The performance of both single-chip and double-chip configurations of TMR sensors was assessed to improve detection performance. The TMR sensors are integrated with an Arduino microcontroller and a basic differential amplifier to provide direct and measurable digital signals. Magnetic nanoparticles were produced through green synthesis methods using Moringa oleifera extract, resulting in soft ferromagnetic properties. The sensor system exhibited good stability and linearity in detecting various concentrations of BSA under low bias magnetic fields, achieving a relative standard deviation (RSD) of less than 15% within a rapid detection time of 30 s. The double-chip configuration demonstrated higher sensitivity of 29.75 mV/(mg/mL), compared with 23.27 mV/(mg/mL) for the single-chip setup, while also achieving a low limit of detection below 1 mg/mL, consistent with typical albumin levels in blood and urine. These results indicate that the double-chip configuration in TMR biosensors is a reliable detection method showing competitive performance with green-synthesized magnetic labels under low bias conditions. This research supports the potential of this system as a prescreening tool in medical diagnostics, which may help reduce the risks of disease progression.