biostudies-literatureUnknown16(3)Wang W<b>Rationale</b>: Early and accurate evaluation of chemotherapy efficacy remains essential, yet conventional imaging approaches rely on delayed morphological changes. Functional alterations such as apoptosis and reduced metabolic activity occur earlier but are difficult to detect noninvasively. Magnetic signal detection offers a promising alternative but is limited by signal instability and biological noise. <b>Methods</b>: We developed a magnetic signal-based monitoring platform by combining magnetically responsive ferromagnetic-superparamagnetic iron oxide nanoparticle (F-SPION) with a spin-exchange relaxation-free magnetometer, with signal amplification achieved through rubidium magnetization. <i>In vitro</i>, we assessed the linear correlation between magnetic signal intensity and tumoTheranostics1123-1142https://www.ebi.ac.uk/biostudies/studies/S-EPMC12679083biostudies-literatureHigh-sensitivity spin-exchange relaxation-free (SERF) magnetometry combined with magnetic-responsive iron oxide nanoparticles for real-time monitoring of malignant tumor therapy.PMC12679083Zhang GDuan JYu MWang BDing NZheng SYu DXiang MHuang ZCheng QZhou DWang WChen YfalseHigh-sensitivity spin-exchange relaxation-free (SERF) magnetometry combined with magnetic-responsive iron oxide nanoparticles for real-time monitoring of malignant tumor therapy.<b>Rationale</b>: Early and accurate evaluation of chemotherapy efficacy remains essential, yet conventional imaging approaches rely on delayed morphological changes. Functional alterations such as apoptosis and reduced metabolic activity occur earlier but are difficult to detect noninvasively. Magnetic signal detection offers a promising alternative but is limited by signal instability and biological noise. <b>Methods</b>: We developed a magnetic signal-based monitoring platform by combining magnetically responsive ferromagnetic-superparamagnetic iron oxide nanoparticle (F-SPION) with a spin-exchange relaxation-free magnetometer, with signal amplification achieved through rubidium magnetization. <i>In vitro</i>, we assessed the linear correlation between magnetic signal intensity and tumo2026-01-01T00:00:00Z20262026-06-06T08:26:05.357Z2026-05-27T03:12:11.986ZS-EPMC126790834135596710.7150/thno.117893