Kottenbrock Kenzington L, Reis Sierra, Agarwal Gunjan, Oberdick Samuel D
Biomedical Engineering Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States.
Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States.
ACS Appl Nano Mater. 2025 Jun 5;8(24):12574-12582. doi: 10.1021/acsanm.5c01383. eCollection 2025 Jun 20.
Magnetic force microscopy (MFM) was used to characterize micropatterned clusters of superparamagnetic iron oxide nanoparticles (SPIONs). Top-down lithography was used to create SPION aggregates with well-defined geometries. The micrometer-scale aggregates exhibited different properties from individual particles and from smaller clusters containing just a few particles. The MFM phase shift from magnetic interactions between the sample and probe tip could be detected at lift heights of several hundred nanometers. The experimental data was compared to a magnetic dipole-dipole interaction model to understand the relationship between MFM phase shift and lift height. Magnetic interactions between the probe tip and the sample also led to an apparent "ballooning" of the feature size, where the aggregates appeared larger with MFM than their physical size obtained from scanning electron microscopy. These results can guide emerging applications of MFM, such as the detection of SPIONs within biological environments.
磁力显微镜（MFM）用于表征超顺磁性氧化铁纳米颗粒（SPIONs）的微图案化簇。采用自上而下的光刻技术来制造具有明确几何形状的SPION聚集体。微米级聚集体表现出与单个颗粒以及仅包含少数颗粒的较小簇不同 的特性。在几百纳米的提升高度下，可以检测到样品与探针尖端之间磁相互作用产生的MFM相移。将实验数据与磁偶极-偶极相互作用模型进行比较，以了解MFM相移与提升高度之间的关系。探针尖端与样品之间的磁相互作用还导致特征尺寸出现明显的“膨胀”，即MFM下聚集体看起来比扫描电子显微镜获得的实际尺寸更大。这些结果可以指导MFM的新兴应用，例如在生物环境中检测SPIONs。
