Poster abstracts
Poster number 31 submitted by Kevin Walsh
Multimodal Magnetic Force Microscopy
Kevin J. Walsh (The Ohio State University), Joshua Sifford (The Ohio State University), Owen Shifflet (The Ohio State University), Tong Sheng (Rice University), Gang Bao (Rice University), Gunjan Agarwal (The Ohio State University)
Abstract:
Magnetic force microscopy (MFM) is a scanning probe technique that can detect nanoscale magnetic domains in a sample. MFM employs a magnetically coated probe to track the sample topography and detect long-range magnetic forces at user defined lift heights above the sample. Although MFM is widely used in solid-state devices, there are several challenges in application of MFM for biological samples. These include contamination of the MFM probe by sticky biological materials, topological cross-talk in MFM images and incompatibility in a fluid environment.
In this study we developed two methods to overcome the limitations of MFM and make it amenable to biological samples. In our first approach, we developed a novel indirect-MFM (ID-MFM) technique to detect fluorescently labeled iron-oxide nanoparticles. In ID-MFM an ultrathin silicon-nitride window is used to create a physical barrier between the sample and the probe. The window prevents direct contact between the sample and the probe thereby eliminating probe contamination and topological cross-talk. Finally, samples prepared for ID-MFM are amenable to multi-modal analysis by fluorescence or electron microscopy.
In our second approach we analyzed rodent spleen tissue sections via conventional MFM. We elucidate how scan rate and surface roughness can impact the topological cross-talk in MFM experiments which can make it difficult to decipher magnetic iron deposits. Thin sections with minimal surface roughness can minimize the topographical cross-talk. In addition, thin sections are compatible for multimodal microscopy analysis by both conventional (direct) and ID-MFM.
Taken together our work has advanced the use of MFM for biological samples. Future work along these directions could enable MFM analysis of physiological and pathological iron deposits in tissues sections in a label-free, multimodal and high throughput manner.
References:
Sifford, J., Walsh, K. J., Tong, S., Bao, G., & Agarwal, G. (2019). Indirect magnetic force microscopy. Nanoscale Advances, 1(6), 2348–2355. https://doi.org/10.1039/C9NA00193J