Abstract: In some examples, a CSS-MBs includes a solid magnetic core, a first shell material which surrounds the solid magnetic core and a second shell material which surrounds the first shell material. The first shell material may be a protective layer. The first shell material may include an inert carbon material. The second shell material may be have surface chemistry which allows for selective interaction of the CSS-MB with certain biomolecules under various buffer conditions.

Abstract: Embodiments of the disclosure are drawn to apparatuses, systems, and methods for enrichment and separation of nucleic acids by size. A sample may include a mixture of nucleic acids of various sizes, and the nucleic acids of interest may be below a particular size threshold. An example enrichment method may include mixing the sample with a first substrate (e.g., magnetic beads). The method may include separating nucleic acids above a first size threshold form a remainder of the sample using the first substrate. The method may include mixing the nucleic acids in the remainder of the sample (e.g., nucleic acids below’ the size threshold) with a second substrate and recovering the nucleic acids below the first size threshold from the second substrate.