Physical Characteristics of 50 and 200 nm Magnetic Beads when Encapsulated with Branched Amphiphilic Peptides (BAP)

Branched Amphipathic Peptide Capsule Magnetic Beads (BAPC-MB) are a new nanoparticle developed for use as in diagnostic platforms. The bases are Maleimide Super Mag Magnetic Beads which are dispersed in 75% ethanol and combined with our proprietary H9Cys BAP. The result of the initial step is a magnetic bead with a monolayer of BAP which are washed to removed excess peptides through magnetic separation. The monolayer BAP magnetic beads are then dispersed with 100% tetrafluoroethylene and the H9 BAP are added and mixed with sonication. The final step is diluting the mixture to more than 85% water. This synthesis results in the formation of BAPC-MB, which exhibit a peptide bilayer BAPC surrounding the individual magnetic beads.

Magnetic beads when encapsulated with BAP have the advantage of not forming aggerates following their suspension on Lacey Transmission Electron Microscopy (TEM) grids. This allows them to avoid clumping into a large mass and be able to remain distributed for delivery to cells.

Encapsulating 50 and 200 nm magnetic beads results in BAPC-MB with final average diameters of 220 nm and 368 nm. As a reference point, the 50 nm magnetic bead has a starting size of 100 nm due to the dextran and maleimide coating on the surface of the magnetic beads.

The magnetic beads prior to BAP encapsulation have a zeta potential surface charge of -30, but when coated/encapsulated with BAP, the surface charge of the 50 and 200 nm magnetic beads are increased to +23 and + 38 mV respectively, which should increase cellular uptake.

Figure 1. Transmission Electron Microscopy (TEM) images of 50 nm and 200 nm BAPC-MB on Lacey TEM grids shows well dispersed magnetic nanobeads coated/capped with a branched amphiphilic peptide bilayer.

Figure 2