Multimode ns3a atomic force microscope

The morphologies of aluminum surfaces were observed by a SIRION scanning electron microscope (SEM, Tescan, Shanghai, China) and a Multimode NS3a atomic force microscope (AFM, Veeco, Town of Oyster Bay, NY, USA), respectively. Contact angles and sliding angles were measured by a DSA100 optical contact angle meter (Kruss, Hamburg, Germany), using a droplet of water as an indicator. The average value of contact angles at three different positions of the sample surfaces was regarded as the final contact angle. The surface roughness was measured by a CLI2000 3D surface profiling (Taylor Hobson, Leicester, UK). The adhesive resistance was investigated by the sliding angle and the adhesive energy of aluminum alloy surfaces.

A Multimode NS-3a atomic force microscope (Veeco, Santa Barbara, CA, USA) was used to examine the morphology and microstructure of the MagNPs and MagNP-DNA complexes. The AFM samples were prepared by mixing plasmid DNA with MagNPs, incubating the mixtures for 30 min, dropping the samples onto fresh sheets of glass, and then air-drying.