Scanning electron micrographs of untreated glass, aminosilane-treated glass, and HA4mer-tethered glass. Glass surfaces appear mostly smooth with occasional spots that are owed to commercial plasma coating (A). Glass surfaces treated with the aminosilane show the presence of APTMS molecules (B). Panel (C) shows aminated surfaces further reacted with enzymatic digests of long-chain HA, containing primarily HA4 (75% w/w). Panels D-F show atomic force micrographs and corresponding peak heights of uncoated glass (D), APTMS (E), and HA4-tethered (F) surfaces. As seen, the HA4mers reacted uniformly across the surface. Magnification: 1500× (A and B) and 900× (C).